Hypertrophic cardiomyopathy in cats: clinical prevalence, risk factors, and outcomes of arterial thromboembolism in a referral population in Tehran, Iran (2020–2024)

Hypertrophic cardiomyopathy (HCM) is the most common cardiac disease in cats, yet epidemiological data from Iran are scarce. This study investigated the prevalence of HCM in a referral population of cats in Tehran, Iran, evaluated breed predisposition, characterized clinical findings, and assessed thromboembolic complications in cats referred for suspected cardiac disease. A retrospective multicenter study was conducted using medical records from seven major veterinary hospitals in Tehran between 2020 and 2024. A total of 7,013 cats evaluated for suspected cardiac disease were included. HCM was diagnosed by echocardiographic evidence of diastolic left ventricular wall thickness > 6 mm, excluding cats with documented or clinically confirmed systemic hypertension or hyperthyroidism. Clinical and diagnostic variables were extracted. Arterial thromboembolism (ATE) was diagnosed based on clinical presentation and Doppler ultrasonography. Univariate logistic regression was performed within the referral cohort to identify factors associated with HCM diagnosis, and Kaplan–Meier analysis was used to assess survival in cats with ATE. HCM was diagnosed in 638 cats, yielding a clinical prevalence of 9.1% within the referral cohort. The highest within-breed prevalence of HCM in the referral cohort was observed in Persian cats (54.8%), followed by Sphynx (46.9%) and British Shorthair (45.0%).Univariate logistic regression analysis (N = 7,013) identified adult age (OR = 5.70, p < 0.001) and high body condition score (OR = 4.05, p < 0.001) as significant predictors of HCM. ATE occurred in 36 cats and carried a poor prognosis; only three cats survived after surgical intervention. Kaplan–Meier analysis demonstrated declining survival probability in cats with arterial thromboembolism over the available follow-up period. HCM is a frequent and clinically significant disease among cats referred for suspected cardiac disease to veterinary hospitals in Tehran, with clear breed predisposition and association with modifiable risk factors. Early screening may facilitate earlier detection and clinical management.