Abstract 13478: Causes of Long-Term Mortality in Patients With Microvascular Obstruction Following ST-Segment Elevation Myocardial Infarction

Abstract

Introduction: The presence of microvascular obstruction (MVO) following ST-segment elevation myocardial infarction (STEMI) portends a poor prognosis and is associated with adverse left-ventricular (LV) remodeling and an increase in mortality in the subsequent year of follow-up. However, the long-term effects of MVO on mortality have not been previously described. Methods: We analyzed the long-term follow-up and cardiac MRIs of 475 patients (Average age = 60 years, 76% male) for the presence (n=337) or absence (n=138) of MVO at a single institution following STEMI and successful reperfusion with primary percutaneous intervention (PCI). Causes of death were determined from the patient's electronic medical record or death certificate. Results: The infarct-related artery was more likely to be the LAD in patients with MVO and the RCA in patients without MVO. Patients with MVO had greater ischemic times (159 vs. 141 mins; p = 0.012) and were more likely to have TIMI 0 flow on presentation (71 vs 54%; p <0.002). Patients with MVO had greater infarct size by cardiac enzymes resulting in greater LV end-diastolic volume index (LVEDVI) (80 vs.75 ml/m2), LV end-systolic volume index (LVESVI) (39 vs 30 ml/m2) and LV mass (146 vs 134 g) and reduced LVEF (48 vs 58 %; all p < 0.01) by cardiac MRI performed 1-3 days following STEMI and PCI . During long-term follow-up a total of 56 patients with MVO died compared to 18 patients without MVO. Patients with MVO died sooner after STEMI (5.9 vs 7.8 years) and were more likely to die from cardiovascular causes such as progressive heart failure or sudden cardiac death (Table). LVEF before death was lower in the MVO group (46 vs 52%). Conclusions: There is significant long-term mortality associated with MVO following STEMI with the majority of patients dying from cardiovascular causes. In contrast, patients with STEMI without MVO rarely died from a cardiac etiology but from cancer and natural causes.