Progressive right ventricular enlargement due to pulmonary regurgitation: Clinical characteristics of a “low-risk” group

Background: The optimal interval between serial cardiac magnetic resonance imaging (CMRI) scans for monitoring right ventricular (RV) enlargement in the setting of severe pulmonic valve regurgitation (PR) is unknown. The purposes of this study were to (1) determine the annual change in RV volume on serial CMRI scans and (2) identify the risk factors for rapid progression of RV enlargement. Methods: A retrospective study of adults with postintervention native valve PR and ≥2 CMRI scans at Mayo Clinic Rochester from 2000 to 2015 was conducted. Rapid progression of RV enlargement was defined as first upper quartile of annual increase in RV end-diastolic volume index (RVEDVi) for the cohort. Results: Of the 63 patients (age, 36 ± 9 years) in the study, 43 (68%) had tetralogy of Fallot, whereas 20 (32%) had valvular pulmonic stenosis. Right ventricular outflow tract interventions that resulted in PR were balloon pulmonary valvuloplasty (n = 4; 7%), transannular patch repair (n = 30; 58%), and nontransannular patch repair (n = 18; 35%). Interval between baseline and second CMRI was 2 (1-4) years. In comparison to baseline CMRI, RVEDVi increased from 130 (109-141) to 135 (126-155) mL/m ² and median annual change in RVEDVi was 3.1 (1.7-5.9) mL/m ² . Univariate risk factors for rapid progression of RV enlargement (annual increase in RVEDVi >6 mL/m ² ) were ≥moderate tricuspid regurgitation and RVEDVi >130 mL/m ² . Among the 24 patients without these risk factors (low-risk subgroup), RVEDVi increased by only 3 (0-7) mL/m ² over 7 (5-9) years. Conclusions: Patients with PR without RVEDVi >130 mL/m ² and/or ≥moderate tricuspid regurgitation represent a low-risk subgroup that may be appropriate for clinical and echo follow-up but may potentially require infrequent CMRI follow-up.