Coronary collaterals in patients with ST-elevation myocardial infarction presenting late after symptom onset

Background: The role of coronary collaterals in ST-elevation myocardial infarction (STEMI) remains controversial. So far, studies examining the effect of collaterals on outcome mainly focused on patients presenting early after symptom onset. We sought to investigate the prognostic influence of coronary collateralization in patients presenting with prolonged ischemia late after symptom onset. Methods and results: The study is a subanalysis of a randomized trial addressing thrombus aspiration in STEMI patients presenting between 12 and 48 h after symptom onset with a follow-up period of a minimum of 4 years. A total of 95 patients with a Thrombolysis In Myocardial Infarction (TIMI) flow grade 0 or 1 prior to percutaneous coronary intervention (PCI) were included in the analysis. Of these, 62 patients (65%) had none or poor coronary collateralization according to the Rentrop classification (Rentrop grade 0 or 1) compared to 33 (35%) with well-developed collateralization (Rentrop grade 2 or 3). In comparison, patients with well-developed collateralization had a smaller area of microvascular obstruction (2.1 ± 3.8 vs. 4.5 ± 4.9% of left ventriclular mass (%LV), p = 0.03) and infarct size (27.9 ± 11.7 vs. 34.8 ± 17.2% LV, p = 0.047) on magnetic resonance imaging. Further, mortality at 4-years follow-up was lower (6% Rentrop grade 2 or 3 vs. 25% Rentrop grade 0 or 1, p = 0.02). Poor collateralization was an independent predictor of long-term mortality on multivariate Cox regression analyses in addition to cardiogenic shock and unsuccessful PCI during the index procedure. Conclusion: Sufficient coronary collateralization has a positive impact on microvascular obstruction, infarct size and long-term mortality in STEMI patients presenting between 12 and 48 h after symptom onset.