Abstract 13327: Prediction of Upcoming Therapeutic Episodes of ICD Through Routine Data in Routine Device Clinic of ICD Patients

Background: Although implantable cardioverter-defibrillator (ICD) prevents sudden death of patients with life-threatening arrhythmia, prediction of upcoming ICD therapy, if possible, would be an important issue in device management. In the present study, the relationship between ICD therapeutic episodes and preceding routine device data was evaluated to clarify the predictors for ICD actuation in near future. Methods: The study population consisted of 100 consecutive ICD patients. All patients were followed up in the device clinic in every 4-month period, and their total follow-up periods of 22.8±4.1 months were divided into 734 4-month observation windows. The common data in device clinic including 12-lead ECG, chest X-ray, and interrogated device data were compared between patients with and without ICD therapeutic episodes during upcoming 4-month windows. To avoid inappropriate weighting on data of specific cases, such as unusual data in cases with frequent shock therapy, sampling number was limited 4-8 times in one case, and all data were evaluated as change during preceding 4 months, e.g., QTc calculated by subtracting 4 month preceding QTc from the recent QTc. Results: During 3.2±1.3 month follow-up, among 734 observation windows, appropriate and inappropriate ICD therapies appeared in 54 (ATP: 29, shock: 25) and 20 (ATP: 11, shock: 9) windows. When the patients were divided into spontaneous rhythm and paced-rhythm groups (n=558 and 170), spontaneous rhythm group did not show any significant difference in parameters between the windows with and without therapeutic episodes. In contrast in paced-rhythm group, RV lead impedance was significantly lower in the windows with therapeutic episodes in comparison with those without (-19.8±43.5Ω vs. 7.4±44.7Ω, p=0.047). Conclusions: Upcoming ICD therapy in near future might be able to be predicted by change in RV lead impedance at least in cases with paced-rhythm in ICD patients. It might reflect the electrical instability in cases with ICD therapeutic episodes.