Significance of prolonged QTc in acute exacerbations of COPD requiring hospitalization

Abstract

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

Acknowledgments

This work was supported by the Flemish Government Agency for Innovation by Science and Technology (IWT). This work was part of the Belgian trial with Azithromycin for acute COPD Exacerbations requiring hospitalization (BACE), which was funded by the Flemish Government Agency for Innovation by Science and Technology (grant number: IWT-TBM130233). The work was supported by the KU Leuven AstraZeneca Chair in Respiratory Pathophysiology. IWT nor AstraZeneca is involved in the study design; in the collection, analysis and interpretation of data; in the writing of the manuscript or in the decision to submit the manuscript for publication. KV and SE are supported as doctoral candidates by the IWT and the Fund for Scientific Research Flanders, respectively. RW and WJ are supported as postdoctoral clinical researchers by the Fund for Scientific Research Flanders. Data were used for a dissertation in the fulfillment of the degree of Master of Medicine. Data have been presented at the American Thoracic Society Conference (Washington, DC, 22 May 2017 – http://www.atsjournals.org/doi/pdf/10.1164/ajrccm-conference.2017.195.1_Meet-ingAbstracts.A3610).

Disclosure

RW has received research funding from Biotronik, Boston Scientific and Medtronic, and speakers and consultancy fees from Biotronik, Boston Scientific, Medtronic, St Jude Medical and Sorin. WJ has received research funding, speakers and consultancy fees from Boehringer Ingelheim, AstraZeneca, Novartis, Chiesi and GSK. The other authors report no conflicts of interest in this work.

Author contributions

All authors contributed toward data analysis, drafting and critically revising the paper and agree to be accountable for all aspects of the work.