Transtelephonic Monitoring and Transmission of Stored Arrhythmia Detection and Therapy Data From an Implantable Cardioverter Defibrillator

A new transtelephonic monitoring device designed for use with implantable Cardioverter defibrillators (ICDs) was evaluated. It is capable of interrogating ICDs and transmitting the following data via telephone: programmed parameters (e.g., ventricular tachycardia [VT] and ventricular fibrillation [VF] detection, therapies), number of VT and VF episodes, identification of successful therapies, the 20 cycle lengths preceding the last episode detected, the 10 cycle lengths after the last delivered therapy, battery voltage, and real‐time transmission of the patient's rhythm. Eighteen patients (mean age 64 ± 17years; 15 males) were implanted with an ICD and epicardial lead system. The patients who did not live near the primary hospital were provided with this transmitter and instructed to transmit monthly and whenever presyncope, syncope, or a shock were experienced. Five hundred ten episodes of spontaneous arrhythmia (495 VT, 15 VF) were detected in 14 of 18 patients in a 24‐month period and the success of each therapy (antitachycardia pacing, cardioversion 0.4‐34 J, defibrillation 34 J) was analyzed. The number of therapies delivered and their success (%) in terminating the arrhythmia were: 380 ramp/86%, 116 burst/84%, 119 cardioversion/57%, and 15 defibrillations/ 100%. Sixty‐three (42%) of the 152 transmissions indicated an arrhythmia. Twenty‐five (16%) of the 152 were transmitted because of symptoms. Sixteen (9.7%) of 165 VT episodes could not be terminated by the full set of programmed VT therapies. Analysis of the pre‐ and post‐episode intervals along with the patient's transmitted rhythm indicated that sinus tachycardia or atrial fibrillation were likely responsible for these episodes. The transmitted data included the real‐time ECG, which provided acute rhythm status plus stored data from the ICDs memory identifying the chronic arrhythmias detected, the therapies delivered, and the number and type of successful and ineffective therapies. This information provided the clinical data to the primary physician in order to determine the effectiveness of the programmed detection and therapy parameters and in some cases recommend to the home physician modifications to the device parameters or medication adjustments for enhanced arrhythmia control. We conclude that telephone transmission of stored ICD data is feasible and useful for patient management. It may obviate the need for patients experiencing symptoms to return to a site capable of device interrogation.