A method and system capable of identifying ectopic foci, rotors, or conduction pathways involved in reentrant arrhythmias within cardiac tissue, and then treating identified ectopic foci, rotors, and/or pathways with either lethal or sub-lethal temperatures. The system includes a medical device having one or more mapping elements and one or more treatment elements, and a computer programmable to identify ectopic foci and rotors based at least in part on signals received from the one or more mapping elements at one or more locations.