EXTENDED MORTALITY BENEFIT OF EARLY POSTINFARCTION REPERFUSION

Background-Reperfusion therapy for myocardial infarction, understood t o reduce mortality by preserving left ventricular function, was initia lly expected to provide increasing benefits over time. Surprisingly, l arge controlled thrombolysis trials demonstrated maximum benefit at 4 to 6 weeks with no subsequent increased treatment advantage. Such stud ies, however, compared groups by assigned treatment, not physiological effectiveness. Methods and Results-We calculated 2-year survival diff erences among 2431 myocardial infarction patients according to early i nfarct artery patency and outcome left ventricular ejection fraction u sing Kaplan-Meier curves. Hazard ratios for significant survival deter minants were derived from Cox regression models. Two-year vital status (minimum, 688 days) was determined in 2375 patients (97.7%). A substa ntial mortality advantage for early complete reperfusion (Thrombolysis in Myocardial Infarction [TIMI] grade 3) and for preserved ejection f raction occurred beyond 30 days. The unadjusted hazard ratio for the T IMI 3 group compared with lesser grades at 30 days was 0.57 (95% confi dence interval [CI], 0.35 to 0.94) and 30 days to greater than or equa l to 688 days was 0.39 (95% CI, 0.22 to 0.69). Consequently, early TIM I 3 flow was associated with approximately a 3 patient per 100 mortali ty reduction the first month with an additional 5 lives per 100 from 3 0 days to 2 years. For ejection fraction >40% compared with less than or equal to 40%, the unadjusted hazard ratio was 0.25 (95% CI, 0.16 to 0.37) at 30 days and 0.22 (95% CI, 0.15 to 0.33) after 30 days throug h 2 years (lives saved, approximate to 9 and 11 per 100, respectively) . Conclusions-Successful reperfusion and myocardial salvage produce si gnificant mortality benefits that are amplified beyond the initial 30 days.