Ventricular-vascular coupling is predictive of adverse clinical outcome in paediatric pulmonary arterial hypertension

Aims Ventricular-vascular coupling, the ratio between the right ventricle's contractile state (E es) and its afterload (E a), may be a useful metric in the management of paediatric pulmonary arterial hypertension (PAH). In this study we assess the prognostic capacity of the ventricular-vascular coupling ratio (E es /E a) derived using right ventricular (RV) pressure alone in children with PAH. Methods One hundred and thirty paediatric patients who were diagnosed with PAH via right heart catheterisation were retrospectively reviewed over a 10-year period. Maximum RV isovolumic pressure and end-systolic pressure were estimated using two single-beat methods from Takeuchi et al (E es /E a (Takeuchi)) and from Kind et al (E es /E a (Kind)) and used with an estimate of end-systolic pressure to compute ventricular-vascular coupling from pressure alone. Patients were identified as either idiopathic/hereditary PAH or associated PAH (IPAH/HPAH and APAH, respectively). Haemodynamic data, clinical functional class and clinical worsening outcomes - separated into soft (mild) and hard (severe) event categories - were assessed. Adverse soft events included functional class worsening, syncopal event, hospitalisation due to a proportional hazard-related event and haemoptysis. Hard events included death, transplantation, initiation of prostanoid therapy and hospitalisation for atrial septostomy and Pott's shunt. Cox proportional hazard modelling was used to assess whether E es /E a was predictive of time-to-event. Results In patients with IPAH/HPAH, E es /E a (Kind) and E es /E a (Takeuchi) were both independently associated with time to hard event (p=0.003 and p=0.001, respectively) and when adjusted for indexed pulmonary vascular resistance (p=0.032 and p=0.013, respectively). Neither E es /E a (Kind) nor E es /E a (Takeuchi) were associated with time to soft event. In patients with APAH, neither E es /E a (Kind) nor E es /E a (Takeuchi) were associated with time to hard event or soft event. Conclusions E es /E a derived from pressure alone is a strong independent predictor of adverse outcome and could be a potential powerful prognostic tool for paediatric PAH.