Post-transplant surveillance for acute rejection and allograft vasculopathy by echocardiography: Usefulness of myocardial velocity and deformation imaging

Author’s Accepted Manuscript Post-Transplant Surveillance for Acute Rejection and Allograft Vasculopathy by Echocardiography: Usefulness of Myocardial Velocity and Deformation ImagingCardiac Allograft Wall Motion and Myocardial Deformation Michael Dandel, Roland Hetzer http://www.jhltonline.org

PII: DOI: Reference:

S1053-2498(16)30345-X http://dx.doi.org/10.1016/j.healun.2016.09.016 HEALUN6380

To appear in: Journal of Heart and Lung Transplantation Received date: 6 May 2016 Revised date: 27 September 2016 Accepted date: 28 September 2016 Cite this article as: Michael Dandel and Roland Hetzer, Post-Transplant Surveillance for Acute Rejection and Allograft Vasculopathy by Echocardiography: Usefulness of Myocardial Velocity and Deformation ImagingCardiac Allograft Wall Motion and Myocardial Deformation, Journal of Heart and Lung Transplantation, http://dx.doi.org/10.1016/j.healun.2016.09.016 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Post-Transplant Surveillance for Acute Rejection and Allograft Vasculopathy by Echocardiography: Usefulness of Myocardial Velocity and Deformation Imaging Short title: Cardiac Allograft Wall Motion and Myocardial Deformation Michael Dandel MD, PhD1,2 ; Roland Hetzer MD, PhD2,3 1

German Centre for Cardiovascular Research (DZHK), Partner site Berlin, Germany

2

Deutsches Herzzentrum Berlin, Germany

3

Cardio Centrum Berlin, Germany

Key Words:

 transplantation echocardiography  myocardial function   rejection coronary disease Correspondence Address: Michael Dandel MD,PhD; Deutsches Herzzentrum Berlin, Augustenburger Platz 1, 13353 Berlin, Germany Telephone: ++4930-8224210; Fax: ++4930-8224210 E-mail [email protected]

Abstract Diagnosing and monitoring acute rejection (AR) and cardiac allograft vasculopathy (CAV) is essential for graft and transplanted patient survival and consequently also a major objective for heart-transplanted patient surveillance. Because functionally relevant CAV can arise and progress without clinical symptoms and subclinical ARs can facilitate the development of CAV, standard surveillance of AR and CAV includes routine endomyocardial biopsy (EMB) and coronary angiography (CA) screenings at predefined time intervals. However, these invasive screenings (distressing and risky for the patients) cannot solely diagnose all subclinical AR episodes and also not always detect coronary stenoses prior to a clinical event. Additional close-meshed non-invasive AR and CAV surveillance strategies are therefore mandatory. After the introduction of tissue-Doppler imaging (TDI) and strain imaging for myocardial wall motion and deformation analysis, echocardiography became particularly promising for that purpose. Allowing quantification of minor myocardial dysfunction not detectable by standard echocardiography, TDI and strain imaging can reveal subclinical AR. Thus, they can be a powerful supplement to EMB enabling more efficient AR-monitoring with fewer EMBs (only diagnostic EMBs) instead of unnecessary and distressing routine EMB-screenings. They can also improve therapeutic decisions and monitoring of myocardial function during anti-rejection therapy. Myocardial velocity and deformation imaging is also suited for early detection of myocardial dysfunction induced by CAV and can be useful for prognostic evaluation and timing of CAs aimed to reduce the number of routine CA-screenings. However, further studies are necessary before specific recommendations for the use of TDI and strain imaging for CAV surveillance are possible.

2

Timely diagnosis of acute rejection (AR) and cardiac allograft vasculopathy (CAV) are paramount for graft and patient survival after heart transplantation (HTx). Invasive screenings at predefined time intervals for AR and cardiac allograft vasculopathy (CAV) are standard procedures for attaining those goals. However, endomyocardial biopsies (EMBs) and cardiac catheterizations are distressing, risky for the patients and also expensive. Also, due to sampling error of EMB, associated with the inhomogeneous nature of AR, histological “false negative” AR can reach 20% and annual routine coronary angiographies (CAs), which are particularly risky for patients with renal dysfunction often fail to detect stenoses prior to a clinical event.1,2 Therefore, non-invasive early diagnosis of AR and monitoring of AR therapy results, early detection of patients with CAV, plus detection of myocardial alteration related to the progression of CAV are major objectives for patient management after HTx.2-4 Echocardiography emerged as one of the most promising tools to achieve those goals, especially after the use of tissue-Doppler imaging (TDI) and strain imaging for ventricular wall motion and myocardial deformation analysis. The article reviews the data on the clinical value of post-HTx echo-assessment of myocardial function for early detection of alterations induced by AR or CAV. Special attention is focused on the usefulness of ventricular wall motion and myocardial deformation analysis for AR and CAV surveillance with the goal to replace routine invasive screenings by optimally-timed EMBs and CAs.

Specific Characteristics of the Cardiac Allograft The denervated donor heart has a particular physiology and pathophysiology with impact on the validity and reliability of non-invasive surveillance for AR and CAV.1,4-7

Specific features of rejection free transplanted hearts with normal coronary arteries The allograft left ventricle (LV) cavity dimensions are usually normal, but the right ventricular (RV) cavity size and the wall thickness of both ventricles are increased compared with those of normal native hearts.4 In addition to afterload-induced myocardial hypertrophy, also cyclosporine and 3

impaired lymphatic drainage in the allograft may contribute to wall thickening. The high prevalence of RV size and geometry alterations is mainly related to the higher pulmonary vascular resistance (PVR) in HTx patients. High prevalence of tricuspid regurgitation (TR) is another particularity of cardiac allografts.4,5 Early post-operative increase in PVR plus preservation-injury and papillary muscle dysfunction can induce transient perioperative severe TR. The main causes of TR beyond the early perioperative period are surgery-related RA geometry changes with valve-ring distortion (often after biatrial anastomosis), biopsy-related trauma and load-related RV size and geometry alterations. In addition, the distinctly load-dependency of RV function limit the usefulness of RV assessment for AR and CAV surveillance. The use of biatrial transplant-technique also produces large atrial cavities with long suture lines, which result in abnormal atrial geometry and function.1,4 Pericardial effusion (PE) is a common finding early after HTx and may complicate AR surveillance. The usually small effusions rapidly become organised, evolving often into pericardial thickening, especially at the LV basal posterior wall, which can change the local wall motion profile and may become misleading for detection of wall motion alterations induced by AR or CAV.4 LV systolic function is usually at the upper limit of normal, possibly due to increased circulating catecholamines. Thus, a normal ejection fraction (EF) does not exclude even moderate AR or CAV. Another particularity is the abnormal (often paradoxical) septal motion revealed by time-motion (M–mode) recordings, which can be misleading for detection of ischemia-induced wall motion alterations.4,5 LV segmental wall motion abnormalities (WMAs) detectable by two-dimensional (2D) echocardiography were often observed in both early and long-term HTx patients without AR or CAV. However, visible differences in regional wall motion do not always indicate regional differences in contractile function (active and passive myocardial tissue movement is visually not distinguishable). Transplanted hearts, especially those with biatrial anastomoses, often show a striking rightward and anterior movement during systole inducing displacement of the LV posterior and lateral wall in direction of their inward movement and ventricular septum displacement in opposite direction to its thickening and inward movement. Correspondingly, the basal lateral and posterior wall show higher displacement 4

