Pulmonary Arterial Histologic Lesions in Patients With COPD With Severe Pulmonary Hypertension

BACKGROUND: The development of pulmonary hypertension (PH) during the course of COPD is a well-known phenomenon, with the prevalence depending on the severity of airway obstruction. When mean pulmonary pressure (mPAP) level at rest is >= 35 mm Hg or >= 25 mm Hg with low cardiac index, the term severe PH is used. For these patients, little is known on the underlying histologic lesions. Our objective was to describe these lesions. METHODS: From the explants of patients undergoing lung transplantation, we compared retrospectively three groups of patients with COPD: severe PH-COPD (n = 10), moderate PH-COPD (mPAP between 25 and 34 mm Hg without low cardiac index) (n = 10), and no PH (mPAP < 25 mm Hg) (n = 10). Histologic analysis of the explanted lungs examined the wall of medium-size arteries, the remodeling of microvessels, and the pulmonary capillary density using morphometric measurements performed on three sections per patient. RESULTS: Compared with the moderate PH group, the remodeling score of the microvessels was significantly higher (P = .0045) and the capillary density was lower (P = .0049) in the severe PH-COPD group. The alterations of the medium-size arteries, important in group 1 PH, seemed less discriminating. CONCLUSIONS: Patients with severe PH-COPD appear to have a specific histologic pattern, different from that observed in patients with COPD with moderate PH or without PH.