Suboptimal coronary blood flow after primary percutaneous coronary intervention for acute myocardial infarction: incidence, a simple risk score, and prognosis.

BACKGROUND: The aim of the present study is to investigate incidence, predictors, and long-term outcomes of suboptimal coronary flow after primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI) in a large population.

METHODS: A total of 2056 consecutive patients with STEMI (mean age 56.2±11.7 years, 1738 men, 318 women) undergoing primary PCI were retrospectively enrolled in the present study. Patients were grouped as optimal [thrombolysis in myocardial infarction (TIMI) 3 flow, n=1939] and suboptimal (TIMI≤2 flow, n=117) according to the TIMI classification in the infarct-related artery at final coronary angiography after primary PCI, and were followed for in-hospital and long-term outcomes for a mean period of 1.9±1.3 years (median of 22 months).

RESULTS: Suboptimal coronary flow was observed in 5.7% (n=117) of the patients. Four variables, selected from the multivariate analysis, were weighted proportionally to their respective odds ratio for suboptimal coronary flow [predilatation before stenting (three points), Killip class 2/3 (two points), glomerular filtration rate<60 ml/min/1.73 m (two points), and anterior myocardial infarction (one point)]. Two strata of risk were defined (low risk, score 0-3; and high risk, score 4-8) and had a strong association with suboptimal coronary flow, and in-hospital and long-term cardiovascular mortalities. The suboptimal group had a higher prevalence of in-hospital mortality compared with the optimal group (22.2 vs. 1.2%, respectively, P<0.001). Long-term cardiovascular mortality was four-fold more in the suboptimal group than the optimal group (15.9 vs 3.7%, respectively, P<0.001).

CONCLUSION: Suboptimal coronary flow after primary PCI in STEMI is strongly related with increased in-hospital and long-term cardiovascular mortalities. Predilatation before stenting is the most powerful predictor of suboptimal coronary flow.