Backgrounds: Adults with repaired tetralogy of Fallot (TOF) are well-known high risk group of ventricular tachycardia (VT), which is related to surgical scars on right ventricular (RV) outflow tract area. Fragmented QRS complex (f-QRS) on standard 12-lead ECG is reported to represent myocardial scarin patients with myocardial infarction.

Methods: We assessed whether f-QRS was associated with cardiac magnetic resonance late gadolinium enhancement(CMR-LGE) or RV dysfunction in consecutive 49 adults with repaired TOF (mean 30.3 with range 15.8-66.4 years old, operation to CMR time=26짹8years). A patient was considered as having f-QRS if >2 notches were found in the R or S wave of QRS complex among ���2 contiguous leads (Figure A). We measured the degree of RV LGE using a 6 segmentation model and linear extent of LGE was scored in each segment (0-3 per segment) and summed up (range 0-18).

Results: f-QRS complexes were mainly located in righ to mid precordial leads while RV LGE was usually detected on RVOT, patched VSD, and RV anterior segments, where the previous surgical procedure had been concentrated (figure B, C). Patients with f-QRS demonstrated significantly higher RV LGE score (median, interquartile ragne 2, 1-3 vs. 7, 5-8; p<0.01). The number of ECG leads with f-QRS showed a positive correlation with RV LGE score (r=0.43, p < 0.01). The presence of f-QRS complex was more closely associated with RV systolic dysfunction (35% vs. 42%, p=0.02) but not with left ventriclur dysfunctoin (53% vs. 54%, p=0.63).

Conclusions: There was a good electricopathologic concordance between fragmented QRS complex on 12-lead ECG and RV scarring suggested by CMR-LGE. f-QRS complex could be considered as a surrogate marker for surgical scars related to ventricular arrhythmia in repaired TOF.