Background The transition of right ventricle (RV) from a compensated to decompensated state contributes to survival in pulmonary arterial hypertension (PAH). This study investigates the significance of right atrial (RA) dysfunction on disease progression in PAH. Methods Eighty patients with PAH, including 58 with hemodynamically compensated RV function (PAH-C) and 22 with decompensated RV function (PAH-D), were compared with 80 age-matched and sex-matched normal controls. RA longitudinal strain and strain rate (SR) parameters corresponding to reservoir (total strain ε s and strain rate SRs), conduit (passive strain ε e and strain rate SRe), and booster pump (active strain ε a and strain rate SRa) phases were derived by a rapid semiautomated method on cine cardiovascular magnetic resonance. Results In PAH compared with controls, significantly reduced RA strains and SRs were observed. Among patients with PAH, PAH-D had significantly impaired RA strains and SRs compared with PAH-C. RA total strain and passive strain were the best parameters for differentiating PAH-D from PAH-C. Lower RA strain correlated with increased RA pressure ( r=-0.57; P<0.0001), RV volume ( r=-0.37; P=0.002) and biomarker ( r=-0.53; P<0.0001), impaired RV function ( r=0.46-0.72; P<0.0001), and lower exercise capacity ( r=0.41; P<0.0001). Reduced RA strains were significantly associated with higher risk of clinical worsening in PAH. RA passive strain was the best predictor of a composite adverse event end point (Harrell's C statistic,0.75; hazard ratio,0.84; P=0.019) compared with other conventional RA and RV functional measurements. Conclusions RA phasic functions are impaired in PAH. Among patients with PAH, impaired RA strains reflect RV decompensation and higher risks and predict adverse clinical outcomes. Clinical Trial Registration https://www.clinicaltrials.gov . Unique identifier: NCT02790918.
Keywords: disease progression; hemodynamics; magnetic resonance imaging; pulmonary hypertension; risk factors.