A method and system for treating ventricular tachycardia (VT) by ablating scarred myocardial tissue containing a reentrant VT circuit. The method generally includes measuring electrical activity at a plurality of sites within a heart, identifying an area of scarred myocardial tissue based at least in part on the electrical activity measurements, and ablating substantially all of the scarred area. The system generally includes a medical device having a distal end, a plurality of electrical conduction sensors coupled to the distal end, and a console in communication with the distal end of the device, the console including a computer with display. The computer may be programmed to identify optimal ablation sites within a target tissue and the location of an isthmus associated with a reentrant VT circuit within a target tissue, the identifications being based at least in part on the measurements of the electrical conduction sensors.
