Atrial functional mitral regurgitation (AFMR) is a condition in which the mitral valve does not close properly, causing blood to leak backward into the atrium. It commonly affects frail or elderly patients and often leads to heart failure. Standard open-heart surgery is frequently too risky in these individuals due to other health problems, leaving medical therapy as the only option. Now, a new study has shown that a minimally invasive valve procedure significantly reduces mortality and hospitalizations compared with medication alone.

Researchers at the Juntendo University Graduate School of Medicine (Tokyo, Japan), in collaboration with other Japanese institutions, investigated the use of transcatheter edge-to-edge repair (TEER) in AFMR patients. TEER is a catheter-based, minimally invasive procedure that clips together parts of the mitral valve to reduce regurgitation. Previously, the technique proved effective in treating ventricular functional mitral regurgitation (VFMR). This study aimed to determine whether similar benefits could be extended to AFMR patients.

The analysis drew from two nationwide registries and included a total of 1,081 elderly patients with AFMR, with a mean age of 80 years. The 441 patients in the OCEAN-Mitral registry underwent TEER, while the 640 patients in the REVEAL-AFMR registry received medical therapy alone. To ensure a fair comparison, the researchers used a statistical approach called propensity score-based overlap weighting, which balanced the characteristics of both groups before evaluating treatment outcomes.

The findings, published in the European Heart Journal, showed that TEER patients had a 35% lower risk of a composite endpoint of all-cause mortality and hospitalization due to heart failure. The risk of death alone was reduced by 42%, with benefits persisting for up to three years. At that time, the combined rate of death or hospitalization was 44.3% in the medical therapy group versus only 21.0% in the TEER group. Importantly, the degree of residual mitral regurgitation strongly influenced outcomes, with greater benefit seen when AFMR was reduced to mild or less.

TEER proved both safe and effective in this elderly population. Over 78% of patients achieved mild or less residual AFMR after the procedure, and complications occurred in only 2.9%. Age, sex, and atrial size did not significantly alter outcomes, though the benefit of TEER was diminished in cases of extreme left atrial enlargement. These results highlight the importance of procedural success in determining long-term benefit.

With Japan’s aging population, cases of AFMR are expected to rise. The study provides compelling evidence that TEER offers a promising treatment pathway for patients who are too frail for surgery but inadequately treated with medication alone. The findings could influence treatment guidelines and improve management strategies for elderly patients with AFMR worldwide.

“Elderly patients with AFMR often fall into a therapeutic gray zone—too high-risk for surgery, yet poorly served by medical therapy alone. TEER may help address this gap by providing a feasible, evidence-supported option that is associated with better outcomes in this vulnerable population,” said Dr. Tomohiro Kaneko, first author of the study.

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