Mitral apparatus assessment by delayed enhancement CMR - relative impact of papillary muscle and left ventricular wall infarction on ischemic mitral regurgitation

Abstract

Summary Lateral wall infarction on DE-CMR, independent of papillary muscle involvement, confers increased risk for ischemic mitral regurgitation. Background The mitral apparatus contains two myocardial components - papillary muscles and the adjacent left ventricular (LV) wall. Delayed enhancement CMR (DE-CMR) enables in-vivo study of potential contributions of LV wall and papillary muscle infarction (PMI) to MR. This study examined the relative impact of papillary muscle and LV wall infarction on mitral regurgitation (MR) following ST elevation MI (STEMI). Methods Multimodality imaging was prospectively performed among patients with first STEMI: DE-CMR (IR-GRE, acquired 10-30 minutes post gadolinium [0.2 mmol/kg]) was used to assess LV infarct pattern - including PMI (graded by location and extent - complete or partial, stratified using threshold of >50% papillary myocardium) and LV wall infarction (17 segment model, 5 point score/segment). Cine-CMR (SSFP) was analyzed for cardiac function and geometry - including LV chamber size, regional wall motion (5 point score/segment), and mitral annular diameter. Echocardiography (echo) was used to quantify MR (0-4+ grade) using established consensus criteria. Each imaging modality was read independently.