Programming Optimization in Implantable Cardiac Monitors to Reduce False-Positive Arrhythmia Alerts: A Call for Research

False-positive alarms in patients with implantable loop recorder followed by remote monitoring: A systematic review

Remote Monitoring (RM) has been shown to provide useful information about arrhythmic events in patients with implantable loop recorders (ILRs), however there is few and conflicting data about the false positive (FP) alarms burden and characteristics among ILR recipients. The aim of the present systematic review was to evaluate incidence and characteristics of FP alarms among ILR patients followed by RM. We developed a systematic research in Embase, MEDLINE and PubMed databases and selected all papers focused on false positive ILR transmissions published from June 1, 2013 to June 1, 2023. Case reports, meeting summaries, posters and simple reviews were excluded. Twelve reports were finally selected, including five prospective and seven retrospective studies. Information about population characteristics, device type and setting, overall transmissions and FP alarms and any adopted strategies to reduce them were extracted from an overall population of 3.305 patients. FP alarms were 59.7% of the overall remote transmissions and were found in 1/5 of the analyzed population. FP alarms for atrial fibrillation were the most common cause of false transmissions and were mainly due to premature atrial and ventricular complexes. No clinical predictors of FP alarms were identified, except for nonparasternal ILR implantation site. Since the overload work due to FP alarms might reduce the benefit of remote monitoring of ILR patients, the device optimization is an important step until an help from machine-learning algorithms is available.

A case report of undetected cardiac arrest in a patient with an insertable cardiac monitor

Insertable cardiac monitors (ICMs) are small electrocardiographs implanted subcutaneously to automatically record electrocardiograms when arrhythmia is detected in patients with syncope. If the ICM misses a significant arrhythmia, it may delay the diagnosis of arrhythmogenic syncope and put the patient at risk. Herein, we describe a case of undetected cardiac arrest in a patient with ICM. An 87-year-old man with syncope was admitted to the hospital. After 8 days of monitoring, the cause could not be determined, and an ICM was implanted. Nine hours after implantation, the patient experienced cardiopulmonary arrest. Despite a body surface electrocardiogram showing ventricular flatline and fibrillation, the ICM failed to record. The cause of failure to record was considered to be the fluctuation in the R-wave amplitude of the ICM and noise oversensing. In conclusion, albeit infrequently, ICMs might overlook life-threatening arrhythmias. Even in cases where the ICM fails to detect an arrhythmia matching the symptoms, it may not be feasible to entirely rule out the presence of arrhythmias.

Learning objective

Insertable cardiac monitors (ICMs) are used to diagnose arrhythmogenic syncope. However, extremely infrequently, ICM may fail to record life-threatening arrhythmias. Failure to capture arrhythmias can happen due to an unfortunate combination of factors such as a low amplitude of the recorded R wave and noise. Even in cases where the ICM does not detect an arrhythmia that matches the symptoms, it may not be feasible to completely exclude the presence of arrhythmias.

Strategic reprogramming of implantable cardiac monitors reduces the false-positive remote alert burden in a nurse-led service

AIMS

Implantable cardiac monitors (ICMs) can generate false-positive (FP) alerts. Although these devices have an extended programmability, there are no recommendations on their optimization to reduce not-relevant activations.We tested a strategic programming optimization guide based on the type of FP and investigated the safety and feasibility of the nurse-led insertion of ICMs with a long-sensing vector.

METHODS AND RESULTS

Consecutive patients implanted by trained nurses with long-sensing vector ICM were enrolled in a 1-month observational stage (Phase A). Patients who had ≥10 FP episodes underwent ICM reprogramming based on the predefined guide and were followed for an additional month (Phase B). A total of 78 patients had successful ICM insertion by nurses with a mean R wave amplitude of 0.96 ± 0.43 mV and an 86% P wave visibility. Only one patient reported a significant device-related issue, and nurse-delivered ICM was generally well accepted by the patients. During Phase A, 11 patients (14%) generated most of FP (3,627/3,849; 94%) and underwent ICM reprogramming. In the following month (Phase B), five patients (45%) were free from FP and six (55%) transmitted 57 FP alerts (98% reduction compared with Phase A). The median number of FP per patient was significantly reduced after reprogramming [195 (interquartile range, 50-311) vs. one (0-10), P = 0.0002].

CONCLUSION

A strategic reprogramming of ICM in those patients with a high FP alert burden reduces the volume of erroneous activations with potential benefits for the remote monitoring service. No concerns were raised regarding nurse-led insertion of ICMs with a long-sensing vector.

Daily and automatic remote monitoring of implantable cardiac monitors: A descriptive analysis of transmitted episodes

BACKGROUND

Remote Monitoring (RM) is recognized for its ability to enhance the clinical management of patients with implantable cardiac monitor (ICM). This study aims to provide a comprehensive description of the arrhythmic episodes transmitted by a daily and automatic RM system from a cohort of ICM patients.

METHODS

The study retrospectively analyzed daily transmissions from consecutive patients who had been implanted with a long-sensing vector ICM (BIOMONITOR III/IIIm) at four sites. All transmitted arrhythmic recordings were evaluated to determine whether they were true positive episodes or false positives (FP).

RESULTS

A total of 14,136 episodes were transmitted from 119 patients (74.8% male, median age 62 years old) during a median follow-up of 371 days. The rate of arrhythmic episodes was 14.2 per patient-year (interquartile range: 1.8-126), with 97 patients (81.5%) experiencing at least one ICM activation. Fifty-five percent of episodes were identified as FP, and 67 patients (56.3%) had at least one inappropriate activation. The FP rate was 1.4 per patient-year (0-40). The best per-episode predictive positive values were observed for bradycardia and atrial fibrillation (0.595 and 0.553, respectively). Notably, the implementation of an algorithm designed to minimize false detections significantly reduced the prevalence of atrial fibrillation FP episodes (17.6% vs. 43.5%, p = 0.008).

CONCLUSION

Daily and automatic RM appears to be a reliable tool for the comprehensive remote management of ICM patients. However, the number of arrhythmic episodes requiring review is high, and further improvements are needed to reduce FP and facilitate accurate interpretation of transmissions.

Strain Imaging and Ventricular Arrhythmia

Ventricular arrhythmia is one of the main causes of sudden cardiac death. Hence, identifying patients at risk of ventricular arrhythmias and sudden cardiac death is important but can be challenging. The indication for an implantable cardioverter defibrillator as a primary preventive strategy relies on the left ventricular ejection fraction as a measure of systolic function. However, ejection fraction is flawed by technical constraints and is an indirect measure of systolic function. There has, therefore, been an incentive to identify other markers to optimize the risk prediction of malignant arrhythmias to select proper candidates who could benefit from an implantable cardioverter defibrillator. Speckle-tracking echocardiography allows for a detailed assessment of cardiac mechanics, and strain imaging has repeatedly been shown to be a sensitive technique to identify systolic dysfunction unrecognized by ejection fraction. Several strain measures, including global longitudinal strain, regional strain, and mechanical dispersion, have consequently been proposed as potential markers of ventricular arrhythmias. In this review, we will provide an overview of the potential use of different strain measures in the context of ventricular arrhythmias.