Patients with atrial functional mitral regurgitation (AFMR) undergoing transcatheter edge-to-edge-repair (TEER) have significantly lower mortality and heart failure hospitalisation rates than those receiving medical therapy alone, research from Japan, published in the European Heart Journal, has shown.
The study led by Tomohiro Kaneko and Nobuyuki Kagiyama (both Juntendo University Graduate School of Medicine, Tokyo, Japan) is described as a large-scale collaborative study involving multiple Japanese centres.
The study included a total of 1,081 patients with AFMR, with a mean age of 80.1±8.2 years, of whom 60.5% were women. Among them, 441 patients, selected from the OCEAN-Mitral registry, underwent TEER, while the remaining 640 patients, chosen from the REVEAL-AFMR registry, were the medically managed controls.
The research team used propensity score-based overlap weighting to balance the characteristics of both groups, enabling an accurate estimation of treatment outcomes. The association between TEER and clinical outcomes was evaluated based on mortality and heart failure-related hospitalizations in patients with AFMR.
Patients who underwent TEER had a 35% lower risk of the primary endpoint—a composite of all-cause mortality and hospitalisation due to heart failure (hazard ratio [HR]: 0.65 [0.43–0.99]). The risk of all-cause mortality alone, which was the secondary endpoint, was also 42% lower (HR: 0.58 [0.35–0.99]).
Survival benefit remained evident over time. Even after three years, the estimated incidence of death or hospitalisation was 44.3% in the medication group, compared to only 21% in the TEER group.
“Elderly patients with AFMR often fall into a therapeutic grey zone—too high-risk for surgery, yet poorly served by medical therapy alone,” says first author Kaneko. “TEER may help address this gap by providing a feasible, evidence-supported option that is associated with better outcomes in this vulnerable population.”
Outcomes were also determined by the degree of residual mitral regurgitation after TEER (residual AFMR). Among patients in whom residual AFMR was mild or less, the risk of death or hospitalisation was more than 50% lower compared to the medication group. However, in cases of moderate or greater residual AFMR, outcomes were no better or worse than those who received medical therapy alone. This suggests that the degree of success after surgery is a key determinant of the benefit of TEER, the researchers claim.
TEER success was notably high in the study’s Japanese cohort, with over 78% achieving mild or less residual AFMR at the time of discharge. Only 2.9% experienced some complications. Moreover, factors such as age, sex, and left atrial volume did not significantly affect the association between TEER and favourable outcomes. However, in cases of extreme left atrial enlargement (>100 mL/m²), this association appeared to be attenuated or possibly absent, the researchers note.
“This was an observational study, not a randomised trial, so unmeasured confounding cannot be ruled out,” notes Kaneko. “Nevertheless, we employed multiple statistical methods to validate our findings, and the consistency across analyses strengthens our confidence in the conclusions.”
With Japan’s growing elderly population, mitral regurgitation could become more prevalent, the study’s authors suggest, noting that their research offers evidence that TEER, when performed successfully, may represent a promising and low-risk treatment option for patients with AFMR who have limited alternatives.
“In an aging world where frailty limits surgical choices, TEER provides a much-needed bridge between risk and reward,” Kagiyama concluded. “Our findings support its use as a real and promising solution for this demographic.”
The research was co-authored by Masanori Yamamoto (Toyohashi Heart Center, Toyohashi, Japan) and Kentaro Hayashida (Keio University School of Medicine, Tokyo, Japan).
