Microvascular obstruction is a major determinant of infarct healing and subsequent left ventricular remodelling following primary percutaneous coronary intervention.

AIMS We studied the time-dependent relationships between microvascular obstruction (MO), infarct size, and left ventricular (LV) remodelling after acute myocardial infarction (MI). METHODS AND RESULTS Forty-two consecutive patients with first-time ST-elevation MI, single-vessel disease, successfully treated with primary percutaneous coronary intervention (PCI) were included. Microvascular obstruction, infarct size, and LV remodelling were assessed by cardiac magnetic resonance. Cardiac magnetic resonance was performed at: 2 days, 1 week, 2 months, and 1 year following PCI. Microvascular obstruction was assessed by first-pass perfusion. Patients were divided into three groups according to the presence or absence of MO at 2 days and 1 week: no detectable MO at any time point (11 patients), MO detectable only at 2 days (16 patients), and MO detectable both at 2 days and 1 week (15 patients). In multivariable analysis adjusting for infarct size at 2 days, detectable MO at 1 week was an independent predictor (P = 0.003) of infarct size at 1 year follow-up, associated with adverse infarct healing, adverse LV remodelling, increased LV volumes, and lower ejection fractions when compared with the rest of the cohort. CONCLUSION Microvascular obstruction is an important determinant of infarct healing. The effect of MO on infarct size translated into distinct patterns of LV remodelling during long-term follow-up.