Abstract
Our current understanding of the pathophysiology of pulmonary vascular disease is incomplete, since information about alterations of the pulmonary vasculature in pulmonary arterial hypertension (PAH) is primarily provided by autopsy or tissue specimens. The aim of this study was to compare the distal pulmonary vasculature of <2 mm in diameter in Systemic Sclerosis (SSc) patients with (n = 17) and without (n = 5) associated PAH using Optical Coherence Tomography during Right Heart catheterization. SSc-PAH patients showed significant thickening of Intima Media Thickening Area compared to patients without PAH (27 +/− 5.8% vs. 21 +/− 1.4%, p = 0.024). A good haemodynamic response to previous targeted PAH treatment was associated with a significantly greater number of small pulmonary artery side branches <300 μm per cm vessel (3.8 +/− 1.1 vs. 1.8 +/− 1.1; p = 0.010) and not associated with Intima Media thickening Area (26 +/− 5.4% vs. 28 +/− 6.7%; p = 0.6). Unexpected evidence of pulmonary artery thrombus formation was found in 19% of SSc-PAH patients. This is the first in-vivo study demonstrating a direct link between a structural abnormality of pulmonary arteries and a response to targeted treatment in PAH. Intravascular imaging may identify subgroups that may benefit from anticoagulation.
Highlights
Our current understanding of the pathophysiology of pulmonary vascular disease is incomplete, since information about alterations of the pulmonary vasculature in pulmonary arterial hypertension (PAH) is primarily provided by autopsy or tissue specimens
In one patient Optical coherence tomography (OCT) was performed during the initial diagnostic evaluation with first RHC. 5 patients with Systemic Sclerosis (SSc) had no evidence for PAH on RHC and formed a control group (mPAP 18 +/− 1 mmHg (Table 1)
No thrombus was found in the SSc-patients without PAH. This is the first study demonstrating the feasibility of routine evaluation of the distal pulmonary vasculature
Summary
Our current understanding of the pathophysiology of pulmonary vascular disease is incomplete, since information about alterations of the pulmonary vasculature in pulmonary arterial hypertension (PAH) is primarily provided by autopsy or tissue specimens. In PAH associated with Systemic Sclerosis (SSc) data point to a more distinct phenotype Both historical[6] and more recent studies suggest that SSc-PAH is characterised by significant intimal thickening, small vessel intimal fibrosis, and less plexiform arteriopathy with reports of a concomitant Pulmonary veno-occlusive disease pattern in some cases[7,8]. Dai et al examined a large mixed PH cohort and found wall thickness to be significantly correlated with mean pulmonary artery pressure and in a small PAH subpopulation remodelling was observed after treatment[12] Another group has studied a mixed PAH population and found wall thickness being predictive of outcome[13]. A PH population with mitral valve disease was recently studied[14]
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