Background: Previous studies suggested that obesity and fat mass are associated with QT interval prolongation, but the role of different body parts’ fat mass is unclear. The associations between total and regional fat mass (FM) and corrected QT interval (QTc) were investigated for the first time in this study.
Methods: In this sub-analysis of Fasa PERSIAN cohort Study data, 3217 subjects aged 35-70 entered our study. Body fat mass was assessed by bioelectrical impedance analysis and QTc interval calculated by the QT interval measured by Cardiax® software from ECGs and Bazett’s formula. Uni- and multi-variable linear and logistic regression was performed in IBM SPSS Statistics v23.
Results: In males, the fat mass to fat-free mass (FM/FFM) ratio in the trunk, arms, total body, and legs were significantly higher in the prolonged QTc group (QTc > 450 ms). Trunk (B = 0.148), total (B = 0.137), arms (B = 0.124), legs (B = 0.107) fat mass index (FMI) showed significant positive relationship with continuous QTc (P-value < 0.001). Also, just the fat-free mass index of legs had significant positive associations with QTc interval (P-value < 0.05). Surprisingly, in females, the mean of FM/FFM ratio in trunk and legs in the normal QTc group had higher values than the prolonged QTc group (QTc > 470 ms). Also, none of the body composition variables had a significant correlation with continuous QTc.
Conclusion: Our study suggested that FMI ratios in the trunk, total body, arms, and legs were positively associated with QTc interval in males, respectively, from a higher to a lower beta-coefficient. Such associations were not seen in females. Our study implies that body fat mass may be an independent risk factor for higher QTc interval and, consequently, more cardiovascular events that should be investigated.
Keywords: Cardio-metabolic; Electrocardiogram; Fat mass; Fat mass to fat-free mass (FM/FFM) ratio; Iran; Load-capacity model; Obesity; QT interval; QTc prolongation.