Efficacy of Benazepril Hydrochloride to Delay the Progression of Occult Dilated Cardiomyopathy in Doberman Pinschers

Background Angiotensin converting enzyme inhibitors (ACEIs) are recommended in people to treat asymptomatic (occult) dilated cardiomyopathy (DCM). Efficacy of therapy in occult DCM in dogs is unknown. Hypothesis ACEIs, specifically benazepril hydrochloride (BH), will delay the onset of overt DCM in Doberman Pinschers. Animals Ninety-one Doberman Pinschers were studied, 57 dogs received BH, and 34 dogs no ACEI. Methods Retrospective study of the medical records of all Doberman Pinschers with occult DCM that received BH or no ACEI between April 1989 and February 2003. Two criteria of left ventricular enlargement were used for enrollment: one independent of body weight (BW) (C1) and the other indexed to BW (C2). Cox proportional hazards analyses were used to identify variables associated with the onset of overt DCM. Results On univariate analysis the median time to onset of overt DCM was significantly longer for the benazepril group (for C1: 425 days for BH, 95% confidence interval [CI] 264-625 days; 339 days for no ACEI, CI 172-453 days, P = .02; for C2: 454 days for BH, CI 264-628 days; 356 days for no ACEI, CI 181-547 days, P = .02). The hazard ratio (HR) (benazepril/no ACEI) was 0.57, CI 0.35-0.94, P = .03 for C1; HR = 0.56, CI 0.34-0.93, P = .02 for C2. On multivariate analysis, BH significantly delayed onset of overt DCM (HR [benazepril/no ACEI] = 0.45, CI 0.26-0.78, P < .01, for C1; HR = 0.36, CI 0.21-0.63, P < .01, for C2). Conclusions BH in particular and ACEIs in general might delay the progression of occult DCM. Prospective studies are warranted to test this theory.