Usefulness of Right Ventricular Volumetric and Afterload Indices for Risk Stratification in Patients With Tetralogy of Fallot

Right ventricular (RV) volume overload due to chronic pulmonary regurgitation is the common mechanism for hemodynamic deterioration after tetralogy of Fallot (TOF) repair. As a result, RV volumetric indices are used for clinical risk stratification in this population. Since RV afterload is a determinant of RV hemodynamic performance, we hypothesized that afterload-adjusted RV volumetric indices will have a better correlation with disease severity compared with RV volumetric indices alone in patients with TOF. Cross-sectional study of adults with previous TOF repair that received care at Mayo Clinic, 2002-2015. We defined disease severity as atrial arrhythmia and/or impaired exercise capacity. We created afterload-adjusted RV volumetric indices by indexing these indices to RV systolic pressure (RVSP) as follows: RV end-diastolic volume (RVEDVi)/RVSP, RV end-systolic volume (RVESVi)/RVSP, and RV ejection fraction (RVEF)/RVSP. The RV volumetric indices were: RVEDVi 141 ± 43 ml/m², RVESVi 79 ± 38 ml/m², and RVEF 44 ± 10%, and RVSP was 48 ± 9 mm Hg. RVESVi was the only RV volumetric parameter that was associated with disease severity (odds ratio [OR] 1.13, 95% confidence interval [CI] 1.01 to 1.32, p = 0.041) with area under the curve (AUC) of 0.612. In contrast RVEF/RVSP (OR 0.73, 95% CI 0.38 to 0.92, p = 0.037, AUC 0.649), and RVESVi/RVSP (OR 1.28, 95% CI 1.14-1.55, p = 0.008, AUC 0.798) were associated with disease severity. Compared with RV volumetric indices alone, the combined RV volumetric and afterload indices had better correlation with disease severity as measured by AUC. Afterload-adjusted RV volumetric indices had better correlation with disease severity, and may potentially improve risk stratification in this population.