Exercise right atrial stiffness associated with mortality in pulmonary hypertension

This prospective observational study enrolled 68 participants, including 42 with precapillary pulmonary hypertension (PH); participants without PH and those with postcapillary PH served as reference groups. Assessments included three-dimensional echocardiography, right heart catheterization, and invasive right atrial (RA) pressure-volume loops at rest and during standardized semisupine exercise. The researchers derived RA filling stiffness from the reservoir phase and divided the precapillary PH group at the median exercise stiffness.

At rest, groups with higher and lower exercise RA stiffness had similar right ventricular function, afterload, and cardiac index. The higher-stiffness group nevertheless had lower RA strain and greater liver stiffness, a measure of venous congestion. During exercise, mean RA pressure rose similarly in both groups, but peak cardiac index was lower in the high-stiffness group (3.3 versus 4.1 L/min/m²; P=0.015). Higher exercise RA stiffness was independently associated with mortality (adjusted hazard ratio, 4.37; 95% CI, 1.20–15.96); resting RA stiffness was not. A model using RA conduit strain and right ventricular functional reserve discriminated high stiffness (area under the curve, 0.90). The small observational cohort supports further study of exercise RA stiffness as a prognostic marker; it does not establish a change to current PH risk assessment.