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Evaluation of Diffuse Myocardial Fibrosis in Heart Failure with Cardiac Magnetic Resonance Contrast-enhanced T1 Mapping
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Abstracts
Heart, Lung and Circulation 2008;17S:S1–S209
ABSTRACTS
usual management-including serial cardiac biomarkers and either exercise stress testing or myocardial perfusion scanning (if biomarkers were negative). Invasive coronary angiography was performed if either biomarkers or functional study were abnormal. Results: 50 patients (mean age 58.2 years, 32 male) were assessed. 3/50 were reclassified as high risk acute coronary syndrome (ACS) with positive Troponin I measured at 6 h. 47/50 had a non-cardiac cause of chest pain or low risk ACS as a final diagnosis. Of the three cases with high risk ACS, CTCA demonstrated one had obstructive disease (>70% stenosis), one had moderate disease (50–70% stenosis) and one had mild disease (<50% stenosis). These findings were confirmed by invasive angiography. Of those with noncardiac chest pain or low risk ACS 15/47 had no disease, 28/47 had mild disease, 3/47 had moderate disease and 1/47 had obstructive disease on CTCA. Conclusions: Dual source CTCA is useful in the assessment of patients with intermediate risk acute chest pain. CT coronary angiography showed good correlation with invasive angiographic findings in those with high risk ACS. In those with non-cardiac diagnosis or low risk ACS there is a significant rate of coronary artery disease identified. doi:10.1016/j.hlc.2008.05.136 136 Two-Dimensional Estimation of Left and Right Ventricular Size and Function—Comparison with Cardiac Magnetic Resonance Imaging Volumetric Analysis Heinz Pfluger 1,∗ , Andre LaGerche 2 , Micha Maeder 1 , Andrew Taylor 1 1 Alfred Hospital Heart Centre and Baker Heart Research Insti-
tute, Melbourne, Australia; Australia
2 St Vincent’s Hospital, Melbourne,
Background: Two-dimensional estimations of left ventricular (LV) and right ventricular (RV) size and function are commonly used for clinical and research indications. However, correlation of two-dimensional estimates with established volumetric analysis methods has not been assessed. Methods: We analysed a random selection (n = 30) of subjects undergoing CMR. Contiguous short axis cine imaging was obtained to assess right and left ventricular volumes and function by volumetric summation-of-disc method. Standard short- and long-axis cine imaging were performed to evaluate linear and planimetric dimensions as well as single (RV) and biplane (LV) functional analysis. Correlation between geometric dimensions and the standard volumetric measurements were analysed. Results: Different linear and planimetric measurements of the RV in standard long and short axis views correlated weakly with standard volumetric measurements (r = 0.34–0.73). RV ejection fraction (EF), when calculated from four-chamber long-axis view by expressing the difference between the RV end-diastolic area and RV end-
systolic area over the RV end-diastolic area, correlated only moderately with the volumetric EF (r = 0.75, p < 0.001). In contrast, estimation of LV volumes, mass and EF by biplane area-length method demonstrated excellent correlation to volumetric data (r = 0.89, 0.92 and 0.91, p < 0.001 for all). Conclusion: Two-dimensional estimations of volume and function correlate well with LV volumetric analysis, but not with RV volumetric analysis. Therefore, estimation of RV size and function based on linear or planimetric assumption models are not reliable, and existing reference values should be interpreted with caution. doi:10.1016/j.hlc.2008.05.137 137 Evaluation of Diffuse Myocardial Fibrosis in Heart Failure with Cardiac Magnetic Resonance Contrast-enhanced T1 Mapping Leah Iles 1,∗ , Heinz Pfluger 1 , Arintaya Phrommintikul 1 , Joshi Cherayath 2 , Pelin Aksit 3 , Sandeep Gupta 3 , David Kaye 1 , Andrew Taylor 1 1 The
