First dose hypotension with enalapril and prazosin in congestive heart failure

Since the introduction of angiotensin converting enzyme inhibitors into the adjunctive treatment of patients with congestive heart failure, cases of severe hypotension, especially on the first day of treatment, have occasionally been reported. To assess the safety of the angiotensin converting enzyme inhibitor enalapril a multicenter, open, randomized, prazosin-controlled trial was designed comparing the incidence and severity of symptomatic hypotension on the first day of treatment. Trial medication was 2.5 mg enalapril or 0.5 mg prazosin. Subjects were 1210 inpatients with New York Heart Association functional class (I)/II and III who were not adequately compensated with digitalis and/or diuretics. In the group receiving enalapril, 3 patients (0.5%) experienced severe hypotension on day 1 and 28 patients (4.7%) moderate hypotension. In those given prazosin, 15 patients (2.6%) experienced severe hypotension and 60 patients (10.3%) moderate hypotension. The difference is statistically significant (P less than or equal to 0.000012). All patients recovered. It was concluded that treatment of patients suffering from congestive heart failure New York Heart Association functional class (I)/II or III with enalapril is comparably well tolerated.