Remote electrocardiographic monitoring with a wireless implantable loop recorder: Minimizing the data review burden

Introduction: Currently available implantable loop recorders (ILRs) are hampered by limited memory, sensing artifacts, and need for manual memory download. Remote monitoring techniques that automatically transfer stored recordings for review may enhance ILR utility. However, automatic electrocardiograph (ECG) detection and transmission of an excessive number of tracings directly to physicians may be burdensome. This pilot study assessed the utility of direct ILR transmission to a central ECG monitoring center on the burden of data to be reviewed by the physician. Methods: Patients with unexplained syncope were implanted with a novel ILR with automatic (i.e., independent of patient intervention) wireless telemetry download. Transmitted recordings underwent a two-step review process: initial algorithmic filtering followed by human overread at a monitoring center using predefined criteria. Results: Forty patients were enrolled and followed for 8.5 ± 5.1 months. A total of 223,226 ECG recordings were transmitted to the monitoring center (on average 660 per patient per month). Algorithmic filtering eliminated 191,305 ECGs as artifact (89%), with monitoring center overread of 31,921 strips. Ultimately, 117 relevant ECGs were selected for further evaluation by the physician (0.0053%). One or more relevant ECGs were identified for 20 patients (50%). Conclusions: Automatic ILR recording and wireless technique is feasible for remote ECG monitoring by ILRs. However, sensitive criteria for recording and transmission may result in an excessive ECG burden. The two-step screening process in this pilot study minimized physician overread time while providing clinically relevant recordings in a substantial proportion of patients.