Alfred and Baker Heart Research Institute, Melbourne, VIC, Australia; 2 GE Healthcare, Melbourne, VIC, Australia; 3 Global Applied Science Laboratory, GE Healthcare, Bethesda, MD, United States Objective: To investigate a non-invasive method for quantifying diffuse myocardial fibrosis with cardiovascular magnetic resonance imaging (CMR). Background: Diffuse myocardial fibrosis is a fundamental process in pathological remodelling in cardiomyopathy, causing increased cardiac stiffness and poor clinical outcomes. Whilst regional fibrosis is easily imaged with CMR, there is currently no non-invasive method for quantifying diffuse myocardial fibrosis. Methods: We performed CMR on 45 subjects (25 with heart failure, 20 controls), on a clinical 1.5 T CMR scanner. A prototype T1 mapping sequence was used to calculate the post-contrast myocardial T1 time as an index of diffuse fibrosis, whilst regional fibrosis was identified by delayed contrast enhancement. Regional and global systolic function was assessed by CMR cine imaging in standard shortand long-axis planes, with echocardiography used to evaluate diastology. An additional nine subjects underwent CMR and endomyocardial biopsy for histological correlation. Results: Post-contrast myocardial T1 times correlated histologically with fibrosis (R = −0.7, p = 0.03) and were shorter in heart failure subjects than controls (383 ± 17 ms vs. 564 ± 23 ms, P < 0.0001). The T1 time of heart failure myocardium was shorter than controls even when excluding areas of regional fibrosis (429 ± 22 ms vs. 564 ± 23 ms, P < 0.0001). The post-contrast myocardial T1 time shortened as diastolic function worsened (562 ± 24 ms in normal diastolic function vs. 423 ± 33 ms in impaired diastolic function vs. 368 ± 20 ms in restrictive function, P < 0.001). Conclusion: Contrast-enhanced CMR T1 mapping identifies changes in myocardial T1 times in heart failure,
Abstracts
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reflecting diffuse fibrosis, which are associated with worsening of diastolic function.
139 A Comparison of Left Atrial Volumes on Transthoracic Echo and Cardiac CT Angiography
doi:10.1016/j.hlc.2008.05.138
Camilla Wainwright ∗ , Rohan Poulter, Melanie Fuentes, Ada Lo, Mark Dooris, John F. Younger
138 Assessment of Pulmonary Vein Velocity in Patients with Atrial Fibrillation Using Cardiac Magnetic Resonance Imaging Payman Molaee ∗ , Pawel Kuklik, Darryl P. Leong, Benjamin K. Dundon, Michael Stokes, Bobby John, Martin K. Stiles, Dennis H. Lau, Hany Dimitri, Karen S.L. Teo, Glenn D. Young, Rae Duncan, Michael Leung, Angelo Carbone, Cynthia Piantadosi, Gary Liew, Prashanthan Sanders, Stephen G. Worthley Royal Adelaide Hospital, Adelaide, Australia Introduction: Pulmonary vein (PV) velocity measurements provide information on phasic left atrial (LA) function. Echocardiography is limited in the assessment of LA function by acoustic windows and inter-observer variability. We assessed the feasibility of cardiac magnetic resonance imaging (CMR) as a non-invasive means of evaluating atrial function by determining PV flow in patients with atrial fibrillation (AF). Methods: Twenty-seven patients with symptomatic drugrefractory AF undergoing ablation had CMR (1.5 T Siemens Sonata system) pre-ablation. The PV anatomy was defined using gadolinium contrast and multiplanar reconstructions. Through-plane velocity measurements within the PVs were performed using phase contrast MRI, with a velocity range of −79 to 79 cm/s. Time–velocity curves were constructed for each of the PVs. Results are presented as mean ± S.D. Results: Twenty patients had paroxysmal and seven had persistent AF. Mean age was 59.9 ± 9.6 years. Four patients had a left common PV, one had a right middle PV and one had a right common PV. Flow was assessable in 90% of the PVs. The S velocity was 31.0 ± 6.3 cm/s, the D velocity was 23.7 ± 4.5 cm/s, and the AR velocity was 7.0 ± 3.1 cm/s. There were no significant differences between those with paroxysmal and persistent AF. The mean LAEF was 38.1 ± 10.9% and correlated with the S wave (r = 0.59, P = 0.001), but did not correlate with the AR wave (r = −0.15, P = 0.45) or D wave (r = −0.05, P = 0.8). Conclusion: PV flow allows evaluation of dynamic atrial function. CMR provides a novel non-invasive modality for evaluating serial atrial function after catheter ablation of AF. doi:10.1016/j.hlc.2008.05.139
