Impact of microvascular obstruction and infarct size on left ventricular remodeling in reperfused myocardial infarction: a contrast-enhanced cardiac magnetic resonance imaging study

Infarct size (IS) and microvascular obstruction (MO) following ST-elevation myocardial infarction (STEMI) reperfusion may affect left ventricular (LV) remodeling. We evaluated the impact of extent and transmurality of IS and MO in LV remodeling using contrast-enhanced cardiac magnetic resonance imaging (MRI). Thirty-six consecutive patients presenting with a first STEMI and undergoing contrast-enhanced cardiac MRI within 5 days of successful primary percutaneous coronary intervention (PPCI) were enrolled. Gadolinium-enhanced MRI at first passage and in delayed imaging was performed to assess MO and IS. LV remodeling was evaluated by echocardiography at 6-month-follow-up and defined as a percent increase in the LV end-diastolic volume >20%. Thirteen patients (36%) developed LV remodeling. IS and MO extent score was associated with LV remodeling (OR 1.5, 95% CI 1.02-2.38, P = 0.04, and OR 3.1, 95% CI 1.45-6.64, P = 0.003, respectively), along with IS and MO trasmurality (OR 1.4, 95% CI 1.007-2.12, P = 0.046, and OR 3.1, 95% CI 1.24-7.89, P = 0.016, respectively). Importantly, IS and MO extent score combination gave an OR of 3.4 (95% CI 1.4-7.9, P = 0.004) and the combination of IS and MO transmurality increased the OR to 4.8 (95% CI 1.5-15.2, P = 0.007). Finally, when combining simultaneously IS and MO extent score and transmurality the OR reached 5.3 (95% CI 3.34-18.2, P = 0.0008). The evaluation of both IS and MO extent and transmurality by MRI is of prognostic utility in patients undergoing PPCI. Importantly, IS and MO transmurality significantly increases the risk of adverse remodeling and should be routinely assessed in post-STEMI patients.