Prognostic value of chronic obstructive pulmonary disease in coronary artery bypass grafting

Coronary and chronic lung diseases have become a common association. This comorbidity has been generically considered by most of the operative risk scores, but its functional severity has seldom been addressed by these models. Our objective was to analyze its prognostic relevance considering preoperative pulmonary function parameters.

All patients undergoing CABG from May 1993 to December 2004 have been reviewed. One thousand four hundred and twelve patients with preoperative pulmonary function test were finally included in the study. Obstructive lung disease was defined when FEV1/FVC<0.7. In-hospital mortality and complication rate related to chronic obstructive pulmonary disease and its degree of severity (FEV1%) were assessed. Logistic regression analysis was used to determine independent predictors of mortality.

A pathologic preoperative pulmonary function test was found in 39% of patients: obstructive in 26% (FEV1/FVC<0.7), restrictive in 9% and combined obstructive-restrictive in 4%. In-hospital mortality was higher in patients with abnormal test: 6.5% versus 0.9% (p<0.001). Mortality was clearly related with the severity of lung disease: 0.9% in patients with FEV1: >80%, 0.4% in FEV1: 60-80%, 10.8% in FEV1: 40-59% and 54% in FEV1: <40%. In the latter group, other intercurrent prognostic factors were observed. Patients with FEV1<60% had higher mortality than those with FEV1>60%: 24.6% versus 1.4% (p<0.001). Chronic obstructive lung disease was not an independent predictor of mortality but FEV1< or =60% was significantly associated with death.

This study on chronic lung comorbidity in CABG patients shows that this association can be of deleterious prognostic value but this effect is directly related to the degree of functional severity. Preoperative FEV1<60% must be considered as a primary prognostic factor in patients undergoing CABG procedures.