Double-Layer Separate Ventricular Activation Patterns During Ventricular Tachycardia Associated With Myocarditis

A 62-year-old woman with a history of myocarditis developed a sustained ventricular tachycardia (VT) refractory to amiodarone. A transthoracic echocardiogram revealed that the left ventricle (LV) was severely dilated with a normal LV wall thickness and LV ejection fraction of u003c25%. She underwent an electrophysiological study and catheter ablation of VT. The VT exhibited a right bundle branch block and right inferior-axis QRS morphology with a cycle length of 540 ms (Figure 1). It was noted that there was a QS pattern in leads I and aVL and the QRS duration was 240 ms, suggesting an epicardial VT origin. Activation mapping during the VT was performed in the LV with a 7.5F, 3.5-mm tip irrigated ablation catheter (Navistar ThermoCool, Biosense Webster, Diamond Bar, CA), revealing a centrifugal activation pattern from the midlateral LV wall where a far-field ventricular prepotential …