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) and its afterload (E), 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/E) 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 (E/E_(Takeuchi)) and from Kind (E/E_(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/E was predictive of time-to-event.

Results: In patients with IPAH/HPAH, E/E_(Kind) and E/E_(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/E_(Kind) nor E/E_(Takeuchi) were associated with time to soft event. In patients with APAH, neither E/E_(Kind) nor E/E_(Takeuchi) were associated with time to hard event or soft event.

Conclusions: E/E derived from pressure alone is a strong independent predictor of adverse outcome and could be a potential powerful prognostic tool for paediatric PAH.