Pulmonary arterial lesions in explanted lungs after transplantation correlate with severity of pulmonary hypertension in chronic obstructive pulmonary disease

Background: Pulmonary vascular findings are largely unreported in end-stage chronic obstructive pulmonary disease (COPD).

Methods: Pulmonary vascular lesions in explanted lungs from 70 patients with COPD/emphysema or α-1-antitrypsin deficiency were analyzed retrospectively. Patients were stratified by the presence and severity of pulmonary hypertension (PH) assessed by right-heart catheterization in 3 hemodynamically distinct groups: (1) non-PH (mean pulmonary arterial pressure [mPAP]<25 mm Hg), (2) mild to moderate PH (mPAP, 25-34 mm Hg), and (3) severe PH (mPAP≥35 mm Hg). The control group comprised 18 patients with idiopathic pulmonary arterial hypertension (IPAH). Vascular lesions were graded 1-6 according to a modified Heath and Edwards (HE) scale.

Results: All COPD patients were in New York Heart Association Functional Class III-IV (forced expiratory volume in 1 second, 23%±8%; total lung capacity, 128%±20% of predicted). Non-PH group: 30 patients (60% women) aged 54±6 years; mPAP, 17.2±3.8 mm Hg; median HE Grade 1 (range, 0-3), with medial hypertrophy of muscular pulmonary arteries and muscularization of pulmonary arterioles. Mild-moderate PH group: 30 patients (50% women) aged 53±6 years; mPAP, 28.6±2.8 mm Hg; median HE Grade 3 (range, 1-3), with additional cellular intimal proliferation. Severe PH group: 10 patients (50% women) aged 54±6 years; mPAP, 40.7±5.2 mm Hg; median HE Grade 3 (range, 2-5), with additional intimal fibrosis. IPAH controls: 18 patients (67% women) aged 36±4 years; mPAP,>50 mm Hg; median HE Grade 4 (range 3-6), with generalized arterial dilatation and plexiform lesions.

Conclusions: The extent of pulmonary vascular lesions in COPD correlate with the severity of PH. Morphologic lesions similar to those characteristic of IPAH can be observed as PH in COPD progresses to levels characteristic of IPAH.