Presumed acute myocardial damage in a British Shorthair cat with previously diagnosed hypertrophic cardiomyopathy

BACKGROUND: Reversible myocardial thickening has been observed in cats and is considered a potential manifestation of acute myocardial injury associated with stress, toxicosis, or systemic illness. However, this phenomenon has not been previously reported in cats with pre-existing hypertrophic cardiomyopathy (HCM). CASE PRESENTATION: A 6-year-old castrated male British Shorthair was presented for heart murmur investigation. Based on physical examination, blood analysis, and echocardiography (maximum left ventricular wall thickness (LVWT): 7.5 mm), the cat was diagnosed with HCM phenotype. Three days after the cardiac examination, the cat re-presented with a history of paracetamol ingestion. During hospitalization, the cat developed signs compatible with congestive heart failure. Thoracic radiographs revealed pleural effusion and a diffuse interstitial lung pattern. Echocardiography showed a remarkably increased LVWT (11.4 mm) and an enlarged left atrial diameter. Intravenous fluids were discontinued, and the cat was treated with diuretics, with improvement of its clinical condition. Six months after the cardiac examination, echocardiography revealed a persistent concentric hypertrophy, albeit similar to the initial echocardiographic assessment. CONCLUSIONS: The present case report identified presumed acute myocardial damage associated with paracetamol ingestion in a cat with pre-existing hypertrophic cardiomyopathy. In acutely ill cats, assessment of left ventricular wall thickness should prompt consideration of acute myocardial damage superimposed on chronic cardiac conditions.