The exact role of papillary muscle infarction (PMI) during the acute phase of acute ST-segment elevation myocardial infarction (STEMI) is not well understood, as existing data on the impact of PMI location is conflicting. We hypothesized that infarction of the posteromedial papillary muscle (PM-PMI) as determined by cardiac magnetic resonance imaging might be associated with an increased incidence of mitral valve regurgitation in the first week after STEMI. 242 patients with first STEMI underwent a late-enhancement (LGE-) cardiac magnetic resonance imaging within a median of 2 (IQR 2-5) days and echocardiography within 3 (IQR 2-5) days after primary angioplasty for the index event. PMI was scored based on short axis slices (AL-PMI: anterolateral PMI, PM-PMI, AL/PM-PMI: AL- and PM-PMI). Patients with PM-PMI had significantly higher odds (OR 2.62, p < 0.01) for the occurrence of mitral regurgitation than patients with no-PMI, AL-PMI or AL/PM-PMI. Furthermore, advanced age, non-anterior infarct location and longer pain-to-balloon time were identified as risk factors for the occurrence of mitral regurgitation. Binary logistic regression analysis revealed that PM-PMI is a predictor of mitral regurgitation independent of infarct location and age (OR 2.229, CI 1.078-4.903, p = 0.031). PM-PMI as determined by cardiac magnetic resonance imaging is an independent predictor of mitral regurgitation in the setting of acute STEMI. Our data might improve our understanding of the dynamic nature of functional mitral regurgitation.
Keywords: Cardiac magnetic resonance; Mitral regurgitation; Papillary muscle infarction; ST-segment elevation myocardial infarction.