Right Atrial Conduit Phase Emptying Predicts Risk of Adverse Events in Pediatric Pulmonary Arterial Hypertension.

Background Idiopathic pulmonary arterial hypertension (PAH) is a severe disease associated with a 20% 5-year mortality, often due to right heart failure. Recent studies suggest that compensatory changes in right atrial (RA) function may precede other clinical and echocardiographic evidence of right ventricular dysfunction. No prior prospective study has evaluated the role of RA emptying pattern as a prognostic marker of adverse clinical events in pediatric PAH. Objective To demonstrate whether RA fractional emptying indices will prospectively predict risk of adverse clinical outcomes in pediatric PAH patients. Methods Single-center, prospective cohort analysis of 41 patients with idiopathic or heritable PAH and 1:1 age and sex-matched controls with normal echo and electrocardiogram. Right atrial area (RAA) was measured just prior to tricuspid valve opening (RAAmax), at electrical p wave (RAAp), and just after tricuspid valve closing (RAAmin). Right atrial conduit fraction percent (RA cF%) was defined as the percentage of total RAA change happening prior to the electrical p wave = (RAAmax – RAAp)/(RAAmax – RAAmin) ∗ 100. Clinical worsening was analyzed with a predefined composite adverse event outcome. Results RA measurements were technically feasible in all study participants. The PAH patients (median age 11.9 years) had decreased RA cF% compared with controls (P  Conclusions Right atrial conduit phase emptying is significantly altered in pediatric PAH. Within the PAH population, decreased RA cF% was prognostic for risk of clinical worsening. The combination of accuracy and ease of measurement could make RA cF% a clinically useful, noninvasive biomarker of early right heart failure and risk of disease progression in pediatric PAH.