PAPER 540 Journal of Small Animal Practice • Vol 51 • October 2010 • © 2010 British Small Animal Veterinary Association J. PAYNE, V. LUIS FUENTES, A. BOSWOOD, D. CONNOLLY, H. KOFFAS * AND D. BRODBELT Journal of Small Animal Practice (2010) 51, 540–547 DOI: 10.1111/j.1748-5827.2010.00989.x Accepted: 7 July 2010 Department of Veterinary Clinical Sciences, The Royal Veterinary College, North Mymms, Hatfield, Hertfordshire AL9 7TA and *NKR Veterinary Specialists, Blue Bell Hill, Kent ME5 9RD http://www.bsava.com/ Population characteristics and survival in 127 referred cats with hypertrophic cardiomyopathy (1997 to 2005) INTRODUCTION Hypertrophic cardiomyopathy (HCM) is a primary myocardial disease characterised by a hypertrophied, non-dilated left ven- tricle (Fox 2003, Maron and others 2006). HCM is the most frequently diagnosed familial heart disease in man, occurring in approximately 1:500 in the general adult population (Maron and others 1995). It is also the most common form of heart dis- ease seen in cats, accounting for 57⋅5% of feline idiopathic cardiomyopathies in one study (Ferasin and others 2003). In a recent study, HCM was found in over 15% of apparently healthy cats (Paige and others 2009). Survival has been evaluated in several previous retrospective studies of feline HCM (Atkins and others 1992, Peterson and others 1993, Fox and others 1995, Rush and others 2002). The posi- tive prognostic factors common to more than one study were absence of clinical signs (Atkins and others 1992, Rush and others 2002) and normal left atrial (LA) size (Peterson and others 1993, Rush and others 2002). Increased heart rate was a poor prognostic sign in Atkins’ study (1992), but not in the study by Rush and others (2002). Age at diagnosis was nega- tively associated with prognosis in one study (Rush and others 2002). In contrast with human HCM studies (MS Maron and others 2003), systolic anterior motion (SAM) of the mitral valve was associated with improved survival in feline studies (Fox and others 1995, Rush and others 2002). The aims of this study were to inves- tigate contemporary characteristics and survival times of cats with HCM seen at a British referral hospital, and to identify prognostic markers of survival. MATERIALS AND METHODS Cases of feline HCM were identified by searching the electronic patient records of cats seen at the Royal Veterinary College Queen Mother Hospital for Animals (QMHA) between April 1997 and April 2005. Cats were included if a diagnosis of idiopathic HCM had been made by a board-certified cardiologist or a cardiology resident supervised by a board-certified cardiologist based on two-dimensional (2D) and/or M-mode echocardiography. Cats were excluded from the study where the diagnosis of HCM had not been made at the QMHA, where concurrent OBJECTIVES: To evaluate the characteristics and survival of a recent population of cats with hypertrophic cardiomyopathy. METHODS: Records at the Royal Veterinary College Queen Mother Hospital for Animals were searched for cats diagnosed with hyper- trophic cardiomyopathy between 1997 and 2005. Referring veteri- narians and owners were contacted to determine survival times. RESULTS: Cats with hypertrophic cardiomyopathy were evaluated for population characteristics (n=127) and survival times (n=109). Overall median survival from date of hypertrophic cardiomyopa- thy diagnosis at the Queen Mother Hospital for Animals was 1276 days. Cats with hypertrophic cardiomyopathy were younger (P=0⋅009), and more likely to be male (P<0⋅001) compared to a hospital control group (n=1473), and Ragdolls were over- represented (P<0⋅05). Characteristics associated with increased survival in univariate analysis included younger age (P=0⋅007), asymptomatic status (P<0⋅001), normal left atrial size (P<0⋅001) and presence of systolic anterior motion of the mitral valve (P=0⋅003). Systolic anterior motion was associated with asymp- tomatic status, and did not influence survival in asymptomatic cats or those in congestive heart failure. Age, left atrial size and breed were significantly associated with survival time in a multivariate analysis. CLINICAL SIGNIFICANCE: Cats with hypertrophic cardiomyopathy and left atrial enlargement have a poorer prognosis. The positive influence of systolic anterior motion on survival is likely to be linked to its association with asymptomatic status.