OBJECTIVES: The effect of vardenafil, a potent and highly selective phosphodiesterase-5 (PDE5) inhibitor, on symptom-limited exercise time, time to first awareness of angina, and time to ischemic threshold (ST-segment depression ≥1 mm from baseline) during exercise tolerance testing (ETT) was examined in patients with stable coronary artery disease (CAD). BACKGROUND: Erectile dysfunction (ED) is common among men with CAD. PDE5 inhibition is increasingly the preferred treatment option for ED. However, the effect of PDE5 inhibition on exercise-induced ischemia in CAD patients has received limited prospective evaluation. METHODS: In this double-blind, crossover, single-dose multicenter study, 41 men with reproducible stable exertional angina due to ischemic CAD received vardenafil 10 mg or placebo, followed by ETT (5 to 10 metabolic equivalents [METS], Bruce protocol) 1 h postdose. Sublingual nitrate use was prohibited for ≥24 h pre- and postexercise study days. End points induded symptom-limited treadmill exercise time, time to first awareness of angina, time to ischemic threshold, and safety. RESULTS: Relative to placebo, vardenafil 10 mg did not alter exercise treadmill time (427 ± 105 s vs. 433 ± 109 s, p = 0.39), or time to first awareness of angina (292 ± 110 s vs. 291 ± 123 s, p = 0.59), but significantly prolonged time to ischemic threshold (334 ± 108 s vs. 381 ± 108, p = 0.0004). At peak exercise, vardenafil 10 mg did not alter blood pressure, heart rate, or rate-pressure product relative to placebo. The most common adverse events (facial flushing and headache) were of mild or moderate intensity, and short-lived. CONCLUSIONS: Vardenafil 10 mg did not impair the ability of patients with stable CAD to exercise at levels equivalent or greater than that attained during sexual intercourse (average of 2.5 to 3.3 METS). © 2002 by the American College of Cardiology Foundation.