Evaluation of Right Ventricular Size Metrics Measured with Cardiac Magnetic Resonance Imaging in Patients with Pulmonary Regurgitation.

In patients with repaired congenital heart disease (CHD) and pulmonary regurgitation (PR), a common metric for guiding the timing of pulmonary valve replacement (PVR) is right ventricular (RV) end-diastolic volume (EDV). The standard practices of indexing RV EDV to body surface area and calculating RV EDV Z-scores are imperfect, and guidelines for PVR based on threshold values for indexed volumes may be insensitive to individual patient circumstances. Indexing RV EDV to left ventricular EDV is an alternative method of normalizing RV volume in patients with PR. We reviewed clinically obtained cardiac magnetic resonance (CMR) studies in patients with a PR fraction ≥ 15% to determine relationships between the RV EDV index (EDVi), RV: LV EDV ratio, and PR fraction, as well as demographic and diagnostic factors mitigating these relationships. The PR fraction correlated better with the RV: LV EDV ratio than with RV EDVi. The correlation between RV: LV EDV ratio and RV EDVi was similar to that between PR fraction and the RV: LV EDV ratio. Factors associated with greater variation in the RV: LV EDV ratio - RV EDVi relationship included a native/patched RV outflow tract vs. a conduit, age at CMR, BSA, weight, height, and significant aortic regurgitation. In patients with repaired CHD and PR, relationships between RV EDVi, the RV: LV EDV ratio, and PR fraction are variable and influenced by a number of demographic, anthropometric, anatomic, and physiologic factors. The RV: LV EDV ratio correlated better with PR fraction than did RV EDVi, and accordingly, it may better reflect the response of the RV to PR.