Introduction

Despite shared features of histopathologic remodeling between pulmonary arterial hypertension (PAH) and combined pre- and post-capillary pulmonary hypertension (CPC-PH), vasoreactivity and its relationship with survival is not well-characterized in CPC-PH.

Aims and Objectives

To 1) compare survival in CPC-PH and PAH; 2) characterize vasoreactivity in CPC-PH; and 3) examine the vasoreactivity-survival relationship in CPC-PH.

Methods

Treatment-naïve PAH and CPC-PH patients were selected who had 1) RHC with nitric oxide vasoreactivity testing and PVR?3WU; 2) no lung disease; and 3) no other PH risk factors including untreated sleep apnea. Vasoreactivity and transplant-free survival were examined.

Results

44 PAH and 46 CPC-PH patients were included. At 10 years, survival was shorter in CPC-PH (vs PAH, median 60 vs 115mo, logrank p=0.001). When adjusted for age, gender, baseline PVR, and connective tissue disease, risk of death remained higher in CPC-PH (hazard ratio [HR] 2.27, p=0.025). Compared to PAH, results were similar in subsets of 1) PH-HFpEF and 2) PVR-matched CPC-PH.

Classic vasoreactive responses were less frequent in CPC-PH (vs PAH, 2 vs 11%, p=0.107). With iNO in CPC-PH, mPAP reductions were smaller (vs PAH, -9 vs -17%, p=0.002). In CPC-PH, PVR reductions were larger (-36 vs -28%, p=0.038) and PCWP increases tended to be greater (16 vs 0%, p=0.095). In the CPC-PH group, there was a trend towards reduced mortality risk with larger relative mPAP reduction (age-adjusted HR 0.971, p=0.059).

Conclusions

In treatment-naïve CPC-PH, 10-year survival was reduced compared to PAH. Vasoreactivity in CPC-PH was mixed, with a trend towards reduced mortality with larger mPAP reduction.