Effect of digoxin and vasodilators on left ventricular function in aortic regurgitation

In order to assess the relative value of digoxin, nifedipine and hydralazine on left ventricular performance at rest and during exercise, we studied 10 men with moderately severe chronic aortic regurgitation using two-dimensional echocardiography. Digoxin after one month at therapeutic serum levels increased resting ejection fraction as compared to control [0.54 +/- 0.08 (SD) vs 0.47 +/- 0.08, respectively, P less than 0.03]. Ejection fraction decreased during exercise but the difference between digoxin and control was maintained. Stroke volume also was higher on digoxin than control at rest (93 +/- 15 vs 83 +/- 17 ml, P less than 0.02) and the larger stroke volume on digoxin was maintained during exercise. By contrast, stroke volume was reduced by one month of therapy with maximally tolerated nifedipine doses compared to control (74 +/- 8 vs 83 +/- 17 ml, P = 0.03) and this difference was maintained during exercise. Hydralazine in doses up to 225 mg/day for one month produced no significant changes in left ventricular performance compared to control at rest or during exercise. However, compared to digoxin ejection fraction at peak exercise was significantly less on hydralazine (0.39 +/- 0.9 vs 0.52 +/- 10, P less than 0.02). These data suggest that digoxin improved left ventricular performance and may be of benefit in the treatment of patients with chronic aortic regurgitation.