Abstract 10532: Physician Interpretation and Characterization of Intracardiac Electrograms at the Time of Non-Cardiac Death

Abstract

Introduction: Electrograms (EGMs) generated by implantable cardiac devices at the time of non-cardiac death may have artifact from non-arrhythmic sources, such as coagulated blood and air bubbles. While few studies have described the nature of terminal EGMs in non-cardiac death, it is clinically and medicolegally important to characterize these EGMs to elucidate events that may otherwise be misinterpreted as device failure. Here we investigated terminal EGM features that may aid clinicians in discerning cardiac from non-cardiac death. Methods: Terminal EGMs were analyzed by independent physician reviewers. Deaths were adjudicated as non-cardiac based on direct clinical data at the time of death using a modified Cardiac Arrhythmia Suppression Trial approach. In total, 16 non-cardiac terminal EGMs were identified and compared to a control cohort of true arrhythmic events. Using a subset of identified EGMs, an 8-question survey was administered to electrophysiologists blinded to cause of death. Several variables were identified as important for the correct classification of EGMs. The statistical performance of each variable for detecting non-cardiac death and true arrhythmias in our sample was evaluated. These results were shared, and the survey was readministered. Results: In our sample, absence of organized atrial activity had a sensitivity (SN) of 78.5%, specificity (SP) of 100%, and positive predictive value (PPV) of 100% for non-cardiac terminal EGMs. Cycle length <130 ms and absence of discernible deflections both had SPs and PPVs of 100% for non-cardiac death but were less sensitive (60% and 20%, respectively). An abrupt change following therapy and response to therapy both had SNs, SPs, and PPVs of 100% for true arrhythmias. Survey response rate was 68.8% and 62.5% for the pre- and post-survey, respectively. Pre-survey scores ranged from 50 – 87.5% correct with a mean of 72.7%. Post-survey scores ranged from 75 – 100% with a mean of 86.3% (p< 0.01). Conclusions: There is variability and inaccuracy among expert physicians' interpretation of EGMs during non-cardiac death. The variables identified in this study will aid in the development of a clinical risk score used to discern non-cardiac death and true device malfunction based on terminal EGMs.