1. In patients with multivessel coronary artery disease and moderate mitral regurgitation, there was no significant benefit on left ventricular reverse remodeling at 12 months with performing mitral valve repair with coronary artery bypass grafting, when compared with bypass surgery alone.
2. There was no significant difference between the two groups in the rate of major cardiac and cerebrovascular events.
3. Patients undergoing the combined surgery experienced higher rates of neurologic adverse events and lengthier hospital and intensive care stays than those undergoing bypass alone.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Ischemic mitral regurgitation is a common complication of ischemic heart disease, and mitral regurgitation has been linked with increased risk of mortality in these patients. Although it is understood that ischemic mitral regurgitation has been associated with higher risk of adverse outcomes in patients undergoing coronary artery bypass grafting (CABG), it is unknown if performing concurrent mitral valve repair offers any benefits. This study randomized patients with multivessel coronary artery disease and moderate ischemic mitral valve regurgitation to receive either CABG with mitral valve repair or CABG-alone. In summary, there was no significant difference between the two groups in the degree of left ventricular reverse remodeling at the 12 month mark. Moreover, there were no significant differences between the two groups in mortality or the rate of major cardiac/cerebrovascular events. Patients undergoing the combined procedure experienced significantly higher rates of neurologic adverse events and lengthier hospitalizations after surgery than those undergoing CABG-alone. Thus, this trial suggests that there is no clinical advantage of adding mitral valve repair in patients with moderate ischemic mitral regurgitation undergoing CABG for multivessel coronary artery disease. Longer term follow-up in this study is ongoing.
Relevant Reading: 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
In-Depth [randomized controlled trial]: A total of 301 patients from 26 sites in Canada and the United States were randomized as part of this study. All adults with multivessel coronary artery disease and moderate ischemic mitral valve regurgitation were considered eligible for this study. The severity of the mitral regurgitation was determined using transthoracic echocardiography. Intraoperatively, transesophageal echocardiography was performed to confirm the absence of mitral valve structural abnormality, and eligible patients were subsequently randomized to receive either CABG with mitral valve repair (i.e., combined procedure) or CABG alone. The primary endpoint was the degree of left ventricular reverse remodeling at the 12-month mark as determined by the left ventricular end-systolic volume index (LVESVI) measured through transthoracic echocardiography. Secondary endpoints included a composite of major cardiac/cerebrovascular events (i.e., death, stroke, subsequent mitral valve surgery, hospitalization for heart failure, increase in New York Heart Association classification) and mortality.
The duration of aortic cross-clamping (p<0.001) and cardiopulmonary bypass (p<0.001) were significantly higher in patients undergoing CABG with mitral valve repair. The mean change in LVESVI from baseline were similar in patients undergoing CABG-alone and the combined procedure (-9.4 mL/m2 and -9.3 mL/m2, respectively). There was no significant difference between the two groups in the rate of mortality (HR 0.90; 95%CI 0.38-2.12). Moreover, there was no significant difference between the two groups in the rate of major cardiac/cerebrovascular events (HR 0.99; 95%CI 0.62-1.59) or any of the individual components of the composite score. Patients who underwent the combined procedure experienced significantly higher rates of neurologic adverse events (e.g., stroke, transient ischemic attack, metabolic encephalopathy) than those undergoing CABG-alone (p=0.03). Patients undergoing CABG-alone also had shorter stays after surgery (p=0.002) and in the intensive care unit (p=0.006) compared to those who had the combined procedure.
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