Myocardial perfusion grade, myocardial salvage indices and long-term mortality in patients with acute myocardial infarction and full restoration of epicardial blood flow after primary percutaneous coronary intervention.

INTRODUCTION AND OBJECTIVES The relationship between microcirculatory myocardial perfusion grade (MPG), myocardial salvage and long-term mortality after acute ST-segment elevation myocardial infarction (STEMI) and full restoration of epicardial blood flow by primary percutaneous coronary intervention (PCI) remains poorly understood. METHODS This study included 1213 patients with STEMI and Thrombolysis in Myocardial Infarction (TIMI) grade-3 flow after primary PCI. The MPG was determined and paired scintigraphic studies (before and 7-14 days after the intervention) were performed. The primary outcome was 5-year mortality. RESULTS The MPG was 0-1 in 217 patients, 2 in 195, and 3 in 801. In patients with an MPG of 0-1, 2 and 3, respectively, the median infarct size was 13% (interquartile range [IQR] 5.6-28%), 12% (IQR 4-27%) and 7% (IQR 1-19%) of the left ventricle, respectively (P< .001), the myocardial salvage index (i.e. the proportion of the initial area at risk that recovered) was 0.44 (IQR 0.22-0.73), 0.46 (IQR 0.25-0.75) and 0.58 (IQR 0.31-0.85), respectively (P< .001), and the Kaplan-Meier estimated 5-year mortality was 16.6% (i.e. 28 deaths), 15.3% (i.e. 25 deaths) and 7.8% (i.e. 48 deaths), respectively. The odds ratio (OR) for death for an MPG of 0-1 vs. 3 was 2.32 (95% confidence interval [CI] 1.42-3.8; P< .001) and for an MPG of 2 vs. 3, 2.3 (95% CI 1.38-3.85; P=.001). The Cox proportional hazards model identified MPG as independently associated with mortality at 5 years: the hazard ratio for an MPG of 3 vs. 0-2 was 0.65 (95% CI 0.41-0.97; P=.037). CONCLUSIONS In patients with STEMI and TIMI grade-3 flow after primary PCI, suboptimal microcirculatory myocardial perfusion (i.e. MPG < or =2) was associated with poorer myocardial salvage, a larger infarct, and higher 5-year mortality than observed in patients whose tissue perfusion was reestablished (i.e. MPG=3).