Divergent Effects of Diltiazem Exertional Angina in Patients With

Fifteen patients with exercise-induced angina were studied at rest and during symptom-limited upright exercise with a Swan-Ganz catheter and an arterial line in place. Cardiac output was measured using the direct Fick principle. The patients were classified on the basis of the mean pulmonary capillary pressure at maximal exercise. In Group I (eight paUents) the mean pulmonary capillary pressure was less than 16 mm Hg and in Group II (seven patients) it was greater than 16 mm Hg. Patients in Group |1 were older and heavier and had more severe angina during exercise and exhibited greater S-T depression at maximal exercise before treatment. Each patient received 120 mg of oral dilUazem and exercise was repeated I hour later. In both groups exercise duration was prolonged (Group I, 5.8 4- 3 versus 6.8 4- 3 minutes [mean -4- standard deviation], p <0.05; Group II, 4.7 4- 2.3 versus 6.2 -I- 1.7 minutes, p <0.05) and the frequency of angina was less (before diltiazem, 11 of 15 had pain, after diltiazem 4 of 15 had pain). During exercise there was a significant reduction in mean systemic arterial pressure (15 percent), systemic resistance (30 percent) and double product (blood pressure X heart rate) (20 percent) after administration of diltiazem. The electrocardiographic evidence of myocardial ischemia at maximal exercise was reduced as a result of diltiazem administration (Group I, 1.12 -t- 1.2 versus 0.3 -I- 0.8 ram, p <0.05; Group II, 2.78 -I- 1.18 versus 0.8 ~ 1.2 ram, p <0.01). After diltiazem patients in Group II showed a significant increase in cardiac output (9.5 4- 1.8 versus 11.0 4- 2.3 liters/min, p <0.05) and a significant reducUon in mean pulmonary arterial pressure (36 + 6 versus 23 -I- 3 mm Hg, p <0.001), mean pulmonary capillary pressure (24 4- 5 versus 12 + 4 mm Hg, p <0.001) and pulmonary vascular resistance (318 -t- 91 versus 172 4- 34 dyne s cm -s, p <0.01) at maximal exercise. These variables were unchanged in patients in Group I.