Mitral Repair at the Time of CABG Provides No Mortality, QoL Benefit at 1 Year
CHICAGO, IL—Adding surgical mitral valve repair to coronary artery bypass grafting (CABG) in patients with moderate ischemic mitral regurgitation (MR) reduces the prevalence of the condition without increasing left ventricular (LV) reverse remodeling, according to results of a study presented on November 18, 2014, at the American Heart Association Scientific Sessions and simultaneously published in the New England Journal of Medicine. But mortality and quality of life (QoL) were unaffected by the combined procedure.
“The trial did not demonstrate a clinically meaningful advantage to the routine addition of mitral valve repair to CABG for patients with moderate ischemic [mitral regurgitation],” according to presenter Robert E. Michler, MD, of Montefiore Medical Center (New York, NY).
Methods
Investigators randomized 301 patients with moderate ischemic MR to CABG with (n = 150) or without (n = 151) mitral valve repair with an undersized valvuloplasty ring from 2009 to 2013. The 2 groups were well balanced with the exception of a higher incidence of A-fib in the CABG-alone group.
The mean LV end-systolic volume index in the CABG-alone group was 54.8 mL/m2 and 59.6 mL/m2 in the combined-procedure group. Moderate MR was confirmed by echocardiographic core lab analysis in 93% of patients at baseline—4% had severe and 3% had mild regurgitation. Eight patients assigned to CABG alone and 3 assigned to the combined procedure crossed over to the other group, mostly due to increased MR and concern over the risk associated with valve repair, respectively.
At 1 year,
mean LV end-systolic volume index decreased similarly by 9.4 and 9.3 mL/m2
for the CABG-alone and combined-procedure groups, respectively. The rate of
death also was similar between the study arms (7.3% vs 6.7%; HR with mitral
valve repair 0.90; 95% CI 0.38-2.12). Moreover, mean LVEF at 12 months was
45.1% in the CABG-alone group and 43.9% in the patients who underwent mitral
repair. Residual moderate or severe MR at 1 year was more common after CABG
alone (31.0% vs 11.2%; P < .001).
Rates of serious adverse events (P = .15) and MACCE (P = .97) and its individual components did not differ between the treatment groups at 1 year. However, the rates of all neurological events and supraventricular arrhythmias were higher (P = .03 for each) and the procedure duration and ICU and overall hospital stays were longer with the combined procedure.
The 30-day death rate did not differ between the CABG-alone (2.7%) and combined-procedure groups (1.3%; P = .68). The most frequent causes of death were heart failure (23.8%), sepsis (14.3%), and respiratory failure (9.5%).
QoL as measured by both the SF-12 and Minnesota Living with Heart Failure questionnaire improved comparably in both treatment arms at 1 year. Similar improvements in NYHA treatment class were observed at 1 year—the proportion of patients classified as NYHA class 1 and 2 increased from 50% at baseline to 80% by 1 year.
Long-Term Follow-Up Needed With Lack of Clinical Endpoint
Dr. Michler explained that his team did not measure a primary clinical endpoint because of the large number of patients and length of time required to achieve statistical significance. However, he did say that patients will be followed through 2 years.
In commentary following the presentation, David H. Adams, MD, of Mount Sinai Hospital (New York, NY), said even longer follow-up, perhaps through 5 years, is needed to “understand the implications…. This is a very important evidence base that we have been sorely lacking, but I caution everyone this is not the end of the story, but rather the beginning. And we will learn much more from this evidence base and the [forthcoming] analyses.”
Dr. Adams said the most important patient groups from this study were the ones who were treated with CABG alone and were either left with moderate-to-severe MR or had complete resolution. “And then of course you have this nagging 10% of patients with surgical failure,” he added. “These are the populations descriptively that we are going to get the most information from. The take-home is that not every patient needs a mitral ring.”
Shifting Toward Tighter Selection in Clinical Practice
Moderator Patrick T. O’Gara, MD, of Brigham and Women’s Hospital (Boston, MA), asked the panel if they would change their clinical practice based on these study results, especially because “we are now in an era in which heart teams make decisions together.”
Dr. Adams replied that the study “reiterates what I have evolved toward—trying to be more selective in specific settings…. You’re gong to have to keep thinking about which patients would benefit from a ring and who wouldn’t.”
Touching on the heart team perspective, he continued, “The time to learn about mitral regurgitation in patients is before you put them to sleep. For patients with myocardial infarction, if you have any suspicion, you should start that discussion before you get to the operating room.”
Dr. Michler said, “The bottom line is that you don’t need to ring it necessarily. We need the follow-up on this patient population to really see whether there is a net clinical benefit related to that lower incidence of mitral regurgitation.”
Another issue Dr. Adams raised is that procedural volume varies throughout the United States and “the average surgeon does single digits per year.” Hence, “your attitude about adding a ring might be different in a high-volume vs regular-volume center…. We don’t want to make people do things without the evidence base that it’s worth it.”
In an editorial accompanying the study, Thoralf M. Sundt, MD, of Massachusetts General Hospital (Boston, MA), says the results will help “to establish the feasibility of conducting prospective, randomized surgical trials, so much a part of the culture of cardiology but less so of cardiac surgery. To be sure, it is not easy to admit equipoise when one must act definitively and is expected by one’s patients to express confidence, not uncertainty. But it is important for all of us in the medical community to do exactly this. The authors have helped us along that way.”
Sources:
1. Smith PK, Puskas JD, Ascheim DD, et al. Surgical treatment of moderate ischemic mitral regurgitation. N Engl J Med. 2014;Epub ahead of print.
2. Sundt TM. Surgery for ischemic mitral regurgitation [editorial]. N Engl J Med. 2014;Epub ahead of print.
Disclosures:
- The study was funded by the National Institutes of Health and the Canadian Institutes of Health Research.
- Drs. Michler and Sundt report no relevant conflicts of interest.
- Dr. O’Gara reports serving as the co-chair of the National Heart, Lung, and Blood Institute-sponsored Cardiothoracic Surgery Network Steering Committee.
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