Cardiac effects of prazosin in chronic aortic insufficiency

Eight patients with chronic moderate to severe aortic insufficiency were assessed by radionuclide angiography at rest and during maximal bicycle exercise after six weeks of placebo, six weeks of prazosin titration up to 10 mg bid and 12 weeks of prazosin maintenance therapy. Prazosin was well tolerated and the final dose amounted to 18.6 +/- 0.7 mg/day. Exercise performance tended to increase (from 8.9 +/- 1.1 to 9.6 +/- 0.8 mins). Resting and exercise blood pressure and heart rate were not affected by prazosin. Left ventricular volumes were decreased and exercise ejection fraction increased by prazosin. Total left ventricular output decreased, whereas regurgitant index improved. The authors conclude that in patients with chronic moderate to severe aortic insufficiency, chronic prazosin therapy causes persistent improvements in left ventricular anatomy and function both at rest and during exercise.