Abstract 11778: Association of Body Mass Index With Corrected QT interval and the Impact of This Association on All-cause Mortality: Results From the National Health and Nutrition Examination Survey (NHANES)

Abstract

Introduction: Given the high prevalence of obesity, the association of body mass index (BMI) with corrected QT interval (QTc) warrants investigation. Although both BMI and QTc are independently associated with mortality, the influence of BMI on QTc and the specific impact of this association on mortality remain unknown. Methods: We analyzed data from 4,579 participants aged 40-65 years from NHANES III for a median of 13.8 years. We divided the weighted sample into 4 categories by BMI as 18.5-25 (reference), >25-30, >30-35 and >35 and 2 categories by Bazette heart rate-corrected QT as normal (<450 ms in males, <460 ms in females) or prolonged. Cox proportional hazards models were used with adjustment for demographic characteristics and traditional cardiovascular risk factors. Results: BMI was significantly associated with QTc with a significantly higher QTc among those with higher BMI (Mean QTc: 428, 429, 433 and 439 ms respectively for BMI 18.5-25, >25-30, >30-35 and >35, P for trend: <0.001). Overall, both prolonged QTc or BMI>35 were independently associated with increased mortality compared with those with normal QTc or BMI 18.5-25. When combined, the risk of mortality was higher among those with both prolonged QTc and higher BMI [Hazard ratio (95% CI): 1.92 (1.03-3.56), 1.75 (0.83-3.68) and 2.29 (1.12-4.69)] for categories of prolonged QTc and BMI 25-30, 30-35 and >35, respectively compared with those with BMI 18.5-25 and normal QTc. There was a significant improvement in risk prediction for mortality when QTc was added to the fully adjusted model with BMI (net reclassification index 0.167, P=0.0001). Conclusions: Those with higher BMI have a significantly longer QTc. This longer QTc among those with higher BMI translates into a higher risk of mortality. These novel observations suggest that individuals with higher BMI should be screened for the presence of prolonged QTc, especially when treated with medications that may prolong QTc.