Time to treatment and three-year mortality after primary percutaneous coronary intervention for ST-segment elevation myocardial infarction-a DANish Trial in Acute Myocardial Infarction-2 (DANAMI-2) substudy

Abstract

In patients with ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention (pPCI), early reperfusion is believed to improve left ventricular systolic function and reduce mortality; however, long-term (>1 year) data are sparse. In the DANish Trial in Acute Myocardial Infarction-2 (DANAMI-2) study, 686 patients with ST-segment elevation myocardial infarction were treated with pPCI. Long-term mortality was obtained during 3 years of follow-up. We classified the patients according to the symptom-to-balloon time (<3, 3 to 5, and > or =5 hours). The groups were compared using a Cox proportional hazards regression model adjusted for confounding factors. The left ventricular systolic ejection fraction was estimated by echocardiography before discharge. Coronary flow was evaluated using the Thrombolysis In Myocardial Infarction score. Mortality did not differ between the 2 earliest symptom-to-balloon groups, and they were therefore combined into 1 group in the analysis of survival. Mortality was significantly increased for patients with a symptom-to-balloon time > or =5 hours (hazard ratio 2.36, 95% confidence interval 1.51 to 3.67, p <0.001), a difference that remained significant after controlling for confounding factors (adjusted hazard ratio 2.44, 95% confidence interval 1.31 to 4.54, p = 0.007). The symptom-to-balloon time was inversely associated with a left ventricular systolic ejection fraction of < or =40% (19.7% vs 22.8% vs 33.1%, p = 0.036), with the latter a major predictor of 3-year mortality in this cohort (hazard ratio 6.02, 95% confidence interval 3.68 to 9.85, p <0.001). A shorter symptom-to-balloon time was associated with greater rates of Thrombolysis In Myocardial Infarction 3 flow after pPCI (86.5% vs 80.9% vs 75.7%, p = 0.002). In conclusion, a shorter symptom-to-balloon time was associated with improved coronary flow, an increased likelihood of subsequent left ventricular systolic ejection fraction >40%, and greater 3-year survival in patients with ST-segment elevation myocardial infarction treated with pPCI.