Potential of remote monitoring to prevent sensing and detection failures in implantable cardioverter defibrillators

Background Sensing malfunction and misinterpretation of intracardiac electrograms (IEGMs) in patients with implantable cardioverter defibrillators (ICDs) may lead to inadequate device activity such as inappropriate shock delivery or unnecessary mode-switching. Remote monitoring has the potential for early detection of sensing malfunction or misclassification and may thus prevent adverse device activity. Therefore, the authors analyzed the amount, nature, and distribution of misclassification in current ICD and cardiac resynchronization therapy defibrillator technology using the device transmissions of the IN-TIME study population. Methods All transmitted tachyarrhythmic episodes in the 664 IN-TIME patients, comprising 2214 device-classified atrial fibrillation (DC-AF) episodes lasting ≥ 30 s and 1330 device-classified ventricular tachycardia or fibrillation (DC-VT/VF) episodes, were manually analyzed by two experienced cardiologists. Results After evaluation of all DC-VT/VF episodes, a total of 300 VT/VF events (23.1%) were false-positive, with supraventricular tachycardia being the most frequent cause (51.7%), followed by atrial fibrillation (21.3%) and T‑wave oversensing (21.0%). A total of 15 patients with false-positive DC-VT/VF received inappropriate shocks. According to the inclusion criteria, 616 IEGMs with DC-AF were assessed. A total of 19.7% were false-positive AF episodes and R‑wave oversensing was the most common reason (55.9%). Conclusions Remote monitoring offers the opportunity of early detection of signal misclassification and thus early prevention of adverse device reaction, such as inappropriate shock delivery or mode-switching with intermittent loss of atrioventricular synchrony, by correcting the underlying causes.