Abstract 297: Prevalence, Predictors, and Functional Consequences of Sub-Clinical Papillary Muscle Infarction Following Acute Myocardial Infarction
Background: While papillary muscle infarction (PMI) with rupture is a devastating complication of ST elevation acute MI (AMI), prevalence and functional consequences of PMI without rupture are unknown. We employed delayed enhancement cardiac MRI (DE-CMR) to assess PMI after AMI.
Methods: CMR and echocardiography (echo) were prospectively acquired in a broad cohort early after first AMI (26±11 days). CMR and echo were performed within 1 day and read independently. DE-CMR was used to quantify LV infarct size and to grade PMI, which was scored as partial (<100% papillary hyperenhancement) or complete. Echo (2D) was used to quantify chamber size and grade mitral regurgitation (MR) severity (0 –3 scale).
Results: 102 pts were studied (57±13 years, infarct artery: 63% LAD, 28% RCA, 9% LCx). PMI was present in 27%, among whom 22% had complete infarction of the affected papillary and the remainder partial PMI. Among affected pts, 74% had posteromedial PMI. PMI was more frequent in pts with LCX (67%) or RCA (48%) vs those with LAD infarcts (11%; p<0.001) despite similar infarct size by DE-CMR (p=0.4) and serum enzymes (p=0.2) between groups. Moderate or severe MR tended to be more common in pts with vs pts without PMI (26% vs. 11%, p=0.06), despite similar EF (48% vs. 52%, p=0.2), LV (5.8±0.5 vs. 5.6±0.4 cm, p=0.3) and LA (4.0±0.5 vs. 4.0±0.6 cm, p=0.9) dimensions. When MR grade was compared (Figure⇓), pts with complete PMI had greater MR severity (1.3±0.9) than pts with partial (0.9±0.7) or no PMI (0.8±0.5; p=0.03).
Conclusions: PMI without rupture occurs in over one fourth of AMI pts, with likelihood increased among those with LCX or RCA infarcts. Extent of PMI is directly related to severity of MR early after AMI.