Hierarchy of risk based on history and location of prior myocardial infarction in the thrombolytic era

Background Among patients receiving thrombolytic therapy for myocardial inf arction, the outcome for those with a history of infarction is dramatically worse than for those with their first event. Methods and Results We performed a post hoc analysis of patients with a his tory of myocardial infarction enrolled in the Global Utilization of Strepto kinase and TPA for Occluded arteries (GUSTO)-I trial, focusing on the impac t of the location of their current and prior events on mortality rates. Wit hin the first 24 hours, mortality rate was greatest among patients with a c urrent infarction in a territory remote from their previous event. By 48 ho urs after examination, mortality rates among patients with a second anterio r infarct had overtaken that among patients with a current inferior/prior a nterior infarct. This hierarchy of risk persisted at both 30 days and 1 yea r (mortality rate at 1 year: current anterior/prior inferior 23.2% +/- 1.4% , current anterior/prior anterior 20% +/- 1.5%, current inferior/prior ante rior 17% +/- 1.2%, current inferior/prior inferior 10.8% +/- 0.9%). Conclusions In patients with ST-elevation myocardial infarction on a backgr ound of prior infarction, the location of current and prior events predicts a hierarchy of short- and long-term risk of death.