Right atrial phasic strain in risk stratification of patients with Pulmonary Arterial Hypertension

Right atrial (RA) phasic function is impaired in individuals with pulmonary arterial hypertension (PAH), evidence for the clinical significance of the RA strain in risk stratification for PAH patients is limited. Participants with PAH from June 2013 to December 2022 were prospectively recruited. C-index, 1-year mortality, and annual event rates were used to evaluate prognostic performance. Risk groups were defined as low (<5%), intermediate (5–20%), and high (>20%) 1-year mortality. A total of 348 PAH patients were included (mean age: 40.0 ± 14.0 years; 93 males), with a median follow-up of 41.5 months (interquartile range: 24.9–61.9 months). RA reservoir strain independently predicted all-cause mortality (HR = 0.950, 95% CI: 0.922–0.979; P < 0.001). Based on cutoff values of 16.1% and 36.8%, RA reservoir strain stratified patients into high-, intermediate-, and low-risk groups with 1-year mortality rates of 24.0%, 5.5%, and 0.0%, demonstrating the highest discriminative ability among CMR-derived metrics (C-index: 0.79, 95% CI: 0.71–0.87). Incorporating RA reservoir strain significantly improved the performance of the REVEAL Lite 2 model (P = 0.03), with comparable prognostic value to that of the combined CMR parameters (both P > 0.05). Similar findings were observed in PAH patients without shunts. RA reservoir strain outperformed RV functional parameters in stratifying PAH patients into low-, intermediate-, and high-risk strata. RA reservoir strain has the potential to be part of the multiparametric evaluation of patients with PAH. This study was registered in the Chinese clinical trial registry (ChiCTR1800019314 and ChiCTR1900025518). URL: https://www.chictr.org.cn/index.html .