Targeting the sympatho-adrenergic link in chronic rheumatic mitral regurgitation: assessing the role of oral beta-blockers

Abstract

Introduction: Chronic mitral regurgitation (MR) is characterized by adverse ventricular remodeling and progressive LV dysfunction leading to heart failure (HF). Beta-blockers (BB) improve LV remodeling and prognosis in patients with HF. As chronic severe MR results in neuroendocrine activation similar to HF, it is likely that BB may also exert favorable effects in these patients. No study has assessed the role of oral BB therapy in chronic rheumatic MR.

Aims: A total of 100 patients of chronic rheumatic MR (mean age 30±13.48 years, NYHA 2.2±0.5) were randomized to BB (Metoprolol, 37±13.5 mg, n=48) vs no BB (n=52) in addition to standard therapy.

Results: Baseline BNP and echocardiographic parameters were comparable in the two groups. At 3 months, BB therapy resulted in significantly lower NYHA class (1.97 vs 2.35), BNP (141 vs 207 pg/mL), LV end-systolic (35.89 vs 51.30) and LV end-diastolic volumes (101 vs 128 mL/m(2) ), LV end-systolic stress (81.1 vs 93.3 dyn/cm(2) ), LV mass (122 vs 154 gm/m(2) ), and LV work (737.02 vs 952.82 mm Hg L/min, all P significant). Therapy with BB resulted in a -15.6%, -10.4%,-12.1%, and -7.3% reduction in LV end-systolic and end-diastolic dimensions and LVESVi and LVEDVi, respectively. Following BB therapy, BNP levels, end-systolic stress, indexed LV mass, and LV work also reduced significantly by 27.3%, 15.6%, 8.7%, and 28%, respectively. The control group had no significant change. The MR grade reduced from severe to moderate in 11% of those on BB (controls: no change). At 6 months, the BB group had further improvement in all echocardiographic parameters ranging from +9.1 to -18.2%.

Conclusion: In this first study of BB in rheumatic MR, targeting the sympatho-adrenergic axis exerted favorable effects on NYHA class, LV volumes, LV end-systolic stress, and LV work. Further studies are required to elucidate the role of BB in rheumatic MR.

Keywords: Infectious diseases; interventional cardiology; valvular heart disease; vascular biology.