Catheter ablation of mitral isthmus ventricular tachycardia using electroanatomically guided linear lesions

Mitral isthmus ventricular tachycardia uses a reentrant circuit with a critical isthmus of conduction bounded by the mitral valve proximally and a remote inferior infarction scar distally. Successful catheter ablation requires placement of a lesion to transect the isthmus so as to prevent wavefront propagation. We report a case with previously unsuccessful ablation in which focal isthmus ablation failed to eliminate arrhythmia. Electroanatomic mapping demonstrated a wide tachycardia isthmus, and a linear lesion placed from the edge of the inferior infarct (as demonstrated on the three-dimensional voltage electroanatomic map) to the base of the mitral valve successfully eliminated tachycardia. In some patients with mitral isthmus VT, a wide isthmus requires linear lesion placement to fully transect the isthmus and eliminate tachycardia. Electroanatomic mapping can be used to define isthmus boundaries and thus guide successful ablation.