Abstract
BACKGROUND: Cardiac magnetic resonance (CMR) is the gold standard for assessing right ventricular (RV) function in repaired tetralogy of Fallot (rTOF), but it is expensive and not always available. ECG is a cost-effective, accessible alternative. This study evaluated ECG parameters, specifically QRS duration (QRSd) and QRS fragmentation (QRSf), to predict RV volumes and function, and developed a new score to guide CMR timing. METHODS: We retrospectively analysed 147 patients with rTOF with pulmonary regurgitation. ECG, echocardiographic and CMR data were collected. Receiver operating characteristic curves identified optimal cut-offs for predicting RV dysfunction and dilation. Logistic regression was used to determine predictors of RV dysfunction and dilation. RESULTS: QRSd showed moderate positive correlations with RV end-diastolic (EDVi) and end-systolic (ESVi) volume indices and negative correlations with RV ejection fraction (EF) and global radial strain. QRSf was associated with larger RVESVi and lower RVEF. We propose a simple risk score of age ≤20 years, QRSd≥160 ms, QRSf and transannular patch repair. A score >2.5 out of 5.5 predicted RVEDVi ≥150 mL/m(2) with 76.5% sensitivity and 63.6% specificity. CONCLUSIONS: This study highlights the value of ECG, particularly QRSd≥160 ms and QRSf, in predicting RV dilation in rTOF. The proposed score, based on clinical data and ECG parameters, offers a practical tool for guiding the timing of CMR.