Change in right atrial minimal volume is a prognostic marker in pulmonary arterial hypertension (PAH)

Background In contrast to the considerable literature on the prognostic value of right ventricular metrics at baseline and follow-up in PAH, the prognostic value of right atrial size and function has been less well studied. The aim of this study was to compare the prognostic value of right atrial length, area and volume measurements in treatment naive patients with PAH and the impact of treatment. Methods Patients with PAH who underwent MRI at baseline and follow up on a 1.5 T MRI scanner were identified. Maximum and minimum right atrial length, area and volume were measured on two and four chamber images. Survival analysis, using univariate and multivariate Cox proportional hazards regression analysis was performed. Results 154 patients were identified, of whom 18 died. Change in minimal right atrial volume predicted mortality (p=0.028). Change in maximal right atrial volume, stroke volume and ejection fraction did not predict mortality, p=0.228, p=0.229 and p=0.915 respectively. Other than change in minimum two chamber right atrial area predicting mortality (p=0.049), individual changes in length and area measurements in the 4 chamber images were not prognostic. Right atrial length and area measures were highly reproducible intraclass correlation coefficient 0.910 to 0.984. Conclusion Change in minimal right atrial volume predicts mortality and maybe of value in the serial evaluation of patients on PAH therapy.