Fragmented QRS complexes predict right ventricular dysfunction and outflow tract aneurysms in patients with repaired tetralogy of Fallot

Background: Fragmented QRS complexes (fQRS) correlate with myocardial scar, and may predict arrhythmias in patients with repaired tetralogy of Fallot (TOF). We investigated the relationship between fQRS in operated TOF patients with right ventricular (RV) dysfunction and RV outflow tract (RVOT) aneurysm.

Methods: We studied 56 operated TOF patients with moderate/severe pulmonary regurgitation, referred for cardiac magnetic resonance imaging (MRI) over a 4.5 year period. The presence of fQRS (additional notches in the R/S wave in ≥ 2 contiguous leads on the ECG) was correlated with MRI findings.

Results: fQRS was observed in 44 (78.6%) patients. Patients with fQRS had significantly larger RV end diastolic volume index (RVEDVi; 162 ml vs 141 ml, p=0.028) and RV end systolic volume index (RVESVi; 88 ml vs 70 ml, p=0.031). Increasing number of leads with fragmentation was independently associated with increasingly lower RV ejection fraction (adjusted co-efficient -0.97, 95%CI -1.83 to -0.12, p=0.026), greater pulmonary regurgitation fraction (1.65, 0.28 to 3.01, p=0.019), larger RVEDVi (6.78, 2.00 to 11.56, p=0.006) and RVESVi (5.41, 1.66 to 9.15, p=0.005). Anterior fragmentation correlated most significantly with RV dysfunction (p<0.05). fQRS had no significant association with LV dysfunction. Presence of any fQRS (OR 17.5, 95%CI 2.1-147.8, p=0.009) and inferior fQRS (OR 9.0, 95%CI 2.7-30.1, p<0.001) were found to be significant predictors for RVOT aneurysm.

Conclusions: The presence of fQRS on the ECG is significantly associated with RV dysfunction and RVOT aneurysms in repaired TOF patients. Increasing burden of fragmentation, especially in the anterior leads, is associated with increasing RV dysfunction.