Longitudinal assessment of right atrial conduit fraction provides additional insight to predict adverse events in pediatric pulmonary hypertension.

BACKGROUND: Recent studies show adverse right atrial (RA) emptying pattern is prognostic for clinical worsening events in pediatric pulmonary arterial hypertension (PAH). No study has reported changes in RA emptying over time or evaluated whether serial measurements offer further prognostic information. METHODS: Prospective study of 32 children with idiopathic or heritable PAH undergoing echocardiogram at baseline and 1-year. RA conduit fraction percent (RA cF%) was measured as percentage of total diastolic RA area change prior to the electrical p wave. Clinical worsening was analyzed with a predefined composite adverse event outcome. RESULTS: Longitudinal subjects (median age 13.3 yr) had RA cF% 61% (IQR 32-68%) at baseline and 60% (IQR 35-73%) at 1-year (NS). 11 subjects had a qualifying event during median 21-month follow-up. Subjects with an event had 1-year RA cF% = 33% (IQR 20-40%) compared to 72% (IQR 63-75%) for those with no event (p < 0.001). Event rates were lowest for subjects with both echocardiograms showing RA cF% > 60% (0%), highest for subjects with neither (80%), and intermediate for those with one (38%, p = 0.003). CONCLUSIONS: Changes in RA cF% inform risk of adverse events in pediatric PAH. This finding supports the role of RA cF% as both a prognostic biomarker and potential treatment target.

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 < .0001), and PAH subjects with lower RA cF% demonstrated higher right ventricular systolic (R = -0.49, P = .019) and end-diastolic (R = -0.52, P = .012) pressure than those with higher RA cF%. Sixteen subjects had a clinical event. Right atrial cF% (hazard ratio = 0.09; P < .001) was highly prognostic for risk of adverse clinical event with area under the curve = 0.90 on receiver operating characteristic curve analysis (median 3.2-year follow-up). 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.