Longitudinal Analysis of Quality of Life, Clinical, Radiographic, Echocardiographic, and Laboratory Variables in Dogs with Myxomatous Mitral Valve Disease Receiving Pimobendan or Benazepril: The QUEST Study

Abstract

Background: Myxomatous mitral valve disease (MMVD) is an important cause of morbidity and mortality in dogs. Objectives: To compare, throughout the period of follow-up of dogs that had not yet reached the primary endpoint, the longitudinal effects of pimobendan versus benazepril hydrochloride treatment on quality-of-life (QoL) variables, concomitant congestive heart failure (CHF) treatment, and other outcome variables in dogs suffering from CHF secondary to MMVD.Animals: A total of 260 dogs in CHF because of MMVD.Methods: A prospective single-blinded study with dogs randomized to receive pimobendan (0.4-0.6 mg/kg/day) or benazepril hydrochloride (0.25-1.0 mg/kg/day). Differences in outcome variables and time to intensification of CHF treatment were compared.Results: A total of 124 dogs were randomized to pimobendan and 128 to benazepril. No difference was found between groups in QoL variables during the trial. Time from inclusion to 1st intensification of CHF treatment was longer in the pimobendan group (pimobendan 98 days, IQR 30-276 days versus benazepril 59 days, IQR 11-121 days; P = .0005). Postinclusion, dogs in the pimobendan group had smaller heart size based on VHS score (P = .013) and left ventricular diastolic (P = .035) and systolic (P = .0044) dimensions, higher body temperature (P = .030), serum sodium (P = .0027), and total protein (P = .0003) concentrations, and packed cell volume (P = .030). Incidence of arrhythmias was similar in treatment groups.Conclusions and Clinical Importance: Pimobendan versus benazepril resulted in similar QoL during the study, but conferred increased time before intensification of CHF treatment. Pimobendan treatment resulted in smaller heart size, higher body temperature, and less retention of free water.

Longitudinal Analysis of Quality of Life, Clinical, Radiographic, Echocardiographic, and Laboratory Variables in Dogs with Preclinical Myxomatous Mitral Valve Disease Receiving Pimobendan or Placebo: The EPIC Study

“…There is a reduction in heart size in dogs with MMVD and DCM administered pimobendan. Earlier studies have only evaluated the effect of initiation of pimobendan on dogs’ heart size after the onset of heart failure in dogs with MMVD.…”

“…Longitudinal effects of pimobendan treatment have been described in dogs with stage C MMVD but have not been reported in dogs with stage B disease. Some dogs show subtle signs associated with their cardiac disease before overt signs of CHF develop.…”

Myxomatous Mitral Valve Disease in Dogs - an Update and Perspectives

“…The median survival times of dogs with moderate and severe congestive heart failure (CHF) was 33 and 9 months, respectively (5). Dogs receiving pimobendan instead of benazepril hydrochloride, additionally to diuretics, have significantly longer survival times (16). The quality of life was similar in dogs receiving pimobendan or benazepril, but the time to increase the treatment regime was longer in pimobendan group, heart size was smaller and water retention was less in the pimobendan group (17).…”

Effect of pimobendan on the incidence of arrhythmias in small breed dogs with myxomatous mitral valve degeneration

“…The biggest trial to date examining pimobendan therapy in dogs with MMVD in CHF has shown survival benefits when compared to ACEi. 5 Previous smaller studies have also shown positive survival benefits. 2,13 However, the veterinary literature evaluating the proarrhythmic effects of pimobendan in dogs with CHF due to MMVD is sparse and conflicting.…”

“…2 Similarly, the QUEST study demonstrated a prolonged time to reach the composite primary endpoint of cardiac death, euthanasia as a consequence of cardiac disease, or treatment failure with pimobendan, and also documented no difference in incidence of arrhythmia compared to benazepril. 5 However, analysis of arrhythmias in the study was limited to a 3 min in-hospital electrocardiogram (ECG), and the number of dogs experiencing sudden death in each group was small. In a study evaluating dogs treated with pimobendan or ACE inhibitor (ACEi), both groups had increased VPCs and atrial premature complexes (APCs) over the duration of the study based on 5-min ECG in a small number of dogs.…”