Introduction Comorbid ischaemic heart disease (IHD) is associated with an adverse impact on health status, symptoms (ARJCCM 2011;183:A2614) and exacerbation recovery in COPD patients (ERJ 2010;954s:E5209). Any impact on exercise capacity is poorly understood. We aimed to assess and quantify differences in exercise capacity in stable COPD patients with and without IHD.
Methods We assessed 6-min walking distance (6MWD) in accordance with ATS guidance (AJRCCM 2002;166:111–117) in patients from the London COPD cohort. All assessments were performed in the stable state with no symptom-defined exacerbations recorded on daily diary cards for 6 weeks prior and 2 weeks following the visit. Dyspnoea and fatigue were measured before and after the test using the Borg scale, as were saturations from a pulse oximeter. Data were analysed using unpaired t-tests, Mann–Whitney U, χ2 tests and multiple regression techniques.
Results 115 patients had a 6MWD assessment, 19 (17%) had IHD (Abstract P47 table 1). COPD patients with IHD had a lower mean ± SD 6MWD than those without (310±138 vs 354±107 m) although this was not statistically significant (p=0.119). Following adjustment for age, gender, FEV1 % predicted, BMI and smoking pack year history, IHD was found to be independently related with a 66 m reduction in 6MWD (95% CI 5 to 127 m), p=0.035. Median (IQR) dyspnoea on the Borg scale before the test was not higher in those with IHD (1(1,2) vs 1(0,3), p=0.135), this increased more in those with IHD compared to those without during the test (2(1,3) vs 1(0,3), p=0.043). Fatigue measured on the Borg scale was higher at the start of the test in those with IHD (1.5(0,3) vs 0(0,2), p=0.038), however, the increase after the test was not different between the groups (0(0,2) vs 0(0,2), p=0.831). The mean ± SD pre-test oxygen saturations and post-test change were similar in those with and without IHD (93.8±2.6% vs 94.1±2.4%, p=0.684; −0.9±4.4% vs −1.4±3.2%, p=0.595).
Conclusions Comorbid IHD is independently associated with a clinically significant lower exercise capacity in COPD patients. Such patients may have a higher level of fatigue before exercise and develop more dyspnoea during exercise. Such patients may be an appropriate target for further intervention such as tailored pulmonary rehabilitation.