Ischemic ECG abnormalities are associated with an increased risk for death among subjects with COPD, also among those without known heart disease

Abstract

Abstract presentation

An abstract, including parts of the results, has been presented at an oral session at the European Respiratory Society International Conference, London, UK, September 2016.

Background

Cardiovascular comorbidity contributes to increased mortality among subjects with COPD. However, the prognostic value of ECG abnormalities in COPD has rarely been studied in population-based surveys.

Aim

To assess the impact of ischemic ECG abnormalities (I-ECG) on mortality among individuals with COPD, compared to subjects with normal lung function (NLF), in a population-based study.

Methods

During 2002–2004, all subjects with FEV₁/VC <0.70 (COPD, n=993) were identified from population-based cohorts, together with age- and sex-matched referents without COPD. Re-examination in 2005 included interview, spirometry, and 12-lead ECG in COPD (n=635) and referents [n=991, whereof 786 had NLF]. All ECGs were Minnesota-coded. Mortality data were collected until December 31, 2010.

Results

I-ECG was equally common in COPD and NLF. The 5-year cumulative mortality was higher among subjects with I-ECG in both groups (29.6% vs 10.6%, P<0.001 and 17.1% vs 6.6%, P<0.001). COPD, but not NLF, with I-ECG had increased risk for death assessed as the mortality risk ratio [95% confidence interval (CI)] when compared with NLF without I-ECG, 2.36 (1.45–3.85) and 1.65 (0.94–2.90) when adjusted for common confounders. When analyzed separately among the COPD cohort, the increased risk for death associated with I-ECG persisted after adjustment for FEV₁ % predicted, 1.89 (1.20–2.99). A majority of those with I-ECG had no previously reported heart disease (74.2% in NLF and 67.3% in COPD) and the pattern was similar among them.

Conclusion

I-ECG was associated with an increased risk for death in COPD, independent of common confounders and disease severity. I-ECG was of prognostic value also among those without previously known heart disease.

Keywords:

• COPD
• ECG
• ischemic heart disease
• epidemiology
• mortality

Acknowledgments

The authors thank professors Eva Rönmark and Bo Lundbäck, the present and former head of the OLIN studies, for their support. Further, the authors thank research assistants Ann-Christine Jonsson and Sigrid Sundberg for collecting data. The authors also thank professors Abdonas Tamosiunas and Ricardas Radisauskas, Lithuanian University of Health Sciences for excellent assistance with the Minnesota coding of the ECGs.

The authors acknowledge the Swedish Heart-Lung Foundation, the Västerbotten County Council, and the Heart Foundation of Northern Sweden for research funding.

Author contributions

All authors have substantially contributed in the process of writing the manuscript and have approved the final version of the manuscript. In addition, UN is the corresponding author and has contributed to the interpretation of data and statistical analysis. AB and BJ contributed to the interpretation of data. HB has contributed to the interpretation of data and statistical analysis. BE contributed to data collection and interpretation of data. AL was responsible for the study design, and took part in data collection and interpretation of data. AL is also the guarantor and takes responsibility for the content of the manuscript and the accuracy of the data analysis.

Disclosure

The authors report no conflicts of interest in this work.