Comparison of the effects of imidapril and enalapril in a prospective, multicentric randomized trial in dogs with naturally acquired heart failure.

OBJECTIVE To compare the efficacy and tolerability of the long-term administration of two different angiotensin-converting enzyme inhibitors, imidapril and enalapril, in a multicentric, prospective, randomized parallel-group scheme clinical trial in dogs with naturally acquired heart disease. ANIMALS One hundred twenty eight dogs with clinical signs of heart failure (stage II (64-50%) - III (45-35%) - IV (19-15%) New York Heart Association) caused by chronic valvular disease or dilated cardiomyopathy were selected. PROCEDURE Imidapril (minimum dosage 0.25 mg/kg) or enalapril (median dosage 0.5 mg/kg) was administered orally once daily for 12 months, either alone or as an add-on therapy to diuretics and/or digoxin. RESULTS The primary outcome measure was the quality of life score after 3 months of therapy. Sixty-one percent of the dogs in the imidapril group (36/59) and 52 % in the enalapril group (30/58) were considered responders. After 12 months, a clear improvement compared to baseline was maintained in each treatment group for most parameters reflecting the quality of life such as fatigue, exercise tolerance, dyspnea, cough and general condition. Quality of life scores and survival times were similar in both groups after 12 months. Both drugs were well tolerated over the one-year follow-up. CONCLUSIONS Imidapril proved to be as effective as the reference drug enalapril in the treatment of dogs with NYHA class II-IV heart failure. As with enalapril, imidapril was well tolerated during the long-term treatment period of one year in the dose range used in the study.