Effects of an early invasive strategy on ischemia and exercise tolerance among patients with unstable coronary artery disease

Background An early invasive approach after an episode of unstable coronary artery disease has beneficial effects on mortality and myocardial infarction, but its effects on exercise capacity and ischemia have not been investigated. Methods In the Fast Revascularisation during InStability in Coronary disease (FRISC) II trial, 2457 patients with unstable coronary artery disease were assigned randomly to an early invasive or noninvasive strategy. A symptom-limited bicycle exercise test was performed before discharge in the noninvasive group and after 3 months in both groups. Results At 3 months, 86% (1046/1222) of the patients in the invasive group and 81% (995/1235) in the noninvasive group performed the exercise test. Before the test, revascularization had been performed in 78% (n = 819) of these patients in the invasive group compared with 28% (n = 281) of those in the noninvasive group. The mean (± SD) exercise capacity was higher (6.4 ± 1.9 vs. 6.2 ± 1.9 metabolic equivalents [METS], P<0.01), and the occurrence of ischemia lower (23% [229/1004] vs. 36% [352/966], P<0.001) in the invasive group. In the noninvasive group, 882 patients performed an exercise test both predischarge and at 3 months. If a revascularization procedure was performed (n = 210), exercise tolerance increased from 5.1 ± 1.4 to 6.0 ± 1.8 METS (P<0.001) and the number of patients with ST depression decreased from 65% (131/203) to 31% (63/203) (P<0.001). Without revascularization (n = 670), exercise tolerance increased from 5.9 ± 2.2 to 6.3 ± 1.9 METS (P<0.001), and there were no differences in the occurrence of ischemia. Conclusion In unstable coronary artery disease, an invasive strategy improves exercise tolerance and reduces exercise-induced ischemia.