Mitral Apparatus Assessment by Delayed Enhancement CMR

• Published in: JACC. Cardiovascular imaging Vol. 6; no. 2; pp. 220 - 234
• Main Authors: Chinitz, Jason S., MD, Chen, Debbie, BA, Goyal, Parag, MD, Wilson, Sean, MD, Islam, Fahmida, BA, Nguyen, Thanh, PhD, Wang, Yi, PhD, Hurtado-Rua, Sandra, PhD, Simprini, Lauren, MD, Cham, Matthew, MD, Levine, Robert A., MD, Devereux, Richard B., MD, Weinsaft, Jonathan W., MD
• Format: Journal Article
• Language: English
• Published: 01.02.2013
• Subjects: Cardiovascular; LCX; DE; myocardial infarction; echocardiography; LV; odds ratio; 2-dimensional; 2D; left anterior descending artery; regurgitant fraction; left circumflex; left ventricular; AMI; 3-dimensional; OR; mitral regurgitation; Echo; MR; CI; CMR; PMI; LAD; right coronary artery; RCA; 3D; delayed-enhanced; RF; papillary muscle infarction; confidence interval; cardiac magnetic resonance; acute myocardial infarction
• ISSN: 1936-878X
• DOI: 10.1016/j.jcmg.2012.08.016

Objectives This study sought to assess patterns and functional consequences of mitral apparatus infarction after acute myocardial infarction (AMI). Background The mitral apparatus contains 2 myocardial components: papillary muscles and the adjacent left ventricular (LV) wall. Delayed-enhancement cardiac magnetic resonance (DE-CMR) enables in vivo study of inter-relationships and potential contributions of LV wall and papillary muscle infarction (PMI) to mitral regurgitation (MR). Methods Multimodality imaging was performed: CMR was used to assess mitral geometry and infarct pattern, including 3D DE-CMR for PMI. Echocardiography was used to measure MR. Imaging occurred 27 ± 8 days after AMI (CMR, echocardiography within 1 day). Results A total of 153 patients with first AMI were studied; PMI was present in 30% (n = 46 [72% posteromedial, 39% anterolateral]). When stratified by angiographic culprit vessel, PMI occurred in 65% of patients with left circumflex, 48% with right coronary, and only 14% of patients with left anterior descending infarctions (p <0.001). Patients with PMI had more advanced remodeling as measured by LV size and mitral annular diameter (p <0.05). Increased extent of PMI was accompanied by a stepwise increase in mean infarct transmurality within regional LV segments underlying each papillary muscle (p <0.001). Prevalence of lateral wall infarction was 3-fold higher among patients with PMI compared to patients without PMI (65% vs. 22%, p <0.001). Infarct distribution also impacted MR, with greater MR among patients with lateral wall infarction (p = 0.002). Conversely, MR severity did not differ on the basis of presence (p = 0.19) or extent (p = 0.12) of PMI, or by angiographic culprit vessel. In multivariable analysis, lateral wall infarct size (odds ratio 1.20/% LV myocardium [95% confidence interval: 1.05 to 1.39], p = 0.01) was independently associated with substantial (moderate or greater) MR even after controlling for mitral annular (odds ratio 1.22/mm [1.04 to 1.43], p = 0.01), and LV end-diastolic diameter (odds ratio 1.11/mm [0.99 to 1.23], p = 0.056). Conclusions Papillary muscle infarction is common after AMI, affecting nearly one-third of patients. Extent of PMI parallels adjacent LV wall injury, with lateral infarction—rather than PMI—associated with increased severity of post-AMI MR.