The RVC has published the results of a study which showed that dogs treated with pimobendan at the preclinical stage of mitral valve disease (MVD) remained asymptomatic for an average 15 months longer and lived for significantly longer than the placebo group.
The EPIC study (Evaluation of Pimobendan In Cardiomegaly), published open access in the Journal of Veterinary Internal Medicine1, is the largest prospective veterinary cardiology study carried out to date. The authors say that the quality of the data it produced rivals that of human clinical trials.
The study was double-blinded, placebo-controlled and randomised. It took seven years to complete and involved 360 dogs across 11 countries in four continents.
To qualify for enrolment in the study, dogs had to be 6 years of age or older, have a body weight ≥4.1 and ≤15 kg, have a characteristic systolic heart murmur of moderate to high intensity (≥ grade 3/6) with maximal intensity over the mitral area, have echocardiographic evidence of advanced MMVD defined as characteristic valvular lesions of the mitral valve apparatus, mitral regurgitation on the colour Doppler echocardiogram, and have echocardiographic evidence of left atrial and left ventricular dilatation, defined as a left atrial-to-aortic root ratio ≥ 1.6 and body weight normalized left ventricular internal diameter in diastole ≥ 1.7, in addition to radiographic evidence of cardiomegaly (vertebral heart sum > 10.5)
In fact, the study was terminated early following an interim analysis as the evidence was considered conclusive and it was deemed unethical to continue to withhold treatment from the placebo group.
Adrian Boswood, Professor of Veterinary Cardiology at the RVC (pictured above right), led the research. He said: "Thanks to the EPIC study results, vets no longer have to adopt a 'watch and wait' approach to suspected preclinical cases of MVD. When a typical mitral valve murmur is detected, vets should now investigate further to look for cardiac enlargement. If demonstrated, this suggests the patient will probably benefit from treatment with pimobendan before the onset of clinical signs.
"It's great that as a trusted treatment, pimobendan has a wealth of safety data behind it in addition to that gleaned from the EPIC study, which can help support vets when prescribing it in this new way."
Adrian added: "As far as evidence-based medicine goes, this is about as good as it gets. The size and design of the study places it in the top-tier. The study was designed and run by an independent team of investigators and sponsored by Boehringer Ingelheim. We, as lead investigators, had the right to publish the results regardless of the outcome. This makes EPIC very special indeed."
In light of the findings, Adrian says vets should now consider testing early for signs of preclinical MVD, and in dogs with cardiomegaly secondary to preclinical MVD, consider the use of pimobendan to delay the onset of congestive heart failure and extend the asymptomatic period.
To read more about the EPIC study and results, visit www.rvc.ac.uk
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PS Pimobendan has many similarities to digitalis, but less side-effects, and, therefore a greater safety margin
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