Effects of pimobendan in cats with hypertrophic cardiomyopathy and recent congestive heart failure: Results of a prospective, double‐blind, randomized, nonpivotal, exploratory field study

Abstract

Abstract Background The benefits of pimobendan in the treatment of congestive heart failure (CHF) in cats with hypertrophic cardiomyopathy (HCM) have not been evaluated prospectively. Hypothesis/Objectives To investigate the effects of pimobendan in cats with HCM and recent CHF and to identify possible endpoints for a pivotal study. We hypothesized that pimobendan would be well‐tolerated and associated with improved outcome. Animals Eighty‐three cats with HCM and recently controlled CHF: 30 with and 53 without left ventricular outflow tract obstruction. Methods Prospective randomized placebo‐controlled double‐blind multicenter nonpivotal field study. Cats received either pimobendan (0.30\u2009mg/kg q12h, n = 43), placebo (n = 39), or no medication (n = 1) together with furosemide (<10 mg/kg/d) with or without clopidogrel. The primary endpoint was a successful outcome (ie, completing the 180‐day study period without a dose escalation of furosemide). Results The proportion of cats in the full analysis set population with a successful outcome was not different between treatment groups (P = .75). For nonobstructive cats, the success rate was 32% in pimobendan‐treated cats versus 18.2% in the placebo group (odds ratio [OR], 2.12; 95% confidence interval [CI], 0.54‐8.34). For obstructive cats, the success rate was 28.6% and 60% in the pimobendan and placebo groups, respectively (OR, 0.27; 95% CI, 0.06‐1.26). No difference was found between treatments for the secondary endpoints of time to furosemide dose escalation or death (P = .89). Results were similar in the per‐protocol sets. Adverse events in both treatment groups were similar. Conclusions and Clinical Importance In this study of cats with HCM and recent CHF, no benefit of pimobendan on 180‐day outcome was identified.