| Abstract: |
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. © 2013 by the American College of Cardiology Foundation. |
| Keywords: |
adult; aged; middle aged; major clinical study; clinical trial; nuclear magnetic resonance imaging; prospective study; prospective studies; logistic models; odds ratio; risk factors; pathology; risk factor; time; time factors; risk assessment; risk; register; registries; diagnostic agent; contrast enhancement; geometry; acute heart infarction; echography; predictive value of tests; chi-square distribution; contrast medium; contrast media; multivariate analysis; statistical model; heart; heart muscle; myocardial infarction; myocardium; predictive value; infarction; transthoracic echocardiography; heart function; chi square distribution; nuclear magnetic resonance scanner; doppler echocardiography; mitral valve; mitral regurgitation; papillary muscle infarction; mitral valve regurgitation; cardiovascular magnetic resonance; humans; human; male; female; priority journal; article; delayed enhancement cardiac magnetic resonance imaging; echocardiograph; heart left ventricle wall; heart papillary muscle; heart papillary muscle infarction; mitral apparatus; anterior myocardial infarction; inferior myocardial infarction; anterior wall myocardial infarction; echocardiography, doppler, color; echocardiography, doppler, pulsed; inferior wall myocardial infarction; magnetic resonance imaging, cine; mitral valve insufficiency; papillary muscles
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