1080 Bilirubin and QT Interval Prolongation (From the Third National Health and Nutrition Examination Survey)

Abstract

INTRODUCTION: The association of bilirubin with cardiovascular disease (CVD) is controversial. We sought to explore the association of total bilirubin levels with QT interval in a multiracial cohort. METHODS: A total of 6,627 participants (59.0 ± 13.3 years; 52.6%% women, 49.7% Non-Hispanic Whites) without cardiovascular disease (CVD) from the Third National Health and Nutrition Examination Survey (NHANES-III) were included in this analysis. QT was automatically measured from digital 12-lead electrocardiogram in a central reading center. A multivariable logistic regression model was used to examine cross-sectional association between tertiles of total bilirubin and prolonged QT interval (≥450 ms in men, ≥460 ms in women). RESULTS: The prevalence of prolonged QT was higher among those with higher levels of total bilirubin (prolonged QT prevalence was 4.7%, 6.8%, and 7.0% across total bilirubin lower (0-0.4 mg/dl), middle (0.5-1.6 mg/dl) and higher (0.70-4.30 mg/dl) tertiles respectively). In a model adjusted for potential confounders, participants within the highest total bilirubin tertile had significantly greater odds of prolonged QT interval (OR (95% CI): 1.53 (1.16-2.02) compared to those with bilirubin levels in the first tertile. Each 0.29 mg/dl increase in total bilirubin levels was associated with a 12% (P-value < .0001) increase in the prevalence of prolonged QT interval (Table 1). This association was stronger in men than women (interaction P-value = 0.04). CONCLUSION:: Recent evidence suggests worse cardiovascular (CV) outcomes with high levels of bilirubin but the mechanism behind worse CV events remains to be elucidated. Our study showed that elevated bilirubin levels are associated with prolonged QT interval. QT interval has been consistently associated with increased risk of all-cause and CV death. Thus, finding an association between total bilirubin levels and prolonged QT interval in our study extends our current knowledge on the relationship between serum bilirubin and CVD by demonstrating a link between higher total bilirubin and abnormal cardiac repolarization. To the best of our knowledge, this is the first study to demonstrate the association between bilirubin and prolonged QT. This association was stronger in men than women. Future studies are needed to establish the causal relationship between bilirubin and QT prolongation and how this association between bilirubin and QT interval could be harnessed to improve CVD risk estimation.