VetMedPimobendan vs benazepril in MMVD heart failure — LIKELY
In dogs with congestive heart failure due to myxomatous mitral valve disease, does pimobendan vs benazepril (each added to conventional therapy) give a longer time to cardiac death, euthanasia for heart failure, or treatment failure?
Shelf #203 · gate-verified and approved by the developer
LIKELY: In dogs with congestive heart failure from myxomatous mitral valve disease, pimobendan plus conventional therapy prolongs the time to sudden cardiac death, euthanasia for cardiac reasons, or treatment failure compared with benazepril plus conventional therapy. In QUEST, a prospective single-blinded study with 260 dogs randomized (252 analysed), the median time to the composite primary endpoint was 267 days on pimobendan vs 140 days on benazepril (hazard ratio 0.688, 95% confidence limits 0.516-0.916; P = .0099) — a 31.2% relative reduction in hazard — and the benefit persisted after adjusting for all baseline variables. The stamp is LIKELY rather than PROBABLE because the trial was single-blinded (not double-blinded) and the comparator is an active drug, not placebo. This pack is Tier C because its endpoint includes cardiac death and euthanasia for heart failure. Drafted Nov 10, 2026 (VetMed build, topic #203); all figures from abstracts fetched and verified at drafting.
QUEST (Häggström 2008): pimobendan extended median time to cardiac death, euthanasia for heart failure, or treatment failure to 267 days vs 140 on benazepril
Prospective single-blinded randomized study (QUEST)
Who: Dogs: 260 client-owned dogs in congestive heart failure caused by naturally occurring myxomatous mitral valve disease, recruited from 28 centers in Europe, Canada, and Australia; randomized to oral pimobendan (0.4-0.6 mg/kg/day) or benazepril hydrochloride (0.25-1.0 mg/kg/day), each in addition to conventional therapy. Eight dogs were excluded from analysis; 124 dogs were randomized to pimobendan and 128 to benazepril in the analysed set.
Result: One hundred and ninety dogs reached the primary endpoint; the median time was 188 days overall (267 days for pimobendan, 140 days for benazepril; hazard ratio = 0.688, 95% confidence limits [CL] = 0.516-0.916, P = .0099) — a 31.2% relative reduction in hazard on pimobendan. The benefit of pimobendan persisted after adjusting for all baseline variables.
Watch out: The record describes the study as 'single-blinded' — not double-blinded — and there is no placebo arm: QUEST shows pimobendan outperforming benazepril as the add-on to conventional therapy, not the effect of either drug against no treatment. Euthanasia for cardiac reasons is part of the composite endpoint and is an owner/clinician decision, which single blinding protects only partly.
Häggström J, Boswood A, O'Grady M et al. Effect of pimobendan or benazepril hydrochloride on survival times in dogs with congestive heart failure caused by naturally occurring myxomatous mitral valve disease: the QUEST study. J Vet Intern Med. 2008;22(5):1124-1135. PMID: 18638016. Registry ID: none in the record. MeSH: Animals · Benzazepines · Cardiotonic Agents · Dog Diseases · Dogs · Female · Heart Failure · Male · Mitral Valve Insufficiency · Multivariate Analysis · Proportional Hazards Models · Pyridazines
Synthesis: a single large single-blinded active-comparator trial carries this shelf
Synthesis
Who: Synthesis of the card above: QUEST (Häggström 2008), the single trial on this shelf — a prospective single-blinded randomized study of 260 dogs (252 analysed) in MMVD congestive heart failure.
Result: This shelf rests on one trial, stated on its face. QUEST randomized dogs already in heart failure to pimobendan or benazepril on top of conventional therapy and found a longer median time to its hard composite endpoint (cardiac death, euthanasia for heart failure, or treatment failure) on pimobendan: 267 vs 140 days, hazard ratio 0.688. Randomization and size support the comparison; single blinding and the absence of a placebo arm are why the stamp is LIKELY, not PROBABLE. The death/euthanasia endpoint makes the pack Tier C.
Watch out: QUEST does not compare either drug against conventional therapy alone, and its dogs had MMVD heart failure specifically — it does not answer the same question for dilated cardiomyopathy heart failure.
Synthesis of Häggström J et al. PMID: 18638016. Registry ID as on the individual card.
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