A structured diet helped older patients with persistent AF lose nearly 10% of their body weight, but the LOSE-AF trial found that slimmer patients did not have fewer symptoms or better rhythm control.
In a recent article published in JAMA, researchers present and discuss the outcomes of the LOSE-AF trial, a randomized clinical trial designed to investigate whether a structured, low-calorie diet could safely reduce body weight in older adults with overweight or obesity and improve the severity of atrial fibrillation (AF) symptoms.
Study findings revealed that, while participants who adhered to the 8-month low-calorie diet intervention achieved moderate, sustained weight loss, 9.7% vs. 3.1% in control, P < 0.001, without evidence of reduced physical performance or intervention-related serious adverse events, it yielded no statistically significant improvement in Atrial Fibrillation Severity Scale (AFSS) symptom scores, P = 0.43.
Furthermore, the analyses failed to identify statistical differences in objective AF burden, biomarkers, or cardiovascular magnetic resonance (CMR) structural parameters, suggesting that while dietary modulation can help senior patients reduce weight, these benefits do not directly translate into improved AF symptoms, rhythm control, AF burden, or cardiac remodeling over the 8-month intervention period.
Background
Atrial fibrillation (AF) is a common arrhythmia in which the heart’s upper chambers, the atria, beat chaotically and out of sync with the lower chambers, causing the heart to quiver instead of pumping blood efficiently. The condition is now considered a major public health epidemic and is estimated to be affecting more than 50 million individuals globally.
Previous research has established excess body weight as a potent, modifiable risk factor for incident AF. Unfortunately, while weight reduction guidelines are robustly supported by data from younger cohorts, with a mean age < 60 years, older patients, more typical of the general AF patient population, present distinct pathophysiological challenges. Existing evidence has focused mostly on younger individuals, leaving uncertainty over whether weight loss benefits older adults with established, persistent AF.
However, in this demographic, the therapeutic risk-benefit ratio of substantial caloric restriction remains largely unverified.
About the study
The present study aimed to address this knowledge gap by evaluating the safety and efficacy of weight reduction in an older cohort through a prospective, open-label clinical trial conducted across two hospitals in the United Kingdom (UK). Named the “LOSE-AF” trial, the study included patients scheduled for direct current cardioversion (DCCV) for persistent AF and ultimately randomized 118 eligible participants aged 60 to 85 years with a BMI of 27 or greater.
The included participants were equally randomized into two parallel groups: the intervention group, n = 59, who were assigned to an 8-month structured program consisting of a low-calorie diet and commercial behavioral support utilizing formula meal products and regular counseling, and the control group, n = 59, who were required to undergo “usual care” comprising one-off nurse-led consultation and written dietary advice.
Participant data collection, “evaluations”, was conducted at baseline, 4 months, and 8 months, with the study’s primary efficacy endpoint being the baseline-adjusted change in the AFSS symptom severity subscale.
The study’s secondary endpoints included quality of life, physical performance, AF burden, cardiac structure, blood pressure, lipid levels, and the need for further AF procedures.
Study findings
As expected, the intervention cohort’s structured dietary regime was observed to induce a clear weight-loss response. Specifically, at 8 months, the baseline-adjusted mean body weight of participants in the intervention cohort, 92.6 kg, was significantly lower, -6.9 kg, than their control cohort counterparts, 99.4 kg, representing an estimated mean weight reduction from baseline of 9.7% in the intervention group compared to 3.1% in the control group, P < 0.001.
Notably, this weight reduction did not correlate with functional decline, as physical performance did not differ between the two study arms. Unexpectedly, however, participants’ weight loss did not statistically alter their AF-related clinical or cardiac metrics.
Study analyses failed to detect a difference in symptom severity, AFSS = 7.9 for intervention group versus 8.9 for controls; P = 0.43, arrhythmia burden, reverse remodeling or cardiac structure, biomarkers or risk markers, including systemic systolic blood pressure, total cholesterol, and high-sensitivity C-reactive protein [hsCRP] compared to before weight loss.
Finally, available follow-up data indicated that while a significant weight difference persisted between groups, long-term AFSS scores and rates of repeat cardioversion or catheter ablation remained statistically indistinguishable.
Conclusions
The LOSE-AF trial indicates that while structured behavioral and low-calorie dietary programs can drive safe, sustained weight reduction in older adults without evidence of reduced physical performance, this intervention does not modify AF symptoms, arrhythmia burden, or underlying cardiac remodeling.
The authors conclude by hypothesizing that weight loss alone may be insufficient to reverse established persistent AF in older adults, although effects may differ in younger patients, those with less advanced AF, or with greater or longer-term weight loss.
