[Diagnostic and intervention value of implantable cardiac monitor in patients over 60 years of age with unexplained syncope].

Objective: To investigate the value of implantable cardiac monitor (ICM) in the diagnosis and treatment of patients over 60 years old with unexplained syncope. Methods: This was a multi-center, prospective cohort study. Between June 2018 and April 2021, patients over the age of 60 with unexplained syncope at Beijing Hospital, Fuwai Hospital, Beijing Anzhen Hospital and Puren Hospital were enrolled. Patients were divided into 2 groups based on their decision to receive ICM implantation (implantation group and conventional follow-up group). The endpoint was the recurrence of syncope and cardiogenic syncope as determined by positive cardiac arrhythmia events recorded at the ICM or diagnosed during routine follow-up. Kaplan-Meier survival analysis was used to compare the differences of cumulative diagnostic rate between the 2 groups. A multivariate Cox regression analysis was performed to determine independent predictors of diagnosis of cardiogenic syncope in patients with unexplained syncope. Results: A total of 198 patients with unexplained syncope, aged (72.9±8.25) years, were followed for 558.0 (296.0,877.0) d, including 98 males (49.5%). There were 100 (50.5%) patients in the implantation group and 98 (49.5%) in the conventional follow-up group. Compared with conventional follow-up group, patients in the implantation group were older, more likely to have comorbidities, had a higher proportion of first degree atrioventricular block indicated by baseline electrocardiogram, and had a lower body mass index (all P<0.05). During the follow-up period, positive cardiac arrhythmia events were recorded in 58 (58.0%) patients in the ICM group. The diagnosis rate (42.0% (42/100) vs. 4.1% (4/98), P<0.001) and the intervention rate (37.0% (37/100) vs. 2.0% (2/98), P<0.001) of cardiogenic syncope in the implantation group were higher than those in the conventional follow-up group (all P<0.001). Kaplan-Meier survival analysis showed that the cumulative diagnostic rate of cardiogenic syncope was significantly higher in the implantation group than in the traditional follow-up group (HR=11.66, 95%CI 6.49-20.98, log-rank P<0.001). Multivariate analysis indicated that ICM implantation, previous atrial fibrillation, diabetes mellitus or first degree atrioventricular block in baseline electrocardiogram were independent predictors for cardiogenic syncope (all P<0.05). Conclusions: ICM implantation improves the diagnosis and intervention rates in patients with unexplained syncope, and increases diagnostic efficiency in patients with unexplained syncope.

Validity of a smartwatch for detecting atrial fibrillation in patients after heart valve surgery: a prospective observational study.

OBJECTIVES: Atrial fibrillation (AF) is a common early arrhythmia after heart valve surgery that limits physical activity. We aimed to evaluate the criterion validity of the Apple Watch Series 5 single-lead electrocardiogram (ECG) for detecting AF in patients after heart valve surgery. DESIGN: We enrolled 105 patients from the University Hospital of North Norway, of whom 93 completed the study. All patients underwent single-lead ECG using the smartwatch three times or more daily on the second to third or third to fourth postoperative day. These results were compared with continuous 2-4 days ECG telemetry monitoring and a 12-lead ECG on the third postoperative day. RESULTS: On comparing the Apple Watch ECGs with the ECG monitoring, the sensitivity and specificity to detect AF were 91% (75, 100) and 96% (91, 99), respectively. The accuracy was 95% (91, 99). On comparing Apple Watch ECG with a 12-lead ECG, the sensitivity was 71% (62, 100) and the specificity was 92% (92, 100). CONCLUSION: The Apple smartwatch single-lead ECG has high sensitivity and specificity, and might be a useful tool for detecting AF in patients after heart valve surgery.

Comparison Between a Single-Lead ECG Garment Device and a Holter Monitor: A Signal Quality Assessment.

