Selective Valve Repair at CABG Supported in Moderate Ischemic MR

April 08, 2016

CHICAGO, IL — For patients with moderate ischemic mitral regurgitation (MR) who are candidates for surgery, the addition of mitral-valve repair to CABG won't improve survival, cardiac structure, or function, nor will it boost quality-of-life scores, over 2 years compared with CABG alone[1], according to an extended follow-up of 301 such patients that mostly confirms results previously reported after 1 year.

But the results deserved a more nuanced interpretation and support an individualized approach, in which, for example, patients with lots of scar in the ventricular wall who might not benefit much from CABG alone might gain from the addition of mitral-valve repair, according to investigators.

Strictly speaking, overall in the cohort there was "no meaningful advantage" to the addition of mitral repair, whether in terms of the study's primary end point of change in left ventricular end-systolic volume index (LVESVI), reflecting reverse ventricular remodeling, or in secondary clinical end points. The latter included mortality, major adverse cardiovascular events, and hospitalization over 2 years, reported Dr Robert E Michler (Montefiore Medical Center–Albert Einstein College of Medicine, New York) here at the American College of Cardiology (ACC) 2016 Scientific Sessions. The study was published at about the same time in the New England Journal of Medicine.

Adding mitral-valve repair increased cross-clamp time and time on cardiopulmonary bypass (CPB) support and was associated with longer hospitalization and more neurologic events and supraventricular arrhythmia, the group reported. On the other hand, patients who received CABG without mitral repair had more postoperative moderate to severe MR than the combined-surgery group.

Dr Robert Michler

But as Michler pointed out for heartwire from Medscape, it should not be a universal rule for moderate ischemic MR that "just because you see it, you don't need to put a ring on it." Some patients do not have enough viable LV myocardium that is suitable for revascularization and likely to improve in function with CABG.

As he noted, improvement in the global wall-motion index was significantly greater (P=0.008) for patients without moderate or severe MR at 2 years, with most of the gain occurring in the first year.

"If I see a patient who has a very poor target for revascularization, I'm probably going to have to complement this operation with a repair," Michler said when interviewed. "If there are excellent targets, and if the ventricle is comparable in size to the ventricles we operated on, then CABG alone should be sufficient. If there are poor targets, if the ventricle is very large, or if there is significant scar formation in the inferior-posterior–lateral walls, I'd consider adding mitral repair to the procedure, provided one could limit the risk to the patient."

The study randomized 301 patients with moderate ischemic mitral regurgitation and multivessel CAD to receive either CABG alone or CABG combined with mitral repair with a downsized "approved rigid or semirigid annuloplasty ring."

Mean aortic cross-clamp time was 42.4 minutes longer and mean CPB time was 56.3 minutes longer in the CABG/repair group than in the CABG-only group (P<0.001 for both comparisons).

Two years later, the mean LVESVI had dropped by 14.1 mL/m2 and 14.6 mL/m2 in the CABG-only and CABG/repair groups, respectively. LVEF changes were also nonsignificantly different, improving by 5.4 and 6.4 percentage points for the CABG-only and CABG/repair groups, respectively.

"The evidence really shows that improvement in wall motion really led to improvement in mitral regurgitation," Michler said, and that applies whether patients received CABG only or both surgeries. And while some patients may gain from both CABG and mitral repair together, "the inference is that CABG alone may be sufficient. This is quite dramatic information."

Michler reports no relevant financial relationships. Disclosures for coauthors are listed on the journal website.

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