A double-blind comparison of a beta-blocker and a potassium channel opener in exercise induced angina.

This randomized, double-blind, parallel study compared the anti-anginal effects of nicorandil and atenolol in 37 patients with exercise-induced angina pectoris. At the end of a single-blind placebo period, patients were randomized and received either atenolol 50 mg o.d. or nicorandil 10 mg b.d. for 3 weeks. On the third week, the dosage was increased (nicorandil 20 mg b.d. or atenolol 100 mg o.d.) for the final 3-week period. Treadmill exercise tolerance tests were performed immediately before and 2 h after dosing at the end of the placebo period, and at the end of the third and sixth week of active treatment. Demographic characteristics and exercise performance with placebo were comparable between both treatment groups, and at the end of the treatment periods a significant improvement in exercise time was observed: an increase in the time to peak exercise of 1.33 +/- 0.29 min (mean +/- standard error of the mean) in atenolol-treated patients (P < 0.001), and of 1.47 +/- 0.40 min (P < 0.005) in nicorandil-treated patients. While the anti-anginal activity of the two drugs was comparable, their effects on the rate-pressure product heart rate x systolic blood pressure were clearly different; atenolol induced a decrease at peak exercise, but this parameter was not changed or was slightly increased with nicorandil. One patient with severe three-vessel disease died suddenly after 3 days of treatment with nicorandil 10 mg twice daily. The most frequent adverse effect in both groups was headache, which led to discontinuation of one patient in the atenolol group and of five patients in the nicorandil group.(ABSTRACT TRUNCATED AT 250 WORDS)