Usefulness of electrocardiographic parameters for risk prediction in arrhythmogenic right ventricular dysplasia.
Ventricular arrhythmias due to ARVD and right ventricular outflow tract arrhythmia (RVOTA) share the same left bundle branch block pattern with inferior axis on the ECG. The former has a more malignant course while the latter has a better prognosis and is more amenable to radiofrequency catheter ablation. Hence differentiating them is of utmost clinical importance in the management of these patients. QRS notching has been mentioned to be one of the differentiating features. Ren L and associates  studied electrocardiographic differentiation of arrhythmias in ARVD from RVOTA and concluded that in addition to QRS notching in lateral leads, QRS duration in lead I of 125 milliseconds or more and a precordial R/S transition beyond V4 are useful in differentiation. The differences are thought to be due to the patchy fibrofatty replacement of myocardial tissue in ARVD which causes slow conduction, unlike in RVOTA with structurally normal heart. Authors claim better sensitivity and specificity by increasing the cutoff value for QRS widening from 120 milliseconds to 125 milliseconds. QRS notching probably has similar significance as fragmented QRS described by other authors  in different