Background-Fragmented QRS complex (fQRS) on 12-lead ECG, a marker of myocardial scar, is a predictor of arrhythmic events in patients with ischemic and nonischemic cardiomyopathy. We investigated whether the presence of fQRS is associated with the severity of the anomaly and with increased arrhythmic events in adult patients with Ebstein anomaly (EA). Methods and Results-In 51 consecutive adult patients with EA (median age, 37 years; 18 males), the severity index of EA calculated from

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... graphic data and clinical arrhythmic events were analyzed. The extent of fQRS in each patient was measured by counting the number of ECG leads showing fQRS. There were 35 (68.6%) patients with fQRS (fQRS group) and 16 (31.4%) patients without fQRS (non-fQRS group). fQRS was observed more frequently in the inferior (n=26) and precordial (n=25) leads versus the lateral leads (n=5). The patients in the fQRS group had a worse functional class, greater cardiothoracic ratios, more severe tricuspid regurgitation, larger atrialized right ventricular areas, higher EA severity scores, and more frequent arrhythmic events compared with those in the non-fQRS group. The atrialized right ventricular area showed a positive correlation with the fQRS extent (r=0.51; P<0.001). In multivariable Cox regression models, the presence of fQRS was independently associated with arrhythmic events (P=0.036). Conclusions-Fragmented QRS on 12-lead ECG was associated with larger atrialized right ventricular area and an increased risk of arrhythmic events in adult patients with EA. (Circ Arrhythm Electrophysiol. 2013;6:1148-1155.) The online-only Data Supplement is available at http://circep.ahajournals.org/lookup/suppl/