Role of QRS fragmentation for risk stratification in adults with tetralogy of fallot

Background-Patients with tetralogy of Fallot (TOF) remain at risk for cardiovascular events despite successful repair. Some of the current risk stratification tools require advanced imaging and invasive studies, and hence are difficult to apply to routine patient care. A recent study showed that QRS fragmentation (QRS-f) is predictive of mortality in patients with TOF. The current study aims to validate this result by assessing whether severity of QRS-f could predict all-cause mortality in a different TOF population. Methods and Results-The authors reviewed the Mayo Adult Congenital Heart Disease database for patients with TOF who had ECG from 1990-2017. QRS-f was defined as notches in QRS complex in ≥2 contiguous leads on ECG, not related to bundle branch block, and classified as none, mild (≤3 leads), moderate (4 leads), or severe (≥5 leads). Of 465 patients (age 37±14 years) in the study, QRS-f was present in 161 (35%): mild (n=43, 9%), moderate (n=77, 17%), and severe (n=41, 9%). There were 55 deaths (12%) during 13.6±8.2 years of follow-up. Severity of QRS-f remained an independent predictor of all-cause mortality after adjustment for other ECG parameters, patient demographics, and atrial and ventricular arrhythmia (hazard ratio, 1.74 per class; 95% confidence interval, 1.08-2.93 [P=0.041]). Conclusions-The presence of severe QRS-f may be used as complementary data to the usual clinical indices to determine whether interventions such as invasive electrophysiology study should be performed in patients with nonsustained ventricular tachycardia or to proceed with pulmonary valve replacement in patients with severe pulmonary regurgitation with ventricular volumes below the guideline-directed threshold for intervention.