amplitudes and velocities in comparison with the septum.4,6 These wall motion particularities can be misleading because displacement and velocity measurements of wall motion can also not differentiate between active and passive movement of a myocardial segment.6 Indeed, in most CAV-free HTx recipients, deformation analyses by non-Doppler 2D-strain imaging, which allows discrimination between active and passive myocardial movement, revealed no relevant regional differences in myocardial deformation, even in patients with regional differences in wall motion amplitude and velocity.6 Even without AR or CAV, the LV often shows also alterations in diastolic function, which can be misleading for allograft echo-surveillance.4,7,8 During the first post-HTx year, both LV relaxation disturbances and restrictive physiology are detectable more frequent. Later, restrictive physiology (reduced compliance) becomes increasingly more evident. Due to the loss of vagal tone, the allograft resting heart-rate is increased (90- 110 beats/minute). Efferent denervation also results in attenuated heart-rate response to exercise and, together with the consequent myocardial hypersensitivity to circulating catecholamines, it also induces delayed return to resting heart-rate after cessation of exercise.4 In the peritransplant period, severe allograft dysfunction can occur even without evidence of AR (incidence ~5%).1,4,6 The major causes are ischemia damage, reperfusion injury and high PVR. Usually, only EMBs allow its differentiation from hyper-acute rejection mediated by preformed antibodies directed against HLA or AB0 blood-group antigens of the donor heart. Non-invasive detection of AR is particularly challenging in the early post-HTx period, as systolic and diastolic function and consequently also both tissue velocity measures and strain parameters are changing during the first post-HTx months even without AR. Rejection free hearts usually show relevant relaxation disturbances, which are detectable very early after HTx and became slowly reversible only after the 1st post-HTx month. In the early postoperative period, relaxation disturbances can be induced by ischemia damage and reperfusion injury, often associated with morphological myocardial changes, which can make also the histological diagnosis of AR particularly challenging.9,10 In rejection free transplant recipients, the ventricular systolic function also shows relevant changes, especially during the 5

first 6 post-HTx months.10,11,12 Unlike diastolic relaxation parameters, which are usually altered during the 1st post-HTx month, the LV systolic wall motion velocity is in the early post-HTx period (especially before catecholamine withdrawal) more often higher than later, after the 3rd post-HTx month.10 However, this doesn’t necessarily indicate a worsening of LV systolic function because wall motion velocities are markedly influenced by the motion of the entire heart (cardiac translation), which is usually higher during the first weeks after HTx. In patients without AR episodes ≥2R during the 1st post-HTx year, the peak global longitudinal strain values, which are independent of cardiac translation, usually improve after the first month indicating an improvement of contractile function.11,12 Thus, without serial follow-up echo-examinations, noninvasive detection of AR can be often unreliable. However, prospective assessment of graft function, from the time of HTx until stabilization of graft function, enables us to determine a fingerprint of myocardial function, which may be used for further prospective surveillance.

Morphologic and functional alterations during acute rejection Even in its early stages, the alloimmune response can induce relevant graft-cell injuries associated with myocardial dysfunction. Nevertheless, in these stages most of the patients are asymptomatic and some of the morphologic changes most frequently described in association with advanced AR (new or increased PE, increase in LV mass, increase in myocardial texture) are usually absent, whereas the detection of rejection-related early changes in ventricular function is challenging.4 AR is an inflammatory response and therefore sudden appearance of PE, increase of a pre-existing PE and myocardial edema-induced LV wall thickening with echo-texture changes, can be important indicators of AR.13 However, moderate or even severe AR often evolve without PE and the magnitude of LV wall thickening is quite variable and often falls within the variability of measurements.4 Ventricular dysfunction is detectable in most patients with biopsy-proven AR.10,14-19 Abnormalities of diastolic function are the earliest cardiac manifestations during AR.14-16 New-onset AR-related systolic dysfunction revealed by EF reduction is generally a late finding and indicates higher grade rejections. However, discordances between AR-induced morphological and functional myocardial 6

alterations are also possible. It was found that neither clinical symptoms, nor LV functional alterations are restricted to histological relevant ARs.10,17,20 Especially patients with mild cellular AR revealed different changes in LV function, which appeared related with clinical symptoms.10,16

Allograft vasculopathy-induced myocardial alterations CAV differs from “ordinary” coronary artery disease angiographically, echocardiographically and also clinically.4,21 Its development can be unusually rapid and therefore clinical suspicion should always lend to repeat angiography. However, HTx patients do not experience classical angina because cardiac allografts are denervated and a possible reinnervation is delayed and incomplete. Early detection of ischemia-induced electrocardiogram (ECG) changes by exercise stress-testing is generally also not very useful, because of baseline ECG changes (more often right bundle-branch block; rarely also left bundle-branch block). Early detection of ischemia-induced regional wall motion alterations by echocardiography is challenging because the most common form of CAV is that of diffuse, primarily distal coronary narrowing involving also the microvascular system. Accordingly, CAV-induced wall motion alterations are more often global (mainly related to angiographic Type-B lesions).4,6,17,20

Limitations of Standard Echocardiography for Allograft Surveillance Although standard M-Mode, 2D and Flow-Doppler echocardiography had provided valuable insight into the allograft changes during AR and CAV, their usefulness for allograft non-invasive surveillance, aimed to improve AR and CAV diagnosis and especially to spare patients unnecessary, risky and distressing routine examinations, remained limited.3,4,19

Limitations of standard echocardiography for diagnosis of acute rejection Although older reports have suggested that sudden changes in myocardial structure (increase in LV wall thickness, myocardial echogenity changes), persistent, increasing or late-onset PE and sudden alterations in ventricular function detectable by standard echocardiography (LVEF reduction, flow-Doppler7

derived diastolic indices changes) can reveal AR, its usefulness for AR surveillance remains limited by its low sensitivity (usually ≤ 50%) even for detection of histological and/or clinically relevant AR.4,13,15,18,22 This low sensitivity for early detection of AR-related ventricular dysfunction is explainable because systolic dysfunction revealed by EF reduction is usually a late finding and baseline diastolic filling abnormalities unrelated to AR are frequent. In addition, the usefulness of EF is limited by the high inter- and intra-observer variability of measurements, whereas the trans-mitral Dopplerderived measurements used for assessment of LV diastolic function are highly dependent also on leftsided heart loading conditions. Multi-parametric assessment can improve the diagnostic value of standard echocardiography for AR detection. However also multi-parametric evaluation is suboptimal (positive predictive value ~ 77%) and not standardized.4 Some studies suggested a correlation between the myocardial performance index (MPI) and AR but the relationship has not been a consistent finding and the MPI showed usually low sensitivity and specificity for AR diagnosis.4,23 This is not surprising because AR appeared associated with both significant increase in isovolumic contraction time (due to reduced contractility) which increases the MPI and decrease in isovolumic relaxation time (due to restrictive ventricular filling with high atrial pressure) which reduces the MPI.23

Limitations of standard echocardiography for detection of CAV-related myocardial alterations Standard echocardiography at rest is more often insensitive for early detection of CAV-related myocardial alterations and has a limited diagnostic accuracy for CAV.4,24-27 There is also a wide range in reported sensitivity of resting WMA for CAV detection which might be mainly related to differences in the patient populations studied (different number of studied patients; different prevalence of resting WMAs in the studied groups). Initial studies on the diagnostic value of stress echocardiography with exercise showed low sensitivity, probably mainly because of the denervation-induced blunted heart-rate response to exercise.26,28 Nevertheless, a more recent study on the diagnostic value of stress echocardiography with exercise for CAV detection in pediatric patients revealed a sensitivity and specificity 8

of 89% and 92%, respectively.29 Thus, further studies with modern echocardiography are warranted before any reliable statement about the sensitivity of exercise stress echocardiography is possible. Dobutamine-stress echocardiography (DSE) has theoretically the advantage to be less affected by that chronotropic incompetence because the denervated allografts display an augmented chronotropic response to catecholamines. Another advantage of DSE in comparison with exercise-stress echocardiography is related to the better inotropic response (with higher myocardial oxygen demand) to dobutamin than to exercise. Nevertheless, clinical studies revealed no definite advantages of DSE in comparison to exercise-stress echocardiography for diagnosis of significant CAV (Table 1 ).30-39 Also for DSE there is a wide range in reported sensitivity and specificity (0%-100% and 55-99%, respectively) for detection of CAV, which appears mainly related to differences in prevalence of resting WMA in the studied groups, differences in defining the presence and severity of CAV, and on whether the gold standard being used is CA or CA combined with intra-vascular ultrasound (IVUS).24,29-35 In a recent study on the adequacy of DSE for cardiac assessment (177 evaluated patients), DSE failed to detect angiographic CAV in the first 5 years after HTx.40

Myocardial Velocity and Deformation Analysis for Allograft Surveillance Myocardial velocity and deformation analyses by echocardiography using highly sensitive tissueDoppler and strain imaging methods, which were more recently developed to quantify regional and global systolic and diastolic ventricular function, are of particular value for heart allograft evaluations. These methods appeared especially useful during follow-up examinations of asymptomatic patients with visually normal ventricular function for early detection of AR and identification of patients with newly developed CAV, or those with aggravation of an already known coronary disease.

