Relation of total bilirubin and QT interval prolongation (from the Third National Health and Nutrition Examination Survey).

Objective: The association of bilirubin with cardiovascular disease (CVD) is controversial. We sought to explore the association of total bilirubin (TB) 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 CVD from the Third National Health and Nutrition Examination Survey 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 the cross-sectional association between tertiles of TB and prolonged QT interval (≥450 ms in men and ≥460 ms in women).

Results: The prevalence of prolonged QT was higher among those with higher levels of TB (prolonged QT prevalence was 4.7%, 6.8%, and 7.0% across TB 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 TB tertile had significantly greater odds of the prolonged QT interval (Odds ratios [95% confidence interval] 1.53 [1.16-2.02]) compared to those with bilirubin levels in the first tertile. Each 0.29 mg/dl increase in TB levels was associated with a 12% (p-value <.0001) increase in the prevalence of prolonged QT interval. This association was stronger in men than in women (interaction p-value = .04).

Conclusion: Elevated bilirubin levels are associated with a prolonged QT interval. This finding extends our current knowledge on the relationship between serum bilirubin and CVD by demonstrating a link between higher TB and abnormal cardiac repolarization.