A method and device for delivering a therapy in response to detection of abnormal cardiac rhythms that includes a first circuit delivering a first therapy and a second circuit delivering a second therapy, the second circuit including an energy storage device for storing energy associated with the second therapy and a charging circuit selectively coupled to the storage device to generate the stored energy. A control circuit controls the first circuit and the second circuit to deliver the first therapy substantially simultaneous with the charging of the energy storage device in response to the predetermined event being detected, and decouples the energy storage device from the charging circuit during a redetect period subsequent to delivery of the first therapy. The control circuit recouples the energy storage device and the charging circuit in response to the microprocessor detecting the predetermined event during the redetect period.