Effect of the initial bolus volume of recombinant tissue-type plasminogen activator on coronary recanalization and infarct size in Japanese acute myocardial infarction patients. Kumamoto University Myocardial Infarction Study (KUMIS) Group.

Coronary recanalization rate and infarct size were compared between 2 different methods of intravenously administering recombinant tissue-type plasminogen activator (rt-PA) 41.4 mg; 1) an initial bolus dose of 30% followed by infusion of the remainder over 60 min (30% group), and an initial bolus dose of 10% followed by infusion of the remainder over 60 min (10% group). Thirty min after beginning rt-PA infusion, the coronary recanalization rate was higher in the 30% group than in the 10% group (82.9% (34/41) vs 53.7% (22/41), p < 0.01). The peak creatine kinase and peak creatine kinase-MB levels were lower in the 30% group than in the 10% group. We conclude that a higher initial bolus dose of rt-PA gives a higher rate of recanalization of the infarct-related artery at the very early phase, and probably leads to a smaller infarct size.