The triglyceride-glucose (TyG) index and its obesity-related derivatives are emerging markers of insulin resistance, though their relationship with atrial fibrillation (AF) and underlying cardiac remodeling remains under evaluation. This post hoc analysis of a prospective cohort included 32,500 participants from the UK Biobank without baseline AF who underwent cardiac magnetic resonance (CMR) imaging.  The study was published in the Cardiovascular Diabetology.

Baseline measures included TyG index and derivatives incorporating obesity parameters: TyG-body mass index (BMI), TyG-waist circumference (WC), and TyG-waist-to-height ratio (WHtR). Associations with incident AF were assessed using multivariable Cox regression, and mediation analyses evaluated contributions of CMR-derived cardiac structural parameters.

Over a median follow-up of 13.61 years, 1,288 participants developed AF. The TyG index alone was not independently associated with incident AF. In contrast, all obesity-related TyG derivatives demonstrated significant associations with AF risk. TyG-WC showed the strongest association (HR 1.245; 95% CI 1.169–1.325), followed by TyG-BMI (HR 1.223; 95% CI 1.158–1.293) and TyG-WHtR (HR 1.190; 95% CI 1.122–1.262). 

Mediation analyses identified left atrial maximum volume (LAVmax) as the primary mediator, accounting for 70.63% of the association for TyG-BMI, 47.83% for TyG-WHtR, and 40.79% for TyG-WC, indicating a central role of atrial structural remodeling.

Obesity-related TyG indices were associated with AF risk, unlike the TyG index alone. Cardiac structural changes, particularly left atrial enlargement, contributed substantially to these associations.