This trial (39) has the greatest relevance to current practice, since it involved the use of stenting and the GP IIb/IIIa platelet inhibitor tirofiban. A total of 2220 patients with unstable angina or non-ST-elevation MI were included. All patients had one of the following: ischemic EKG changes, elevated cardiac markers, or history of coronary artery disease. All patients received aspirin, heparin, and tirofiban. Patients in the invasive arm underwent coronary angiography within 4-48 h (mean of 24 h), and were revascularized if indicated. Patients in the conservative arm underwent cardiac catheterization only with refractory angina, a positive stress test, new MI or rehospitalization for unstable angina, or hemodynamic instability. At 6-mo follow-up, coronary angiography had been performed in 97% of patients in the invasive arm and 51% in the conservative arm. Revas-cularization had been performed in 61 and 44%, respectively. The primary end point of
Fig. 6. Outcomes of both treatment groups in the TACTICS-TIMI18 trial. Reproduced with permission from Cannon et al. TACTICS (Treat Angina with Aggrastat and Determine Cost of Therapy with an Invasive or Conservative Strategy). Thrombolysis in Myocardial Infarction 18 Investigators. Comparison of early invasive and conservative strategies in patients with unstable coronary syndromes treated with the glycoprotein IIb/IIIa inhibitor tirofiban. N Engl J Med 2001;344:1879-1887.
death, MI, or rehospitalization for acute coronary syndrome occurred significantly less often in the invasive arm (15.9 vs 19.4%, p = 0.025) (Fig. 6). In addition, death or MI alone was also significantly reduced by an invasive strategy (7.3 vs 9.5%,p < 0.05). One important finding of TACTICS-TIMI 18 is the verification of the "troponin hypothesis", whereby patients with elevated baseline troponin T levels achieved the greatest benefit from an early invasive strategy (14.3 vs 24.2%, p < 0.001) (Fig. 7). Thus, in the current era of GP IIb/IIIa inhibitors and stents, it appears that an invasive strategy is beneficial in patients with unstable angina or non-ST-elevation MI. The greatest benefit seems to be achieved in high risk patients with elevated troponin T levels and ischemic ECG changes.
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