Wearable electronics are increasingly common and useful as health monitoring devices, many of which feature the ability to record a single-lead electrocardiogram (ECG). However, recording the ECG commonly requires the user to touch the device to complete the lead circuit, which prevents continuous data acquisition. An alternative approach to enable continuous monitoring without user initiation is to embed the leads in a garment. This study assessed ECG data obtained from the YouCare device (a novel sensorized garment) via comparison with a conventional Holter monitor. A cohort of thirty patients (age range: 20-82 years; 16 females and 14 males) were enrolled and monitored for twenty-four hours with both the YouCare device and a Holter monitor. ECG data from both devices were qualitatively assessed by a panel of three expert cardiologists and quantitatively analyzed using specialized software. Patients also responded to a survey about the comfort of the YouCare device as compared to the Holter monitor. The YouCare device was assessed to have 70% of its ECG signals as "Good", 12% as "Acceptable", and 18% as "Not Readable". The R-wave, independently recorded by the YouCare device and Holter monitor, were synchronized within measurement error during 99.4% of cardiac cycles. In addition, patients found the YouCare device more comfortable than the Holter monitor (comfortable 22 vs. 5 and uncomfortable 1 vs. 18, respectively). Therefore, the quality of ECG data collected from the garment-based device was comparable to a Holter monitor when the signal was sufficiently acquired, and the garment was also comfortable.

Effectiveness, utilisation and cost associated with implantable loop recorders versus external monitors after ischaemic or cryptogenic stroke.

OBJECTIVE: Implantable loop recorders (ILRs) are increasingly used for long-term rhythm monitoring after ischaemic and cryptogenic stroke, with the goal of detecting atrial fibrillation (AF) and subsequent initiation of oral anticoagulation to reduce risk of adverse clinical outcomes. There is a need to determine the effectiveness of different rhythm monitoring strategies in this context. METHODS: We conducted a retrospective cohort analysis of individuals with commercial and Medicare Advantage insurance in Optum Labs Data Warehouse who had incident ischaemic or cryptogenic stroke and no prior cardiovascular implantable electronic device from 1 January 2016 to 30 June 2021. Patients were stratified by rhythm monitoring strategy: ILR, long-term continuous external cardiac monitor (>48 hours to 30 days) or Holter monitor (≤48 hours). The primary outcome was risk-adjusted all-cause mortality at 12 months. Secondary outcomes included new diagnosis of AF and oral anticoagulation, bleeding, and costs. RESULTS: Among 48 901 patients with ischaemic or cryptogenic stroke, 9235 received an ILR, 29 103 long-term continuous external monitor and 10 563 Holter monitor only. Mean age was 69.9 (SD 11.9) years and 53.5% were female. During the 12-month follow-up period, patients who received ILRs compared with those who received long-term continuous external monitors had a higher odds of new diagnosis of AF and oral anticoagulant initiation (adjusted OR 2.27, 95% CI 2.09 to 2.48). Compared with patients who received long-term continuous external monitors, those who received ILRs had similar 12-month mortality (HR 1.00; 95% CI 0.89 to 1.12), with approximately $13 000 higher costs at baseline (including monitor cost) and $2500 higher costs during 12-month follow-up. CONCLUSIONS: In this large real-world study of patients with ischaemic or cryptogenic stroke, ILR placement resulted in more diagnosis of AF and initiation of oral anticoagulation, but no difference in mortality compared with long-term continuous external monitors.

Long-term continuous monitoring of arrhythmias in pigs with insertable cardiac monitors.

Arrhythmia detection is essential when assessing the safety of novel drugs and therapies in preclinical studies. Many short-term arrhythmia monitoring methods exist, including non-invasive ECG and Holter. However, there are no reliable, long-term, non-invasive, or minimally invasive methods for cardiac arrhythmia follow-up in large animals that allows free movement with littermates. A long follow-up time is needed when estimating the impact of long-lasting drugs or therapies, such as gene therapy. We evaluated the feasibility and performance of insertable cardiac monitors (ICMs) in pigs for minimally invasive, long-term monitoring of cardiac arrhythmias that allows free movement and species-specific behavior. Multiple implantation sites were tested to assess signal quality. ICMs recognized reliably many different arrhythmias but failed to detect single extrasystoles. They also over-diagnosed T-waves, resulting in oversensing. Muscle activity and natural startles of the animals caused noise, leading to a heterogeneous signal requiring post-recording evaluation. In spite of these shortcomings, the ICMs showed to be very useful for minimally invasive long-term monitoring of cardiac rhythm in pigs.

Wearable electrocardiogram devices in patients with congenital long QT syndrome: The SMART-QT study.

