Frequency and Relevance of Ischemic Electrocardiographic Findings in Patients With Chronic Obstructive Pulmonary Disease

Abstract

Cardiovascular disease is common in patients with chronic obstructive pulmonary disease (COPD) but often remains unrecognized. Ischemic electrocardiographic (ECG) changes are associated with a higher risk of dying from coronary heart disease but have never been systematically evaluated in COPD. Also, their relation to clinical outcome has not been studied. We aimed to determine the frequency of ischemic ECG changes and its relevance in relation to clinical outcome and predictors of impaired survival in patients with COPD. Clinical characteristics, pulmonary function, and co-morbidities were assessed in 536 patients with COPD during baseline assessment of a comprehensive pulmonary rehabilitation program. Moreover, electrocardiograms at rest were obtained in all patients. All electrocardiograms were scored independently by 2 cardiologists using the Minnesota scoring system. Major or minor Q or QS pattern, ST junction and segment depression, T-wave items, or left bundle branch block were considered ischemic ECG changes. One hundred thirteen patients (21%) had ischemic ECG changes. Moreover, 42 of 293 patients (14%) without self-reported cardiovascular co-morbidities had ischemic ECG changes. In addition, patients with ischemic ECG changes had higher dyspnea grades (Modified Medical Research Council (mMRC) 2.9 ± 1.1 vs 2.6 ± 1.1, p = 0.032), worse exercise performance (6-minute walking distance 387 ± 126 vs 425 ± 126 m, p = 0.004), more systemic inflammation (high-sensitivity C-reactive protein 11.2 ± 16.2 vs 7.9 ± 10.7 mmol/l, p = 0.01), higher scores on the Charlson Co-morbidity Index (1.8 ± 0.9 vs 1.5 ± 0.8 points), and higher scores BODE (5.3 ± 3.7 vs 4.5 ± 3.4 points, p = 0.033) and on ADO indexes (5.2 ± 1.7 vs 4.8 ± 1.7 points, p = 0.029) compared to patients without ischemic ECG changes, whereas forced expiratory volume in the first second was similar (40.8 ± 15.2% vs 42.6% ± 15.9%, p = 0.30). In conclusion, ischemic ECG changes are common in patients with COPD and associated with poor clinical outcome irrespective of forced expiratory volume in the first second. These results suggest an important role for cardiovascular disease in impaired survival in these patients.