Presence of coronary collaterals in ST-elevation myocardial infarction patients does not affect long-term outcome

INTRODUCTION The significance of coronary collateral circulation in the prognosis of patients after myocardial infarction remains disputable.
OBJECTIVES The aim of the study was to evaluate the effect of coronary collateral circulation, assessed by the Rentrop score, on long-term prognosis in patients treated with primary percutaneous coronary intervention (PCI) in ST-segment elevation myocardial infarction (STEMI).
PATIENTS AND METHODS Coronary collateral flow was assessed by angiography in 330 patients with myocardial infarction using the Rentrop score. Patients were followed up for the mean period of 26 ±12 months with the clinical endpoints of cardiac death, nonfatal reinfarction, and repeat percutaneous or surgical revascularization.
RESULTS Collateral circulation was graded Rentrop 0 in 39%, Rentrop 1 in 36%, Rentrop 2 in 18%, and Rentrop 3 in 7% of the patients. The mortality rate was 8.7%. Reinfarction occurred in 4.7% of the subjects, and repeat coronary revascularization was performed in 10.9% of the patients. These endpoints were not correlated with the degree of collateral circulation. A significant inverse association was observed between the Rentrop score and the infarct-related artery antegrade flow (P <0.001). 
CONCLUSIONS The degree of collateral circulation assessed by the Rentrop score during primary PCI is not a useful long-term prognostic factor in the population with STEMI in the current therapeutic approach. This may result from the negative correlation between the Rentrop score and the degree of blood flow in the infarct-related artery. Thus, collateral circulation in a patient with STEMI should not discourage intensive cardiovascular risk factor control in secondary prevention of coronary artery disease.