PURPOSE: Pulmonary hypertension (PHTN) is a known risk factor for morbidity and mortality in patients with COPD. Identifying COPD patients at risk for developing PHTN may improve outcomes. Hypoxic pulmonary vasoconstriction, destruction of alveolar capillaries and hyperinflation are proposed mechanisms of PHTN in COPD, but only a few studies have evaluated the ability of pulmonary function testing to identify PHTN in these patients.
METHODS: A retrospective review of PFT and echocardiography databases for patients with COPD fulfilling GOLD criteria was performed at two institutions. Inclusion criteria: completion of transthoracic echocardiogram within one year of PFT, smoking history, TLC ≥ 80% predicted and left ventricular ejection fraction (LVEF) ≥35%. Lung volumes were measured by body plethysmography. Univariate and multivariate linear regression was completed with right ventricular systolic pressure (RVSP) as dependent variable. PHTN was defined as RVSP ≥ 36 mm Hg. Spirometry values are post-bronchodilator administration.
RESULTS: Of 2643 COPD patients screened, 519 had echocardiograms and 212 met inclusion criteria. PHTN was seen in 75 patients (35.4%) with a mean RSVP of 48 ± 12 mm HG. Patients with PHTN were older, weighed less, were more likely to be former than current smokers, had more airflow obstruction (FEV1 55.6 ± 17.3 vs. 62.9 ± 19.4 % predicted, p=0.013) and had lower diffusion capacity. There were no differences in LVEF, gender, height, cigarette pack-years, RV, FRC or TLC between groups. There were statistically significant correlations between RVSP and age, FEV1 percent predicted, specific airways conductance, and DLCO percent predicted, but only age and DLCO predicted PHTN by multivariate regression (r2=0.23, p<0.0001) and logistic regression (r2=0.16, p<0.0001).
CONCLUSION: Advanced age and a low DLCO are predictors of PHTN. Hyperinflation does not appear to be the major mechanism accounting for PHTN in patients with COPD.
CLINICAL IMPLICATIONS: Decreased diffusion capacity and older age may warrant screening for pulmonary hypertension in patients with COPD.
DISCLOSURE: Vadim Fayngersh, No Financial Disclosure Information; No Product/Research Disclosure Information