Objective
Prognosis in pulmonary hypertension is largely determined by right ventricular (RV) function. However, uncertainty remains about what metrics of RV function might be most clinically relevant. The purpose of this study was to assess the clinical relevance of metrics of RV functional adaptation to increased afterload.
Methods
Patients referred for pulmonary hypertension (PH) underwent right heart catheterization and RV volumetric assessment within 48 hours. A RV maximum pressure (Pmax) was calculated from the RV pressure curve. The adequacy of RV systolic functional adaptation to increased afterload was estimated either by a stroke volume (SV)/end-systolic volume (ESV) ratio, a Pmax/ mean pulmonary artery pressure (mPAP) ratio, or by ejection fraction (RVEF). Diastolic function of the RV was estimated by a diastolic elastance coefficient β. Survival analysis was via Cox proportional hazard ratio and Kaplan-Meier with the primary outcome of time to death or lung transplant.
Results
Patients (n=50; age 58±13) covered a range of mPAP (13–79 mmHg) with an average RVEF of 39±17% and ESV of 143±89 ml. Average estimates of the ratio of end-systolic ventricular to arterial elastance were 0.79±0.67 (SV/ESV) and 2.3±0.65 (Pmax/mPAP-1). Transplantation-free survival was predicted by right atrial pressure, mPAP, pulmonary vascular resistance, β, SV, ESV, SV/ESV, and RVEF but after controlling for right atrial pressure, mPAP, and SV, SV/ESV was the only independent predictor.
Conclusions
The adequacy of RV functional adaptation to afterload predicts survival in patients referred for pulmonary hypertension. Whether this can simply be evaluated using RV volumetric imaging will require additional confirmation.
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