Royal Brisbane and Women’s Hospital, Brisbane, QLD, Australia Background: Left atrial volume (LAV), assessed by twodimensional echocardiography, is an important prognostic indicator in patients with cardiovascular disease. The volume is routinely calculated from the apical views using an area–length formula or ellipsoid method. Cardiac computed tomography angiography (CTA) permits visualization of the LA and assessment of LAV using similar methods. The relationship between measurements obtained with CTA and echocardiography has not been defined. Aims: To establish the relationship between LAV measurements as assessed by TTE and by CTA. Methods: The scans of 20 patients (14 M, 6 F, 63 ± 9 years) undergoing CTA and TTE were retrospectively analyzed. For echo and CT, the LAV was calculated using the area-length formula [LA.vol = (0.85 × A1 × A2)/L] and the ellipsoid model [LA.vol = (D1 × D2 × D3) × 0.523], indexed to body surface area. Results: Calculated LAVs (mean ± S.D., range; ml/m2 ) were 30 ± 12 (15,57) [echo ellipsoid], 41 ± 14 (18,68) [echo area–length], 32 ± 12 (17,61) [CT ellipsoid] and 52 ± 16 (27,113) [CT area–length]. Estimated volumes using the ellipsoid model did not differ significantly between CT and echo (mean difference ± S.E.M. 2 ± 2 ml/m2 , p = 0.4). The two CT measures showed much better agreement (r = 0.89, p < 0.001) than did the two echo measures (r = 0.62, p = 0.03). CTA derived volumes using the area–length model were larger than echo volumes (mean difference ± S.E.M. 11 ± 3 ml/m2 , p < 0.0001), and this appeared to be a systematic difference with the two modalities showing good correlation overall (r = 0.63, p = 0.001). Conclusions: Left atrial volume can be assessed with CTA in a manner similar to echocardiography. Knowledge of the relationship between CTA and echo measures may allow accurate reporting of LAV after CTA. doi:10.1016/j.hlc.2008.05.140 140 Reduction in Left Atrial Volume Following Percutaneous Transluminal Septal Myocardial Ablation for Severe Hypertrophic Obstructive Cardiomyopathy Wai-ee Thai ∗ , Stuart Moir, Ian Meredith, Catherine Mylrea, Philip Mottram Monash Cardiovascular Research Centre, MonashHEART, Southern Health & Department of Medicine (MMC), Monash University, Melbourne, Victoria, Australia Background: Left atrial (LA) dilatation reflects chronic elevation of LA pressure and independently predicts clinical outcomes in a wide range of cardiovascular disorders.
ABSTRACTS
Heart, Lung and Circulation 2008;17S:S1–S209
Abstracts
Heart, Lung and Circulation 2008;17S:S1–S209
ABSTRACTS
usual management-including serial cardiac biomarkers and either exercise stress testing or myocardial perfusion scanning (if biomarkers were negative). Invasive coronary angiography was performed if either biomarkers or functional study were abnormal. Results: 50 patients (mean age 58.2 years, 32 male) were assessed. 3/50 were reclassified as high risk acute coronary syndrome (ACS) with positive Troponin I measured at 6 h. 47/50 had a non-cardiac cause of chest pain or low risk ACS as a final diagnosis. Of the three cases with high risk ACS, CTCA demonstrated one had obstructive disease (>70% stenosis), one had moderate disease (50–70% stenosis) and one had mild disease (<50% stenosis). These findings were confirmed by invasive angiography. Of those with noncardiac chest pain or low risk ACS 15/47 had no disease, 28/47 had mild disease, 3/47 had moderate disease and 1/47 had obstructive disease on CTCA. Conclusions: Dual source CTCA is useful in the assessment of patients with intermediate risk acute chest pain. CT coronary angiography showed good correlation with invasive angiographic findings in those with high risk ACS. In those with non-cardiac diagnosis or low risk ACS there is a significant rate of coronary artery disease identified. doi:10.1016/j.hlc.2008.05.136 136 Two-Dimensional Estimation of Left and Right Ventricular Size and Function—Comparison with Cardiac Magnetic Resonance Imaging Volumetric Analysis Heinz Pfluger 1,∗ , Andre LaGerche 2 , Micha Maeder 1 , Andrew Taylor 1 1 Alfred Hospital Heart Centre and Baker Heart Research Insti-
