EFFECT OF SUSTAINED-RELEASE DILTIAZEM (DILTIAZEM-R) IN PATIENTS WITH STABLE EFFORT ANGINA

Ca++-antagonist is effective not only for variant angina but also for effort angina. The effects of sustained release diltiazem (diltiazem-R) and beta 1-blocker (atenolol) on exercise tolerance were studied in seven patients with stable effort angina in a cross over trial. Diltiazem-R (100mg) or atenolol (50mg) was given once a day, each treatment period lasting for two weeks after a two-week control period. The treadmill exercise test was performed on the last day of each protocol. Both diltiazem-R and atenolol decreased heart rate at rest and the decrease with atenolol was greater than that with diltiazem-R. The systolic blood pressure was unchanged at rest by both drugs. At maximal work levels, atenolol decreased the heart rate and pressure rate product significantly, but diltiazem-R did not. Both diltiazem-R and atenolol significantly prolonged the exercise time (average 137 and 165 seconds respectively), time to onset of 1mm ST depression (240 and 288 seconds respectively). There was no significant difference in exercise tolerance between diltiazem-R and atenolol. These findings suggest that diltiazem-R, a sustained release Ca++-antagonist, provides beneficial effects in patients with stable effort angina.