Prognostic relevance and clinical features of papillary muscle infarction with mitral regurgitation in patients with ST segment elevation myocardial infarction

BACKGROUND: Papillary muscle infarction (PapMI) combined with mitral regurgitation (MR) is a severe complication of ST-segment elevation myocardial infarction (STEMI). The features detected by cardiac magnetic resonance (CMR) imaging in PapMI have not been characterized. The aim of the present study was to assess the incidence, determinants, and the prognostic significance of PapMI with MR at 1-year follow-up in a study of patients with STEMI after primary percutaneous coronary intervention (pPCI). METHODS: We enrolled 209 patients with STEMI reperfused by pPCI (<12 hours after symptom onset) at 2 centers. CMR and echocardiography were performed within 1 week after infarction using a standardized protocol. According to the results of CMR and echocardiography, patients were divided into PapMI with MR, PapMI (PapMI without MR), and non-PapMI groups. The primary clinical endpoint of the study was the occurrence of major adverse cardiovascular events (MACE). RESULTS: PapMI with MR was found in 27 patients (13%). The existence of PapMI with MR was associated with age (P<0.001), impaired left ventricular ejection fraction (LVEF) (P=0.005), higher SYNTAX score (P=0.002), concentration of troponin I (P<0.001), longer time to reperfusion (P<0.001), more diabetics (P<0.001), and microvascular occlusion (MVO) (P<0.001). Binary logistic regression with stepwise backward selection analysis showed that advanced age, MVO, and impaired LVEF were independent risk factors for PapMI with MR. Patients in the PapMI with MR group had significantly more MACE compared with the PapMI and non-PapMI groups [PapMI with MR, 23 (85.2%) vs. PapMI, 21 (55.3%) vs. non-PapMI, 29 (20.1%)] at 1-year follow-up (P<0.001). However, there were no pronounced differences in mortality rates among the 3 groups (P=0.071). CONCLUSIONS: The presence of PapMI with MR in patients with STEMI is associated with advanced age, MVO, and impaired LVEF, which can increase the rates of MACE.