The implantable loop recorder (ILR), also known as insertable cardiac monitor (ICM) is a subcutaneous device used for diagnosing heart rhythm disorders. These devices have been strongly improved and miniaturized during the last years showing several reliable features along with the availability of remote monitoring which improves the diagnostic timing and the follow‐up strategy with a potential reduction of costs for health care. The recent advent of injectable ILRs makes the procedure even easier and more tolerated by patients. ILR allows the investigation of unexplained recurrent syncope with uncertain diagnosis, revealing a possible relationship with cardiac arrhythmias. In addition, it has recently been equipped with sophisticated algorithms able to detect atrial fibrillation episodes. This new opportunity may provide to the physicians systematic heart rhythm screening with possible effects on patient antiarrhythmic and anticoagulant therapy management. The use of such devices will surely increase, since they may be helpful to diagnose a wide range of disorders and pathologies. Indeed, further studies should be performed in order to identify all the potentialities of these tools.
19 November 2021 in Journal of Cardiovascular Electrophysiology
Introduction: Implantable cardiac monitors (ICMs) provide long-term arrhythmia monitoring, but high rates of false detections increase the review burden. The new “SmartECG” algorithm filters false detections. Using large real-world data sets, we aimed to quantify the reduction in workload and any loss in sensitivity from this new algorithm.Methods: Patients with a BioMonitor IIIm and any device indication were included from three clinical projects. All subcutaneous ECGs (sECGs) transmitted via remote monitoring were classified by the algorithm as “true” or “false.” We quantified the relative reduction in workload assuming “false” sECGs were ignored. The remote monitoring workload from five hospitals with established remote monitoring routines was evaluated. Loss in sensitivity was estimated by testing a sample of 2000 sECGs against a clinical board of three physicians.Results: Of our population of 368 patients, 42% had an indication for syncope or pre-syncope and 31% for cryptogenic stroke. Within 418.5 patient-years of follow-up, 143,096 remote monitoring transmissions contained 61,517 sECGs. SmartECG filtered 42.8% of all sECGs as “false,” reducing the number per patient-year from 147 to 84. In five hospitals, nine trained reviewers inspected on average 105 sECGs per working hour. This results in an annual working time per patient of 83 min without SmartECG, and 48 min with SmartECG. The loss of sensitivity is estimated as 2.6%. In the majority of cases where true arrhythmias were rejected, SmartECG classified the same type of arrhythmia as “true” before or within 3 days of the falsely rejected sECG.Conclusion: SmartECG increases efficiency in long-term arrhythmia monitoring using ICMs. The reduction of workload by SmartECG is meaningful and the risk of missing a relevant arrhythmia due to incorrect filtering by the algorithm is limited.