Significance of prolonged QTc in acute exacerbations of COPD requiring hospitalization

Abstract

Oliver Van Oekelen,1,* Kristina Vermeersch,1,2,* Stephanie Everaerts,1,2 Bert Vandenberk,3,4 Rik Willems,3,4 Wim Janssens1,2 1Department of Respiratory Diseases, University Hospitals Leuven, Leuven, Belgium; 2Department of Chronic Diseases, Metabolism and Ageing, Laboratory of Respiratory Diseases, KU Leuven, Leuven, Belgium; 3Department of Cardiology, University Hospitals Leuven, Leuven, Belgium; 4Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium *These authors contributed equally to this work Background: A prolonged QT interval is associated with increased risk of Torsade de Pointes and cardiovascular death. The prevalence and clinical relevance of QT prolongation in acute exacerbations of COPD (AECOPD), with high risk for cardiac morbidity and mortality, is currently unclear. Methods: A dual cross-sectional study strategy was therefore designed. A retrospective study evaluated 140 patients with an AECOPD requiring hospitalization, half of which had prolonged QTc on the admission ECG. Univariate and multivariate analyses were conducted to determine associated factors; Kaplan–Meier and Cox regression analyses to assess prognostic significance. A prospective study evaluated 180 pulmonary patients with acute respiratory problems requiring hospitalization, to determine whether a prolonged QTc at admission represents an AECOPD-specific finding and to investigate the change in QTc-duration during hospitalization. Results: Retrospectively, hypokalemia, cardiac troponin T and conductance abnormalities on ECG were significantly and independently associated with QTc prolongation. A prolonged QTc was associated with increased all-cause mortality (HR 2.698 (95% CI 1.032–7.055), p=0.043), however, this association was no longer significant when corrected for age, FEV1 and cardiac troponin T. Prospectively, QTc prolongation was observed in 1/3 of the patients diagnosed with either an AECOPD, lung cancer, pulmonary infection or miscellaneous acute pulmonary disease, and was not more prevalent in AECOPD. The QTc-duration decreased significantly during hospitalization in patients with and without COPD. Conclusion: A prolonged QTc is a marker of underlying cardiovascular disease during an AECOPD. It is not COPD-specific, but a common finding during the acute phase of a pulmonary disease requiring urgent hospital admission. Keywords: COPD, acute exacerbation, cardiovascular morbidity, prolonged QT interval, ECG, Bazett

Keywords

• COPD — acute exacerbation — cardiovascular morbidity — prolonged QT interval — ECG