Efficacy of carvedilol in exercise-induced myocardial ischemia

The exercise response to a single oral dose (25 mg) of a new beta-blocking agent that also has potent vasodilating properties, carvedilol, was assessed in 15 patients with stable exertional angina, positive exercise tests (greater than or equal to 1 mm ST depression) and coronary artery disease. A placebo-controlled, randomized, crossover study was carried out. Compared with placebo, carvedilol significantly reduced both resting heart rate (HR) and blood pressure (BP) at rest. After the administration of carvedilol, 10 of the 15 patients did not have angina at peak exercise and 5 had ST shifts less than 1 mm. Total exercise time and time to 1 mm ST depression were prolonged, and ST segment depression at peak exercise was significantly reduced. Systolic BP was reduced both at peak exercise and at 1 mm ST depression whereas mean HR at peak exercise did not change significantly compared with placebo. Overall, mean HR-BP product at peak exercise was significantly reduced by carvedilol compared with placebo. However, four patients achieved similar or higher HR-BP product and yet did not experience angina and had less ST depression (or no ST segment shifts) during exercise. This indicates an increase in their coronary flow reserve. These results suggest that carvedilol is effective therapy for effort-induced angina, and this may be related to its combined beta-blocking and vasodilatory properties.