Importance of Raw-Data Analysis When Determining the Cause of Pause Alerts Transmitted by an Implantable Loop...

Use of implantable loop recorder (ILR) for the diagnosis and documentation of cardiac arrhythmia has gained popularity during the last decade. Most ILRs are accompanied by remote monitoring (RM) devices, which allow automated daily interrogations of the ILR. These transmit arrhythmic or pause alerts to the treating clinic, enabling timely medical attention and treatment. Although ILR RM transmissions have been shown to have significant false positive alerts, a true positive alert suggesting a wrong arrhythmia diagnosis has not been shown to date.

We revised all ILR pause transmissions arriving to our hospital device clinic during 2024, looking for pause alerts which were initially misdiagnosed. We report a case series of patients in whom a RM pause alert has been transmitted with a suspected apparent diagnosis of sinus arrest. However, when interrogating the ILR in clinic, these episodes were diagnosed as high-degree atrioventricular block (AVB) pauses, for which an urgent permanent pacemaker (PPM) might be indicated. Review of these cases revealed that in contrast with the automated RM PDF alerts, in which the figure resolution cannot be changed (and thus small P waves may be unnoticed), the raw-data episode recording on the RM web page enables one to increase the image resolution to clearly discern initially unnoticed non-conducted P waves.

ILR RM pause alerts should always be reviewed via the raw-data RM web page or alternatively via ILR device interrogations, to achieve a sufficiently high-resolution image to assure these pauses are not due to AVB.