Is treatment of feline hypertrophic cardiomyopathy based in science or faith? A survey of cardiologists and a literature search

Abstract

Practical relevance: Feline hypertrophic cardiomyopathy (HCM) is the most common cardiac disease of cats. Treatment of HCM is usually directed at controlling signs of congestive heart failure (CHF), preventing occurrence or recurrence of systemic thromboembolism or delaying/preventing/reversing progression of subclinical disease.

Study objective and design: Despite the laudable goals of therapy, however, little objective evidence supporting therapeutic decisions has been published. We, therefore, hypothesized that cardiologists base their treatment strategies on information other than published clinically relevant science. To gain insight into therapeutic decisions that cardiologists and clinicians with an interest in cardiology (n=99) make for cats with HCM, and on what information they base these decisions, we presented participants with, and asked them to select therapy for, 12 hypothetical scenarios of HCM (± CHF). Responses and justifications for treatment choices were compiled and compared with the results of a comprehensive literature search for published information about treatment of feline HCM.

Findings: Evaluation of the therapeutic strategies chosen for these hypothetical cases of HCM suggests that cardiologists or clinicians with a strong interest in cardiology often prescribe treatments knowing that little documented evidence supports their decisions.

FIG 1

(a) Intent to alter primary disease progression or to treat congestive heart failure (CHF). Collated responses were restricted to drugs or interventions that are not obviously antithrombotic or anticoagulant. (b) Intent to reduce risk of occurrence of aortic thromboembolism (ATE). Collated responses were restricted to clopidogrel, aspirin, low molecular weight heparin (LMWH) and heparin. In (a) and (b) cardiologist respondents are represented by the pink bars, non-cardiologist respondents by the black bars. (c) Use of clopidogrel or LMWH

FIG 2

(a) Number of different treatment combinations adopted by respondents for each scenario. (b) Percentage of respondents prescribing three or more medications to patients with each scenario. CHF = congestive heart failure

FIG 3

Cardiologist respondents are represented by the pink bars, non-cardiologist respondents by the black bars. Numbers above bars represent the left ventricular outflow tract (LVOT) velocity (expressed in m/s) associated with LVOT obstruction presented in that particular scenario. CHF = congestive heart failure

FIG 4

(a) Angiotensin-converting enzyme inhibitor (ACEI) use increases with increasing severity of hypertrophic cardiomyopathy (HCM). (b) Diltiazem use is substantially lower than ACEI use and is inversely correlated with β-blocker use. Cardiologist respondents are represented by the pink bars, non-cardiologist respondents by the black bars