Hemodynamic phenotypes in patients with systemic sclerosis screened for pulmonary hypertension (PH) – the impact of the new defintion of PH

Background: In this study we investigated the impact of the new hemodynamic definition of pulmonary hypertension (PH) with mean pulmonary arterial pressure (mPAP) > 20 mmHg, pulmonary arterial wedge pressure ≤ 15 mmHg and pulmonary vascular resistance (PVR) ≥ 3 WU, as proposed by the 6th PH World Symposium in patients with systemic sclerosis (SSc).

Methods: In consecutive SSc-patients who were prospectively screened for PH including right heart catheterization in 2 PAH/SSc centers (Heidelberg and Zurich) hemodynamic and clinical variables have been reassessed according to the new PAH-definition. Long-term follow-up and survival analysis have been performed. Patients with significant lung or left heart disease were excluded from comparative analyses.

Results: The final dataset included 284 SSc-patients who have been followed for 3.7 ± 3.7 (median 3.4) years, 146 patients (49.2%) had mPAP ≤ 20 mmHg, 19.3% had mildly elevated mPAP (21 – 24 mmHg) and 29.4% had mPAP ≥ 25 mmHg ([Fig. 1]). In the group of mildly elevated mPAP, only four patients (1.4% of the whole SSc-cohort) had PVR-values ≥ 3WU and could be reclassified as manifest SSc-APAH according to the new definition. If a threshold for PVR ≥ 2WU would be used, 28 (9,85%) patients would have been newly diagnosed with PAH ([Fig. 2]). These patients (mPAP 21 – 24 mmHg, PVR ≥ 2WU) had already an early pulmonary vascular disease with reduced 6-minute walking distance (p < 0.001), tricuspid annular plane systolic excursion (p = 0.004), pulmonary arterial compliance (p < 0.001) and long-term survival (p = 0.002) ([Fig. 3]) compared to those with normal hemodynamic values.

Fig. 1 Study flow chart.

Fig. 2 Different PVR thresholds in patients with mPAP 21 – 24 mmHg and ≥ 25 mmHg.

Fig. 3 Survival in different hemodynamic groups according to mPAP.

Conclusions: The new hemodynamic PAH definition did not have a significant impact on the diagnosis of PH. The data of this study suggest, that a PVR threshold > 3WU may be too high and significantly impairs the possibility of an early diagnosis with significant impact on survival ([Fig. 3]).