Correlation Between Fragmented QRS and Ventricular Function from Cardiac Magnetic Resonance in Patients with Repaired Tetralogy of Fallot.

Fragmented QRS is an abnormal sign in an ECG resulting from ventricular dyssynchrony. The presence of fragmented QRS (fQRS) is related to mortality in patients with repaired tetralogy of Fallot (rTOF). This study aimed to analyze the correlations between fQRS and ventricular function parameters from cardiac magnetic resonance (CMR) images. A total of 54 patients with rTOF or repaired DORV, TOF type who had been investigated by CMR at Songklanagarind Hospital from January 2012 to August 2019 were retrospectively reviewed. Most of the patients (47 patients, 87%) were diagnosed with TOF and most of these (57.4%) were treated with a transannular patch (TAP) on the right ventricular outflow tract (RVOT). Forty-four patients (81%) had fQRS. The median time interval between EKG and CMR was 4.2 months (IQR 1.1, 6.9). Patients with fQRS had significantly higher RVEDVi (145.6 [IQR 121.1, 173.1) vs. 115.9 [IQR 96.2, 146.9] mL/m, p = 0.037), higher RVESVi (82.5 [IQR 62.9, 100.8] vs. 58.6 [IQR 46, 77.2] mL/m, p = 0.032) and higher RVEDV/LVEDV ratio [1.6 (IQR 1.4, 1.9) vs. 1.4 (IQR 1.3, 1.5), p = 0.026]. The extent of fQRS was significantly associated with an increase in RVEDVi (r = 0.39, p = 0.004) and RVESVi (r = 0.45, p < 0.001) but a decrease in RVEF (r =  - 0.37, p = 0.006). Fragmented QRS had higher sensitivity and lower specificity than prolonged QRS duration (≥ 160 ms) to predict all of the parameters indicating pulmonary valve replacement (PVR). Patients with rTOF who had fQRS were significantly associated with RV dilatation. The extent of fQRS had only low to moderate correlation with right ventricular parameters (RVEDVi, RVESVi and RVEF). Fragmented QRS could be used for early detection of RV dilatation and the need for PVR in patients with rTOF.