Ablation of epicardial macroreentrant ventricular tachycardia associated with idiopathic nonischemic dilated cardiomyopathy by a percutaneous transthoracic approach.

Characterization of the substrate and mechanism of epicardial ventricular tachycardia (VT) associated with idiopathic nonischemic dilated cardiomyopathy is limited. We report a case of successful mapping and ablation of an epicardial VT by a percutaneous transthoracic approach in a patient with idiopathic dilated cardiomyopathy, frequent VT, and previously unsuccessful endocardial ablation. Evidence of myocardial scar was limited to the epicardium. Electroanatomic and entrainment mapping defined a figure-of-eight macroreentrant circuit within the epicardial scar. VT terminated at the onset of low-power radiofrequency application to the central isthmus of the circuit. VT was no longer induced and did not recur during long-term follow-up.