Surgery Improves Outcomes for Patients With Atrial Functional Mitral Regurgitation

Patients with atrial functional mitral regurgitation (AFMR) who undergo mitral valve (MV) surgery experience significantly better outcomes than those who rely solely on medical management, according to new research published in JAMA Network Open.¹

AFMR is a recently identified condition—first described in 2011—where mitral regurgitation develops due to left atrial disease, without involvement of left ventricular enlargement or intrinsic mitral valve issues.^2,3 It is commonly linked to long-term atrial fibrillation, and research from the past few years indicates this condition is associated with a higher risk of death and recurrent heart failure hospitalizations.

Conducted across 26 Japanese centers, the REVEAL-AFMR study reviewed data from 177,235 echocardiograms performed in 2019 and found that 11.4% of patients with moderate or severe MR were diagnosed with AFMR specifically, with a mean (SD) age of 77.8 (9.5) years.¹ Of the 1007 patients diagnosed with AFMR, 807 had atrial fibrillation and 113 underwent MV surgery, with 92 of them also receiving tricuspid valve surgery.

This study highlights the potential benefits of surgical intervention in AFMR over medical management alone | Image credit: totojang1977 – stock.adobe.com

Patients who underwent surgery were younger but with more severe MR (57.5% vs 9.4%), larger left atrial volumes (152.5 mL/m2 vs 87.7 mL/m2), and higher rates of heart failure at advanced stages (26.5% vs 9.3%) than patients who stuck with medical therapy only.

After a median follow-up of nearly 3 years, 28.4% of patients diagnosed with AFMR experienced the combined primary outcome of heart failure hospitalization and all-cause mortality, with 141 hospitalizations and 179 all-cause deaths. Importantly, patients who underwent surgery had a significantly lower rate of adverse outcomes (18.3%) compared with those who did not (33.3%) over this 3-year period.

Analysis showed that patients who had MV surgery were less likely to experience heart failure or die compared to those who did not have surgery. When considering just 1 factor in a univariable model, surgery reduced the risk by about 38%, and when adjusting for 25 different factors, the risk dropped by 57%. Even when considering the patients’ overall surgical risk using a specialized score, surgery still lowered the risk by 45%. All these results were statistically significant, meaning the findings are unlikely due to chance.

The study highlighted the potential benefits of surgical intervention in AFMR, a condition often linked with atrial fibrillation and seen mostly in older patients. Consistent with prior findings of multiple sensitivity analyses, these new findings suggest that surgery could offer critical improvements in survival and quality of life, warranting further research to clarify its role in managing AFMR and informing cardiovascular treatment strategies.

This study’s generalizability may be limited due to it being conducted solely in Japanese adults, and that patients in this study had characteristics that were “clearly different from typical characteristics of young patients with degenerative MR,” Other limitations include that, while AFMR diagnosis relied primarily on transthoracic echocardiography, the imaging was reviewed by highly trained cardiologists and confirmed in a subset of patients. The study’s retrospective design also raises the possibility of unmeasured confounders, despite using comprehensive statistical methods to minimize bias. Despite these limitations, the study authors said their findings should serve as a vital basis for the clinical and scientific understanding of AFMR, and more research is needed to learn about the relationship between MV surgery and AFMR outcomes.

“By identifying the prevalence and characteristics of AFMR in a clinical setting, along with the outcomes of surgical intervention, this study provides valuable insights into the literature and may offer useful information for clinicians and researchers,” the authors said. “The low rate of recurrent MR after MV surgery and differences in event rates between the treatment groups will be crucial in planning future clinical trials. However, owing to the study design, the association between MV surgery and low event rates should not be interpreted as a causal relationship.”

References

1. Kagiyama N, Kaneko T, Amano M, et al. Clinical outcomes of mitral valve surgery in atrial functional mitral regurgitation in the REVEAL-AFMR registry. JAMA Netw Open. Published online August 15, 2024. doi:10.1001/jamanetworkopen.2024.28032
2. Vannan MA, Rajagopal V, Yadav PK. Atrial functional mitral regurgitation. Circ Cardiovasc Imaging. 2023;16(5):e015396. doi:10.1161/CIRCIMAGING.123.015396
3. Fan Y, Wan S, Wong RH, Lee AP. Atrial functional mitral regurgitation: mechanisms and surgical implications. Asian Cardiovasc Thorac Ann. 2020;28(7):421-426. doi:10.1177/0218492320941388