Patients with functional mitral regurgitation who need coronary artery bypass graft (CABG) surgery can be treated off-pump with a device that simultaneously reshapes both the left ventricle (LV) and the mitral annulus, according to the RESTOR-MV trial published in the Dec. 7 issue the Journal of the American College of Cardiology.
Functional mitral regurgitation occurs when ventricular remodeling impairs valve function. In the RESTOR-MV (Randomized Evaluation of a Surgical Treatment for Off-Pump Repair of the Mitral Valve) trial, researchers used the Coapsys device (Myocor), a ventricular shape-change device placed without cardiopulmonary bypass to reduce functional mitral regurgitation.
The device, implanted without cardiotomy, compresses the mitral annulus and reshapes the ventricle. It consists of posterior and anterior extracardiac epicardial pads connected by a flexible, transventricular subvalvular chord. The posterior pad compresses both the mitral annular and papillary muscle levels. The device is sized intraoperatively by shortening the chordal length of the device, thus drawing the pads together. Cardiothoracic surgeons utilize echocardiography to simultaneously assess mitral regurgitation reduction.
RESTOR-MV was a randomized, prospective, multicenter study of patients with functional mitral regurgitation and coronary disease that was terminated early when the sponsor failed to secure ongoing funding; 165 patients had been randomized.
Eugene A. Grossi, MD, from the New York University School of Medicine in New York City, and colleagues stratified patients to the standard indicated surgery: either CABG alone or CABG with mitral valve repair. In each stratum, randomization was to either control (indicated surgery) or treatment (CABG with ventricular reshaping).
Investigators evaluated patients at baseline, intraoperatively, before hospital discharge, post-operatively at three, six, 12, 18 and 24 months, and annually thereafter.
The primary outcomes were all-cause mortality, primary adverse events—defined as death (cardiac and noncardiac), stroke, MI, reoperation (for bleeding, valvular dysfunction or life-threatening arrhythmias) and mechanical device failure—and mitral regurgitation decrease. Secondary outcomes included NYHA functional class.
Grossi and colleagues found that those in the device arm had improved survival at two years (87 vs. 77 percent) and significantly greater complication-free survival (including death, stroke, MI and valve reoperation) at two years (85 vs. 71 percent).
The authors noted that a significant portion of primary adverse events occurred in the early perioperative time frame. They suggested, therefore, that the Coapsys device may confer an advantage from its off-pump, less invasive placement.
"The ability to conduct a higher-risk operation, such as combined mitral valve repair and CABG without the need for cardiopulmonary bypass, may convey the previously reported benefits of isolated off-pump coronary revascularization, such as decreased inotrope dependence, decreased bleeding and transfusion, faster intensive care unit recovery and shorter length of hospital stay," they wrote.
In the surviving patients of the CABG plus mitral valve repair stratum, both the control and device arms had significant and similar improvements in NYHA functional class. However, the control annuloplasty stratum did not show an improved survival or better symptom reduction.
"It is most likely that the survival benefit was related to the ventricular shape change effected by the device. The Coapsys has an acute positive reshaping effect on the entire ventricle, whereas the effect of traditional annuloplasty is limited to the base of the ventricle," they said.
"This effect was demonstrated again in the current trial with twice the initial decrease in LV end-diastolic dimension in patients receiving CABG plus Coapsys compared with those receiving CABG plus mitral valve repair. It is additionally possible that the long-term survival benefit seen with the device is due to a global and progressive reversal of LV remodeling. ..."
While the trial was stopped prematurely, the researchers maintain that the trial holds importance because the "significant outcomes of the intention-to-treat analysis were reinforced by similar, stronger outcomes in the as-treated analysis."