Aortic Stiffness

JACC VOL. 66, NO. 13, 2015

Letters

SEPTEMBER 29, 2015:1516–23

2. Biner S, Rafique A, Rafii F, et al. Reproducibility of proximal isovelocity surface area, vena contracta, and regurgitant jet area for assessment of mitral regurgitation severity. J Am Coll Cardiol Img 2010;3:235–43. 3. Nishimura RA, Otto CM, Bonow RO, et al., American College of Cardiology; American College of Cardiology/American Heart Association; American Heart Association. 2014 AHA/ACC guideline for the management of patients with valvular heart disease: a report of the American College of Cardiology/ American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2014;63:2438–88.

2 relatively common conditions: mild MR and restrictive cardiomyopathy. A patient with symptomatic restrictive cardiomyopathy and mild MR that is mistakenly graded as severe by echocardiography is at high risk of undergoing inappropriate surgery. In summary, we believe echocardiographers should use all information available to them, including LV size, to determine MR severity. However, given the potential inaccuracy of echocardiography, and the cost

REPLY: Left Ventricular Size Is Critical for

and complications of open heart surgery, we are

the Echocardiographic Assessment of

steadfast in our conclusion that cardiac MRI should be

Chronic Severe Mitral Regurgitation

a strong consideration when important clinical decisions are being made based on MR severity, even in

We read with interest the letter by Drs. Rafique and

the presence of symptoms.

Siegel, and thank them for their comments. In our uses the additional criterion of a left ventricular end-

Seth Uretsky, MD *Steven D. Wolff, MD, PhD

diastolic dimension (LVEDD) $55 mm, concordance

*Carnegie Hill Radiology

between echocardiography and magnetic resonance

170 East 77th Street

imaging (MRI) improves from 32% to 58%. They

New York, New York 10075

conclude LVEDD should be a key parameter in the

E-mail: [email protected]

echocardiographic

http://dx.doi.org/10.1016/j.jacc.2015.06.1341

subpopulation of surgical patients, they show if one

assessment

of

chronic

mitral

regurgitation (MR). It is well accepted that chronic MR causes an increase in LV size. We previously used this important relationship to validate the accuracy of MRI for quantifying regurgitant volume (1). We showed a tight coupling between MR regurgitant volume and LV enddiastolic volume (r 2 ¼ 0.8), but this study was limited to patients with isolated, primary MR. Using LV size as an additional criterion may improve the accuracy of echocardiography in a population of patients, but it is no substitute for the accurate determination of MR severity in an individual patient. This is because many other common diseases

Please note: Dr. Wolff is the owner of NeoSoft, LLC, and NeoCoil, LLC, medical device companies that make software and hardware for use with magnetic resonance imaging. Dr. Uretsky has reported that he has no relationships relevant to the contents of this paper to disclose. Helmut Baumgartner, MD, served as Guest Editor for this paper.

REFERENCES 1. Uretsky S, Supariwala A, Nidadovolu P, et al. Quantification of left ventricular remodeling in response to isolated aortic or mitral regurgitation. J Cardiovasc Magn Reson 2010;12:32–8. 2. Uretsky S, Gillam L, Lang R, et al. Discordance between echocardiography and MRI in the assessment of mitral regurgitation severity: a prospective multicenter trial. J Am Coll Cardiol 2015;65:1078–88. 3. Gillam LD, Schwartz A. Primum non nocere: the case for watchful waiting in asymptomatic “severe” degenerative mitral regurgitation. Circulation 2010; 121:813–21. discussion 821.

and conditions affect LV size. Myocardial infarction, nonischemic cardiomyopathy, and athletic heart can substantially increase LV size without increasing MR. Similarly, diseases such as restrictive cardiomyopathy and aortic stenosis can substantially decrease LV size without decreasing MR. Table 4 shows the limi-

Aortic Stiffness Complex Evaluation But Major Prognostic Significance Before TAVR

tations of using LVEDD as a criterion for MR severity (2). For example, patient #29 had an LVEDD of 62 mm,

We read with great interest the paper by Yotti et al.

yet had mild MR, and patient #38 had an LVEDD of

(1) regarding vascular load and transcatheter aortic

53 mm, yet had severe MR.

valve replacement (TAVR). This study underlines the

Using LV size as a surrogate to avoid overestimation

interaction between valvular and vascular functions

of MR severity is similar to the strategy advocated by

in patients with aortic stenosis (AS). The authors

some, to delay surgery until patients are symptomatic.

highlighted the increase of vascular load after TAVR,

The thought being that the presence of symptoms

which limits the afterload relief acutely and may

avoids the possibility of inappropriate surgery in MR

endanger the cardiovascular prognosis later on.

patients that are mistakenly graded as severe (3).

