Evaluation of benazepril in cats with heart disease in a prospective, randomized, blinded, placebo-controlled clinical trial

Background: Heart disease is an important cause of morbidity and mortality in cats, but there is limited evidence of the benefit of any medication. Hypothesis: The angiotensin-converting enzyme inhibitor benazepril would delay the time to treatment failure in cats with heart disease of various etiologies. Animals: One hundred fifty-one client-owned cats. Methods: Cats with heart disease, confirmed by echocardiography, with or without clinical signs of congestive heart failure, were recruited between 2002 and 2005 and randomized to benazepril or placebo in a prospective, multicenter, parallel-group, blinded clinical trial. Benazepril (0.5-1.0 mg/kg) or placebo was administered PO once daily for up to 2 years. The primary endpoint was treatment failure. Analyses were conducted separately for all-cause treatment failure (main analysis) and heart disease-related treatment failure (supportive analysis). Results: No benefit of benazepril versus placebo was detected for time to all-cause treatment failure (P =.42) or time to treatment failure related to heart disease (P =.21). Hazard ratios (95% confidence interval [CI]) from multivariate analysis for benazepril compared with placebo were 1.00 (0.57-1.74) for all-cause failure, and 0.99 (0.50-1.94) for forward selection and 0.93 (0.48-1.81) for bidirectional selection models for heart disease-related failure. There were no significant differences between groups over time after administration of the test articles in left atrium diameter, left ventricle wall thickness, quality of life scores, adverse events, or plasma biochemistry or hematology variables. Conclusions and Clinical Relevance: Benazepril was tolerated well in cats with heart disease, but no evidence of benefit was detected.