VN April 2021

Vetnuus | April 2021 38 Recent Clinically Relevant Research from Around theWorld Routine therapy of CHF in dogs with mitral valve disease has, for over a decade, consisted of three drugs: a loop diuretic (usually furosemide), an ACEI, and pimobendan. Studies in the early 1990s suggested that ACEI improve outcomes, and a study in 2008 showed that pimobendan produced a greater benefit than an ACEI when added to furosemide. However, no studies have examined whether an ACEI, when added to pimobendan and furosemide, would provide an even greater benefit than just using pimobendan and furosemide. This study by Gerhard Wess and co-workers, over 15 years in the making, examined that question. The investigators decided that they would like to see at least a 3-month improvement in “cardiac survival” (defined as euthanasia for cardiac reasons, sudden cardiac death, or development of refractory CHF) with the added ACEI, taking the median survival from 9 months to 12 months. Put another way, they expected 75% of the non-ACE inhibitor group to have reached the endpoint by 1 year, compared to 50% in the ACEI group. They calculated the number of dogs they would need to demonstrate this effect. The study was largely based on the QUEST study that originally demonstrated superiority of pimobendan over benazepril. Clinicians evaluating the cases were blinded to treatment, but owners were not. The investigators found no difference in time to event for the TT group compared to the DT group. While this raises the concerns of “insufficient power” to detect a difference, evaluation of the data suggests that this is not likely to be the case. First, the authors had a very high percentage of dogs reach the endpoint. Second, the pimobendan/furosemide group had more male dogs (which tend to have worse outcomes) – therefore, this would tend to favor the TT group if there was an added effect of the ACEI. Third, the pimobendan/furosemide group had the higher value for median survival (227 versus 186 days), removing doubt that maybe, if they had recruited a fewmore dogs, the results would have become significant in favor of TT. Fourth, the median survival times were similar to those observed with previous studies of mitral valve disease and CHF – about 8 to 10 months. Overall, this study suggests that small-breed dogs with mitral valve disease and CHF do not benefit from an ACEI if they are receiving pimobendan (and, of course, furosemide). For decades, veterinarians have believed that ACEI are instrumental in managing these patients, and this study will be hard for many to accept. Nevertheless, regardless of the theoretical basis for prescribing ACEI, therapy should be based on clinical outcomes rather than theoretical benefits. Consequently, clinicians should consider that ACEI might have an extremely limited role in treating heart disease in dogs (or cats). v SMALL ANIMALS Efficacy of adding ramipril (vasotop) to combination therapy in dogs with mitral valve degeneration: the valve trial (Source: Advances in Small Animal Medicine and Surgery) This study by JN King and co-workers was a thorough and well-done study that unfortunately found no benefit to adding benazepril to the treatment of cats with heart disease. One limitation of the study, also noted by the authors, is that it looked at heart disease in general, not specific heart conditions, which can be quite different from each other and may individually respond differently to benazepril. Also, cats without clinical signs of heart disease were included, which can bemore difficult to assess in their response to treatment. A strength of the study is that 151 cats were included, which is a large enough group to draw solid conclusions. A control group was included which also strengthens the study. Being client-owned cats, compliance and other variables were harder to control than they would have been in a research study, but it seems as though the study-controlled variables aswell as couldbedone.The cats analysedwere treatedbetween2002 and2005, which is quite awhile ago, andmuch has changed inmedicine overall and treatment of feline cardiac disease specifically. However, the conclusions drawn are still valid and applicable to treatment of feline cardiac disease today. v Evaluation of benazepril in cats with heart disease