Benefits and limitations of wall motion velocity analyses for allograft surveillance Because wall motion velocity analysis can detect ventricular dysfunction earlier than standard echocardiography it is suited for early detection of WMAs induced by AR and CAV.4,10,41,42 The superiority 9

of velocity measurements compared with standard echo-measurements for evaluation of allograft function was confirmed also by real-time 3D-echocardiography which showed that the time to minimum systolic LV volume is a more sensitive parameter than LVEF for predicting AR grade ≥ 2 and suggested as well that during AR, reduction of ejection velocity precedes reduction of EF.41 Wall motion velocities are usually assessed by TDI, using color-Doppler or pulsed-Doppler mode. Color-TDI allows myocardial motion to be imaged as color-coded velocities superimposed on 2D grayscale image in real time. The analysis of velocity traces allows direct comparison of velocities in different segments on the same image. However, because velocity analysis must be often done as post-processing, color-TDI analyses are usually time-consuming. Because the color-TDI provides mean velocities, whereas the pulsed-wave tissue-Doppler imaging (PW-TDI) presents the peak of the instantaneous velocity spectrum, the velocities measured in a certain region by color-TDI are lower than those measured by PW-TDI. Color-TDI measurements can be altered by reverberations (i.e. echoes due to reflexions within the body). PW-TDI has the advantage of a high temporal and velocity range resolution. It is also easy to perform and not time-consuming. Its disadvantages are limited spatial resolution and the possibility to obtain velocity data only from one region at a time. Like other Doppler modalities, TDI is angle-dependent, because only velocity components in the beam direction are recorded. These limitations must be considered during velocity recordings and interpretation of measurements.6 The influence of tethering effects (myocardium in one region is tethered to neighbouring myocardium), cardiac translation (motion of the entire heart) and ventricular loading on velocity measurements reflect the limitation of velocity as a parameter of myocardial contractility.4,6 Wall motion velocity measurements are unable to distinguish between active and passive myocardial tissue movement. Tissue Doppler imaging for rejection surveillance The majority of the studies which addressed the diagnostic performance of TDI to detect biopsyproven AR revealed reductions in LV myocardial systolic and diastolic velocities during AR.10,43-49 However there is a high heterogeneity in results which might be explainable by differences in study 10

design, differences in LV wall-segments selected for velocity measurements, as well as differences in the number of evaluated patients and prevalence of AR-episodes in the studied population. Other causes for the different results can be differences in post-HTx time and differences in translational motion of the allograft (especially after biatrial anastomoses), because they also affect wall motion velocities.10 Especially the translational motion varies largely from one patient to another and has important influence on TDI parameters, which will also vary correspondingly. Due to the resulting high inter- and intra-patient variability of TDI parameters, the detection of a velocity change during serial follow-up examinations is more useful for AR diagnosis than the actual absolute value of the respective velocity measurement. It is also important to compare only measurements which reflect the wall motion of the same myocardial region in the same direction.10 An overview on the diagnostic value of selected TDI-derived LV wall motion velocity parameters for detection of AR is shown in Table 2 . Because diastolic dysfunction often precedes systolic abnormalities, special attention was focused on assessment of the potential usefulness of LV early (E’) and late (A’) diastolic velocities for early detection of AR. Many studies revealed significant reductions of both E’ and A’ (also known as Em and Am) velocities during biopsy-proven AR.10,43-50 Nevertheless, there is controversy on the diagnostic value of LV diastolic velocities for detection of biopsy-proven AR.4,44,46,50-52 Different studies revealed for E’ sensitivity and specificity values between 69%-92% and 59-92%, respectively.10,42,52-54 For the A’ wave the sensitivity reached 67%-82%, but the specificity only 49%-53%.53,54 Because the diastolic velocity-profile shows high inter-individual variability in AR-free patients without CAV, the use certain cut-off velocity values appeared not advantageous and is possibly also a cause for different study results. Thus, in two studies using similar PW-TDI measurements at the basal posterior wall, E’ revealed high specificity (between 88% and 92%) and negative predictive value (between 92% and 95%) for biopsy-proven AR.10,44 However, whereas the study which used a cut-off value for E’ (16cm/s) revealed only a sensitivity of 76% for moderate AR, the study which used a E’ reduction with > 10% as possible sign for AR, revealed a sensitivity of 92% for clinical relevant biopsy-proven 11

AR.10,44 A limitation for the use of LV diastolic velocities for AR surveillance is the progressive increase in myocardial stiffness (especially by fibrosis) with restrictive physiology, which makes increasingly difficult to detect AR-related acute myocardial relaxation disturbances.4,10 Especially beyond the first post-HTx year, E’ measurements become increasingly less reliable for rejection surveillance.10 TDI of the tricuspid annulus was also tested for its potential usefulness in the follow-up of HTx patients.46,47 Although patients with AR showed lower tricuspid annulus E’ and A’ velocities, the usefulness of RV diastolic velocity parameters for early AR diagnosis remains unclear. LV systolic wall motion TDI-parameters like systolic peak velocity (S’, or its synonym Sm) and timeto-peak systolic velocity (TS’) were also used for rejection surveillance.4,10,17,46,48,49 S’ measurements at the basal LV posterior wall showed a significant correlation with LVEF.20 However, in patients with normal LVEF, due to the hyperbolic function which describes the relationship between EF and S’, already minor alterations of systolic function, with almost undetectable LVEF reduction, can induce relevant S’ reductions (>20%).20 Nevertheless, there is controversy on the diagnostic value of S’ for AR diagnosis because comparisons of S’ values obtained from patients with and without biopsy-proven AR did not always reveal significant differences.44 This might be explainable by the large differences in S’ values existing between individual HTx patients. Due to the large variability of S’ values in the patient groups with and without AR, comparisons of such groups might not always reveal significant differences, especially because in non-rejection groups usually predominate long-term transplanted patients with typically lower S’ values, whereas in AR groups predominate recently transplanted patients with often higher S’ before AR. Serial TDI examinations, which allow intra-individual comparison, are therefore necessary for early detection of AR-related LV systolic dysfunction. A comparison of PW-TDI measurements obtained from the same patient throughout serial examinations revealed that S’ reduction with >10% can reach a 88% sensitivity and 94% specificity for detection of therapeutically relevant AR (all grade ≥2 plus 1A and 1B in symptomatic patients).10 The discordant results of different studies can also be explained by the discordance between AR-induced morphological and functional myocardial alterations because, neither clinical symptoms, nor LV dysfunction are restricted to histological relevant 12

ARs.10,17 Especially patients with histological mild cellular AR can exhibit different changes in LV function which appeared related with clinical symptoms.10 Thus, whereas asymptomatc patients showed no PW-TDI parameter alterations, patients with clinically manifested AR showed significant alterations of systolic parameters comparable with those found in patients with higher grades of cellular AR.10 However, symptomatic patients with unexpectedly low degree of cellular infiltration often showed vascular (humoral) antibody-mediated rejection components, which are known to be associated with a more severe clinical course.10,55 The afterload sensitivity of S’ must be taken into consideration during AR surveillance.10,56 Sudden increase in arterial pressure can induce S’reduction. Misleading S’ reduction can also be induced by beta-blocker therapy. Due to the angle-dependency of TDI measurements, it is useful to select from several tracings (obtained in the same myocardial region during sinus rhythm) the highest velocity for the final S’ value.10 A prolongation of TS’ with >10% revealed similar diagnostic value, but the reproducibility of TS’ measurements might be lower in comparison with S’.10 Tissue Doppler imaging for CAV surveillance TDI has also been tested for its usefulness to detect ischemia-induced myocardial dysfunction in AR-free allograft recipients without visible regional WMAs.10,17,20,57-60 PW-TDI, which is highly sensitive for detection of local wall motion disturbances has also proved beneficial for the assessment of LV global function in patients without visible ventricular asynergy.20,56,57 In comparison to patients without CAV, even those with angiographically non-visible and only by IVUS detectable CAV can already show significant alterations in systolic PW-TDI parameters. In AR-free HTx patients, LV systolic radial and longitudinal wall motion velocity alterations at the basal posterior wall appeared predictive for CAV (Table1).20 However, there were differences in the diagnostic value of PW-TDI depending on whether the gold standard being used was CA or CA plus IVUS and also whether PW-TDI should detect the presence of CAV (with and without focal coronary stenoses) or only the presence of relevant focal stenoses ( ≥ 50% coronary narrowing). Thus, in HTx recipients without visible WMAs, radial S’, ≤ 10cm/s reached 90% sensitivity for 13

identification of patients with angiographic and/or by IVUS detectable CAV, whereas even lower radial S’ values (≤ 9 cm/s) reached maximum 51% sensitivity for detection of those with focal stenoses at the main epicardial coronary arteries.20 Potentially misleading S’ alterations due to LV afterload changes must be taken into consideration also during CAV surveillance. Although with CAV, the PW-TDI pattern showed also significant changes for diastolic radial and longitudinal velocity parameters, these changes appeared not predictive for CAV.20 This might be mainly related to the observation that in most heart-transplanted patients the CAV aggravates an already present diastolic dysfunction rather than being its primary cause.20