BACKGROUND: In patients with congenital long QT syndrome (LQTS), the risk of ventricular arrhythmia is correlated with the duration of the corrected QT interval and the changes in the ST-T wave pattern on the 12-lead surface electrocardiogram (12L-ECG). Remote monitoring of these variables could be useful. AIM: To evaluate the abilities of two wearable electrocardiogram devices (Apple Watch and KardiaMobile 6L) to provide reliable electrocardiograms in terms of corrected QT interval and ST-T wave patterns in patients with LQTS. METHODS: In a prospective multicentre study (ClinicalTrials.gov identifier: NCT04728100), a 12L-ECG, a 6-lead KardiaMobile 6L electrocardiogram and two single-lead Apple Watch electrocardiograms were recorded in patients with LQTS. The corrected QT interval and ST-T wave patterns were evaluated manually. RESULTS: Overall, 98 patients with LQTS were included; 12.2% were children and 92.8% had a pathogenic variant in an LQTS gene. The main genotypes were LQTS type 1 (40.8%), LQTS type 2 (36.7%) and LQTS type 3 (7.1%); rarer genotypes were also represented. When comparing the ST-T wave patterns obtained with the 12L-ECG, the level of agreement was moderate with the Apple Watch (k=0.593) and substantial with the KardiaMobile 6L (k=0.651). Regarding the corrected QT interval, the correlation with 12L-ECG was strong for the Apple Watch (r=0.703 in lead II) and moderate for the KardiaMobile 6L (r=0.593). There was a slight overestimation of corrected QT interval with the Apple Watch and a subtle underestimation with the KardiaMobile 6L. CONCLUSIONS: In patients with LQTS, the corrected QT interval and ST-T wave patterns obtained with the Apple Watch and the KardiaMobile 6L correlated with the 12L-ECG. Although wearable electrocardiogram devices cannot replace the 12L-ECG for the follow-up of these patients, they could be interesting additional monitoring tools.

The world's longest lasting VVI pacemaker device for over 40 years.

INTRODUCTION: Implantable permanent pacemaker function is supported by their energy sources for a mean period of 8.8-12.4 years. We previously published this case of a patient with a normally functioning VVI pacemaker, 31 years after implantation. METHODS AND RESULTS: In this report, we state that the device is still functioning normally 40 years after implantation. The most recent device interrogation revealed pacing threshold of 0.9 V/0.5 ms. Holter monitoring for 24 hours recorded a total of 98.707 beats with 97.78% paced beats, without any indication of pacemaker malfunction and with stable heart rate at 70-71 bpm. CONCLUSION: Most patients with implantable devices have the appropriate follow-up and settings of low energy consumption. Manufacturing companies should focus on prolonging device longevity, to produce future devices with higher energy capacity.

Incidental and anticipated arrhythmic diagnoses in patients with an implantable cardiac monitor.

AIMS: In this study, we investigated a cohort of unselected patients with various indications for an implantable cardiac monitor (ICM). Our main objectives were to determine the incidence of arrhythmic diagnoses, both anticipated and incidental in relation to the ICM indication, and to assess their clinical relevance. METHODS: We examined remote monitoring transmissions from patients with an ICM at four Italian sites to identify occurrences of cardiac arrhythmias. Concurrently, we collected data on medical actions taken in response to arrhythmic findings. RESULTS: The study included 119 patients, with a median follow-up period of 371 days. ICM indications were syncope/presyncope (46.2%), atrial fibrillation management (31.1%), and cryptogenic stroke (22.7%). In the atrial fibrillation management group, atrial fibrillation was the most common finding, with an incidence of 36% [95% confidence interval (CI) 22-55%] at 18 months. Rates of atrial fibrillation were not significantly different between patients with cryptogenic stroke and syncope/presyncope [17% (95% CI 7-40%) vs. 8% (95% CI 3-19%), P  = 0.229].For patients with cryptogenic stroke, the incidence of asystole and bradyarrhythmias at 18 months was 23% (95% CI 11-45%) and 42% (95% CI 24-65%), respectively, similar to estimates obtained for patients implanted for syncope/presyncope ( P  = 0.277 vs. P  = 0.836).Overall, 30 patients (25.2%) required medical intervention following ICM-detected arrhythmias, predominantly involving atrial fibrillation ablation (10.9%) and medication therapy changes (10.1%). CONCLUSION: In a real-life population with heterogeneous insertion indications, approximately 25% of patients received ICM-guided medical interventions within a short timeframe, including treatments for incidental findings. Common incidental arrhythmic diagnoses were bradyarrhythmias in patients with cryptogenic stroke and atrial fibrillation in patients with unexplained syncope.

