Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats and an important cause of morbidity and mortality.

Background 

The disease causes thickening of the wall of the important pumping chamber, the left ventricle (LV) which results in the build-up of pressure in the heart leading to heart failure, rhythm disturbance and often sudden death. To date we know very little about the biochemical and cellular processes which lead to the thickening of the LV and early death. A better understanding would enable us to target treatment towards preventing LV thickening before the cat shows clinical signs. One such process is the development of fibrous tissue within the wall of the heart before the thickening of the muscle occurs which has been identified in human patient genetically predisposed to HCM.

Our aim was to investigate fibrous tissue metabolism in genetically predisposed ragdoll cats and compare this with LV wall thickness. This will indicate whether an altered fibrotic state exists in heart before the wall becomes very thick. Knowing this may enable us to develop anti-fibrotic therapies to help prevent the wall becoming thickened and thereby prevent clinical signs developing.

Methods

Cats were recruited for HCM screening using echocardiography and genotyping. Circulating markers of fibrous tissue metabolism (collagen biomarkers) were measured using ELISA assays. Correlation between circulating concentrations of collagen biomarkers and echocardiographic variables was analysed, and collagen biomarker concentrations were compared between genetically predisposed cats and negative cats without LVH.

Results

We showed that genotype was independently associated with collagen biomarker concentration.

Clinical Significance

This study proved that circulating collagen biomarker concentrations were higher in genetically predisposed ragdoll cats than negative controls.This suggests altered collagen metabolism occurs before the development of clinical signs and overt wall thickening. This knowledge may help develop future therapies for HCM.

The work was done under A(SP)A in order to take blood for the purposes of the study, and it also allowed skin scrapes and hair pluck to be used for another study.