Benefits and limitations of myocardial deformation analysis Myocardial deformation analysis by echocardiography is a new technology enabling more reliable and comprehensive assessment of myocardial contractile function being particularly suited for post-HTx follow-up visits, because strain and strain rate (Sr) parameters are independent of overall cardiac motion which is more pronounced in transplanted hearts. Its major advantage for cardiac allograft surveillance is the ability to discriminate between active and passive myocardial movement.6,61 In addition to its usefulness for early diagnosis of AR and CAV, deformation imaging also appeared helpful in estimating the burden of LV dysfunction that evolves independent of CAV or AR and correlates with long-term clinical outcome.1,25,57 Echocardiographic deformation imaging allows strain and Sr calculations derived either from TDI-based 1-dimensional velocity measurements or from data obtained by tracking speckles in the 2-dimesional (2D) or three-dimensional (3D) ultrasonic image. The lack of angle-dependency, better spatial resolution, deformation analysis in 2 or 3 dimensions plus less time-consuming data acquisition and processing are major advantage of non-Doppler speckle-tracking echocardiography (STE), whereas higher temporal resolution and less dependency on echo-image quality are the main advantages of TDI-based strain imaging.6 STE also gives information of global ventricular function in a single number and the bulls eye plot gives a fast regional overview, which both can be helpful advantages for allograft surveillance. 14

Strain imaging for rejection surveillance First findings on the usefulness of strain imaging for early detection of AR were provided by TDIderived myocardial deformation data, which showed that LV longitudinal and radial systolic strain and Sr measurements are beneficial for AR diagnosis (Table 3 ).62,63 LV radial strain reduction with ≥ 30% at the basal posterior wall reached 80% and 95% positive and negative predictive value, respectively, for AR ≥ 1 B.63 Although nearly 10 years ago, preliminary observations on 2D-STE parameter changes during AR already suggested the usefulness of STE for AR surveillance, its diagnostic value was investigated only during the last few years.6,42,61-72 Most studies revealed significant reductions for LV global longitudinal systolic strain (GLS), even during mild (1R) AR. One study also revealed significant increase of GLS in the resolving period of moderate AR.72 Nevertheless, although stable GLS appeared able to exclude AR with high probability (90% and 99% negative predictive value for AR ≥ 1 B and ≥ 2R, respectively), the diagnostic value of GLS remained limited by its reduced positive predictive value for detection of AR.65,66 However, the reduced positive predictive value might be also due to the reduced prevalence of AR in the evaluated EMBs, which makes the positive predictive value lower and the negative predictive value higher than it would be in a sample with higher prevalence of AR. Also the high number of false positive STE results might be in part related to possible false negative EMBs. Thus, sampling error associated with the patchy nature of AR, variability in histology-interpretation and non-routine screening for antibody-mediated AR may result in underestimation of AR severity or miss the diagnosis of AR.1,55 The reduced sensitivity of GLS in comparison with the TDI-derived longitudinal strain at the LV lateral wall might also be related with the regional differences in longitudinal strain and Sr changes which were found in response to AR (reduction at the basal and mid lateral wall; no changes at the ventricular septum).63 In a recent study, STE-derived longitudinal strain and Sr measurements using a Velocity-Vector-Imaging software did not reveal significant changes during asymptomatic biopsy-proven AR in the first post-HTx year.71 A recent study revealed also for the RS significantly lower values during moderate AR (2R) and, at a 15

cutoff value of 25%, the average peak RS reached 100% sensitivity and negative predictive value, but only poor specificity and positive predictive value for moderate (2R) AR.70 However, unlike STEderived longitudinal strain and Sr, both radial (RS) and circumferential strain (CS) and Sr were less frequently found different between patients with and without biopsy-proven AR, although preliminary experimental studies on 2D-STE parameter-changes during AR revealed significant reduction in both radial and circumferential systolic strain and Sr.67-69 The lack of significant changes in STEderived radial strain and Sr in certain studies is also in contradiction to the TDI-derived myocardial deformation data, which revealed high sensitivity, specificity and predictive values for radial strain and Sr.63 A possible explanation might be the differences in AR severity between the patients included in those studies, because longitudinal deformation changes alone were usually detected at earlier stages of AR, when LV contractile function is predominantly impaired in the longitudinal direction.65 However, as shown in Figures 1 and 2, radial and circumferential systolic strain can be altered also by mild AR. It is striking that deformation analysis showed differences not only between TDI-based strain imaging and STE-derived findings, but also between different studies which assessed the diagnostic value of STE. Among others (differences in study design, number of evaluated patients and in prevalence of AR episodes in the studied population) this might also be explainable by the diversity of commercially available STE software-packages where each has its own proprietary algorithms for imaging tracking and calculations. It is currently unknown in the field how results from different vendor’ softwarepackages correspond with one another.71 A recent study assessing the usefulness of 3D-STE for AR surveillance in HTx recipients, also revealed significant reduction in peak GLS and no significant changes in both global peak radial and circumferential strain during AR ≥1B (Table 3). A peak GLS strain value of less than -9.55% appeared able to predict grade 1B or higher AR with sensitivity of 87.5%, but with a specificity of only 54.2%.73 These results may suggest that 3D-STE is less useful than TDI or 2D-STE for noninvasive rejection monitoring. However, the study is not conclusive because of the small number of AR episodes ≥1B (n = 8) in the studied population.73 16

Strain imaging for CAV surveillance There are few data on the usefulness of myocardial deformation imaging at rest for detection of patients with new onset of CAV or with aggravation of already known CAV (Table 3 ).8,74-77 These studies indicated that CAV surveillance remains challenging even with STE because the predominantly diffuse, primarily distal coronary narrowing, induces mainly global impairment of contractile function which can also exist without CAV, not only during AR, but also in AR-free patients. Systolic radial, longitudinal, and circumferential strain and Sr were found significantly lower in patients with angiographic CAV in comparison to those without CAV.76,77 In a multivatiate analysis only GLS appeared correlated to CAV.76 This is not unexpected because, due to their subendocardial position, the longitudinal fibers are very sensitive to reduced perfusion. Nevertheless, GLS revealed no appropriate sensitivity for detection of patients with angiographic CAV (with diffuse coronary lesions ± focal stenoses ≥ 50%).76 As shown in Table 1 , at certain cut-off values, systolic GLS and GLSr can exclude focal stenoses of ≥ 50% with 87% and 95% probability, respectively. However, low GLS and GLSr values in AR-free patients with apparently normal LV kinetics reached only low positive predictive values for focal coronary stenoses (58% and 64%, respectively).77 This is not surprising because CAV, regardless of the presence or absence of focal coronary stenoses, is associated low global strain and Sr. Therefore, STE-derived assessment of synchrony and synergy of LV contraction, able to detect regional differences in LV dysfunction, might be more useful for CAV surveillance.41,74,77 Indeed, at certain cut-off values, the sensitivity of the LV systolic asynchrony and dyssynergy indexes reached 77% and 79%, respectively, whereas their specificity reached even 87% and 98%, respectively.77 These indexes also revealed positive and negative predictive values of ≥ 90%, which suggest their potential usefulness for CAV surveillance even at rest (Table 1 ). As shown in Figure 3 , CAV can also induce LV circumferential strain alterations which depend on the presence or absence of proximal coronary stenoses (≥ 50% narrowing). CAV detection by myocardial deformation analysis under exercise or pharmacologic stress appeared also beneficial for allograft surveillance.33,60,78 Myocardial deformation imaging was able to increase the sensitivity of DSE for detection of CAV (any angiographic abnormalities including focal stenoses), from 17

63% to 88%.33 The diagnostic value of exercise stress-echocardiography can also be improved by STE-derived strain measurements.60,78 LV longitudinal deformation during exercise stress-tests assessed by STE appeared strongly associated with the presence and degree of CAV.60

