Background: Comorbid ischemic heart disease (IHD) is a common and important cause of morbidity and mortality in patients with COPD. The impact of IHD on COPD in terms of a patient's health status, exercise capacity, and symptoms is not well understood.
Methods: We analyzed stable-state data of 386 patients from the London COPD cohort between 1995 and 2009 and prospectively collected exacerbation data in those who had completed symptom diaries for ≥ 1 year.
Results: Sixty-four patients (16.6%) with IHD had significantly worse health status as measured by the St. George Respiratory Questionnaire (56.9 ± 18.5 vs 49.1 ± 19.0, P = .003), and a larger proportion of this group reported more severe breathlessness in the stable state, with a Medical Research Council dyspnea score of ≥ 4 (50.9% vs 35.1%, P = .029). In subsets of the sample, stable patients with COPD with IHD had a higher median (interquartile range [IQR]) serum N-terminal pro-brain natriuretic peptide concentration than those without IHD (38 [15, 107] pg/mL vs 12 [6, 21] pg/mL, P = .004) and a lower exercise capacity (6-min walk distance, 225 ± 89 m vs 317 ± 85 m; P = .002). COPD exacerbations were not more frequent in patients with IHD (median, 1.95 [IQR, 1.20, 3.12] vs 1.86 (IQR, 0.75, 3.96) per year; P = .294), but the median symptom recovery time was 5 days longer (17.0 [IQR, 9.8, 24.2] vs 12.0 [IQR, 8.0, 18.0]; P = .009), resulting in significantly more days per year reporting exacerbation symptoms (median, 35.4 [IQR, 13.4, 60.7] vs 22.2 [IQR, 5.7, 42.6]; P = .028). These findings were replicated in multivariate analyses allowing for age, sex, FEV(1), and exacerbation frequency where applicable.
Conclusions: Comorbid IHD is associated with worse health status, lower exercise capacity, and more dyspnea in stable patients with COPD as well as with longer exacerbations but not with an increased exacerbation frequency.