Extent, location, and clinical significance of non-infarct-related coronary artery disease among patients with ST-elevation myocardial infarction.

<bold>Importance: </bold>Little information exists about the anatomical characteristics and clinical relevance of non-infarct-related artery (IRA) disease among patients with ST-segment elevation myocardial infarction (STEMI).<bold>Objectives: </bold>To investigate the incidence, extent, and location of obstructive non-IRA disease and compare 30-day mortality according to the presence of non-IRA disease in patients with STEMI.<bold>Design, Setting, and Participants: </bold>Retrospective study of patients pooled from a convenience sample of 8 independent, international, randomized STEMI clinical trials published between 1993 and 2007. Follow-up varied from 1 month to 1 year. Among 68,765 patients enrolled in the trials, 28,282 patients with valid angiographic information were included in this analysis. Obstructive coronary artery disease was defined as stenosis of 50% or more of the diameter of a major epicardial artery. To assess the generalizability of trial-based results, external validation was performed using observational data for patients with STEMI from the Korea Acute Myocardial Infarction Registry (KAMIR) (between November 1, 2005, and December 31, 2013; n = 18,217) and the Duke Cardiovascular Databank (between January 1, 2005, and December 31, 2012; n = 1812).<bold>Main Outcomes and Measures: </bold>Thirty-day mortality following STEMI.<bold>Results: </bold>Overall, 52.8% (14,929 patients) had obstructive non-IRA disease; 29.6% involved 1 vessel and 18.8% involved 2 vessels. There was no substantial difference in the extent and distribution of non-IRA disease according to the IRA territory. Unadjusted and adjusted rates of 30-day mortality were significantly higher in patients with non-IRA disease than in those without non-IRA disease (unadjusted, 4.3% vs 1.7%, respectively; risk difference, 2.7% [95% CI, 2.3% to 3.0%], P < .001; and adjusted, 3.3% vs 1.9%, respectively; risk difference, 1.4% [95% CI, 1.0% to 1.8%], P < .001). The overall prevalence and association of non-IRA disease with 30-day mortality was consistent with findings from the KAMIR registry (adjusted, 3.6% for patients with non-IRA disease vs 2.5% in those without it; risk difference, 1.1% [95% CI, 0.6% to 1.7%]; P < .001), but not with the Duke database (adjusted, 4.7% with non-IRA disease vs 4.3% without it; risk difference, 0.4% [95% CI, -1.4% to 2.2%], P = .65).<bold>Conclusions and Relevance: </bold>In a retrospective pooled analysis of 8 clinical trials, obstructive non-IRA disease was common among patients presenting with STEMI, and was associated with a modest statistically significant increase in 30-day mortality. These findings require confirmation in prospectively designed studies, but raise questions about the appropriateness and timing of non-IRA revascularization in patients with STEMI. [ABSTRACT FROM AUTHOR]