Patients with pulmonary arterial hypertension (PAH) have elevated cell-free DNA (cfDNA), which increases with disease severity, according to a study published in Circulation. Samuel B. Brusca, MD, and colleagues measured plasma cfDNA in two PAH cohorts (A: N=48; B: N=161) and controls (N=48) to examine its significance. Patients were divided into low, medium, and high Registry to Evaluate Early and Long-term PAH Disease Management  (REVEAL) risk groups. Survival was compared between cfDNA tertiles and REVEAL risk groups. cfDNA concentrations differed among patients with PAH of varying REVEAL risk and controls in both cohorts; the greatest concentrations were seen in the high- versus low-risk category. Death or lung transplant occurred in 14 of 54, 23 of 53, and 35 of 54 patients in the lowest, middle, and highest cfDNA tertiles, respectively, in cohort B. Transplant-free survival was predicted by cfDNA levels stratified into tertiles and REVEAL risk groups. Discrimination was improved with the addition of cfDNA to REVEAL.