Determinants of coronary collateral formation in patients with acute ST-elevation myocardial infarction and total occlusion of infarct-related artery

Background: The presence or absence of collateral circulation to the infarct-related artery territory significantly impacts the infarct size and resulting left ventricular function and hence the prognosis. However, the determinants of collateral formation have been poorly understood.Materials and Methods: The present single-center observational study examined 200 patients with acute ST-elevation myocardial infarction (STEMI), irrespective of the status of thrombolysis, undergoing coronary angiogram within 48 h showing complete occlusion of infarct-related coronary artery.Results: High-grade collaterals (Rentrop Grade 2 and 3) were seen in 17% of patients (n = 34). High-grade coronary collaterals were more often seen in patients belonging to the age group of 46–70 years compared to elderly individuals >70 years of age (38.2% vs. 2.9%,P < 0.009). The occurrence of collaterals to culprit coronary artery either left anterior descending artery or right coronary artery was similar. There was a lower prevalence of high-grade collaterals to infarct-related artery territory in smokers versus nonsmokers (5.9% vs. 43.4%,P < 0.001). The prevalence of collaterals in patients with diabetes was lower compared to nondiabetics (11.8% vs. 47.6%,P < 0.001). There was a significantly higher prevalence and recruitment of collaterals in patients with a history of angina before they developed acute coronary syndrome (88.2% vs. 16.9%,P < 0.001). There was no significant association between hypertensive status and the prevalence of coronary collateral circulation.Conclusions: The finding of high-grade coronary collaterals was seen more in patients who had angina prior to STEMI. High-grade collaterals were significantly more in middle-aged individuals compared to the elderly. Diabetes mellitus and smoking status were negative predictors of high-grade collaterals.