A method for mapping an anatomical structure includes sensing activation signals of physiological activity with a plurality of electrodes disposed in or near the anatomical structure, each activation signal having an associated cycle length, estimating an action potential duration and diastolic interval for each cycle length, generating a restitution curve based on the estimated action potential duration and diastolic interval from a preceding cycle length, iteratively optimizing each estimated action potential duration and corresponding diastolic interval to maximize a functional relationship between the estimated action potential duration and estimated diastolic interval from preceding cycle length, and generating an action potential duration restitution curve based on the optimized action potential durations and diastolic intervals.