Predictors of Success for Pulmonary Vein Isolation With Pulsed-field Ablation Using a Variable-loop Catheter With 3D Mapping Integration: Complete 12-month Outcomes From inspIRE.

BACKGROUND: We previously presented the safety and early efficacy of the inspIRE study (Study for Treatment of Paroxysmal Atrial Fibrillation [PAF] by Pulsed-field Ablation [PFA] System With Irreversible Electroporation [IRE]). With the study's conclusion, we report the outcomes of the full pivotal study cohort, with an additional analysis of predictors of success. METHODS: InspIRE was a prospective, multicenter, single-arm clinical trial of drug-refractory paroxysmal atrial fibrillation. Pulmonary vein isolation was performed with a variable-loop circular catheter integrated with a 3-dimensional mapping system. Follow-up with 24-hour Holter was at 3, 6, and 12 months, as well as remote rhythm monitoring: weekly from 3 to 5 months, monthly from 6 to 12 months, and for symptoms. The primary effectiveness end point (PEE) was acute pulmonary vein isolation plus freedom from any atrial arrhythmia at 12 months. Additional subanalyses report predictors of PEE success. RESULTS: The patient cohort included 186 patients: aged 59±10 years, female 30%, and CHA2DS2-VASc 1.3±1.2. The previously reported primary adverse event rate was 0%. One serious procedure-related adverse event, urinary retention, was reported. The PEE was achieved in 75.6% (95% CI, 69.5%-81.8%). The clinical success of freedom from symptomatic recurrence was 81.7% (95% CI, 76.1%-87.2%). Simulating a monitoring method used in standard real-world practice (without protocol-driven remote rhythm monitoring), this translates to a freedom from all and symptomatic recurrence of 85.8% (95% CI, 80.8%-90.9%) or 94.0% (95% CI, 90.6%-97.5%), respectively. Multivariate analyses revealed that left ventricular ejection fraction ≥60% (adjusted odds ratio, 0.30) and patients receiving ≥48 PFA applications (adjusted odds ratio, 0.28) were independent predictors of PEE success. Moreover, PEE success was 79.2% in patients who received ≥12 PFA applications per vein compared with 57.1% in patients receiving fewer PFA applications. CONCLUSIONS: The inspIRE study confirms the safety and effectiveness of pulmonary vein isolation using the novel 3-dimensional mapping integrated circular loop catheter. An optimal number of PFA applications (≥48 total or ≥12 per vein) resulted in an improved 1-year success rate of ≈80%. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04524364.

Tracking Tidal Volume From Holter and Wearable Armband Electrocardiogram Monitoring.

A novel method for tracking the tidal volume (TV) from electrocardiogram (ECG) is presented. The method is based on the amplitude of ECG-derived respiration (EDR) signals. Three different morphology-based EDR signals and three different amplitude estimation methods have been studied, leading to a total of 9 amplitude-EDR (AEDR) signals per ECG channel. The potential of these AEDR signals to track the changes in TV was analyzed. These methods do not need a calibration process. In addition, a personalized-calibration approach for TV estimation is proposed, based on a linear model that uses all AEDR signals from a device. All methods have been validated with two different ECG devices: a commercial Holter monitor, and a custom-made wearable armband. The lowest errors for the personalized-calibration methods, compared to a reference TV, were -3.48% [-17.41% / 12.93%] (median [first quartile / third quartile]) for the Holter monitor, and 0.28% [-10.90% / 17.15%] for the armband. On the other hand, medians of correlations to the reference TV were higher than 0.8 for uncalibrated methods, while they were higher than 0.9 for personal-calibrated methods. These results suggest that TV changes can be tracked from ECG using either a conventional (Holter) setup, or our custom-made wearable armband. These results also suggest that the methods are not as reliable in applications that induce small changes in TV, but they can be potentially useful for detecting large changes in TV, such as sleep apnea/hypopnea and/or exacerbations of a chronic respiratory disease.

Impact of an expanded reimbursement policy on utilization of implantable loop recorders in patients with cryptogenic stroke in Korea.

