Study Bolsters MitraClip Benefit in Functional MR

Survival was markedly worse with conservative treatment than with MitraClip therapy for severe functional mitral regurgitation (MR), according to a retrospective study, adding support to the benefits seen in the COAPT trial.

The 3-year mortality was 33% among MitraClip patients vs 45% for those who got medical therapy alone (adjusted HR 1.79, 95% CI 1.34-2.39), reported the group led by Friso Kortlandt, MD, of St. Antonius Hospital in Nieuwegein, The Netherlands, in the study published online in EuroIntervention.

That finding in the consecutive patient cohort study appeared to support the survival benefit attributed to MitraClip therapy in COAPT, rather than the lack of benefit in the MITRA-FR trial, which Kortlandt’s group argued was not powered for mortality.

They cited “the potential positive effect of repair on left ventricle remodeling since LVEF [left ventricular ejection fraction] and MR grade are both associated with mortality. Another cause could be that patients who were treated with MitraClip received a higher standard of heart failure care through better outpatient follow-up.”

High-risk patients with severe functional MR may be considered for percutaneous therapy, according to European guidelines, whereas the American Heart Association and American College of Cardiology recommendations do not touch on clipping for this group.

The lowest mortality in Kortlandt’s study was seen among patients who got surgery (23% at 3 years); but the difference was not significant compared with MitraClip in these functional MR patients (HR 0.86, 95% CI 0.54-1.38).

The similar results between surgery and MitraClip in functional MR might be because mitral insufficiency in itself is not the biggest contributor to this disease, the researchers hypothesized, suggesting there are potentially more important factors, such as reduced LVEF to be considered.

“In other words, reducing mitral regurgitation by either surgical or percutaneous intervention does not entirely reverse the clinical problem at hand,” the investigators said. They pointed to the MATTERHORN trial (due for completion in December 2019) as potential confirmation of this theory.

Kortlandt’s study included 568 consecutive MitraClip recipients who were matched by risk criteria and the timing of their MR diagnosis to 173 surgical patients and 295 patients who got medication only treatment at four Dutch centers. Mortality data was retrieved from a national death registry.

Among the 1,036 high-risk patients with symptomatic MR, 688 had moderate-severe disease, while the remainder had severe disease.

Among the 275 patients with degenerative rather than functional MR, unadjusted 3-year mortality rates were 30% with MitraClip, 23% with surgery, and 48% with medical therapy. However, survival differences were not analyzed between groups in degenerative MR because of the small sample size and potential for patient selection bias.

As for the multivariable analysis of the functional MR cohort, different baseline characteristics between groups might have left residual confounding despite the authors’ best attempt at adjustment, the investigators acknowledged. For example, MitraClip patients comprised the highest-risk arm, whereas the conservative management group tended to have a lower LVEF.