Usefulness of Myocardial Velocity and Deformation Imaging for Timing of Cardiac Biopsies and Catheterizations Despite several limitations, LV wall motion assessment by PW-TDI has evolved in many transplant centers into a basic tool for routine surveillance of allograft function. PW-TDI allows only regional wall motion analyses but these can reflect the functional state of large myocardial areas. Thus, S` measured at the LV basal posterior wall correlates with LVEF, but it has the advantage that in patients with normal LVEF, already minor alterations of systolic function, without detectable LVEF reduction, can induce relevant S’ reductions.20 This makes PW-TDI suited for the early detection of LV contractile dysfunction linked to AR and CAV. According to observations so far, in asymptomatic patients with stable S’ at the basal posterior wall (parasternal and/or apical long-axis views), a therapeutically relevant AR is unlikely, especially for patients with S’ ≥10cm/s.10,46 Thus, serial PW-TDI examinations can save patients from unnecessary routine EMBs. A sudden S’ reduction with >10%, without any increase of arterial pressure, indicates the necessity of EMB for diagnostic clarification, especially if STIderived global strain and/or Sr values are also lower than before.10 The negative and positive predictive values for AR of S’ changes appeared appropriate for non-invasive PW-TDI monitoring which may allow efficiently timed, instead of routinely scheduled, EMBs. In an observational study, the comparison of two patient groups who underwent different AR surveillance strategies during the first post-HTx year, one group monitored by routine EMBs plus a noninvasive strategy that included PW-TDI and a telemetric monitoring of the intra-myocardial electrogram (IMEG) from a dual-chamber pacemaker, the other by the same noninvasive strategy (PW-TDI and IMEG) plus “diagnostic” EMBs (performed only if AR was suspected clinically and/or by PW-TDI ± IMEG alterations) instead of time-based routine EMBscreenings, revealed no differences between the groups, neither in the number of histologically and therapeutically relevant AR episodes, nor in patient outcome.79 This suggests, that close-meshed non18

invasive monitoring by PW-TDI plus IMEG allows optimal timing of EMBs and might be therefore also able to save patients from unnecessary routine EMBs even during the first post-HTx year. STE is more promising than TDI for timing of EMBs, but the existing data are insufficient to define the real value of serial STE to attain that goal. Because STE-technology is still in development, currently, only data obtained with the same ultrasound-system are comparable. In addition, global and regional strain data obtained in a patient at a particular time by 2D-STE and 3D-STE can differ and are therefore not directly comparable.80 Thus, future studies are needed to standardize STE for testing its reliability and clinical safety as a non-invasive surveillance method aiming to save patients from unnecessary routine EMBs. Serial PW-TDI can also be useful for early detection of patients who develop CAV. However, although PW-TDI is more sensitive than standard echocardiography for detection of incipient LV dysfunction linked to CAV, its diagnostic value for detection of patients with newly developed focal coronary stenoses or progression of already known coronary stenoses is insufficient.20 Nevertheless, in patients with stable S’ values of ≥ 11cm/s angiographic CAV is unlikely and a routine CA can be delayed, especially in patients with impaired renal function.20,81 Patients without already known CAV who repeatedly show S’ values < 10cm/s need invasive clarification of diagnosis, because after AR exclusion the probability of CAV is ~ 95%.20 Although PW-TDI appeared helpful to predict angiographic CAV, it showed only little value for a differentiated prediction of CAV with and without proximal coronary stenoses.20 However, serial PW-TDI in combination with additional annual electron-beam computed tomography for detection and quantification of coronary calcifications appeared useful for timing of CAs.81 Thus, in patients with S’ > 9 cm/s, normal LVEF (without visible wall motion disturbance) and low coronary calcification score (Agatston score > 50) relevant coronary stenoses (> 50% occlusion) are unlikely (negative predictive value 91.0%). Relevant coronary stenoses are also unlikely in patients with high coronary calcification scores (especially in patients with chronic renal insufficiency) if S’ values are ≥ 11cm/s.81 Among all echo-derived methods for assessment of cardiac function, deformation imaging (especially 19

STE) appears definitely to be most promising for a possible timing of CAs. In patients with apparently normal ventricular function, STE-derived synchrony and synergy data of LV contraction allow a differentiated prediction of CAV with and without focal proximal coronary stenoses even at rest (positive and negative predictive values of ≥ 90% for proximal focal coronary stenoses with > 50% narrowing) and appeared therefore potentially useful for optimal timing of CAs.77,81 Exercise-stress echocardiography and DSE using STE-derived strain measurements might also be promising.60,78 However, the existing data are insufficient to define the real value of serial STE for optimal timing of CAs aimed to facilitate early detection of CAV and to spare patients with high-risk for renal insufficiency to be spared from unnecessary routine CAs.

Usefulness of Myocardial Velocity and Deformation Imaging for Therapeutic Decisions The EMB scoring-system is the basis of therapeutic decisions for AR. However, the severity of ARrelated cardiac dysfunction AR is not always reflected by that scoring.10,17,55,72 Thus, histologically mild AR (grade 1R) can be accompanied by myocardial dysfunction detectable by TDI and/or STE even in asymptomatic patients and subclinical histological moderate AR (grade 2R) are not always associated with myocardial velocity and deformation parameter alterations. In the Berlin Heart Center, all grade 1R rejections associated with S’ reduction are mandatory treated because patients with recurrent ARs associated with left ventricular S’ and systolic Sr reduction appeared at high risk for early development of CAV. This strategy is supported by the observation that recurrent AR has a cumulative effect on the onset of CAV.82 Recently it was suggested to consider the routine use of GLS as a marker of graft function involvement during AR and to include GLS into therapeutic decision-making (i.e. to treat asymptomatic AR grade 2R differentially, depending on the presence or absence of relevant GLS reduction).76 As shown in Figure 2 , STE can also be useful for monitoring the effects of anti-rejection therapy on myocardial function. However, further randomized trials are necessary to clarify the potential usefulness of TDI and deformation imaging parameters as therapeutic markers of subclinical AR.

20

Simultaneous Assessment of Myocardial Contractile Function and Coronary Flow by Echocardiography Theoretically, simultaneous assessment of myocardial contractile function and coronary flow reserve (CFR), might improve the noninvasive detection of subclinical CAV. In a more recent study, CFR assessed by transthoracic Doppler echocardiography showed 100% sensitivity, but only modest (64%) specificity and positive predictive value for angiographic CAV, whereas DSE revealed not only a modest specificity (64%), but also low sensitivity (56%).32 By combination of DSE with Dopplerderived CFR, the sensitivity became 78% (i.e. higher for DSE than before, but lower than the sensitivity revealed by CFR alone) and the specificity rose up to 87% (i.e. higher than the specificity of each parameter separate).32 However, these results were not better than those reported for DSE using STE for assessment of dobutamine-induced WMAs (sensitivity 80%, specificity 85%).33 This suggests that visual assessment of ventricular wall motion during DSE is less reliable for detection of CAV-induced myocardial contractile dysfunction and might also explain the previously reported lack of correlation between decreased CFR and the presence of dobutamine-induced regional WMAs.83 Thus, a combination of Doppler-derived CFR measurements with DSE, using speckle-tracking derived strain imaging for evaluation of myocardial contractile function, appears promising for improvement of CAV surveillance by echocardiography. Allowing simultaneous echo-assessment of both myocardial contractile function and perfusion, realtime myocardial contrast echocardiography (MCE) at rest, during exercise or throughout dobutamine infusion was also found useful for the diagnosis of hemodynamically relevant CAV and feasible for CAV surveillance.83,84 In a prospective study, addition of MCE to conventional DSE was able to increase the sensitivity, negative predictive value and accuracy for detection of significant CAV (ischemia) from 71%, 56% and 80%, respectively, up to 86%, 75% and 90%, respectively. Combination of real- time MCE for assessment of myocardial perfusion with DSE using speckletracking derived strain imaging for evaluation of myocardial contractile function might further increase the reliability of echocardiography for CAV surveillance. 21

