PAH-specific treatment for patients with combined pre- and post-capillary pulmonary hypertension

Abstract Introduction Pulmonary hypertension (PH) due to left heart disease (PH-LHD) is the most frequent form of PH, constituting approximately 70% of PH patients. Depending on the extent of pressure increase in the pre-capillary bed, PH-LHD is divided into isolated post-capillary PH, where pulmonary vascular resistance (PVR) is ≤2 WU, and combined pre- and post-capillary PH (Cpc-PH), where PVR exceeds 2 WU. Compared to Ipc-PH, Cpc-PH portents substantial morbidity and poor prognosis. Current PH guidelines recommend optimal treatment of underlying pathology, with drugs approved for pulmonary arterial hypertension (PAH) being not recommended; however, therapeutic regimens specifically targeting increases in pre-capillary pressure are urgently required. Methods For this analysis, we included all patients diagnosed with Cpc-PH invluding using right heart catheterization, who presented at the PH outpatient clinic of the Medical University of Vienna, Austria, between 02/2022 and 02/2023. Cpc-PH was defined hemodynamically as an elevated mean pulmonary arterial pressure (mPAP) of >20 mmHg and a PVR >2 WU. Results A total of 30 (6.5%) patients were diagnosed with Cpc-PH. Of these, 21 (70%) were female; median age was 75 [70, 76] years. Cardiovascular risk factors were arterial hypertension in 27 (90%), diabetes mellitus in 7 (23%), hyperlipidemia in 22 (73%), atrial fibrillation in 24 (80%), chronic kidney disease in 21 (70%), and coronary artery disease in 13 (43%) patients. At diagnosis, median mPAP was 42 [36, 53] mmHg, with a PVR of 5.5 [3.4, 5.3] WU. Laboratory evidence of heart failure was illustrated by elevated NT-proBNP levels (2076 [1461, 3959] pg/mL). Transthoracic echocardiography showed mildly, moderately and severely reduced right ventricular (RV) function in 7 (23%), 9 (30%) and 3 (10%) patients. At diagnosis, 6 (20%), 20 (67%) and 4 (13%) patients were in WHO functional class II, III and IV, respectively. PAH-specific therapy was initiated in 11 (37%) patients: 7 (23%) were put on treprostinil, 4 (13%) on macitentan, 3 (10%) on riociguat, and 3 (10%) on sildenafil. In 3 (10%) patients, combination therapy was started; one (3%) patient received triple therapy. In patients in whom PAH-specific therapy was initiated, PVR at baseline was higher (6.9 [5.4, 9.9] vs. 4.9 [3.1, 5.9] WU, p=0.019). Patients on PAH-specific therapy had a higher rate of improvement in WHO-FC at follow-up (82% vs. 31%, p=0.019). Conclusions In patients suffering from Cpc-PH, PAH-specific therapy leads to improvement of symptoms. Further studies are required to extend this finding to a larger patient group to assess whether PAH-specific drugs may also improve hemodynamics, right ventricular function and mortality.