Effect of beta blockade with betaxolol on left ventricular systolic function in chronic stable angina pectoris and left ventricular dysfunction

To assess the effect of β blockade on left ventricular (LV) performance in patients with LV dysfunction and stable angina pectoris, 18 subjects taking a placebo followed by incremental doses of the cardioselective β-adrenergic blocking agent betaxolol (5, 10, 20, 40 and 80 mg/day) were studied. The study ended with the achievement of optimal clinical β blockade (heart rate at rest 50 to 60 beats/min, a 20% or smaller increase in heart rate during stage I of symptom-limited treadmill exercise using the modified Bruce protocol). Optimal clinical β blockade produced a decrease in mean frequency of angina, from 6.8 ±1.7 to 0.7 ±0.8 episodes per week (p < 0.0005) and an increase in mean treadmill exercise capacity, from 3.1 ±1.7 to 7.7 ±2.8 minutes (p < 0.0005). LV systolic function was assessed at rest and during symptom-limited exercise with radionuclide left ventriculography. Mean LV ejection fraction (EF) during therapy with placebo was 39 ±7% at rest and 40 ± 8% at peak exercise. Mean LVEF during optimal clinical β blockade was 43 ±11 % at rest and 45 ± 10% at peak exercise. Neither of these changes was statistically significant. No patient had clinical or radiographic signs of LV failure. The results suggest that optimal clinical β blockade with betaxolol, in doses sufficient to significantly reduce the frequency of angina and improve exercise capacity in patients with stable angina pectoris and mild to moderate LV systolic dysfunction, does not cause significant deterioration of LV systolic function or produce LV failure.