Background: Small- and medium-scale studies have suggested that increasing body mass index (BMI) is associated with corrected QT (QTc) interval prolongation, and thereby a higher risk of ventricular arrhythmia. However, there is a lack of large-scale studies to corroborate this finding. Given the increasing prevalence of obesity, we sought to investigate the association between anthropometric measurements and QTc among a large sample of the UK population.
Methods: The Airwave Health Monitoring Study database consists of 53,114 participants from 26 police forces across the UK, of which 46,201 had 12-lead ECG. Univariate and multivariate analyses were performed to explore the relationship between QTc and demographic variables (age, sex, ethnicity) and seven pre-specified anthropometric measures (BMI [kg/m2], whole-body impedance [IMP, Ω], % body fat [BF, %], waist:hip ratio [WHR], hip girth [HG, cm], waist girth [WG, cm] and total body water [TBW, kg]).
Results: Full datasets were available for 39,026 individuals (14,457 female; mean age 40 years). In unadjusted univariate analysis, QTc was positively correlated with age, IMP and BF (p<0.001) and BMI (p=0.023). QTc was negatively correlated with WHR, WG and TBW (all p<0.001). There was no significant correlation between QTc and HG. In adjusted multivariate analysis, BMI and BF were no longer significantly associated with QTc. QTc increased by 0.38 ms/year and 0.40 ms/kg with respect to age and TBW, respectively (both p<0.01). QTc was negatively correlated to IMP, WHR and WG, all of which are measures of adiposity, and decreased by 0.015 ms/Ω (p<0.01), 7.1 ms/unit (p=0.011) and 0.07 ms/cm (p=0.024), respectively.
Conclusion: QTc was negatively correlated with measures of adiposity and central obesity, specifically IMP, WHR and WG. There was no direct relationship between QTc and BMI, which is a less specific measure of adiposity. These data suggest a possible direct effect of adipose tissue on ventricular repolarisation.