tute, Melbourne, Australia; Australia
2 St Vincent’s Hospital, Melbourne,
Background: Two-dimensional estimations of left ventricular (LV) and right ventricular (RV) size and function are commonly used for clinical and research indications. However, correlation of two-dimensional estimates with established volumetric analysis methods has not been assessed. Methods: We analysed a random selection (n = 30) of subjects undergoing CMR. Contiguous short axis cine imaging was obtained to assess right and left ventricular volumes and function by volumetric summation-of-disc method. Standard short- and long-axis cine imaging were performed to evaluate linear and planimetric dimensions as well as single (RV) and biplane (LV) functional analysis. Correlation between geometric dimensions and the standard volumetric measurements were analysed. Results: Different linear and planimetric measurements of the RV in standard long and short axis views correlated weakly with standard volumetric measurements (r = 0.34–0.73). RV ejection fraction (EF), when calculated from four-chamber long-axis view by expressing the difference between the RV end-diastolic area and RV end-
systolic area over the RV end-diastolic area, correlated only moderately with the volumetric EF (r = 0.75, p < 0.001). In contrast, estimation of LV volumes, mass and EF by biplane area-length method demonstrated excellent correlation to volumetric data (r = 0.89, 0.92 and 0.91, p < 0.001 for all). Conclusion: Two-dimensional estimations of volume and function correlate well with LV volumetric analysis, but not with RV volumetric analysis. Therefore, estimation of RV size and function based on linear or planimetric assumption models are not reliable, and existing reference values should be interpreted with caution. doi:10.1016/j.hlc.2008.05.137 137 Evaluation of Diffuse Myocardial Fibrosis in Heart Failure with Cardiac Magnetic Resonance Contrast-enhanced T1 Mapping Leah Iles 1,∗ , Heinz Pfluger 1 , Arintaya Phrommintikul 1 , Joshi Cherayath 2 , Pelin Aksit 3 , Sandeep Gupta 3 , David Kaye 1 , Andrew Taylor 1 1 The
Alfred and Baker Heart Research Institute, Melbourne, VIC, Australia; 2 GE Healthcare, Melbourne, VIC, Australia; 3 Global Applied Science Laboratory, GE Healthcare, Bethesda, MD, United States Objective: To investigate a non-invasive method for quantifying diffuse myocardial fibrosis with cardiovascular magnetic resonance imaging (CMR). Background: Diffuse myocardial fibrosis is a fundamental process in pathological remodelling in cardiomyopathy, causing increased cardiac stiffness and poor clinical outcomes. Whilst regional fibrosis is easily imaged with CMR, there is currently no non-invasive method for quantifying diffuse myocardial fibrosis. Methods: We performed CMR on 45 subjects (25 with heart failure, 20 controls), on a clinical 1.5 T CMR scanner. A prototype T1 mapping sequence was used to calculate the post-contrast myocardial T1 time as an index of diffuse fibrosis, whilst regional fibrosis was identified by delayed contrast enhancement. Regional and global systolic function was assessed by CMR cine imaging in standard shortand long-axis planes, with echocardiography used to evaluate diastology. An additional nine subjects underwent CMR and endomyocardial biopsy for histological correlation. Results: Post-contrast myocardial T1 times correlated histologically with fibrosis (R = −0.7, p = 0.03) and were shorter in heart failure subjects than controls (383 ± 17 ms vs. 564 ± 23 ms, P < 0.0001). The T1 time of heart failure myocardium was shorter than controls even when excluding areas of regional fibrosis (429 ± 22 ms vs. 564 ± 23 ms, P < 0.0001). The post-contrast myocardial T1 time shortened as diastolic function worsened (562 ± 24 ms in normal diastolic function vs. 423 ± 33 ms in impaired diastolic function vs. 368 ± 20 ms in restrictive function, P < 0.001). Conclusion: Contrast-enhanced CMR T1 mapping identifies changes in myocardial T1 times in heart failure,
Abstracts
S61
reflecting diffuse fibrosis, which are associated with worsening of diastolic function.
