A patients response to anti-arrhythmic drug changes can be monitored using cardiac activity information, such as using cardiac electromechanical time intervals adjusted for heart rate. A cardiac electromechanical time interval can include an R-S2 interval or an S2-R interval. Tracking changes in cardiac electromechanical time intervals adjusted for heart rate can be used to provide information about a patient, including anti-arrhythmic drug effect information and patient condition information.
