Importance of time to reperfusion on outcomes with primary coronary angioplasty for acute myocardial infarction (results from the Stent Primary Angioplasty in Myocardial Infarction Trial)

The mortality benefit of thrombolytic therapy for acute myocardial infarcti on (AMI) is strongly dependent on time to treatment. Recent observations su ggest that time to treatment may be less important with primary percutaneou s transluminal coronary angioplasty (PTCA). Patients with AMI of < 12 hours duration, without cardiogenic shock, who were treated with primary PTCA fr om the Stent PAMI Trial (n=1,232) were evaluated to assess the effect of ti me to reperfusion on outcomes. Thrombolysis In Myocardial Infarction grade 3 flow was achieved in a high proportion of patients regardless of time to treatment. Improvement in ejection fraction from baseline to 6 months was s ubstantial with reperfusion at < 2 hours but was modest and relatively inde pendent of time to reperfusion after 2 hours (<2 hours, 12.3% vs <greater t han or equal to>2 hours, 4.2%, p=0.004). There were no differences in 1- or 6-month mortality by time to reperfusion (6-month mortality: <2 hours [5.5 %], 2 to <4 hours [4.6%], 4 to <6 hours [4.5%], >6 hours [4.2%], p=0.97). T here were also no differences in other clinical outcomes by time to reperfu sion, except that reinfarction and infarct artery reocclusion at 6 months w ere more frequent with later reperfusion. The lack of correlation between t ime to treatment and mortality in patients without cardiogenic shock sugges ts that the survival benefit of primary PTCA may be related principally to factors other than myocardial salvage. These data may also have implication s regarding the triage of patients with AMI for primary PTCA. (C) 2001 by E xcerpta Medica, Inc.