Adding mitral valve repair to CABG does not improve outcomes in patients with moderate ischemic mitral regurgitation

CHICAGO — Compared with CABG alone, CABG plus surgical mitral valve repair did not improve outcomes in patients with moderate ischemic mitral regurgitation, researchers found.

In the trial, part of the Cardiothoracic Surgical Trials Network, researchers randomly assigned 301 patients with moderate ischemic mitral regurgitation to receive CABG alone or CABG combined with mitral valve repair.

“There has been a long controversy about what to do with patients with moderate ischemic [mitral regurgitation],” researcher Annetine C. Gelijns, PhD, chair of the department of population science and health policy, Icahn School of Medicine at Mount Sinai, and principal investigator for the data coordinating center of the Cardiothoracic Surgical Trials Network, said in an interview with Cardiology Today. “In recent years, practice has been moving toward the combined procedure, with the bypass procedure and the mitral valve repair at the same time.”

Annetine C. Gelijns

According to previously reported data, at 1 year, the groups did not differ in survival or left ventricular end-systolic volume index (LVESVI).

They presented 2-year results of clinical and echocardiographic endpoints at the American College of Cardiology Scientific Session and published them in the New England Journal of Medicine.

“We found that [adding mitral valve repair] does not make any difference in terms of LV reverse remodeling or overall adverse events or the composite of [major adverse CV events], but if you do the repair procedure, which requires much longer bypass time, there is a risk for more serious neurological events and more supraventricular arrhythmias,” Gelijns said.

At 2 years, mean LVESVI was 41.2 ml/m² (mean improvement over baseline, –14.1 ml/m²) in the CABG-alone group and 43.2 ml/m² (mean improvement over baseline, –14.6 ml/m²) in the CABG plus mitral valve repair group, according to the researchers.

The rate of death was 10.6% in the CABG group vs. 10% in the CABG plus mitral valve repair group (HR = 0.9; 95% CI, 0.45-1.83), while there was no difference in rank-based assessment of LVESVI including death between the groups at 2 years (z score = 0.38; P = .71).

However, the combined-procedure group had a lower rate of moderate or severe residual mitral regurgitation than the CABG group (11.2% vs. 32.3%; P < .001), the researchers found.

In contrast, serious neurologic events were more common in the combined-procedure group (14 vs. 4; P = .02), as were supraventricular arrhythmias (24 vs. 11; P = .04), they found.

Overall readmission and CV readmission did not differ between the groups, and more than half (53%) of the CV readmissions were for HF, they wrote.

Serious adverse events did not differ at 2 years (CABG group, 84 per 100 patient-years; combined group, 92 per 100 patient-years; P = .35), and increased at similar rates between 1 year and 2 years, they found.

Gelijns said that the researchers were interested in whether over time, the reduced rates of mitral regurgitation produced by combined therapy would translate into reduced HF and other events, but as of 2 years, that has not happened in this population, unlike what was seen in a trial of patients with severe ischemic mitral regurgitation. She said follow-up through 5 years is planned.

Alan J. Moskowitz

One issue clinicians must keep in mind, researcher Alan J. Moskowitz, MD, FACP, vice chair of the department of population science and health policy at Icahn School of Medicine at Mount Sinai and co-principal investigator for the data coordinating center of the Cardiothoracic Surgical Trials Network, told Cardiology Today, is that “ischemic mitral valve disease really isn’t a valve disease, it’s a ventricular myocardial disease that causes distortion of the supporting structure of the valve. We showed that efforts to correct the regurgitation of the valve were reasonably successful, but did not translate into better clinical outcomes. Correction doesn’t seem to change the course of things, so at this point, there is little advantage to intervening in the moderate ischemic mitral regurgitation population, and we anticipate that this finding will change practice.”

He added that “these are patients with areas of active ischemia in the myocardium. The [CABG] alone is responsible for a considerable amount of the improvement.”

An important distinction is that “the value of repair is probably strong in degenerative mitral valve disease,” Gelijns said. “People have applied the importance of repair in degenerative disease to ischemic mitral valve disease. Because ischemic mitral regurgitation really is a different type of disease, repairing the mitral valve may not have the same benefits as in degenerative disease.” – by Erik Swain

References:

Michler RE, et al. Featured Clinical Research I. Presented at: American College of Cardiology Scientific Session; April 2-4, 2016; Chicago.

Michler RE, et al. N Engl J Med. 2016;doi:10.1056/NEJMoa1602003.

For more information:

Annetine C. Gelijns, PhD, and Alan J. Moskowitz, MD, FACP, can be reached at Department of Health Science and Policy, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Pl., Box 1077, New York, NY 10029; email: annetine.gelijns@mountsinai.org and alan.moskowitz@mountsinai.org.

Disclosure: The study was funded by the NIH and the Canadian Institutes of Health Research. Gelijns and Moskowitz report no relevant financial disclosures. Please see the full study for a list of the other researchers’ relevant financial disclosures.