Right ventricular-pulmonary arterial coupling in schistosomiasis associated pulmonary arterial hypertension

Background Schistosomiasis associated pulmonary arterial hypertension (Sch-PAH) is a highly relevant form of pulmonary hypertension, particularly in developing countries. Compared with idiopathic pulmonary arterial hypertension (IPAH), Sch-PAH has a better prognosis, though without identified mechanisms that justify this clinical course. Right ventricular-arterial pulmonary (RV-PA) coupling, expressed by the relationship between right ventricular contractility and afterload, has been studied as a potential marker of cardiac response to pulmonary vascular disease. However, there are no studies evaluating RV-PA coupling in Sch-PAH. Methods Retrospective cohort including patients diagnosed with Sch-PAH or IPAH who underwent right heart catheterization (RHC) at our institution from 2013 to 2018. Clinical and hemodynamic characteristics were reviewed and, by means of the recorded and digitized RHC pressure curves, right ventricular maximum isovolumic pressure (Pmaxiso) was estimated through the single-beat method to calculate right ventricular elastance at the end systole (Ees). The RV-PA was expressed by the Ees and the pulmonary artery elastance (Ea) ratio. Results A total of 101 patients were included (33 with Sch-PAH and 68 with IPAH). Sch-PAH patients were older (55.5 +/- 15.1 vs 42.7 +/- 15.2; p <0.001) with no significant difference in terms of traditional hemodynamics; nevertheless, Sch-PAH patients had better survival (p=0.031). Patients with Sch-PAH showed higher RV-PA coupling (0.95 +/- 0,58 vs 0.67 +/- 0.41; p = 0.004), higher Ees (2.07 +/- 1.65 vs 1.33 +/- 0.91; p = 0.005) without any difference in Pmaxiso and Ea compared with IPAH. At univariate analysis, RV-PA coupling was associated with survival. The RV-PA coupling remained an independent prognostic marker in the multivariable analysis adjusted for the type of pulmonary arterial hypertension (p = 0.030; HR = 0.287; 95% CI, 0.093-0.883). Conclusions RV-PA coupling is better preserved in Sch-PAH patients and is significantly associated with survival, suggesting that the right ventricular response to the increased afterload in Sch-PAH might represent an important pathophysiological mechanism that could explain the better clinical course observed in this relevant form of PAH.