Quantitative analysis of the impact of total ischemic time on myocardial perfusion and clinical outcome in patients with ST-elevation myocardial infarction.

Early reperfusion of the infarct-related coronary artery is an important issue in improvement of outcomes after ST-segment elevation myocardial infarction (STEMI). In this study, the clinical significance of total ischemic time on myocardial reperfusion and clinical outcomes was evaluated in patients with STEMI treated with primary percutaneous coronary intervention and thrombus aspiration and additional triple-antiplatelet therapy. Total ischemic time was defined as time from symptom onset to first intracoronary therapy (first balloon inflation or thrombus aspiration). All patients with STEMI treated with primary percutaneous coronary intervention with total ischemic times ≥30 minutes and <24 hours from 2005 to 2008 were selected. Ischemic times were available in 1,383 patients, of whom 18.4% presented with total ischemic times ≤2 hours, 31.2% >2 to 3 hours, 26.8% >3 to 5 hours, and 23.5% >5 hours. Increased ischemic time was associated with age, female gender, hypertension, and diabetes. Patients with total ischemic times <5 hours more often had myocardial blush grade 3 (40% to 45% vs 22%, p <0.001) and complete ST-segment resolution (55% to 60% vs 42%, p = 0.002) than their counterparts with total ischemic times >5 hours. In addition, patients with total ischemic times ≤5 hours had lower 30-day mortality (1.5% vs 4.0%, p = 0.032) than patients with total ischemic times >5 hours. In conclusion, in this contemporary cohort of patients with STEMI treated with primary percutaneous coronary intervention, triple-antiplatelet therapy, and thrombus aspiration, short ischemic time was associated with better myocardial reperfusion and decreased mortality. After a 5-hour period in which outcomes remain relatively stable, myocardial reperfusion becomes suboptimal and mortality increases.