Effect of treatment with atenolol on 5-year survival in cats with preclinical (asymptomatic) hypertrophic cardiomyopathy

Objectives: To investigate the effect of treatment with atenolot on 5-year survival in cats with preclinical hypertrophic cardiomyopathy (HCM). Animals: 63 Client-owned cats with preclinical HCM and 31 healthy control cats. Methods: Prospective, observational, open-label, clinical cohort study. Cats with HCM were diagnosed by echocardiography, treated with atenolol (6.25-12.5 mg q12h, PO; n = 42) or untreated (n = 21), and were observed for 5 years after enrollment. The study end point was death from any cause. Cats of similar body weight, age, gender, and breed without evidence of heart disease were studied concurrently and served as controls. Results: During the observational period, 27 cats with HCM died; 14 (22%) due to cardiac disease and 13 (21%) due to non-cardiac disease. Ten control cats (32%) died of non-cardiac disease. There was no significant difference (P = 0.307) in all-cause mortality between control and HCM. Cardiac mortality was higher in cats with HCM compared to control cats (P = 0.005). There was no significant difference in all-cause mortality (P=0.729) and cardiac mortality (P=0.897) between cats with HCM treated or untreated with atenolol. Age and left atrial size at diagnosis were the only predictors of 5-year outcome. Conclusions: Our study failed to demonstrate an effect of atenolol on 5-year survival in cats with preclinical HCM. (C) 2013 Elsevier B.V. All rights reserved.