EFFECT OF BETA-ADRENOCEPTOR BLOCKADE ON ATRIAL-NATRIURETIC-PEPTIDE LEVELS DURING EXERCISE IN ANGINA-PECTORIS

The effects of epanolol (200 mg once daily) and diltiazem (60 mg three times daily) on the response of atrial natriuretic peptide (ANP) to exercise were investigated in a double-blind placebo-controlled crossover study in 16 patients with angina pectoris. Exercise tolerance as assessed by peak oxygen consumption was similar with all treatments. Peak heart rate (mean and 95% confidence intervals) was lower (P < 0.05) with epanolol (121 (115-130) beats min-1) than with diltiazem (137 (126-148) beats min-1) or placebo (141 (130-152) beats min-1). ANP did not change from resting values with placebo or diltiazem, but rose significantly (P < 0.05) with epanolol from 19.7 (13.0-29.8) pg ml-1 (geometric mean and 95% confidence intervals) during supine rest to 49.6 (33.7-73.0) pg ml-1 at peak exercise. Since ANP release is stimulated by atrial distension, patients with untreated angina may stop exercise before atrial dilatation occurs. With adrenoceptor blockade, a reduction in peak heart rate may necessitate increased chamber volumes to maintain cardiac output, accounting for the rise in ANP.