β1-Receptor Blockade for Chronic Mitral Regurgitation - β1-Receptor Blockade for Chronic Mitral Regurgitation
The goal of the trial was to evaluate treatment with beta-blockade compared with placebo among patients with moderate to severe mitral regurgitation.
Beta-blockade will attenuate left ventricular (LV) remodeling and preserve systolic function.
- Placebo Controlled
- Patients with moderate to severe mitral regurgitation
- LVEF >55%
- LV end-systolic dimension <40 mm
- Echocardiographic thickening of mitral valve leaflets and prolapse
Number of enrollees: 38
Duration of follow-up: 2 years
Mean patient age: 53 years
Percentage female: 58%
Ejection fraction: 62%
New York Heart Association (NYHA) class: 100% with functional class I or II
- Patients with New York Heart Association functional class III or IV symptoms
- Prior myocardial infarction or significant coronary artery disease
- Valvular disease other than mitral
- Renal insufficiency
- Change in LV EDV/BSA
- Change in LV ED mass /LV EDV
- Change in LV ED radius/wall thickness
- Change in LV EF
- Change in LV ESV/BSA
- Change in peak systolic longitudinal strain rate
- Change in peak early filling rate
Asymptomatic patients with moderate to severe mitral regurgitation were randomized to metoprolol succinate (Toprol XL) 25-100 mg daily (n = 19) versus placebo (n = 19) for 2 years. Metoprolol succinate was titrated every 2 weeks to a maximum of 100 mg daily. Cardiac magnetic resonance imaging (MRI) was performed at baseline, and 6, 12, 18, and 24 months.
Overall, 38 patients were randomized. The mean age was 53 years, 58% were women, mean blood pressure was 125/75 mm Hg, mean heart rate was 66 bpm, and mean ejection fraction (EF) was 62%. No patient had atrial fibrillation.
At 2 years, there was no change in LV end-diastolic volume/body surface area (EDV/BSA), LV ED mass/LV EDV, LV ED radius/wall thickness, LV end-systolic volume/BSA, and peak systolic longitudinal strain rate for beta-blockade versus placebo.
However, at 2 years there was a benefit favoring beta-blockade for LVEF (p = 0.0060), and peak early filling rate (p = 0.0011).
In this small pilot trial, in patients with asymptomatic moderate to severe mitral regurgitation, 2 years of beta-blockade treatment prevented progressive decline in LVEF compared with placebo. However, beta-blockade did not prevent parameters of LV remodeling. A large multicenter trial appears warranted.
Ahmed MI, Aban I, Lloyd SG, et al. A Randomized Controlled Phase IIb Trial of β1-Receptor Blockade for Chronic Mitral Regurgitation. J Am Coll Cardiol 2012;Jul 18:[Epub ahead of print].
Keywords: Body Surface Area, Follow-Up Studies, Mitral Valve Insufficiency, Stroke Volume, Blood Pressure, Metoprolol, Heart Rate, Magnetic Resonance Imaging
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