Effects of tissue plasminogen activator and a comparison of early invasive and conservative strategies in unstable angina and non-Q-wave myocardial infarction. Results of the TIMI IIIB Trial. Thrombolysis in Myocardial Ischemia.

BACKGROUND Although coronary thrombosis plays a critical role in the pathogenesis of unstable angina and non-Q-wave myocardial infarction (NQMI), the effects of thrombolytic therapy in these disorders is not clear. Also, the role of routine early coronary arteriography followed by revascularization has not been established.

METHODS AND RESULTS Patients (n = 1473) seen within 24 hours of ischemic chest discomfort at rest, considered to represent unstable angina or NQMI, were randomized using a 2 x 2 factorial design to compare (1) TPA versus placebo as initial therapy and (2) an early invasive strategy (early coronary arteriography followed by revascularization when the anatomy was suitable) versus an early conservative strategy (coronary arteriography followed by revascularization if initial medical therapy failed). All patients were treated with bed rest, anti-ischemic medications, aspirin, and heparin. The primary end point for the TPA-placebo comparison (death, myocardial infarction, or failure of initial therapy at 6 weeks) occurred in 54.2% of the TPA-treated patients and 55.5% of the placebo-treated patients (P = NS). Fatal and nonfatal myocardial infarction after randomization (reinfarction in NQMI patients) occurred more frequently in TPA-treated patients (7.4%) than in placebo-treated patients (4.9%, P = .04, Kaplan-Meier estimate). Four intracranial hemorrhages occurred in the TPA-treated group versus none in the placebo-treated group (P = .06). The end point for the comparison of the two strategies (death, myocardial infarction, or an unsatisfactory symptom-limited exercise stress test at 6 weeks) occurred in 18.1% of patients assigned to the early conservative strategy and 16.2% of patients assigned to the early invasive strategy (P = NS). In the latter, the average length of initial hospitalization, incidence of rehospitalization within 6 weeks, and days of rehospitalization all were significantly lower.

CONCLUSIONS In the overall trial, patients with unstable angina and NQMI were managed with low rates of mortality (2.4%) and myocardial infarction or reinfarction (6.3%) at the time of the 6-week visit. These results can be achieved using either an early conservative or early invasive strategy, the latter resulting in a reduced incidence of days of hospitalization and of rehospitalization and in the use of antianginal drugs. The addition of a thrombolytic agent is not beneficial and may be harmful.