Conclusions and Future Directions The newly developed echo-modalities for myocardial velocity and deformation analysis, using highly sensitive tissue-Doppler and strain imaging techniques for timely detection of myocardial dysfunction induced by AR or CAV can substantially improve the clinical value of echocardiography for noninvasive surveillance of HTx patients. Allowing quantification of minor myocardial dysfunction not detectable by standard echocardiography, TDI and strain imaging enable the diagnosis of subclinical AR. Nevertheless, myocardial velocity and deformation measurements cannot stand alone for AR surveillance. Anyway, they can be a powerful supplement to EMB enabling more efficient, reliable and save AR monitoring even during the first post-HTx year, with less but optimally timed histologic examinations (i.e. diagnostic EMBs based on non-invasive detection of incipient myocardial dysfunction) instead of unnecessary and distressing timebased routine EMB-screenings. TDI and strain imaging can also detect functionally and prognostic relevant ARs which are underestimated by EMB and appeared useful for improvement of therapeutic decisions. In comparison to EMB, myocardial velocity and deformation imaging has the advantage to be also suited for close monitoring of anti-rejection therapy effects on myocardial function. However, current literature does not support unequivocally the preferential use of certain myocardial velocity or deformation parameters or the use of a certain STE software-package for AR surveillance. The high degree of methodological heterogeneity, which may have overestimated or underestimated the actually diagnostic accuracy of different TDI and strain imaging parameters, is probably the main cause for the discrepancy of study results. Strain imaging study results might have additionally been affected by the continuous progression of the technique and device update, which would also explain the inconsistency of certain preliminary findings. Thus, future studies aimed to standardize both AR surveillance strategy and methodology for myocardial velocity and deformation assessment are therefore necessary before specific recommendations for the use of TDI and STE for rejection monitoring are possible. Myocardial velocity and deformation imaging is particularly suited for early detection of CAV-induced

22

myocardial dysfunction and can be useful to reduce the number of routine CA-screenings by optimizing the timing of CAs. However, even strain imaging which can discriminate between active and passive myocardial movement, appeared unable to predict reliably the existence of relevant coronary focal stenoses (> 50% narrowing) in asymptomatic patients with visually normal ventricular function. Nevertheless the high negative predictive value of stable TDI and STE parameters suggests that after initial invasive exclusion of coronary stenoses, annual follow-up CA-screenings might not be mandatory for all patients as long as TDI and STE parameters remain stable. Thus, TDI and STE might be able to save certain patients (especially those with impaired renal function) from unnecessary routine angiographies. However, further studies are necessary to standardize the use of TDI and STE for CAV surveillance because the current literature does yet not yet sufficiently support the reliability of these new echotechniques for non-invasive timing of angiographies after HTx. The overall goal for HTx physicians is to improve long-term outcome of their patients. However, the 4 and 8 year post HTx survival improved only slightly between 2002 and 2008 and after 2008, the 4 year post-HTx survival remained stable, although cardiac allograft function surveillance by echocardiography became more reliable.85 There are many possible causes for the lack of expected survival benefits of echocardiography after the introduction of TDI and strain imaging. The main causes might be the lack of standardization in the use of myocardial velocity and deformation assessment and the fact that strain imaging has been introduced only recently in only few HTx units for cardiac allograft surveillance. Thus, there is real hope that extended and standardized application of TDI and STE will in the future be able to improve long-term outcome after HTx.

Conflicts of interest No conflicts of interest or grant for this article.

23

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44. Puleo JA, Aranda JM, Weston MW. et al. Noninvasive detection of allograft rejection in heart transplant recipients by use of Doppler tissue imaging. J Heart Lung Transplant 1998;17:176-84 . 45. Mankad S, Murali S, Kormos RL. et al. Evaluation potential role of color-coded tissue Doppler echocardiography in the detection of allograft rejection in heart transplant recipients Am Heart J 1999; 138 ( 4 Pt 1):721-30 46. Lunze FI, Colan SD, Gauvreau K. et al. Tissue Doppler imaging for rejection surveillance in pediatric heart transplant recipients. J Heart Lung Transplant 2013; 32:1027-33 47. Resende MVC, Vieira MLC, Bacal F. et al. Tissue Doppler echocardiography in the diagnosis of heart transplantation rejection. Arq Bras Cardiol 2011; 97(1):8-16 48. Fabregas RI, Crespo-Leiro MG, Regueiro M. et al. Usefulness of pulse Doppler tissue imaging for non-invasive detection of cardiac rejection after heart transplantation. Transplant Proc 1999; 31(6):2545-47 49. Pauluks LB, Pietra BA, DeGroff CG. et al. Non-invasive detection of acute allograft rejection in children by tissue Doppler imaging: myocardial velocities and myocardial acceleration during isovolumic contraction. J Heart Lung Transplant 2005; 24(7 Suppl):S239-48 50. Eun LY, Gajarski RJ, Graziano JN. et al. Relation of left ventricular diastolic function as measured by echocardiography and pulmonary wedge pressure to rejection in young (≤ 30 years) patients. Am J Cardiol 2005; 96(6):857.60 51. Palka P, Lange A, Galbraith A. et al. The role of left and right ventricular early diastolic Doppler tissue echocardiographic indices in evaluation of acute rejection in orthotopic heart transplant. J Am Soc Echocardiogr 2005; 18:107-15 52. Bader FM, Islam N, Mehta NA. et al. Noninvasive diagnose of cardiac allograft rejection using echocardiography indices of systolic and diastolic function. Transplant Proc 2011; 43(10):3877-81 53. Stengel SM, Allemann Y, Zimmerly M. et al. Doppler tissue imaging for assessing left ventricular diastolic dysfunction in heart transplant rejection. Heart 2001: 86:432-7

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54. Sun JP, Abdalla IA, Asher CR. et al. Non-invasive evaluation of heart transplant rejection by echocardiography. J Heart Lung Transplant 2005; 24(2):160-5 55. Tang ZY, Kobashigawa J, Rafiei M.et al. The natural history of biopsy-negative rejection after heart transplantation. J Heart Lung Transplant 2013;32(7):744-46 56. Yamada H, Oki T, Tabata T. et al. Assessment of left ventricular systolic wall motion velocity with pulsed tissue Doppler imaging: comparison with peak dP/dt of left ventricular pressure curve J Am Soc Echocardiogr 1998; 11:442-9 57. Eleid MF, Caracciolo G, Cho EJ. et al. Natural history of left ventricular mechanics in transplanted hearts. J Am Coll Cardiovasc Imaging 2010; 3(10):989-1000 58. Giacomin E, Gasparini S, Zaká V. et al. Relationship of coronary microcirculatory dysfunction and left ventricular long-axis function in heart transplant recipients. J Heart Lung Tranplant 2007; 26(12):1349-50 59. Hummel M, Dandel M, Knollmann F. et al. Long-term surveillance of heart transplanted patients: noninvasive monitoring of acute rejection episodes and transplant vasculopathy. Transplant Proc 2001; 33:3359-42 60. Clemmensen ST, Eiskjǽr H, Løgstrup BB. et al. Noninvasive detection of cardiac allograft vasculopathy by stress exercise assessment of myocardial deformation. J Am Soc Echocardiogr. 2016; 29(5):480-490 61. Dandel M, Lehmkuhl H, Knosalla C Hetzer R. Non-Doper Two-dimensional Strain Imaging - Clinical Applications J Am Soc Echocardiogr 2007;20(8):1019 62. Marciniak A, Eroglu E, Marciniak M. et al. The potential clinical role of ultrasonic strain and strain rate imaging in diagnosing acute rejection after heart transplantation. Eur J Echocardiogr 2007;8:213-21 63. Kato TS, Oda N, Hashimura K et al. Strain rate imaging would predict subclinical acute rejection in heart transplant recipients. Eur J Cardiothorac Surg 2010; 37:1104-10

