Retrospective evaluation of the safety and tolerability of pimobendan in cats with obstructive vs nonobstructive cardiomyopathy

Q: What are the key findings of this study?

Pimobendan-related adverse effects occurred in 4.6% of cats with CHF overall, with no significant difference between cats with outflow tract obstruction (2%) and nonobstructive disease (5.4%, P=0.70).

Q: What is the clinical evidence from this study?

Study design: Cohort. Population: Feline cardiomyopathy and congestive heart failure (with vs without outflow tract obstruction) (n=260). Intervention: Outflow tract obstruction (in cats treated with oral pimobendan) vs. Nonobstructive cardiomyopathy (in cats treated with oral pimobendan). Primary outcome: Adverse effects suspected to be related to pimobendan administration within 45 days of initiation (p=0.70).

Q: What does this research mean for the field?

Pimobendan is well tolerated in cats with cardiomyopathy and congestive heart failure, with no significant difference in the incidence of adverse effects between cats with and without left ventricular outflow tract obstruction. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Jessica Ward; Efrem Z. Kussin; Melissa A. Tropf; Sandra Tou; Teresa C. DeFrancesco; Bruce W. Keene

doi:10.1111/jvim.15920

October 7, 2020Journal of Veterinary Internal MedicineOpen Access

Retrospective evaluation of the safety and tolerability of pimobendan in cats with obstructive vs nonobstructive cardiomyopathy

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Key result

Pimobendan adverse effects in feline CHF do not differ by outflow tract obstruction status.

P=0.70
n=260

Why the study?

Pimobendan is frequently used off-label to treat cats with CHF, but concern exists regarding its safety in cats with outflow tract obstruction.

Does the incidence of adverse effects associated with oral pimobendan differ between cats with outflow tract obstruction and cats with nonobstructive cardiomyopathy and congestive heart failure?

Study Design

Type

Cohort (n=260)

Multicenter

Yes

Structured PICO

Does the incidence of adverse effects associated with oral pimobendan differ between cats with outflow tract obstruction and cats with nonobstructive cardiomyopathy and congestive heart failure?

P

Population

260 cats with cardiomyopathy and congestive heart failure (57 with outflow tract obstruction, 203 with nonobstructive disease), median age 10.0 years, 28.1% female, treated with oral pimobendan at two US veterinary centers for a median of 137 days.

E

Exposure

Oral pimobendan (median initial dose 0.56 mg/kg/day, typically 1.25 mg PO q12h per cat; median final dose 0.61 mg/kg/day) administered for a median of 137 days (range 0-2674 days) in cats with outflow tract obstruction (OTO, n=57).

C

Comparator

Oral pimobendan (median initial dose 0.55 mg/kg/day; median final dose 0.61 mg/kg/day) in cats with nonobstructive cardiomyopathy and CHF (n=203), with both groups receiving standard CHF background therapy (including furosemide in 93.5%, clopidogrel in 82.6%, ACE inhibitors in 72.9%).

O

Outcome

Incidence of adverse effects suspected to be related to pimobendan administration (occurring within 45 days of initial pimobendan administration and resolving with discontinuation)safety

Main Result

Absolute Event Rate: 2% vs 5.4%

p-value: p=0.70

In this veterinary retrospective study of 260 cats with cardiomyopathy and congestive heart failure, off-label oral pimobendan was well tolerated with a low rate of adverse effects (4.6%) that did not differ between cats with or without outflow tract obstruction.

Limitations

Retrospective design with no placebo or alternate treatment control group
Difficulty in definitively classifying feline cardiomyopathy phenotypes and assessing diastolic function at high feline heart rates
Modified IRIS staging relied on single creatinine values at CHF diagnosis and follow-up which might reflect acute kidney injury in addition to chronic kidney disease
Case management and drug prescribing practices may have varied between clinicians, institutions, and over the 15-year study period
Potential underreporting of owner-observed or subclinical adverse events in medical records
Retrospective design with no untreated or placebo control group, precluding assessment of efficacy
Inherent difficulty in defining feline cardiomyopathy phenotypes and assessing diastolic function
Creatinine values used for IRIS staging might have reflected a combination of chronic kidney disease and acute kidney injury
Non-standardized case management and prescribing practices across clinicians, institutions, and time
Medical record review may have missed unreported or subclinical adverse events

Implication

Supports pimobendan tolerability in feline CHF irrespective of obstruction; leaves open randomized confirmation before routine adoption.

Abstract

BACKGROUND: Pimobendan is frequently used off-label for treatments of cats with congestive heart failure (CHF). Concern exists regarding the safety of pimobendan in cats with outflow tract obstruction (OTO). OBJECTIVES: In cats treated with pimobendan, incidence of adverse effects will not differ between cats with OTO vs cats with nonobstructive cardiomyopathy. ANIMALS: Two-hundred sixty cats with CHF (57 with OTO, 203 with nonobstructive disease). METHODS: Retrospective medical record review. Groups were compared using 2-sample t-tests, Wilcoxon rank-sum tests, and Fisher exact tests. RESULTS: Compared to cats with nonobstructive cardiomyopathy, cats with OTO were younger (8.9 [interquartile range (IQR) 6.6] vs 10.8 [6.3] years, P = .0036), more likely to have a heart murmur (51/57 [90%] vs 76/203 [37.8%] cats, P < .0001), more likely to manifest CHF as pulmonary edema (53/57 [83%] vs 144/203 [70.9%] cats, P = .0004), and less likely to have pleural effusion (19/57 [33%] vs 122/203 [60.1%] cats, P = .0005). Adverse effects suspected to be related to pimobendan administration occurred in 12/260 cats (4.6%), including 11/203 cats (5.4%) with nonobstructive cardiomyopathy and 1/57 cat (2%) with OTO (P = .7). Pimobendan was discontinued due to adverse effects in 4/260 cats (1.5%), 3 with nonobstructive disease and 1 with OTO (P = 1.0). Acute adverse hemodynamic effects after pimobendan administration were not detected in any cats. CONCLUSIONS AND CLINICAL IMPORTANCE: Pimobendan is well tolerated in cats with cardiomyopathy and CHF, regardless of the presence of OTO.

Discussion

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Cite This Study

Ward et al. (2020) conducted a cohort in Feline cardiomyopathy and congestive heart failure (with vs without outflow tract obstruction) (n=260). Outflow tract obstruction (in cats treated with oral pimobendan) vs. Nonobstructive cardiomyopathy (in cats treated with oral pimobendan) was evaluated on Adverse effects suspected to be related to pimobendan administration within 45 days of initiation (p=0.70). Pimobendan-related adverse effects occurred in 4.6% of cats with CHF overall, with no significant difference between cats with outflow tract obstruction (2%) and nonobstructive disease (5.4%, P=0.70).

synapsesocial.com/papers/6a71b6a0e36a167817e3722f https://doi.org/10.1111/jvim.15920

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Retrospective evaluation of the safety and tolerability of pimobendan in cats with obstructive vs nonobstructive cardiomyopathy

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

Retrospective evaluation of the safety and tolerability of pimobendan in cats with obstructive vs nonobstructive cardiomyopathy

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

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