Background: Chronic cor pulmonale (CCP) is a strong predictor of death in chronic obstructive pulmonary disease (COPD). The aims of this study were to assess the prognostic role of individual ECG signs of CCP and of the interaction between these signs and abnormal arterial blood gases.
Methods and results: Two hundred sixty-three patients (217 men) with COPD, mean age 67+/-9 years, were grouped according to whether they had no ECG signs (group 1, n=100) or >/=1 ECG signs (group 2, n=163) of CCP and were followed up for 13 years after an exacerbation of respiratory failure. The median survival was significantly shorter in group 2 than in group 1 (2.58 versus 3. 45 years, respectively; Mantel-Cox test, 9.58; P=0.002). The Cox regression analysis identified S1S2S3 pattern, right atrial overload (RAO), and alveolar-arterial oxygen gradient (PAO2-PaO2) >48 mm Hg during oxygen therapy as the strongest predictors of death, with hazard rate (HR)=1.81 (95% CI, 1.22 to 2.69), HR=1.58 (95% CI, 1.15 to 2.18), and HR=1.96 (95% CI, 1.19 to 3.25), respectively. The median survivals of patients having both S1S2S3 pattern and RAO (n=14) and of patients having either S1S2S3 pattern or RAO (n=77) were 1.33 and 2.70 years, respectively (P=0.022). Group 2 patients had a 3-year survival of 18% or 53%, depending on whether their PAO2-PaO2 during oxygen therapy was or was not >48 mm Hg.
Conclusions: Some ECG signs of CCP and PAO2-PaO2 >48 mm Hg during oxygen therapy qualified as a simple and inexpensive tool for targeting subsets of COPD patients with severe or very severe short-term prognosis.