Factors associated with progression of right ventricular enlargement and dysfunction after repair of tetralogy of Fallot based on serial cardiac magnetic resonance imaging

OBJECTIVES: Although progressive right ventricular (RV) enlargement (RVE) is common in patients with pulmonary regurgitation after tetralogy of Fallot (TOF) repair, the rate of RVE and progression of RV dysfunction varies among patients. The present study aimed to investigate the independent predictors of rapid RVE and RV dysfunction after the repair of TOF, using serial cardiac magnetic resonance imaging (MRI). METHODS: The study included consecutive patients who underwent serial cardiac MRI more than twice between January 2005 and March 2015 after the repair of TOF. Patients who underwent surgical pulmonary valve implantation or any transcatheter cardiac intervention between two consecutive MRI assessments were excluded. The study patients were divided into rapid RVE and non-rapid RVE groups according to the rate of RVE. The upper first quartile of the patients was considered to have rapid RV dilatation (defined as rapid RVE group). Remaining patients in other three quartiles were included in the non-rapid RVE group. Additionally, the study patients were divided into rapid right ventricular ejection fraction (RVEF) change and non-rapid RVEF change groups according to the rate of change in the RVEF. The groups were compared, and multiple logistic regression analyses were performed to identify the independent risk factors for rapid RVE and RV dysfunction. RESULTS: The study included 116 patients. The mean number of cardiac MRI assessments performed in each patient was 2.8 ± 0.8. The time to the initial MRI assessment after TOF repair was 14.2 ± 10.3 years, and the interval between the initial and last MRI assessments was 4.5 ± 2.2 years. The mean right ventricular end-diastolic volume index (RVEDVi) change rate was 2.7 ± 6.1 ml/m(2)/year. The initial RVEDVi was not different between the rapid RVE and non-rapid RVE groups. Restrictive RV physiology was an independent risk factor for rapid RVE (odds ratio, 3.64; 95% confidence interval, 1.263-10.494; P = 0.02), and a previous palliative shunt procedure was a negative predictor for rapid RVE (odds ratio, 0.08; 95% confidence interval, 0.010-0.778; P = 0.03). We did not find any predictive factors for rapid RV dysfunction. CONCLUSIONS: In patients with rapid RV dilatation, restrictive RV physiology might be frequently noted at the initial MRI assessment. Therefore, careful follow-up may be necessary in patients with restrictive RV physiology to determine the optimal timing of pulmonary valve implantation.