Abstract
Background
Cardiovascular involvement is frequent in Chronic Obstructive Pulmonary Disease (COPD), with autonomic dysfunction a recognized feature. However, the dynamics of QT interval, a known marker of autonomic dysfunction, from rest to peak exercise in COPD patients has not yet been investigated.
Aim
To examine the changes in QT and heart-rate corrected QT (QTc) intervals from rest to peak exercise in a population of stable COPD outpatients and of healthy controls.
Methods
Prospectively collected data on COPD patients and healthy controls who underwent spirometry and maximum cardiopulmonary exercise testing with a continuous 12-lead ECG recording, were retrospectively analyzed. Distribution of variables was assessed with Shapiro-Wilk test and group comparisons were conducted utilizing the paired samples T-test or Wilcoxon rank test, as appropriate. Level of p<0.05 was considered significant.
Results
The study population consisted of 143 patients (63.6% male; 62.8±7.4 years old; FEV1%=32.3±14) and 18 age and gender-matched controls. Among controls, the QT interval shortened (361.1±39.1 vs 270±27.7, p<0.001), while QTc increased (396.4±24.4 vs. 422.7±32.9, p<0.001) from rest to peak exercise. Among COPD patients, QTc interval did not increase (406.2±25.8 vs 411.9±34.2, p=0.53). QT interval shortened (333.4±34.7 vs. 299±32, p<0.001), but its absolute change was smaller, when compared to controls. Medications known to prolong QT interval did not impact on QT dynamics.
Conclusion
COPD patients demonstrate a different exercise response; QTc interval does not increase, and QT shortening is about 30% of that seen in healthy controls.
- © 2014 ERS
