Background/Purpose:  Pulmonary hypertension (PH) is a leading cause of death in patients (pts) with Systemic Sclerosis (SSc). The World Health Organization (WHO) classifies PH into groups: pulmonary arterial hypertension (PAH, WHO1); PH secondary to left heart dysfunction or isolated post-capillary PH (WHO2); and PH secondary to pulmonary disease (WHO3). The purpose of this study was to describe the clinical characteristics and outcomes of those pts in the PHAROS cohort categorized as WHO2.

Methods:  Pts were enrolled in PHAROS within 6 months of the diagnosis of PH. PH was defined by a mean pulmonary artery pressure (mPAP)≥25 mmHg on right heart catheterization (RHC.) Pts were categorized as WHO2 if they had a pulmonary capillary wedge pressure (PCWP)>15 mmHg. Pts with Interstitial Lung Disease (ILD) as defined by a forced vital capacity (FVC) <65% predicted and/or significant fibrosis on chest CT with a normal PCWP were included in WHO3. Clinical expertise from the treating centers was also used to categorize pts best, as individuals may have features of more than one group. Statistical analysis was carried out using Shapiro-Wilk, Kruskal-Wallis, Kaplan-Meier and stratified log-rank tests.

Results: There are 335 pts with PH in the PHAROS database: WHO1 – 215, WHO2 – 57, and WHO3 –63. As shown in table 1, WHO2 pts are different from WHO1 but similar to WHO3 pts in that they are more likely to be African American, to have diffuse SSc and to be scl70 positive. WHO2 pts had lower FVC and FVC%/DLCO% ratio than WHO1 pts. They had normal ejection fractions but significantly larger left atrial measurements. WHO2 patients by definition have higher PCWP, which is associated with a lower pulmonary vascular resistance on RHC.  Stratified log-rank tests did not show a significant difference in time to death between the groups, p=0.28. Survivals for 1, 3, and 5 years are shown below in table 2. WHO2 patients had a significantly higher proportion of deaths related to scleroderma than WHO1 (95% v. 70%, p=0.02). The most common cause of death among WHO2 pts was PH (37%) followed by multifactorial causes (26%.) WHO I pts died most commonly from PAH (50%), while the most common cause among WHO III patients was pulmonary fibrosis (46%, p<0.001).

Conclusion: Patients with WHO2 PH have different features that help to separate them from WHO1 pts. Overall survival in the PH pts enrolled in PHAROS has improved over historical values. WHO group classification did not affect survival in these incident patients. However, pts with WHO2 PH were more likely to die from scleroderma-related causes.      

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-characterization-of-patients-with-world-health-organization-group-2-pulmonary-hypertension-in-the-pulmonary-hypertension-assessment-and-recognition-of-outcomes-in-scleroderma-cohort/