Although no outcome data were available in this

However, as is the case with using any surrogate, a

study, we recently confirmed this prognostic impact

potential problem is the possibility of confounding

by assessing the significance of ascending aortic cal-

illnesses, especially when they are common. Consider

cifications (AAC)—a surrogate of stiffness measured

1521

1522

JACC VOL. 66, NO. 13, 2015

Letters

SEPTEMBER 29, 2015:1516–23

by computed tomography—on cardiovascular events

elaborates on the clinical relevance that systemic

after TAVR (2). An impaired survival was clearly evi-

vascular load may have in patients with aortic ste-

denced in patients with a calcified aorta indepen-

nosis (AS) undergoing valve replacement. In this re-

dently of usual confounders.

gard, we would like to emphasize that our study was

The study by Yotti et al. (1) also suggests that the

designed to address specifically the impact of the

usual tools would be unable to assess vascular

stenotic valve on measurements of vascular load. For

impedance while the aorta is unloaded because of AS.

this purpose, we combined state-of-the-art mea-

It is rather challenging to separate valvular and

surement and signal-processing techniques with the

vascular functions (3) and evidently, although very

mechanistic model of acute relief of the valvular load

accurate, the approach used by Yotti et al. (1) could

provided by transcatheter aortic valve replacement

not be used routinely. Quantifying AAC on the sys-

(TAVR). Albeit limited to a small sample size, we

tematic pre-TAVR computed tomography is an easy

provided ancillary follow-up data suggesting a po-

way to estimate aortic stiffness that should be more

tential link between the acute vascular changes

appropriate in the presence of AS because it is pres-

and the clinical functional improvement after the

sure independent.

intervention (2). This should be interpreted only as

We would like to emphasize the critical role of

a hypothesis-driven finding, which must be con-

vascular load after TAVR while it is currently

firmed in a large clinical cohort. However, the highly

neglected. This deserves, to our view, implementing

sophisticated methods we used in our study are

a simple stiffness index (e.g., AAC), in the pre-TAVR

obviously nonsuitable for this purpose.

work-up. On top of being a stratifying variable that

Systemic arterial compliance can be accurately

should be considered to refine the medical decision,

approximated noninvasively using echocardiography

high vascular load represents a potential avenue for

and sphygmomanometry in patients without AS (3),

new destiffening strategies and prompts us to target

and has proved to be a very powerful predictor of

high blood pressure.

cardiovascular events in a number of populations. Data from our study (2) validates the noninvasive

*Brahim Harbaoui, MD Pierre-Yves Courand, MD Nicolas Girerd, MD, PhD Pierre Lantelme, MD, PhD

surrogate of systemic arterial compliance in patients

*Cardiology Department

n ¼ 46 pooled pre- and post-TAVR data). Alternative

Hôpital de la Croix-Rousse

indices based on tonometry (4) and ultrasound-

103 Grande Rue de la Croix-Rousse

based wave-intensity analyses (5) are also proven

69004 Lyon

predictors of cardiovascular events, but have not

France

been validated in the presence of AS. Quantifying the

E-mail: [email protected]

degree of ascending aortic calcification as proposed

http://dx.doi.org/10.1016/j.jacc.2015.06.1342

by Harbaoui et al. is an interesting surrogate of

Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

arterial stiffness because it is particularly well suited

REFERENCES 1. Yotti R, Bermejo J, Gutierrez-Ibanes E, et al. Systemic vascular load in calcific degenerative aortic valve stenosis: insight from percutaneous valve replacement. J Am Coll Cardiol 2015;65:423–33.

with AS (intraclass correlation coefficient ¼ 0.82 and 0.80 vs. the gold-standard invasive exponential decay and the diastolic area methods, respectively;

to fit in the screening workflow of patients considered for valve replacement, but more evidence supporting its clinical value is needed. We believe the results of our findings suggest that metrics of vascular load should be incorporated

2. Harbaoui B, Courand PY, Charles P, Lantelme P. Aortic calcifications present the next challenge after TAVR. J Am Coll Cardiol 2015;65:1058–60.

to optimize patient periprocedural management.

3. Garcia D, Barenbrug PJ, Pibarot P, et al. A ventricular-vascular coupling model in presence of aortic stenosis. Am J Physiol Heart Circ Physiol 2005;

the prognostic value of measuring the ventricular-

288:H1874–84.

Long-term prospective studies will finally establish vascular interaction before and after valve interventions. Particularly important is to clarify the confusion caused by diastolic dysfunction, kidney

REPLY: Aortic Stiffness

disease, age, and coronary artery disease, amongst

Complex Evaluation But Major Prognostic Significance

other highly prevalent conditions in patients with AS.

Before TAVR

Only when such information becomes available it shall be possible to establish how indices of vascular load

We very much appreciate the interest of Dr. Harbaoui

may aid selecting the best management strategy for

and colleagues in our work (1). Their letter further

patients with AS.