139 A Comparison of Left Atrial Volumes on Transthoracic Echo and Cardiac CT Angiography
doi:10.1016/j.hlc.2008.05.138
Camilla Wainwright ∗ , Rohan Poulter, Melanie Fuentes, Ada Lo, Mark Dooris, John F. Younger
138 Assessment of Pulmonary Vein Velocity in Patients with Atrial Fibrillation Using Cardiac Magnetic Resonance Imaging Payman Molaee ∗ , Pawel Kuklik, Darryl P. Leong, Benjamin K. Dundon, Michael Stokes, Bobby John, Martin K. Stiles, Dennis H. Lau, Hany Dimitri, Karen S.L. Teo, Glenn D. Young, Rae Duncan, Michael Leung, Angelo Carbone, Cynthia Piantadosi, Gary Liew, Prashanthan Sanders, Stephen G. Worthley Royal Adelaide Hospital, Adelaide, Australia Introduction: Pulmonary vein (PV) velocity measurements provide information on phasic left atrial (LA) function. Echocardiography is limited in the assessment of LA function by acoustic windows and inter-observer variability. We assessed the feasibility of cardiac magnetic resonance imaging (CMR) as a non-invasive means of evaluating atrial function by determining PV flow in patients with atrial fibrillation (AF). Methods: Twenty-seven patients with symptomatic drugrefractory AF undergoing ablation had CMR (1.5 T Siemens Sonata system) pre-ablation. The PV anatomy was defined using gadolinium contrast and multiplanar reconstructions. Through-plane velocity measurements within the PVs were performed using phase contrast MRI, with a velocity range of −79 to 79 cm/s. Time–velocity curves were constructed for each of the PVs. Results are presented as mean ± S.D. Results: Twenty patients had paroxysmal and seven had persistent AF. Mean age was 59.9 ± 9.6 years. Four patients had a left common PV, one had a right middle PV and one had a right common PV. Flow was assessable in 90% of the PVs. The S velocity was 31.0 ± 6.3 cm/s, the D velocity was 23.7 ± 4.5 cm/s, and the AR velocity was 7.0 ± 3.1 cm/s. There were no significant differences between those with paroxysmal and persistent AF. The mean LAEF was 38.1 ± 10.9% and correlated with the S wave (r = 0.59, P = 0.001), but did not correlate with the AR wave (r = −0.15, P = 0.45) or D wave (r = −0.05, P = 0.8). Conclusion: PV flow allows evaluation of dynamic atrial function. CMR provides a novel non-invasive modality for evaluating serial atrial function after catheter ablation of AF. doi:10.1016/j.hlc.2008.05.139
Royal Brisbane and Women’s Hospital, Brisbane, QLD, Australia Background: Left atrial volume (LAV), assessed by twodimensional echocardiography, is an important prognostic indicator in patients with cardiovascular disease. The volume is routinely calculated from the apical views using an area–length formula or ellipsoid method. Cardiac computed tomography angiography (CTA) permits visualization of the LA and assessment of LAV using similar methods. The relationship between measurements obtained with CTA and echocardiography has not been defined. Aims: To establish the relationship between LAV measurements as assessed by TTE and by CTA. Methods: The scans of 20 patients (14 M, 6 F, 63 ± 9 years) undergoing CTA and TTE were retrospectively analyzed. For echo and CT, the LAV was calculated using the area-length formula [LA.vol = (0.85 × A1 × A2)/L] and the ellipsoid model [LA.vol = (D1 × D2 × D3) × 0.523], indexed to body surface area. Results: Calculated LAVs (mean ± S.D., range; ml/m2 ) were 30 ± 12 (15,57) [echo ellipsoid], 41 ± 14 (18,68) [echo area–length], 32 ± 12 (17,61) [CT ellipsoid] and 52 ± 16 (27,113) [CT area–length]. Estimated volumes using the ellipsoid model did not differ significantly between CT and echo (mean difference ± S.E.M. 2 ± 2 ml/m2 , p = 0.4). The two CT measures showed much better agreement (r = 0.89, p < 0.001) than did the two echo measures (r = 0.62, p = 0.03). CTA derived volumes using the area–length model were larger than echo volumes (mean difference ± S.E.M. 11 ± 3 ml/m2 , p < 0.0001), and this appeared to be a systematic difference with the two modalities showing good correlation overall (r = 0.63, p = 0.001). Conclusions: Left atrial volume can be assessed with CTA in a manner similar to echocardiography. Knowledge of the relationship between CTA and echo measures may allow accurate reporting of LAV after CTA. doi:10.1016/j.hlc.2008.05.140 140 Reduction in Left Atrial Volume Following Percutaneous Transluminal Septal Myocardial Ablation for Severe Hypertrophic Obstructive Cardiomyopathy Wai-ee Thai ∗ , Stuart Moir, Ian Meredith, Catherine Mylrea, Philip Mottram Monash Cardiovascular Research Centre, MonashHEART, Southern Health & Department of Medicine (MMC), Monash University, Melbourne, Victoria, Australia Background: Left atrial (LA) dilatation reflects chronic elevation of LA pressure and independently predicts clinical outcomes in a wide range of cardiovascular disorders.
ABSTRACTS
Heart, Lung and Circulation 2008;17S:S1–S209