Effects of Bisoprolol and Losartan Treatment in the Hypertrophic and Failing Right Heart

- Compensated chronic right heart failure was induced by moderate pulmonary trunk banding.
- Increasing the severity of the banding induced decompensated right heart failure.
- Bisoprolol and losartan did not prevent the development of right ventricular hypertrophy.
- Nor did the treatments improve right ventricular function compared with placebo.

BackgroundSympathetic adrenergic stimulation and the renin-angiotensin-aldosterone system are highly elevated in right heart failure. We evaluated if treatment with the adrenergic receptor blocker bisoprolol or the angiotensin II receptor blocker losartan could prevent the progression of right ventricular (RV) hypertrophy and failure in rats after pulmonary trunk banding (PTB).Methods and ResultsMale Wistar rats were randomized to severe PTB with a 0.5-mm banding clip (PTB0.5, n = 29), moderate PTB with a 0.6-mm banding clip (PTB0.6, n = 28), or sham operation (SHAM, n = 13). The PTB0.5 and PTB0.6 rats were randomized to 6 weeks of 10 mg/kg/d bisoprolol treatment, 20 mg/kg/d losartan treatment, or vehicle treatment. The PTB caused hypertrophy, dilation, and reduced function of the RV in all rats subjected to the procedure. Rats subjected to the more severe banding developed decompensated RV failure with extracardiac manifestations. Treatment with bisoprolol slowed the heart rate, and treatment with losartan lowered mean arterial pressure, confirming adequate dosing, but none of the treatments improved RV function or arrested the progression of RV hypertrophy and failure compared with vehicle.ConclusionsIn our PTB model of pressure overload-induced RV hypertrophy and failure, treatment with bisoprolol and losartan did not demonstrate any beneficial effects in compensated or decompensated RV failure.