Background: Collateral flow to the infarct artery territory after acute myocardial infarction may be associated with improved clinical outcomes and may also impact the benefit of subsequent recanalization of an occluded infarct-related artery.
Methods and results: To understand the association between baseline collateral flow to the infarct territory on clinical outcomes and its interaction with percutaneous coronary intervention of an occluded infarct artery, long-term outcomes in 2173 patients with total occlusion of the infarct artery 3 to 28 days after myocardial infarction from the randomized Occluded Artery Trial were analyzed according to angiographic collaterals documented at study entry. There were important differences in baseline clinical and angiographic characteristics as a function of collateral grade, with generally lower-risk characteristics associated with higher collateral grade. Higher collateral grade was associated with lower rates of death (P=0.009), class III and IV heart failure (P<0.0001) or either (P=0.0002) but had no association with the risk of reinfarction. However, by multivariate analysis, collateral flow was neither an independent predictor of death nor of the primary end point of the trial (composite of death, reinfarction, or class IV heart failure). There was no interaction between angiographic collateral grade and the results of randomized treatment assignment (percutaneous coronary intervention or medical therapy alone) on clinical outcomes.
Conclusions: In recent myocardial infarction, angiographic collaterals to the occluded infarct artery are correlates but not independent predictors of major clinical outcomes. Late recanalization of the infarct artery in addition to medical therapy shows no benefit compared with medical therapy alone, regardless of the presence or absence of collaterals. Therefore, revascularization decisions in patients with recent myocardial infarction should not be based on the presence or grade of angiographic collaterals. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00004562.