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64. Sato T, Kato TS, Komamura K. et al. Utility of left ventricular systolic torsion derived from 2-dimensional speckle-tracking echocardiography in monitoring acute cellular rejection in heart transplant recipients. J Heart Lung Transplant 2011;30(5):536-43 65. Sera F, Kato TS, Farr M. et al. Left ventricular longitudinal strain by speckle-tracking echocardiography is associated with treatment-requiring cardiac allograft rejection. J Card Fail 2014;20(5):359-64 66. Mingo-Santos S, Moňivas-Palomero V, Garcia-Lunar I.et al. Usefulness of two-dimensional Strain parameters to diagnose acute rejection after heart transplantation. Am Soc Echocardiogr 2015;28:1149-56 67. Sehgal S, Blake JM, Sommerfield J, Aggarwal S. Strain and strain rate imaging using speckle tracking in acute allograft rejection in children with heart transplantation. Pediatr Transplantation 2015; 19:188-95 68. Pieper GM, Shah A, Harmann L. et al. Speckle-tracking echocardiograpy: a new noninvasive tool to evaluate acute rejection in cardiac transplantation. J Heart Lung Transplant 2010; 29(9):1039-46 69. Shi J, Pan C, Shu X, et al. The role of speckle tracking imaging in the noninvasive detection of acute rejection after heterotopic cardiac transplantation in rats. Acta Cardiol 2011;66:779-785 70. Ruiz Ortiz M, Peña ML, Mesa D et al. Impact of asymptomatic acute cellular rejection on left ventricle myocardial function evaluated by means of two-dimensional speckle tracking echocardiography in heart transplant recipients. Echocardiography 2015;32:229-37. 71. Ambardekar AV, Alluri N, Patel AC. et al. Myocardial strain and strain rate from speckletracking echocardiography are unable to differentiate asymptomatic biopsy-proven cellular rejection in the first year after cardiac transplantation. J Am Soc Echocardiogr 2015; 28(4):478-85 72. Clemmensen ST, Løgstrup BB, Eiskjǽr H, Poulsen H. Changes in longitudinal myocardial deformation during acute cardiac rejection: the clinical role of two-dimensional speckletracking Echocardiography. J Am Soc Echocardiogr 2015; 28:330-9 73. Du GQ, Hsiung MC, Wu Y. et al. Three-dimensional speckle-tracking echocardiographic monitoring of acute rejection in heart transplant recipients. J Ultrasound Med. 2016;35(6):1167-76 30

74. Dandel M, Lehmkuhl H, Knosalla C, Grauhan O, Weng Y, Pasic M, Hetzer R. Echocardiographic 2D-strain imaging for early detection of patients with focal coronary stenoses after heart transplantation. J Heart Lung Transplant 2008; 27(2 Suppl1):S95-96 75. Budhe S, Richmond ME, Gilbert J, Lai WW. Longitudinal strain by speckle-tracking echocardiography in pediatric heart transplant recipients. Congenit Heart Dis 2015; 10:362-70 76. Clemmensen TS, Løgstrup BB, Eiskjær H, Poulsen SH. Evaluation of longitudinal myocardial deformation by 2-dimensional speckle-tracking echocardiography in heart transplant recipients: relation to coronary allograft vasculopathy. J Heart Lung Transplant 2015; 34(2):195-203 77. Dandel M, Wellnhofer E, Lehmkuhl H. et al. Early detection of left ventricular wall motion alterations in heart allografts with coronary artery disease: diagnostic value of tissue Doppler and two-dimensional (2D) strain echocardiography. European Journal of Echocardiography 2006; 7(Suppl.1):127-128 78. Hussein S, Dandel M, Hetzer R. Exercise echocardiography with speckle-tracking derived strain and strain-rate analysis allows detection of heart transplant recipients with focal coronary stenoses. Circulation 2014;130(Suppl 2): A 18742 79. Dandel M, Müller J, Hummel M. et al. Post-transplant cardiac rejection monitoring with and without routine biopsy screenings: comparison of two different strategies. J Am Coll Cardiol 2003; 41(6):208A 80. Urbano-Moral JA, Arias-Godinez JA, Ahmad R. et al. Evaluation of myocardial mechanics with three-dimensional speckle tracking echocardiography in heart transplant recipients: Comparison with two-dimensional speckle tracking and relationship with clinical variables European Heart Journal – Cardiovascular Imaging 2013; 14:1167-73 81. Dandel M, Konollmann F, Wellnhofer E. et al. Noninvasive strategy for early prediction of transplant coronary arteriopathy and timing of coronary angiographies in heart transplant recipients. In: Lewis B.S, Hamilton DA, Flugelmann MY, Gensini GF, eds. Frontiers in Coronary Artery Disease. Monduzzi Editore, Bologna, Italy 2003: 327-32 31

82. Raichlin E, Edwards BS, Kremers WK. et al. Acute cellular rejection and the subsequent development of allograft vasculopathy after cardiac transplantation. J Heart Lung Transplant 2009; 28:320-27 83. Jackson PA, Akosah KO, Kirchberg DJ. et al. Relationship between dobutamine-induced regional wall motion abnormalities and coronary flow reserve in heart transplant patients without angiographic coronary artery disease. J Heart Lung Transplant. 2002 ;21(10):1080-9 84. Hacker M, Hoyer HX, Uebleis C. et al. Quantitative assessment of cardiac allograft vasculopathy by real time myocardial contrast echocardiography analyses and [Tc99m]sestamibi Spect. Eur J Echocardiogr 2008; 9:494-500 85. Lund LH, Edwards LB, Kucheryavaya AY. et. al. The Registry of the International Society of Heart and Lung Transplantation: Thirty-second Official Adult Transplantation Report-2015. Focus Theme: Early Graft Failure Heart Lung Transplant 2015 34(10):1264-77

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Table 1. Diagnostic value of echocardiography for detection of left ventricular myocardial dysfunction associated with cardiac allograft vasculopathy Echocardiographic method

Standard for CAV diagnosis

2D- echocardiography at rest

Angiography*

Exercise stress echocardiography

Angiography**

Dobutamine stress echocardiography (DSE)

Angiography**

Angiography* plus IVUS

Studies

Sensitivity Specificity % %

PPV (%)

NPV (%)

Spes et al.24 Collings et al.26 Smart et al.27

14 – 58

69 – 88

44 – 86

67 - 87

Collings et al.26 Cohn et al.28 Chen et al.29

33 – 89

82 – 92

62 – 73

86 – 97

Akosah et al.37 Derumeaux et al.39 Bacal et al.36 Spes et al.24 Clerkin et al.40

0 – 100

55 – 99

0 – 69

82 – 100

Derumeaux et al.39 Spes et al.24 Stork et al.38 Herregods et al.34

50 – 86

71 – 95

86

91

Angiography*

Bharat et al.35 Sade et al.32

33 78

94 64

67 —

81 —

IVUS

Spes et al.24

79

83

88

71

32

78

87

—

—

DSE plus echo-CFR

Angiography*

Sade et al.

PW-TDI systolic parameters at rest

Angiography*

Dandel et al.20

77 – 80

89 – 90

81 – 82

88 – 93

Angiography* plus Dandel et al.20 IVUS Angiography** Dandel et al.20

89 – 90

88 – 94

92 – 97

83 – 85

51

87 - 91

63 – 65

80

42

93

78

72

60 / 63 71 / 85 71 / 77 83 / 89

84 / 87 85 / 87 97 / 98 97 / 99

55 / 58 62 / 64 90 / 95 90 / 95

85 / 87 91 / 95 91 / 93 95 / 97

88

85

—

—

2D-STE at rest

Angiography* Clemensen et al.76 peak systolic GLS$ Dandel et al. Angiography** † peak GRS / GLS peak GRSr / GLSr‡ syst.ASI§ R / L syst DSI# R / L

DSE with 2D-STE analysis

Angiography*

74,77

Eroglu et al.33

CAV = cardiac allograft vasculopathy; PPV = positive predictive value; NPV = negative predictive value; echo-CFR = echoderived coronary flow reserve; PW-TDI = pulsed-wave tissues Doppler imaging; IVUS = intravascular ultrasound; STE = speckle-tracking echocardiography; GLS = global longitudinal strain; GLSr = global longitudinal strain rate; GRS = global radial strain, GRSr = global radial strain rate; syst. ASI = systolic asynchrony index (standard deviation / mean of regional Q to peak global strain time); syst. DSI = systolic dyssynergy index. (standard deviation / mean [numerical average] of regional strain values at the end of systole; * CAV with and without focal proximal coronary artery stenoses; ** CAV with focal proximal stenoses (≥50%) in ≥1 coronary vessel; † cutoff value for GRS < 30% and for GLS < -15%; ‡ cutoff value for GRSr < 1.4/s and for GLSr < -0.9/s; § cutoff value for ASI > 20% (for both radial and longitudinal strain); # cut-off for radial strain > 15%, for longitudinal strain > 20%); $ cut-off for GLS ≤ -14%. 33

TABLE 2. Diagnostic Value of Tissue Doppler Imaging Derived Left Ventricular Systolic and Diastolic Wall Motion Velocities for Detection of Acute Rejection after Heart Transplantation TDI-derived wall motion velocity

