Beneficial effects of betaxolol, a selective antagonist of beta-1 adrenoceptors, on exercise-induced myocardial ischemia in patients with coronary vasospasm

Abstract

Although beta-blockers can not be used for the treatment of vasospastic angina, the effect of beta-blockers with vasorelaxant property on coronary vasospasm remains uncertain. In this study, we evaluated the effect of betaxolol, a new beta-blocker with calcium antagonistic property, as an additional therapy on vasospastic angina (VSA) with anginal attacks on effort. We enrolled 12 patients with VSA and anginal attacks with ST segment depression during exercise stress test. All patients received 1.25–5 mg of betaxolol for 3 months. Treadmill exercise stress test and adenosine triphosphate stress thallium-201 myocardial scintigraphy were performed before and 3 months after the onset of the betaxolol treatment. The other drugs including calcium antagonists, nitrates and nicorandil were continued. No patients experienced the exacerbation of angina during the betaxolol treatment. Exercise time to chest pain (317.5±72.1–454.2±75.5 s, P<0.01) and maximal ST segment depression (1.67±0.67–1.16±0.46 mm, P<0.01) obtained by exercise stress test, the defect score (8.6±2.7–5.3±2.1, P<0.01), the extent score (14.8±5.8–8.8±4.6%, P<0.01), the severity score (17.5±7.3–11.3±5.2, P<0.01) and washout rate (31.4±5.6–37.6±5.0%, P<0.01) obtained by the scintigraphy were improved by betaxolol. Our results suggest that betaxolol increases regional myocardial blood flow and improves exercise capacity in patients with VSA. Betaxolol may become a drug for a new potential therapy for VSA.