Effects of diltiazem on cardiovascular responses during exercise in systemic hypertension and comparison with propranolol.
Sixteen patients with uncomplicated systemic hypertension were treated with placebo, diltiazem (180 mg/day) and propranolol (60 mg/day) for 1 month each. Each patient performed multistage symptom-limited treadmill exercise tests during each period of administration. There was no significant difference in maximal exercise duration between placebo, diltiazem and propranolol. Diltiazem significantly decreased both systolic and diastolic blood pressure (BP) and heart rate at rest, during submaximal exercise at the same work load and maximal exercise. Propranolol produced similar changes in systemic BP and heart rate at rest and during exercise. However, the reductions in systolic BP, heart rate and pressure-rate product with diltiazem during exercise were smaller than those with propranolol at small doses, suggesting that diltiazem in its usual therapeutic dose was almost devoid of beta-blocking activity. Thus, diltiazem may be of benefit to hypertensive patients because it reduces systemic BP even during exercise. It is particularly useful when systemic hypertension occurs in association with coronary artery disease because of its effects of coronary artery dilatation and heart rate reduction.