[Evaluation of the effects of a new calcium antagonist, diltiazem, in patients with stable effort angina and a therapeutic comparison with nifedipine].

The comparative efficacy of diltiazem, a new calcium-antagonist drug, and nifedipine were evaluated with computerized treadmill exercise test in 12 patients with stable effort angina. The drugs were administered in a random single-blind fashion in divided doses (diltiazem 60 mg three times daily and nifedipine 10 mg four times daily) over 3 weeks. Maximal exercise tests were performed before and at the end of each 3-week treatment period. Both diltiazem and nifedipine increased the total duration of exercise (p less than 0.001) and the time to appearance of 1.5 mm of ST depression (p less than 0.001). Both drugs reduced resting systolic and diastolic blood pressure; however the effect was greater with nifedipine. Nifedipine, but not diltiazem, caused a significant increase of resting heart rate (p less than 0.05). Both drugs blunted the blood pressure and heart rate response to exercise: nifedipine had a greater effect on the former (p less than 0.001), diltiazem on the latter (p less than 0.05). The rate-pressure product was significantly reduced at rest (p less than 0.01) and submaximal (p less than 0.001), but not maximal exercise with both drugs. The reduction of rate-pressure product is possible as the mechanism by which calcium-antagonist drugs enhance the duration of exercise in the coronary patients. Our results documented a comparable therapeutic efficacy of the two drugs, but side effects were more common with nifedipine.