Effects of atenolol on left atrial and left ventricular function in healthy cats and in cats with hypertrophic cardiomyopathy.

This study aimed to assess the effects of atenolol on left ventricular (LV) and left atrial (LA) function in healthy cats and investigate the relationship between atenolol administration and LA enlargement (LAE) in cats with hypertrophic cardiomyopathy (HCM). In study 1, nine experimental cats were used to assess the effects of atenolol in healthy subjects. Cats were administered one of three medication protocols for 7 days: atenolol 6.25 mg/cat twice daily, 12.5 mg/cat twice daily, or placebo (biofermin) 1 tab/cat twice daily. In study 2, cats with HCM were retrospectively recruited and divided into four groups according to atenolol administration [(control group (Cont) or atenolol administration group (Ate)] and the presence or absence of LAE as follows: Cont LAE (-) group (n=42), Cont LAE (+) group (n=20), Ate LAE (-) group (n=17), and Ate LAE (+) group (n=12). LV and LA functions were compared in both studies. LV and LA functions were decreased by atenolol administration in study 1. In study 2, the peak myocardial velocity during early diastole (E') was significantly decreased in the Cont LAE (+), Ate LAE (-), and Ate LAE (+) groups compared to that in the Cont LAE (-) group, but there were no significant differences between LAE (+) groups. Multivariate logistic analysis revealed that atenolol administration was not associated with LAE. Diastolic dysfunction may be associated with LAE; however, atenolol administration did not affect LAE in cats with HCM.