Usefulness of late coronary thrombolysis (recombinant tissue-type plasminogen activator) in preserving left ventricular function in acute myocardial infarction

This study assesses whether administration of recombinant tissue-type plasminogen activator (rt-PA) up to 8 hours after onset of symptoms of acute myocardial infarction (AMI) may result in a significant improvement in left ventricular function. Sixty patients were classified into 3 groups: group A (n = 21) received rt-PA within 4 hours from symptom onset; the remaining 39 patients, admitted between 4 and 8 hours, were randomized into 2 groups—group B (n = 19) received rt-PA, and group C (n = 21) was treated with conventional therapy. Coronary and left ventricular angiograms were recorded 8 to 10 days after rt-PA administration. The patency rate of the infarct-related artery was 76% in group A, and 63 and 35% in group B and C, respectively. The Thrombolysis in Myocardial Infarction trial perfusion grade was higher in group A and B than in group C (A vs C: p < 0.005; B vs C: p < 0.01). Left ventricular ejection fraction was significantly higher in group A (60.2 ± 10%) and B (54.7 ± 12%) compared with group C (44.2 ± 12%) (A vs C: p < 0.01; B vs C: p < 0.05). Regional wall motion of the entire ischemic zone was better in group A and B than in group C (A vs C: p < 0.001; B vs C: p < 0.01). In contrast, the kinesis of the central ischemic zone was significantly better in group A than in both group B and C (A vs B: p < 0.05; A vs C: p < 0.001). The number of hypokinetic, akinetic and dyskinetic segments were lower in group A and B than in group C (A vs B: p < 0.01, B vs C: p < 0.05 and A vs C: p < 0.01 and B vs C: p < 0.01, respectively). Thus, these data confirm the efficacy of early thrombolysis and suggest that late reperfusion may act beneficially in preserving left ventricular volumes and function.