Repaired tetralogy of fallot: ratio of right ventricular volume to left ventricular volume as a marker of right ventricular dilatation

Purpose: To compare indexed right ventricular (RV) end-diastolic volume (RVEDVi) and the ratio of RV volume to left ventricular (LV) volume (RV/LV ratio) in prediction of significant pulmonary regurgitation (PR) after tetralogy of Fallot (TOF) repair and to assess sex differences in the RV/LV ratio. Materials and Methods: The ethics committee approved this retrospective single-center study, and patients or their parents or guardians signed written informed consent. RVEDVi, RV/LV ratio, and PR were measured with the use of magnetic resonance imaging in 155 consecutive patients with repaired TOF (mean age, 29.2 years ± 10.9 [standard deviation]; 98 [63.2%] male and 57 [36.8%] female patients). PR fraction of 20% or greater was considered significant. The capability of the RVEDVi and that of the RV/LV ratio for prediction of significant PR were compared by using logistic regression analysis and receiver operating characteristic curve analysis. Results: RVEDVi was significantly higher in male (162.8 mL/m(2) ± 50.4) than in female (138.2 mL/m(2) ± 37.5) patients (P = .001). Conversely, the RV/LV ratio was similar in both sexes (1.82 ± 0.56 [male] vs 1.69 ± 0.46 [female], P = .13) both in the entire cohort and after excluding patients with significant (≥ 30 mm Hg) RV outflow tract gradient and/or other residual hemodynamic abnormalities (P = .63). Receiver operating characteristic analysis revealed better discrimination of significant (≥ 20%) from insignificant (< 20%) PR with the use of the RV/LV ratio than with RVEDVi (area under the receiver operating characteristic curve, 0.937 [model 4] vs 0.849 [model 1], P = .01). In multivariate analysis, the only independent predictor of PR fraction was the RV/LV ratio. Conclusion: The RV/LV ratio is more accurate than the RVEDVi in differentiation of significant from insignificant PR. After TOF repair, female and male patients have similar RV/LV ratios despite significant differences in RVEDVi between the sexes. ? RSNA, 2012 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120051/-/DC1.