Peak systolic velocity (S’)

Study

Evaluated patients

Clemmensen et al.72 PW-TDI*

n = 64

0.02

—

—

—

—

—

n = 363

88

94

90

93

n = 122

0.001 > 10% (↓) < 0.001 > 15% (↓)

88

93

31

99.5

n = 34

< ≥ 10% 0,001 (↓)

92

—

—

—

76

88

—

92

92

92

87

95

10

Dandel et al. PW-TDI**

Lunze et al.46 PW-TDI† Derumeaux et al.39 Peak early diastolic velocity color-coded TDI‡ (E’) Puleo et al.44 PW-TDI§

n = 121 n = 363

Dandel et al.10 PW-TDI**

No Changes Sensitivity Specificity PPV NPV AR (Cutoff) % % % % vs AR P value

< 0.16 cm/s 0.001 > 10% < (↓) 0.001

n = 78

< 13.5 cm/s 0.001

93

71

—

98

Dandel et al.10 PW-TDI**

n = 363

< > 10% 0.001 (↓)

92

94

90

95

Lunze et al.46 Peak late diastolic velocity PW-TDI† (A’)

n = 122

< > 5% (↓) 0.001

95

64

9

99.7

Peak-to-peak Mankad et al.45 mitral annular color-coded TDI# velocity (S’ + E’) Time-to-peak early diastolic velocity (TE’)

AR = acute rejection; PPV and NPV = positive and negative predictive value, respectively; TDI = tissue Doppler imaging; (↓) = reduction; PW-TDI = pulsed-wave tissue Doppler imaging; * mitral annular velocity (average of septal, lateral, anterior and posterior) cross-section analysis: no AR vs. AR grade 2R; ** basal posterior wall radial wall motion, serial assessment: no AR vs. biopsy-proven clinically relevant acute cardiac rejection; †

basal longitudinal wall motion, serial assessment in children: < 2R vs. ≥ 2R; ‡ septum

and endocardium of posterior wall serial assessment: no AR vs. biopsy-proven AR (including mild AR); § inferior wall motion, cross-section analysis: “no” AR (ISHLT 0, 1A, 1B) vs. moderate AR

34

#

posterior wall and mitral annular velocity analysis: biopsy proven “no” AR (< 1B) vs.

≥ 1B

TABLE 3. Diagnostic Value of Echocardiographic Myocardial Deformation Imaging for Detection of Acute Rejection after Heart Transplantation Deformatio n imaging methods TDI-derived strain and strain rate

Authors

Evaluated parameter s

Kato et al.63 LV systolic peak GLS Marciniak LV early diastolic peak et al.62 LSr LV (SA) systolic peak RS LV (SA) systolic peak RSr LV (LW4CV) systolic peak LS LV (LW4CV) systolic peak LSr

EM No AR Change Sensitivit Specificit PPVNPV y% % % B vs AR s y AR P value (Cutoff) % grade ≥ 1B* ≥ 1B

< 0.00 1 < 0.00 1

- 27.4% - 2.8 sec-1

82 76

82 75

36 21

97 96

≤ 30% ≤ 3.0/sec1 — —

85 80 — —

90 86 — —

80 72 — —

93 90 — —

< 0.05 < 0.00 1 < 0.05 < 0.05

35

2D speckletracking

3D speckletracking

Sato et al.64 % of LV torsion Sera et al.65 LV systolic peak GLS LV systolic Mingo66 peak GRS Santos et al. LV systolic peal GCS LV systolic peak GLS Clemmense RV free wall n et al.72 peak LS Sehgal et LV and RV al.67 systolic LS LV systolic peak GRS Ambardekar and GCS et al.71 LV systolic (Velocity peak GLS Vector LV systolic Imaging peak LS software) LV systolic Ruiz Ortiz peak RS et al.70 LV systolic 73 peak CS and Du et al. CSr LV systolic peak GLS and GLSr LV systolic CS and CSr LV diastolic LSr and CSr LV systolic average RS LV systolic peak GLS LV systolic peak RS and CS

≥ 2R ≥ 1B*

≥ 2R

≥ 2R ≥ 2R

≤ 2R**

2R ≥ 1B†

< 0.00 1 < 0.0 5 > 0.05 > 0.05 < 0.00 1 < 0.00 1 < 0.00 1 > 0.05 < 0.00 1

25% decrease < -14.8% — — < -15.5% < -17% < -17% ; < -15.5% — — — — — — — — < 25%

74

95

60

97

64 — —

63 — —

24 — —

90 — —

86 86 100 —

81 91 77 —

25 43 26 —

99 99 100 —

—

—

—

—

— — —

— — —

— — —

— — —

— — —

— — —

— — —

— — —

100

48

6

100

87.5 —

54 —

— —

— —

< - 9.6% —

0.05 < 0.05 < 0.01 > 0.05 > 0.05 > 0.05 0.00 1 < 0.0 5 > 0.05

PPV = positive predictive value; NPV = negative predictive value; GLS = global longitudinal strain; LSr = longitudinal strain rate; GLSr = global longitudinal strain; RS = radial strain; GRS = global radial strain; GCS = global circumferential strain; CS = circumferential strain, CSr = circumferential strain rate; IV = interventricular; SA = short axis view; LW = lateral wall; 4CV = 4 chamber view; * significant in both univariate and multivariate analyses; ** asymptomatic AR; † AR ≥1B: n = 8

36

A

B

PGRS PGRS

TPS

D

C

PGCS PGCS

Figure 1. Speckle-tracking-derived strain alterations at basal LV myocardial wall segments (parasternal short-axis views) during histological mild (1R) acute rejection (AR) in two different heart-transplanted patients without LV ejection fraction alterations AR. A: Normal radial strain (RS) pattern before AR. The mean value of end-systolic maximum myocardial thickening in the 6 evaluated wall segments, which represents the peak global radial strain (PGRS), reached 34%. B: RS alterations before histological confirmation of AR. PGRS reduction (from 34% to 17%) and prolongation of the time-to-peak radial strain (TPS) without relevant asynchrony and dyssynergy of contraction and relaxation indicate a global worsening of LV function. C: Normal circumferential strain (CS) pattern in another patient recorded before AR. The mean value of end-systolic maximum myocardial circumferential shortening in the 6 evaluated wall segments which represents the peak global circumferential strain (PGCS) reached -19.8%. D: PGCS reduction from -19.8% to -8.8%, prolongation of TPS and no relevant changes in CS synchrony and synergy in the 6 wall segments, indicate a global worsening LV function.

37

D

PGCS

PGCS

E

B

PGLS

PGLS

F

C

20% to 26%, the peak global circumferential strain (PGCS) from -9% to -20% and the peak global longitudinal strain (PGLS) from -9.5% to -16%. 38

after methylprednisolone therapy (0.5g intravenously for 3 days) in a patient with histological mild acute rejection. The peak global radial strain (PGRS) increased from

Figure 2. Normalization of rejection-induced alterations in speckle-tracking derived radial (A and D), circumferential (B and E) and longitudinal strain pattern (C and F)

PGRS

PGRS

A

PGRS

PRS

B AW

AW

AW-PRS

PW -PRS PRSPPRS

C

a compensatory increase systolic thickening with a PRS of 48%.

39

In the ischemic anterior wall (AW) the peak radial strain (PRS) reaches only 18% and the strain curve also shows a delayed relaxation. The posterior wall (PW) shows

C: Striking difference between the anterior wall (AW) and posterior wall (PW) RS values in a patient with a >50% stenosis of the left anterior descending coronary artery.

CAV (Type B lesions without proximal stenoses of the great epicardial coronary arteries).

B: Uniform LV myocardial systolic thickening and diastolic thinning with low PGRS (only 20%) and increased time to peak strain (TPS) in a patient with angiographic diffuse

(PGRS), which represents the end-systolic maximum radial wall thickening, reached 40%.

A: Uniform myocardial systolic thickening and diastolic thinning in the 6 evaluated wall segments in a patient with normal coronary angiogram. The peak global radial strain

patients with different angiographic results. In all three patients the LV ejection fraction was in the normal range an acute rejection was excluded by endomyocardial biopsy.

Figure 3. Left ventricular (LV) speckle-tracking derived radial strain (RS) recordings (parasternal short-axis views) obtained at rest in three asymptomatic heart-transplanted

PGRS

A