Chronic obstructive pulmonary disease and coronary artery bypass grafting
In the present issue of the Canadian Respiratory Journal, Manganas et al (1) published a study of coronary artery bypass grafting (CABG) in patients with and without chronic obstructive pulmonary disease (COPD). This is an important subject, because coronary artery disease and COPD are both related to smoking and therefore frequently coexist; many COPD patients die of coronary artery disease (2). In any event, Manganas et al identified more than 300 patients who had spirometry soon before undergoing CABG and categorized them into three groups: those with normal spirometry results; those with mild-moderate COPD (forced expiratory volume in 1 s [FEV1]/forced vital capacity [FVC] 0.7 or less, FEV1 of at least 50% of the predicted normal value); and severe COPD (FEV1/FVC 0.7 or less, FEV1 less than 50% of the predicted value). The mean FEV1 in the last group was 0.98 L. The groups were well balanced in terms of cardiac disease severity and use of cardiac drugs, and had similar surgery, although internal mammary artery grafts were used less often in both COPD groups. Mortality was very low in all groups and not related to COPD; indeed, none of the 68 severe COPD patients died. None of the seven deaths were due to respiratory disease. On the other hand, COPD patients had slightly longer hospital stays than those with normal spirometry, and had more episodes of bronchitis and pneumonia -- approximately 25% of the severe COPD patients had one of these complications. As Manganas et al indicate, these are fairly soft diagnoses in such a retrospective study. Furthermore, there was a tendency for atrial fibrillation to occur more often in COPD patients.