Ventricular tachycardia with a myocardial fibre travelling from the origin in the right aortic sinus cusp to the epicardial breakout site of the right ventricular outflow tract.

A 74-year-old man with idiopathic ventricular tachycardia (VT) with a QRS morphology with a left bundle branch block and right inferior axis underwent electrophysiologic testing. Successful ablation was achieved at the right coronary cusp (RCC) where an excellent pace map with long stimulus-to-QRS interval (St-QRS) (85 ms) was obtained. An excellent pace map was also obtained on the epicardial surface approximately 1 cm away from the successful ablation site and the St-QRS was shorter (40 ms). These findings suggested that a myocardial fibre travelling from the origin in the RCC to the epicardium of the right ventricular outflow tract might exist.