Similar Survival Benefits from Surgery, MitraClip in Symptomatic, High-Risk Mitral Regurgitation

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In symptomatic patients with severe mitral regurgitation (MR) at high surgical risk, transcatheter valve repair and surgery result in similarly high rates of survival, according to a study published in the August 2014 issue of JACC: Cardiovascular Interventions. Additionally, both interventions were superior to medical therapy in terms of survival.

The 3 groups had similar baseline characteristics with no difference in sex between the surgery and medically treated patients. However, there were more men in the MitraClip group compared with the surgery or medically treated groups (67.6% vs 50.9% and 54.2%, respectively; P = .051). Patients in the MitraClip group had higher log EuroSCORE than the other groups, with no difference between the surgery and conservatively treated patients. Additionally, LVEF was highest in the surgical group and similar between the MitraClip and medically treated groups.

The majority of patients in all 3 groups had functional MR (77% in the MitraClip arm, 58.5% in the surgery arm, and 81.3% in the medical therapy arm).

Interventions Both Increase Survival vs Medical Therapy

At 1 year, survival was equivalent between the transcatheter repair and surgery groups, with both having better survival rates than the medical therapy group. The same trend was seen at 2 and 3 years (table 1).

Table 1. Survival Rates

There was no difference in survival when the 2 interventions were compared (HR 1.25; 95% CI 0.72 to 2.16), and the benefit for either intervention compared with conservative treatment remained after propensity score weighting and controlling for cardiac resynchronization therapy and log EuroSCORE:   

• Transcatheter repair (HR 0.41; 95% CI 0.22-0.78)
• Surgery (HR 0.52; 95% CI 0.30-0.88) 

However, when only patients with functional MR were included, the disparate survival between the transcatheter and medically treated groups was slightly attenuated (HR 0.46; 95% CI 0.23 to 0.93), and was no longer significant between the surgical and medically treated groups (HR 0.54; 95% CI 0.29 to 1.02).

Aiming at the Wrong Target?

“Our report expands the EVEREST II data on high-surgical-risk patients, suggesting that transcatheter [mitral valve] repair may even be as good as surgical therapy,” Dr. Swaans and colleagues write. Furthermore, they say, it contradicts the suggestion that surgical repair is no better than conservative therapy in high-risk patients with functional disease.

“Patients with [functional] MR may even benefit the most from transcatheter [mitral valve] repair, as has been suggested by others,” the study authors write, adding that European valvular heart disease guidelines recommend transcatheter repair in these patients—if feasible at low procedure risk—to provide short-term improvement in functional class and LV function.

But in an editorial accompanying the study, Robert O. Bonow, MD, MS, of Northwestern University Feinberg School of Medicine (Chicago, IL), notes that indications for intervention in functional MR are “more ambiguous” than those for primary MR.

“[I]n an individual patient with LV dysfunction, it is difficult to ascertain whether secondary MR is merely a marker of a sicker left ventricle or whether it is a contributor to the sicker left ventricle”, he adds. “Hence, it remains uncertain whether secondary MR should be a target for therapy.”

In fact, Dr. Bonow observes that secondary MR is primarily a disease of the heart muscle, not the valve itself. Therefore, the appropriate initial target for treating secondary MR is the left ventricular dysfunction, he writes.

Dr. Bonow also points out that the study does not include information on type of medical therapy, nor did the authors adjust to account for baseline risk among groups.

Dearth of Needed Data

Yet in a telephone interview with TCTMD, Ted Feldman, MD, of Evanston Hospital (Evanston, IL), said the study, though limited by these and other factors, is timely and needed given the lack of randomized data comparing high-surgical-risk patients across transcatheter, surgical, and medical therapy strategies.

“We need as much information as we can get on this comparison, and this paper is a good attempt at trying to do this,” he said. “But they have 3 retrospective groups of patients that are not well matched. The strength is that it reflects practice, but the weakness is that it makes true comparison difficult. The greatest message here is the need to fill in a very big blank.”

While Dr. Feldman agreed with Dr. Bonow regarding treating the ventricle in patients with functional MR, “we also have a lot of hints out of our broad experience that if we can interrupt the cycle of MR feeding worsening LV dysfunction … we can make some of these patients better.

“It remains unproven,” he said, “but there are those ‘Hail Mary’ cases where someone has late stage cardiomyopathy and nothing is done specifically to treat the ventricle but the patient does improve with MitraClip. Diminishing the hemodynamic load of MR may be what some of these failing ventricles need in order to do better for a while.” Additionally, there are numerous reports of symptom improvement and decreased re-hospitalization rates in this patient population after MitraClip therapy, he reported.

Reimbursement Evolving Amid Ongoing Trials

Drs. Bonow and Feldman say currently enrolling trials comparing transcatheter valve repair and medical management—namely COAPT and RESHAPE-HF—should provide a clearer picture of the best strategy for patients with LV dysfunction and functional MR.

Also to be determined is how the National Coverage Determination (NCD), issued August 12, 2014, by the Centers for Medicare & Medicaid Services will affect use of MitraClip in the United States. The NCD, which provides a national framework for Medicare coverage, complements the agency’s approval of a new technology add-on payment for the MitraClip system.

“Until now, the [diagnosis-related group] was significantly undervaluing the cost of the procedure to the hospital,” Dr. Feldman said. “My sense is that institutions chose either not to adopt a commercial [MitraClip] program or put it on the back burner, so I think this will have a significantly positive effect on utilization in the US. I don’t think any of us know how big the label-approved patient population is, but the NCD will certainly have a favorable impact.”

Sources: 
1. Swaans MJ, Bakker ALM, Alipour A, et al. Survival of transcatheter mitral valve repair compared with surgical and conservative treatment in high-surgical-risk patients. J Am Coll Cardiol Intv. 2014;7:875-881. 

2. Bonow RO. The saga continues: does mitral valve repair improve survival in secondary mitral regurgitation [editorial]? J Am Coll Cardiol Intv. 2014;7:882-884.

Disclosures:

• Dr. Swaans reports serving as a faculty member of Crossroads, the Abbott Vascular Education Network. 
• Dr. Bonow reports no relevant conflicts of interest. 
• Dr. Feldman reports serving as a consultant to and receiving honoraria or institutional research support from Abbott, Boston Scientific, Edwards Lifesciences, and WL Gore.  
  
  

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