Effect of beta-adrenergic blockade on haemodynamic responses to dynamic and isometric exercise in angina pectoris

Abstract

The effect of treatment for 1--4 weeks with metoprolol, a beta 1-selective blocking agent, or alprenolol, on the heart rate and blood pressure response to isometric exercise was studied in two groups of 12 patients with angina. Measurements were made during the peak effect of metoprolol 10, 40 or 50 mg, and alprenolol 200 mg as Aptin Durules. After 1 min of sustained handgrip at 50% of maximal voluntary contraction, systolic (6--15%) and diastolic (8--12%) blood pressure after both drugs was significantly lower than without any beta-blockade; Heart rate was decreased by 19--22% by metroprolol but not by alprenolol. The blood pressure rise during handgrip was not attenuated by either drug. The rise in heart rate was significantly reduced (by 36--50%) by metoprolol 40 and 50 mg and alprenolol 200 mg. No patient experienced angina during handgrip. In contrast, all but one were restricted by angina during bycycle exercise without treatment, at a level that produced the same increase in heart rate as the handgrip test, vis. 3 min at a load of 33 W). The cardiovascular response to sustained handgrip is too small to provide a useful challenge for determinatin of the anti-anginal efficacy of drugs. However, slight ECG changes of ischaemia did occur during handgrip, which were reversed by beta-blockade.