Determinants of microvascular damage recovery after acute myocardial infarction: results from the acute myocardial infarction contrast imaging (AMICI) multi-centre study

AIMS: Microvascular damage (MD) occurring soon after primary percutaneous coronary intervention (PPCI) may reverse or remain sustained within the first week after ST-elevation myocardial infarction (STEMI). We investigated the incidence, determinants, and long-term clinical relevance of MD reversal after PPCI. METHODS AND RESULTS: Serial two-dimensional echocardiograms (2DE) and a myocardial contrast study were obtained within 24 h of PPCI (T1) and at pre-discharge (T2) in 110 successfully re-perfused STEMI patients. Six months 2DE and 2-year clinical follow-up were obtained. After PPCI myocardial re-perfusion was normal at T1 only in 40 patients (36%, 'normal reflow'), recovered at T2 in 33 (30%, 'reversible MD'), and remained abnormal in 37 (34%, 'sustained MD'). At follow-up, normal reflow and reversible MD were coupled with a significant reduction in the infarct area, decrease in cardiac volumes, and a slight non-significant improvement in systolic function. Conversely, in the sustained MD group, the infarct area did not change and cardiac volumes significantly increased with a parallel worsening in systolic function. By multivariate analysis, independent predictors of reversible MD were: absence of family history of coronary artery disease (CAD), younger age, shorter time to re-perfusion, and absence of diabetes. The 2-year combined events rate was significantly lower in reversible MD (log-rank test P= 0.03) compared with sustained MD patients. CONCLUSIONS: In STEMI patients treated according to the current guidelines, MD frequently occurs soon after re-perfusion but it is reversible in ∼50% of cases and it is associated with a favourable functional and clinical outcome. Family history of CAD, aging, time to re-perfusion, and diabetes are independent predictors of MD reversibility.