Particular Histological Pattern Linked to Severe Pulmonary Hypertension in COPD

Compared with individuals with chronic obstructive pulmonary disease (COPD) with moderate pulmonary hypertension (PH) or without PH, those with acute PH-COPD have lower capillary density and significantly greater pulmonary microvessel muscularization, according to a study recently published in CHEST.

This study included 30 participants with COPD who underwent lung transplant, 10 of whom had acute PH-COPD, 10 of whom had moderate PH-COPD (mean pulmonary pressure, 25-34 mm Hg without low cardiac index), and 10 with no PH (mean pulmonary pressure <25 mm Hg). The 3 groups were compared retrospectively in terms of muscular pulmonary arterial wall thickness, microvascular muscularization, and pulmonary capillary density. Dunn’s post-test, chi-squared test, and the Kruskal-Wallis test were used to perform univariate analyses, while a Spearman test was used to estimate correlation coefficients.

Compared with individuals with moderate pulmonary hypertension, the acute PH-COPD group had significantly greater microvessel remodeling scores (1.284 vs 0.867; P =.0045) and lower capillary density (0.00235 per μm² vs 0.00526 per μm²; P =.0049). Medium-size arterial alterations were less discriminating. Low levels of ERG staining in participants with acute PH appears to be associated with capillary network loss.

Limitations to this study included a retrospective design, a low number of participants with PH-COPD, a slightly older definition of acute PH-COPD, and the exclusive examination of lungs with end-stage lung disease.

The researchers of the study concluded that “the morphological correlate or hallmark of severe PH-COPD, when compared with moderate PH-COPD, lies in the substantially increased muscularization of pulmonary microvessels (arterioles and/or venules), as well as in the lower capillary density. Importantly, no significant differences were observed in the muscular-type pulmonary arteries, which are relevant in PAH (group 1) and no typical PAH lesions, such as plexiform lesions or onion-skin lesions (concentric laminar intimal fibrosis) were detected, stressing at least the different morphological phenotype of severe PH-COPD and [pulmonary arterial hypertension].”

Reference

Bunel V, Guyard A, Dauriat G, et al. Pulmonary arterial histological lesions in COPD patients with severe pulmonary hypertension [published online March 11, 2019]. CHEST. doi:10.1016/j.chest.2019.02.333