Augmented mean systolic ejection rate in coronary patients treated with diltiazem

The effect of a single 120-mg oral dose of diltiazem on the mean systolic ejection rate (MSER) was studied in 18 patients with exercise-induced angina pectoris, at rest, during, and after symptom-limited, multi-stage, treadmill testing. The patients were subdivided into two groups according to the mean pulmonary capillary pressure at maximal exercise. In group I (9 patients), the mean pulmonary capillary pressure was 16 mm Hg or lower, and in group II (9 patients), this variable was higher than 16 mm Hg at maximal exercise. Before diltiazem, MSER increased in response to exercise in both groups. MSER was correlated with stroke volume (r = 0.90), heart rate (r = 0.34), and systemic vascular resistance (r = 0.82), but not correlated with mean pulmonary capillary pressure (r = 0.18) or mean arterial pressure (r = 0.06) for all patients. 1 h after the administration of diltiazem, patients in group I showed no significant change in MSER. Group II patients showed significant increases in MSER at two submaximal workloads (267 vs. 295, p less than 0.05, 292 vs. 325, p less than 0.02), maximal exercise (289 vs. 333, p less than 0.05), and the 3rd min of recovery (216 vs. 278, p less than 0.05). In patients with exertional left ventricular dysfunction, diltiazem improved cardiac performance, and the changes in MSER suggest that contractility was influenced favorably. Increased coronary blood flow is postulated as a mechanism for this improvement.