Beneficial effects of diltiazem combined with beta blockade in angina pectoris.

The effects of combining diltiazem, a calcium channel blocking agent, with beta adrenergic blockade were evaluated in 11 patients with obstructive coronary artery disease. All patients had stable angina pectoris and were receiving oral beta blocking therapy. Symptomatic, metabolic, coronary and systemic haemodynamic responses were monitored at rest and during atrial pacing. Following the administration of diltiazem, resting arterial blood pressure, systemic vascular resistance and heart rate fell significantly with no adverse effects on left ventricular function. During pacing diltiazem produced significant decreases in rate-pressure product and myocardial oxygen consumption. As a consequence there was a significant increase in mean pacing time to angina from 151 +/- 42 to 406 +/- 72 s (P less than 0.001). Concomitantly, myocardial lactate extraction was improved significantly from mean lactate production of -2 +/- 12% to mean lactate extraction of 12 +/- 7% (P less than 0.05). This study indicates that intravenous diltiazem can be administered to patients receiving chronic oral beta blockade without adverse haemodynamic effects and that combination therapy has significant beneficial effects in coronary artery disease.