Association between timeliness of reperfusion therapy and clinical outcomes in ST-elevation myocardial infarction

Abstract

Context: Guidelines emphasize the importance of rapid reperfusion of patients with ST-elevation myocardial infarction (STEMI) and specify a maximum delay of 30 minutes for fibrinolysis and 90 minutes for primary percutaneous coronary intervention (PPCI). However, randomized trials and selective registries are limited in their ability to assess the effect of timeliness of reperfusion on outcomes in real-world STEMI patients.

Objectives: To obtain a complete interregional portrait of contemporary STEMI care and to investigate timeliness of reperfusion and outcomes.

Design, setting, and patients: Systematic evaluation of STEMI care for 6 months during 2006-2007 in 80 hospitals that treated more than 95% of patients with acute myocardial infarction in the province of Quebec, Canada (population, 7.8 million).

Main outcome measures: Death at 30 days and at 1 year and the combined end point of death or hospital readmission for acute myocardial infarction or congestive heart failure at 1 year by linkage to Quebec's medicoadministrative databases.

Results: Of 1832 patients treated with reperfusion, 392 (21.4%) received fibrinolysis and 1440 (78.6%) received PPCI. Fibrinolysis was untimely (>30 minutes) in 54% and PPCI was untimely (>90 minutes) in 68%. Death or readmission for acute myocardial infarction or heart failure at 1 year occurred in 13.5% of fibrinolysis patients and 13.6% of PPCI patients. When the 2 treatment groups were combined, patients treated outside of recommended delays had an adjusted higher risk of death at 30 days (6.6% vs 3.3%; odds ratio [OR], 2.14; 95% confidence interval [CI], 1.21-3.93) and a statistically nonsignificant increase in risk of death at 1 year (9.3% vs 5.2%; OR, 1.61; 95% CI, 1.00-2.66) compared with patients who received timely treatment. Patients treated outside of recommended delays also had an adjusted higher risk for the combined outcome of death or hospital readmission for congestive heart failure or acute myocardial infarction at 1 year (15.0% vs 9.2%; OR, 1.57; 95% CI, 1.08-2.30). At the regional level, after adjustment, each 10% increase in patients treated within the recommended time was associated with a decrease in the region-level odds of overall 30-day mortality (OR, 0.80; 95% CI, 0.65-0.98).

Conclusion: Among patients in Quebec with STEMI, reperfusion delivered outside guideline-recommend delays was associated with significantly increased 30-day mortality, a statistically nonsignificant increase in 1-year mortality, and significantly increased risk of the composite of mortality or readmission for acute myocardial infarction or heart failure at 1 year.