Comparison of the immediate and long‐term effects of captopril and isosorbide dinitrate as adjunctive treatment in mild heart failure.

1. The efficacy of captopril and isosorbide dinitrate (ISDN) as adjunctive therapy to digoxin and diuretics in mild heart failure was compared in a double‐blind study. 2. Twenty‐one patients were randomly allocated to captopril (twice or three times daily) or ISDN. Eighteen patients completed a protocol of placebo run‐in, dose titration and maintenance treatment for 3 months. 3. Symptom‐limited exercise tolerance, ejection fraction and radionuclide indices of diastolic function estimated by gated blood pool scan did not change with either treatment. 4. Captopril improved functional class (Canadian Cardiovascular Society) and reduced requirements for increased diuretic dosage at both 1 and 3 months of maintenance treatment. Patients treated with ISDN required increased diuretic and did not improve their functional class. Differences between the treatments were significant only for diuretic dosage requirements. 5. We conclude that adjunctive therapy of mild heart failure with captopril administered twice daily provides a diuretic‐sparing effect and may improve functional class during 3 months of maintenance treatment. 1989 The British Pharmacological Society