Clinical evaluation of RV wall stress in pulmonary arterial hypertension: A follow-up study using magnetic resonance imaging

Background: In pulmonary arterial hypertension (PAH) survival is strongly associated with right ventricular (RV) function and its ability to adapt to the increased pulmonary artery pressure (PAP). RV remodeling to the increased load is often characterized by dilatation, and hypertrophy. RV wall stress is a simple parameter that contains the effects of PAP, dilatation and hypertrophy. Therefore this study aims to evaluate RV wall stress in patients during follow-up. Methods and results: At baseline 53 patients underwent magnetic resonance imaging (MRI) and right heart catheterization (RHC). In all patients RV end-systolic wall stress (RVESWS) was calculated using the law of Laplace. Eight patients died during the first year of follow-up and therefore 45 patients underwent MRI and RHC after 1-year follow-up. During a median long term follow-up of 57 months another 10 patients died. At baseline, RVESWS appeared to be similar in survivors and non-survivors (n=53, p=0.765). In contrast, change of RVESWS during the 1-year follow-up differed significantly (n=45, p=0.014) between survivors and non-survivors. Survivors showed a decrease in RVESWS during 1-year follow-up, whereas non-survivors showed an increase of RVESWS during 1-year follow-up. Kaplan-Meier analysis showed a higher mortality rate in patients with an increase of RVESWS>17 mmHg than in patients with an increase of RVESWS Conclusion: Progressive RV failure is characterized by an increase of RVESWS.