Effect of an intensive lifestyle intervention on the structural and functional substrate for atrial fibrillation in people with metabolic syndrome.

Aims: To evaluate the effect of an intensive lifestyle intervention (ILI) on the structural and functional cardiac substrate of atrial fibrillation (AF) in overweight or obese people with metabolic syndrome (MetS).
Methods: Participants of the PREDIMED-PLUS trial (n=6874) were randomised 1:1 to an ILI program based on an energy-reduced Mediterranean diet, increased physical activity, and cognitive-behavioural weight management, or to a control intervention of low-intensity dietary advice. Left atrial (LA) strain, function, and volumes were evaluated by a core echocardiography lab in 534 participants at baseline, 3-year and 5-year follow-up. Mixed models were used to evaluate the effect of the ILI on LA structure and function.
Results: In the subsample, baseline mean age was 65 years (SD 5 years), and 40% of the participants were women. Over the 5-year period, both groups experienced worsening of LA structure and function, with increases in LA volumes and stiffness index and decreases in LA longitudinal strain, LA function index and LA emptying fraction over time. Changes in the ILI and control group were not significantly different for any of the primary outcomes (LA emptying fraction: -0.95% (95%CI -0.93, -0.98) in control group, -0.97% (95%CI -0.94, -1.00) in ILI group, p _{between groups} =0.80; LA longitudinal strain: 0.82% (95%CI 0.79, 0.85) in control group, 0.85% (95%CI 0.82, 0.89) in ILI group, p _{between groups} =0.24) or any of the secondary outcomes.
Conclusions: In overweight or obese people with MetS, an ILI had no impact on the underlying structural and functional left atrial substrate measurements associated with AF risk.