Chronic Lung Disease and Mortality after Cardiac Surgery: A Prospective Cohort Study

Abstract

Objective: To investigate the 1-year survival in cardiac surgical patients with lung disease, including previously undiagnosed cases.

Design: Prospective cohort study.

Setting: Tertiary hospital.

Participants: Patients scheduled for elective coronary artery bypass graft (CABG) surgery.

Interventions: None.

Measurements and main results: Pulmonary function tests (PFTs) were performed in 454 patients before surgery. Abnormal respiratory patterns were defined as follows: obstructive (forced expiratory volume in 1 second/forced vital capacity <0.70), restrictive (forced expiratory volume in 1 second/forced vital capacity ≥0.70 and forced vital capacity <80% of predicted), and mixed. Overall 1-year mortality was 3.3%. Among 31 patients with documented chronic obstructive pulmonary disease (COPD), mortality was 9.6%, hazard ratio (HR) 1.28, 95% confidence interval (CI) 1.02-12.80, p = 0.04. Of 423 patients without history of COPD, 57 obstructive, 46 restrictive, and 4 mixed abnormal patterns were identified. Of a total of 72 with obstructive lung disease confirmed by PFT (ie, 15 of COPD patients and 57 newly identified cases), 6.9% died, HR 2.75, 95% CI 0.98-8.07, p = 0.06. When combined with cases of COPD where a respiratory abnormality was confirmed (26 patients), newly diagnosed obstructive lung disease (57 patients) was significantly associated with 1-year mortality, HR 4.13, 95% CI 1.50-11.42, p = 0.006. The adjustment for EuroSCORE II did not change the results.

Conclusions: Combination of confirmed preexisting lung disease and newly diagnosed cases provides a clear link to mid-term mortality.

Keywords: cardiac surgery, mortality; chronic obstructive pulmonary disease; obstructive lung disease; obstructive respiratory pattern; pulmonary function tests.