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Updated results from the Cardiothoracic Surgical Trials Network study show that major outcomes for severe ischemic mitral regurgitation approaches are largely equal at 2 years, but consequences of lower recurrence after valve replacement versus repair are beginning to emerge.

The degree of , measured by left ventricular end-systolic volume index as the primary endpoint, improved from baseline to year two by 9.0 mL/m² with repair versus 6.5 mL/m² with replacement (rank-based P=0.19), similar to the lack of difference in 1-year results released in 2013.

Likewise, 2-year results were similar for repair and replacement on cumulative mortality (19.0% versus 23.2%, hazard ratio 0.79, P=0.39) and the composite of death, stroke, hospitalization for heart failure, worsening heart failure, or mitral-valve reintervention (42.1% versus 42.4%, P=0.96).

However, the rate of recurrence of moderate or severe mitral regurgitation jumped from 32.6% versus 2.3%, respectively, at 1 year to 58.8% versus 3.8% at year two (both P<0.001), , of Montefiore Medical Center in New York City, reported at the American Heart Association meeting in Orlando and simultaneously online in the New England Journal of Medicine.

And that showed up clinically with more serious adverse events related to heart failure (P=0.05) and more cardiovascular readmissions (P=0.01).

That group also saw a trend for less improvement on the Minnesota Living with Heart Failure quality of life scale, which "although not conclusive, were consistent with these clinical events," the researchers noted in the NEJM paper. "The 7.9-point difference in average improvement over baseline in favor of the replacement group was not significant (P=0.07), but the magnitude of change exceeded the 5-point threshold for clinically meaningful improvement used in other studies."

"This deficiency in the durability of correction of mitral regurgitation is disconcerting, given that recurrence confers a predisposition to heart failure, atrial fibrillation, and repeat interventions and hospitalizations," they added.

"We now see a divergence in clinical outcome that we did not see in the 1 year paper," Goldstein noted at a press conference for the late-breaking clinical trial. "We believe the replacement provides a more durable correction for significant mitral regurgitation."

, of Christiana Care Health System in Newark, Del., a past president of the AHA and an on the 1-year results, noted that the longer follow-up is "confirming for many people that it's reasonable to do a replacement rather than repair."

However, the consensus at the late-breaking clinical trial press conference presentation and among experts commenting to MedPage Today was that "reasonable" does not constitute a mandate for first-line preference.

"It's not black and white -- there's too much variation," Gardener said in an interview. Even as a randomized trial, "you can't account for all of the differences."

The big difference not accounted for in the study is the opportunity to avoid the lifelong anticoagulation needed with mitral valve replacement, which sways the decision in many cases. Identifying those patients for whom that surgery really would benefit most will be key, Goldstein noted.

His group's prior analysis identified "only the presence of a basal aneurysm or dyskinesis as an independent predictor of recurrent mitral regurgitation."

Surgeon experience is also a prime consideration, said , of Hôpital Européen Georges Pompidou in Paris, study discussant at the press conference. He suggested that young surgeons inexperienced with valve repair shouldn't feel guilty doing valve replacement.

The trial included 251 patients randomly assigned to mitral-valve repair or replacement by a group of surgeons experienced with both techniques.

Limitations included the relatively short follow-up period, use of an echocardiographic measure as the primary endpoint rather than a clinical outcome, and the possibility that "transthoracic echocardiography may have underestimated the presence and severity of mitral regurgitation in patients after replacement."

Longer-term follow-up is needed, all agreed, although disagreeing on just how long.

Given the generally poor prognosis of severe ischemic mitral valve disease, "few of those patients are likely to make it out to 10 years so that does somewhat mitigate the concern about the prosthetic valve," Gardener said.

But , of the University of California San Diego, argued that the trial selected out a healthier group of patients and thus should follow patients at least to 10 years.

"We anticipate that even putting bioprosthesis in, it should be good for 10 to 15 years," he told MedPage Today. "That's what we typically tell people. We know that's the case for bioprosthetic valves at the moment. I would want to know that repairs did at least as well."

From the American Heart Association:

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