Abstract 14887: A Randomized Controlled Trial of β1-Receptor Blockade for Chronic Degenerative Mitral Regurgitation
Background. The volume overload of isolated mitral regurgitation (MR) currently has no proven therapy to attenuate LV remodeling or preserve systolic function. Animal and human studies have demonstrated increased adrenergic drive even in early compensated MR.
Methods. 38 asymptomatic subjects with moderate to severe, isolated MR were randomized to either Placebo or β1-aderergic receptor blockade (β1-AR blockade, Toprol-XL) for two years. Magnetic resonance imaging (MRI) with tissue tagging and 3 dimensional (3D) analysis was performed at baseline and at six month intervals for two years. Rate of progression analysis was performed for end-point variables: LV end-diastolic volume/body surface area (EDV/BSA), LVED mass/EDV ratio, LVED 3D radius/wall thickness (r/wt), LV end-systolic volume (ESV)/BSA, LV ejection fraction (EF), LV longitudinal strain rate, and LV early diastolic filling rate.
Results. Baseline LV MRI or demographic variables did not differ between the two groups. Over two years, six patients in placebo and two patients in β1-AR blockade group required mitral valve surgery (p = 0.23). There were no significant treatment effects found on LVED or LVES volumes, LVEDV/mass or LVED 3D r/wt, or LV longitudinal strain rate. However, significant treatment effects were found on LVEF (p=0.006) and LV early diastolic filling rate (p=0.0011), such that in untreated patients these systolic and diastolic parameters decreased over time on an intention to treat analysis, which remained significant following sensitivity analysis.
Conclusions. β1-AR blockade does not attenuate LV remodeling in chronic isolated MR but preserves LV systolic and diastolic function over a two-year follow-up.
- © 2011 by American Heart Association, Inc.