Long-term monotherapy of angina pectoris with diltiazem

Eighteen patients with exertional angina were treated with diltiazem (360 mg/day). Serial exercise testing was performed and the results were compared to evaluations when patients were receiving placebo at the initiation and termination of the study. Serial exercise tests indicated significant improvement in duration of exercise (+18%, p less than 0.001), time to 1 mm ST depression (+32%, p less than 0.005), and time to angina (+46%, p less than 0.001) when patients were receiving diltiazem. During diltiazem treatment, there was a significant reduction in myocardial oxygen demand as indicated by the change in submaximal pressure rate product. This may contribute to the beneficial effect of diltiazem in patients with exertional angina. The reduction in pressure rate product was due primarily to a change in heart rate. This study provides evidence that diltiazem is an effective long-term monotherapy for angina; no evidence of drug tachyphylaxis was apparent after a total of 16 months treatment with diltiazem.