Hypertrophic Cardiomyopathy in Cats: predicting HCM Development and Phenotypic Variations

Hypertrophic cardiomyopathy (HCM) is the most common feline heart disease, affecting 15% of cats. HCM phenotype is characterised by an increased left ventricular wall thickness in the absence of abnormal loading conditions, i.e. unexplained left ventricular hypertrophy. The clinical gold standard to diagnose HCM is echocardiography, though histopathology is the ultimate examination to confirm the disease. Even though HCM is the most frequent cardiac disease in cats, there are still many areas of uncertainty from aetiology to diagnosis and to therapy. In the diagnosis arena a thorough search for HCM mimickers, a better understanding of the natural progression of HCM and an improved morphological characterization of HCM is mandatory to fully characterise the phenotype of this common disease in cats. This session will focus on some of our most recent research trying to tackle this complex disease.

We have followed over 5 years a large population of cats from rehoming centres to assess HCM progression over time and morbidity/mortality in a general (non-referral) cat population. We have identified predictors of HCM development, that can help predict cats at increased risk of developing HCM when their hearts are still normal. This has allowed us to better understand the natural history of HCM.

We have been, as well, evaluating the accuracy of micro-CT in diagnosing HCM. Micro-CT is a post-mortem imaging modality used for non-invasive necropsies (‘virtual autopsy’). We have assessed its ability to detect the main pathological features of HCM. Micro-CT can maximize the yield of post-mortem examinations. Moreover, it is a technique that facilitates the interaction between specialists, as it can be used by pathologists, cardiologists and radiologists or ideally interdisciplinary teams.

Finally, we have been trying to identify HCM mimickers and better characterise phenotypic variations in HCM. We have described a form of ‘transient HCM’ (transient myocardial thickening) in cats and have been looking into forms of end-stage HCM.