The prevalence of QTc-prolongation increase by GOLD stage in COPD

Background: COPD is a major cause of mortality worldwide, and cardiovascular comorbidity is common. A prolonged QTc interval confers increased risk of life-threatening ventricular arrhythmias, but it is unclear if prolonged QTc interval is associated with COPD. Aim: To compare the prevalence of QTc prolongation among subjects with normal lung function (NLF) and COPD, and by GOLD stage. Methods: In 2002-04, all subjects with FEV1/VC ≤0.70 (COPD, n=993) and age and sex-matched referents without COPD were identified from population-based cohorts. In 2005, structured interview, post-BD spirometry and 12-lead resting ECG was collected from subjects with COPD (n=634) and referents (n=991) whereof 787 with NLF. QT and R-R interval were manually measured, and adjusted for heart-rate according to Bazett and Frederica. Prolonged QTc was defined as ≥450 ms for men and ≥460 ms for women. Results: The prevalence of QTc prolongation was similar in NLF and COPD (6.5 and 6.8%, p=0.84). The prevalence increased by COPD severity, assessed as GOLD stage (test for trend p=0.01) and when assessed as FEV1 pp adjusted for age and sex. Among men with COPD the prevalence of QTc prolongation increased by GOLD stage; GOLD 1 (3.4%) compared to GOLD 2 (11.0%) and GOLD 3-4 (17.9%), (p=0.04; p=0.03), and by FEV1 pp also when adjusted for age and BMI. Among women, the prevalence of QTc prolongation increased between GOLD 1 (3.5%) and GOLD 2 (6.1%) (p=0.03) while no cases found in GOLD 3-4, and FEV1 pp was non-significant. Conclusion: In this population based study, the prevalence of prolonged QTc was similar among subjects with NLF and COPD. Prolonged QTc prevalence increased by COPD severity, among men also when adjusted for common confounders.