Background/Purpose: Pre-capillary pulmonary hypertension (PH) is a feared complication in patients with systemic sclerosis (SSc) and is associated with high mortality despite new treatment options. Pre-capillary PH is diagnosed by right heart catheterization (RHC) with mean pulmonary artery pressure (mPAP) ≥25 mmHg and a pulmonary artery wedge pressure (PAWP) of ≤15 mmHg. The 6^th World Symposium on Pulmonary Hypertension proposed new definitions for pre-capillary PH, lowering the mPAP value to ≥ 21 mmHg and including pulmonary vascular resistance (PVR) ≥3.0 Wood Units (WU).  The aim of this study was to explore the impact on prevalence of PH in an SSc cohort by applying the new definitions.

Methods: All SSc patients from the Oslo University Hospital SSc cohort who had performed at least one RHC (n=191) were included. We used data from the first RHC with mPAP ≥ 21 mmHg when available. Using the current pre-capillary PH definitions, PH was defined as mPAP ≥25 mmHg and PAWP ≤ 15 mmHg. Borderline PH was defined as mPAP 21-24mmHg. Pulmonary arterial hypertension (PAH) and PH due to interstitial lung disease (ILD) were defined as pre-capillary PH in absence or presence of ILD on high resolution CT scan with < / >10 % pulmonary fibrosis, respectively. Secondly, the newly proposed haemodynamic definitions for pre-capillary PH including mPAP ≥ 21 mmHg, PAWP ≤15 mmHg and PVR ≥3 WU were applied.

Results: Of the 191 SSc patients, 150/191 (79%) were female, 143/191 (75%) had limited cutaneous SSc and 85/191 (45%) were anti-centromere antibody positive. Mean age of the patients was 57 years and mean time from SSc diagnosis to PH diagnosis was 6 years. Using the current PH criteria 51/191 (27%) SSc patients were diagnosed with PAH, 36/191(19%) patients with PH-ILD and 45 (24%) patients with borderline PH. Using the newly proposed definitions the frequency of PAH and PH-ILD changed as shown in Figure 1. 24 patients had an mPAP ≥ 21 mmHg and a PVR value 2.0-2.9 WU. The mean mPAP in these 24 patients was 23.8 mmHg, the mean PAWP 10.1 mmHg, 20/26 (77%) were female and 16/26 (62%) were anti-centromere antibody positive.

Conclusion: Lowering the mPAP to ≥ 21 mmHg and including PVR ≥ 3.0 WU did not substantially change the PH prevalence in our cohort due to the PVR cut-off value. We still need more knowledge about the long-term outcome of SSc patients with pre-capillary PH when changing definitions for pre-capillary PH. Also, it will be important to decide how and when to treat these patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/diagnosing-pulmonary-hypertension-using-the-proposed-6th-world-symposium-on-pulmonary-hypertensions-new-definitions/