Coronary Artery Bypass Surgery With or Without Mitral Valve Annuloplasty in Moderate Functional Ischemic Mitral Regurgitation: Final Results of the Randomized Ischemic Mitral Evaluation (RIME) Trial

Study Questions:

Among patients with moderate ischemic mitral regurgitation (MR) undergoing coronary artery bypass grafting (CABG), does concomitant mitral valve repair (MVr) result in improved functional capacity and left ventricular (LV) reverse remodeling compared with CABG alone?

Methods:

RIME (Randomized Ischemic Mitral Evaluation) was a multicenter, single-blinded, randomized, controlled trial, which recruited patients from six centers in the United Kingdom and one in Poland between March 2007 and July 2011. In the RIME trial, a group of 73 patients with moderate ischemic MR and LV ejection fraction >30%, who were referred for CABG, were randomly assigned to undergo CABG plus MVr (34 patients) or CABG only (39 patients). The study was stopped early after review of interim data, when 70 patients had been enrolled.

Results:

At 1 year, there was greater improvement in the primary endpoint of peak oxygen consumption in the CABG plus MVr group compared with the CABG group (3.3 ml/kg/min vs. 0.8 ml/kg/min; p < 0.001). There was also a greater improvement in the secondary endpoints in the CABG plus MVr group compared with the CABG group: LV end-systolic volume index (22.2 ml/m2 vs. 4.4 ml/m2 [p = 0.002]), MR volume (28.2 ml/beat vs. 9.2 ml/beat [p = 0.001]), and plasma B-type natriuretic peptide reduction (557.4 pg/ml vs. 394.7 pg/ml [p = 0.003]). Operation duration, blood transfusion, intubation duration, and hospital stay duration were greater in the CABG plus MVR group. Deaths at 30 days (3% in the CABG plus MVr group vs. 3% in the CABG only group [p = 1.00]) and 1 year (9% in the CABG plus MVr group vs. 5% in the CABG only group [p = 0.66]) were similar in both groups.

Conclusions:

Concomitant mitral annuloplasty at the time of CABG among patients with moderate ischemic MR may improve functional capacity, LV reverse remodeling, MR severity, and B-type natriuretic peptide levels, compared with CABG alone. The impact of these benefits on longer-term clinical outcomes remains to be defined.

Perspective:

Few data from randomized controlled trials address patients with ischemic MR undergoing CABG. Guidelines do not provide strong recommendations, and opinions run strong as to whether additional operative complexity and longer cross-clamp and cardiopulmonary bypass times associated with MVr are justified in terms of improved clinical outcomes. The present study, although small, provides additional data from a randomized trial that MVr at the time of CABG results in improved functional capacity and improvement in some measures of LV reverse remodeling. Outcomes at individual medical centers likely will be affected by local surgical expertise in the performance of mitral annuloplasty. However, this study adds important data supporting the performance of mitral annuloplasty at the time of CABG among patients with moderate ischemic MR.

Clinical Topics: Cardiac Surgery, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Valvular Heart Disease, Cardiac Surgery and Heart Failure, Cardiac Surgery and VHD, Acute Heart Failure, Heart Failure and Cardiac Biomarkers, Heart Transplant, Interventions and Structural Heart Disease, Mitral Regurgitation

Keywords: Great Britain, Mitral Valve Insufficiency, Poland, Heart Transplantation, Heart Diseases, Blood Transfusion, Intubation, Oxygen Consumption, Ventricular Remodeling, Heart Failure, Cardiopulmonary Bypass, Mitral Valve Annuloplasty, Bufanolides, Cardiac Surgical Procedures, Coronary Artery Bypass, Natriuretic Peptide, Brain


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