[Efficacy of low-dose mutant tissue-type plasminogen activator followed by planned rescue percutaneous transluminal coronary angioplasty as reperfusion therapy for acute myocardial infarction].

Objectives: The efficacy of injection of a low-dose mutant tissue-type plasminogen activator (mt-PA), monteplase, followed by planned rescue percutaneous transluminal coronary angioplasty (PTCA) was compared with that of primary PTCA.

Methods: A total of 164 patients with acute myocardial infarction within 12 hr from onset were randomly assigned to a treatment with 80 x 10(4) U bolus of monteplase (Group M) or no administration (Group P) by the envelope method, followed by immediate angiography with angioplasty in patients with Thombolysis in Myocardial Infarction (TIMI) flow grade 0, 1 or 2.

Results: There were no differences in baseline characteristics between the two groups. Initial angiography showed a higher reperfusion rate (TIMI 2 + 3: 21% + 38% vs 13% + 9%, p < 0.001) and the median time to TIMI 3 was shorter (63 vs 78 min, p < 0.005) in Group M than in Group P, but the final TIMI 3 rate was similar (93% vs 96%). Peak creatine kinase was lower, and predischarge left ventricular ejection fraction measured in 70% of all patients was higher (59 +/- 9% vs 54 +/- 14%, p = 0.02) in Group M than in Group P. Recurrent ischemia with ST elevation occurred in three patients in Group M, but death, re-acute myocardial infarction or stroke did not occur in either group and the rate of bleeding complication was similar (4.9% vs 3.7%). PTCA was performed less frequently in Group M, but medical expenses were comparable in both groups.

Conclusions: Low-dose mt-PA followed by rescue PTCA is effective for early recanalization and preservation of left ventricular function without increases in bleeding complications or medical expenses. These results suggest that low-dose mt-PA should be given to all patients with acute myocardial infarction who are scheduled to undergo primary PTCA.