This case report describes the electrophysiological findings of a 62-year-old patient with chronic Chagas' disease and two distinct morphologies of sustained ventricular tachycardia that involved a mitral isthmus. Multiple RF applications were necessary to obtain a bidirectional conduction block in the mitral isthmus that was related to the interruption of both tachycardias. After the procedure, the patient presented massive cerebral infarction that progressed to coma and death. Autopsy showed acute and old lesions at the mitral isthmus and recent mitral annulus thrombosis.