A system for assessing risk associated with a suspected heart rhythm disorder includes at least one sensor for generating a signal received from a beating human heart over a plurality of time segments, and an analytic engine that receives the signal and calculates a change in the signal among at least a first time segment and a second time segment in response to a change in at least one of rate and regularity induced in the beating human heart. The analytic engine generates a risk score for the heart rhythm disorder based at least in part on the change in the signal. The system may further be configured to control modification of tissue of the beating human heart based on the risk score.
