A method and system is provided for responding, from internally within a patient, to an atrial arrhythmia in a heart including measuring from within the patient at least one electrocardiogram characteristic indicative of the atrial arrhythmia, and controlling from within the patient drug therapy delivery to the patient responsive to measuring the at least one electrocardiogram characteristic. Drug therapy is initiated to the patient responsive to measuring the at least one electrocardiogram characteristic. According to one aspect of the present invention, the drug therapy is staged within the patient prior to measuring the at least one electrocardiogram characteristic. According to another example embodiment, the heart is paced from within the patient at a predefined rate responsive to measuring the at least one electrocardiogram characteristic, pacing occurring alone, or in combination with drug therapy.