Abstract 15343: Increasing Left Ventricular Mass is Associated With Greater Microvascular Obstruction During ST-elevation Myocardial Infarction

Abstract

Introduction: The development of microvascular obstruction (MVO) in the setting of ST-Elevation Myocardial Infarction (STEMI) is a powerful predictor of reduced left-ventricular (LV) function, adverse LV remodeling and increased mortality. Although MVO is associated with increasing infarct size and ischemic duration, additional causes of MVO have not been clearly identified. Although MVO may arise from intravascular obstruction from embolization of thrombus, it may also arise from compression of the microvasculature due to increased myocardial edema and extravascular compressive forces. Hypothesis: Because left-ventricular hypertrophy (LVH) is associated with increased extravascular compressive forces, we hypothesized that patients with greater LV mass may be more susceptible to the development of MVO during STEMI. Methods: We measured MVO in 385 patients (59.4 + 12.3 years; 77% male) admitted to our Institution with STEMI who underwent cardiac MRI for measurement of LV function and infarct size following successful primary PCI. A total of 219 patients (57%) had MVO on cardiac MRI measured 1-3 days following PCI of which 172 patients had paired measurements of LV mass. Results: Patients with MVO (13.7 + 13.9 grams) had significantly greater infarct size (54 vs. 31 g; p < 0.001) and LV mass (151 vs 140 g; p<0.01) but reduced LVEF (43.1 vs. 47.8%) despite having similar ischemic times. Among patients with MVO, there was a linear increase in MVO with increasing LV mass (Figure). Conclusions: MVO increases with increasing LV mass and may contribute to the known adverse effects of LVH in STEMI.