[Usefulness of combination therapy of hybrid thrombolysis followed by back-up percutaneous transluminal coronary angioplasty in patients with acute myocardial infarction].

OBJECTIVES

Conventional thrombolytic therapy for acute myocardial infarction is effective for early reperfusion but has the disadvantage of a higher rate of bleeding complications. The purpose of this study is to elucidate efficacy and safety of a combined approach using a bolus injection of low dose of mutant tissue plasminogen activator (mt-PA) with heparin and aspirin to ensure definite antithrombin and antiplatelet efficacy, followed by back-up percutaneous transluminal coronary angioplasty(PTCA).

METHODS

Patients with acute myocardial infarction aged < 80 years who were admitted to our institution within 3 hr of onset of symptoms were immediately treated with oral aspirin 330 mg and intravenous heparin 5,000 IU and were randomized to receive an intravenous bolus of mt-PA (monteplase) 15,000 IU/kg (thrombolytic group, n = 25) or no mt-PA (control group, n = 21), followed by angiography with PTCA if indicated.

RESULTS

There were no differences between the two groups in patient characteristics, time from onset to hospital arrival, time to initial angiography, or infarct-related arteries. Significantly more patients had Thrombolysis in Myocardial Infarction flow grade 3 and grade 2/3 at the initial angiography in the thrombolytic group than in the control group (32.0% vs 4.8%, 68.0% vs 14.3%; p = 0.020, p = 0.0003, respectively). PTCA was performed in 88% of the thrombolytic group (stenting employed in 64%) and 95.5% of the control group (stenting in 57%), and the success rate was 95.5% and 100%, respectively. No acute or subacute coronary occlusion was found in either group. Bleeding complications occurred in only one patient in the thrombolytic group, which was bleeding associated with vomiting, and no difference was found in other complications between the two groups. Radionuclide ventriculography using quantitative gated single photon emission computed tomography showed left ventricular end-diastolic volume and left ventricular end-systolic volume tended to be smaller, and the ejection fraction after 3 months of treatment tended to be higher in the thrombolytic group. Myocardial salvage volume was significantly higher in the thrombolytic group.

CONCLUSIONS

Hybrid thrombolysis using a low dose of mt-PA with aspirin and heparin promoted significantly early reperfusion. Also, successful reperfusion is achievable at higher rates with back-up PTCA without an increase in complications.