In older patients with overweight and persistent atrial fibrillation (AF) referred for direct current cardioversion, an 8-month structured dietary weight loss and behavioural support program leads to a significant reduction in weight without inducing functional decline. However, this metabolic benefit does not translate into improvements in AF outcomes, according to the LOSE-AF trial.
Patients who underwent the weight loss and behavioural support program (intervention group) lost an average of 9.7 percent of their body weight over 8 months, while those who received usual care lost an average of 3.1 percent (p<0.001). [JAMA 2026;doi:10.1001/jama.2026.5787]
Despite these differences in weight, no significant between-group differences were observed in the main outcome of Atrial Fibrillation Severity Scale (AFSS) symptom severity scores at 8 months (7.9 vs 8.9; p=0.43; estimated difference, −0.9, 95 percent confidence interval [CI], −3.3 to 1.4).
AFSS symptom burden scores were also similar between the intervention and usual care groups at 8 months (15.8 vs 15.0; p=0.59), as was health-related quality of life as assessed using the EQ-5D-5L visual analogue scale (75.3 vs 74.2; p=0.70). Freedom from AF was achieved in 42 percent of patients in the intervention group vs 49 percent in the usual care group (p=0.58).
Weight loss had no adverse effect on functional status, with physical performance testing scores of 32.6 in both groups (p=0.99).
At long-term follow-up of 3.5 years, patients in the intervention group still had a significantly lower body weight than those in the usual care group (estimated difference, 4.9 kg, 95 percent CI, 2.1–7.7; p<0.001). However, no significant between-group differences were observed in AF recurrence following the index cardioversion (hazard ratio [HR], 1.04, 95 percent CI, 0.69–1.58; p=0.85), repeat cardioversion (HR, 0.64, 95 percent CI, 0.35–1.16; p=0.14), or AF ablation (HR, 1.00, 95 percent CI, 0.48–2.10; p>0.99).
In LOSE-AF, 118 patients (mean age 68 years, 66.9 percent male) were randomly allocated to the intervention group (n=59) or the usual care group (n=59). The median AF duration was 9.6 months in the intervention group and 13.1 months in the usual care group, and 44 percent and 51 percent of patients in the respective groups had long-standing persistent AF. All patients were taking direct oral anticoagulants.
The structured dietary weight loss and behavioural support program involved regular, individually tailored appointments with a local counsellor to deliver behavioural coaching, monitor weight, and supply formula meal products. Usual care, on the other hand, consisted of a single face-to-face consultation with a research nurse and written materials on dietary weight loss.
Early intervention may be needed
“One reasonable conclusion to take from this study may be that long-standing persistent AF is unlikely to be amenable to weight loss. This fits well with growing evidence that early intervention for AF tends to be especially effective,” commented Dr Gregory Marcus from the University of California, San Francisco, US, in an accompanying editorial. [JAMA 2026;doi:10.1001/jama.2026.6094]
Close to half of the patients in each group had long-standing persistent AF (presence of continuous AF for ≥12 months), which Marcus described as “notoriously recalcitrant.”
“Difficulties in treating long-standing persistent AF have been attributed to adverse atrial remodelling, essentially AF begetting AF for such a long time that the atria become much less amenable to achieving and maintaining sinus rhythm,” he said.
Marcus also pointed out that the LOSE-AF participants did not achieve the guideline-recommended goal of ≥10-percent weight loss, which highlights “the difficulty in actually achieving and maintaining prescribed amounts of weight loss.”
“Rather than taking findings from the current study as supporting inaction with respect to weight loss, these current data, alongside prior evidence, may spur on a sense of urgency to help patients with healthy lifestyle choices as soon as an AF diagnosis is made,” Marcus wrote.
Additionally, high-quality implementation research is needed “to identify feasible strategies that can lead to effective weight loss or sufficient evidence to determine precisely what types of infrastructure and support would be needed,” he added.