Right Atrial Function Predicts Clinical Outcome in Patients with Precapillary Pulmonary Hypertension

Although the primary role of right atrial (RA) size in the diagnosis and risk stratification of precapillary pulmonary hypertension (PH) has been studied, little is known about the clinical significance of RA function. In line with studies assessing left atrial function in heart failure, the aim of this study was to introduce the RA function index (RAFi) and to explore its prognostic power in precapillary PH.

RA emptying fraction was calculated as (RA end-systolic volume - RA end-diastolic volume) × 100/(RA end-systolic volume). RAFi was calculated as (RA emptying fraction × right ventricular outflow tract velocity-time integral)/(RA end-systolic volume index). Patients were followed for the end point of clinical failure, which was defined as death, hospitalization because of PH, or disease progression.

In total, 47 patients with precapillary PH were included. Mean RAFi was 16.1 ± 22.3%. Over a median follow-up period of 25 months (interquartile range, 9.5-41.1 months), 29 patients experienced clinical failure. Univariate Cox proportional-hazard analysis showed that RAFi was a predictor of clinical failure (hazard ratio, 0.935; 95% CI, 0.890-0.981; P = .007). Addition of RAFi to established predictors of outcomes, including 6-minute walk distance, N-terminal pro-B-type natriuretic peptide, and RA area, improved their prognostic power.

RAFi is an easily assessed echocardiographic parameter, which is strongly predictive of clinical outcomes in patients with precapillary PH. Further studies are needed to validate RAFi and define its role in clinical practice.