Double-bolus alteplase for myocardial infarction - Tips from Other Journals

Date: May, 1992

The efficacy of a three-hour infusion of 100 mg of recombinant tissue-type plasminogen activator (TPA) in acute myocardial infarction is well-established. Front-loaded dosage regimens of alteplase (predominantly one-chain TPA) may promote early infarct-related coronary artery patency and improve myocardial salvage. Purvis and associates studied the efficacy of alteplase therapy, administered as two boluses, in patients with symptoms of acute myocardial infarction.

The study included 59 patients who presented within six hours of the onset of symptoms of acute myocardial infarction. Patients received a total dose of either 70 or 100 mg of alteplase divided into two bolus injections separated by 30 minutes. Three dosage regimens of alteplase were used: 20 mg followed by 50 mg (group A), 50 mg followed by 20 mg (group B) or 50 mg followed by 50 mg (group C).

Coronary angiography 60 minutes after the first bolus showed infarct-related coronary artery patency in 13 of 16 patients (81 percent) in group A, 12 of 17 patients (71 percent) in group B and 10 of 11 patients (91 percent) in group C. The overall patency rate at 60 minutes was 80 percent. At 90 minutes, patency rates were 75 percent in groups A and B, and 95 percent in group C, with an overall patency rate of 81 percent.

Residual thrombus was identified with the 90-minute angiogram in seven patients in group A, five in group B and three in group C.

Although no statistically significant difference in patency was observed between the three groups, there was a trend toward increased patency and more complete thrombolysis at 90 minutes in group C. No episodes of bradyarrhythmia, hypotension or cerebrovascular bleeding were observed. Seven episodes (12 percent) of reocclusion and three deaths (5 percent) occurred during the one-month period of follow-up.

The authors conclude that double-bolus alteplase therapy is convenient and effective therapy for promotion of early coronary artery patency during acute myocardial infarction. (American Journal of Cardiology, December 15, 1991, vol. 68, p. 1570.)

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