The Preventative Effects of Vasodilating Beta-Blockers in Cardiovascular Disease

The beta-blocking drugs are known to modify the course of hypertensive and atherosclerotic heart disease and significantly reduce the mortality and morbidity associated with these diseases. The place of vasodilating beta-blocking drugs, of which carvedilol is an example, has not been so clear, although they have obvious theoretical advantages. We performed a study on 12 hypertensive subjects using the technique of continuous ambulatory intra-arterial blood pressure recording which demonstrated that carvedilol (50 mg bid) achieved satisfactory blood pressure control throughout the full 24 h cycle. The addition, there was a marked reduction in left ventricular end-systolic and end-diastolic volumes with prolonged administration, suggesting a decrease in heart size, confirmed in other studies. A second study in patients with chronic stable angina and impaired left ventricular wall motion showed that carvedilol 25 mg bid not only improved exercise tolerance, but also reduced heart size, improved left ventricular ejection fraction, and abolished wall motion abnormalities. These results prompted a further study in 17 patients with chronic ischaemic heart failure. The haemodynamic and clinical responses to intravenous carvedilol followed by the oral drug 50 mgm b.i.d. for 8 weeks were studied. There was an improvement in all haemodynamic indices, although postural hypotension necessitated withdrawing two patients and clinical deterioration was evident in two others. The beneficial effects of carvedilol were considered to be related to the combined reduction in afterload and inhibition of neurohumeral activation. These results have been confirmed in placebo-controlled, double-blind studies from other workers.