Effects of benazepril in the treatment of feline hypertrophic cardiomyopathy Results of a prospective, open-label, multicenter clinical trial

Abstract

To evaluate the efficacy of benazepril on clinical signs and echocardiographic parameters in cats with primary hypertrophic cardiomyopathy (HCM). ACE-inhibitors have positive effects in man with HCM, and contribute to a reduction of myocardial hypertrophy. Addition of an ACE-inhibitor to the standard treatment of HCM in cats may have beneficial effects. A total of 32 cats which were either asymptomatic or in stabilised congestive heart failure (ISACHC* class Ib, II or IIIa) were included in a one-year, prospective, open-label, clinical trial in 5 centres in Switzerland. 28 of these cats were allocated to one of two treatment groups: 1) standard therapy (ST) alone (n=9), consisting of a long-acting formulation of diltiazem (6-9 mg/kg sid) and optional acetylsalicylic acid (50 mg twice weekly, or 2) the same ST plus benazepril (0.33 - 0.75 mg/kg sid, n=19). Cats treated with benazepril showed a statistically significant decrease (mean +/- SEM, 0.11 +/- 0.03 mm/month, p = 0.002) in the left ventricular wall thickness (LVWD) from baseline, while no change (increase of 0.02 +/- 0.04 mm/month, p=0.66) was observed in cats on ST alone. Differences in LVWD between the two groups reached statistical significance (p=0.02). Benazepril treated cats showed more improvement in clinical signs (20-53%) than cats receiving ST alone (0-20%) but differences between the groups were not statistically significant (p>0.1). No change in septal thickness (IVSD) or left atrial to aortic root ratio (LA/Ao) was observed in either group. Benazepril had some beneficial effects on clinical signs and cardiac remodelling in cats with HCM and was well tolerated. These results, however, need to be confirmed in additional controlled studies. * ISACHC classification is described in the previous paper (Bench-study).