BACKGROUND/AIMS: The reimbursement policy for cryptogenic stroke (CS) was expanded in November 2018 from recurrent strokes to the first stroke episode. No reports have demonstrated whether this policy change has affected trends in implantable loop recorder (ILR) utilization. METHODS: We identified patients who received an ILR implant using the Korea Health Insurance Review and Assessment Service database between July 2016 and October 2021. Patients meeting all the following criteria were considered to have CS indication: 1) prior stroke history, 2) no previous history of atrial fibrillation or flutter (AF/AFL), and 3) no maintenance of oral anticoagulant for ≥4 weeks within a year before ILR implant. AF/AFL diagnosed within 3 years after ILR implant or before ILR removal was considered ILR-driven. RESULTS: Among 3,056 patients, 1,001 (32.8%) had CS indications. The total ILR implant number gradually increased for both CS and non-CS indications and the number of CS indication significantly increased after implementing the expanded reimbursement policy. The detection rate for AF/AFL was 26.3% in CS patients over 3 years, which was significantly higher in patients implanted with an ILR within 2 months after stroke than those implanted later. CONCLUSION: The expanded coverage policy for CS had a significant impact on the number of ILR implantation for CS indication. The diagnostic yield of ILR for AF/AFL detection seems better when ILR is implanted within 2 months than later. Further investigation is needed to demonstrate other clinical benefits and the optimal ILR implantation timing.

Use of wearable technology in cardiac monitoring after cryptogenic stroke or embolic stroke of undetermined source: a systematic review.

INTRODUCTION: Prolonged cardiac monitoring after cryptogenic stroke or embolic stroke of undetermined source (ESUS) is necessary to identify atrial fibrillation (AF) that requires anticoagulation. Wearable devices may improve AF detection compared to conventional management. We aimed to review the evidence for the use of wearable devices in post-cryptogenic stroke and post-ESUS monitoring. METHODS: We performed a systematic search of PubMed, EMBASE, Scopus and clinicaltrials.gov on 21 July 2022, identifying all studies that investigated the use of wearable devices in patients with cryptogenic stroke or ESUS. The outcomes of AF detection were analysed. Literature reports on electrocardiogram (ECG)-based (external wearable, handheld, patch, mobile cardiac telemetry [MCT], smartwatch) and photoplethysmography (PPG)-based (smartwatch, smartphone) devices were summarised. RESULTS: A total of 27 relevant studies were included (two randomised controlled trials, seven prospective trials, 10 cohort studies, six case series and two case reports). Only four studies compared wearable technology to Holter monitoring or implantable loop recorder, and these studies showed no significant differences on meta-analysis (odds ratio 2.35, 95% confidence interval [CI] 0.74-7.48, I 2 = 70%). External wearable devices detected AF in 20.7% (95% CI 14.9-27.2, I 2 = 76%) of patients and MCT detected new AF in 9.6% (95% CI 7.4%-11.9%, I 2 = 56%) of patients. Other devices investigated included patch sensors, handheld ECG recorders and PPG-based smartphone apps, which demonstrated feasibility in the post-cryptogenic stroke and post-ESUS setting. CONCLUSION: Wearable devices that are ECG or PPG based are effective for paroxysmal AF detection after cryptogenic stroke and ESUS, but further studies are needed to establish how they compare with Holter monitors and implantable loop recorder.

Detection of paroxysmal atrial fibrillation preceding persistent atrial fibrillation in a horse using an implantable loop recorder with remote monitoring.

Implantable loop recorders (ILRs) are increasingly used in equine cardiology to detect arrhythmias in the context of collapse, poor performance or monitoring for recurrence of atrial fibrillation (AF). However to date, the ILR has never been reported to be used with a remote monitoring functionality in horses, therefore the arrhythmia is only discovered when a clinician interrogates the ILR using dedicated equipment, which might delay diagnosis and intervention. This case report describes the use of an ILR with remote monitoring functionality in a horse with recurrent AF. The remote monitoring consisted of a transmission device located in the stable allowing daily transmission of arrhythmia recordings and functioning messages to an online server, available for the clinician to evaluate without specialised equipment. The ILR detected an episode of paroxysmal AF approximately three months after implantation. Seven months after implantation, initiation of persistent AF was seen on an episode misclassified by the ILR as bradycardia, and the horse was retired. This report shows the feasibility and benefits of remote monitoring for ILRs in horses, but also the shortcomings of current algorithms to interpret the equine electrocardiogram.

[Characterization of atrial fibrillation burden using wearables]. / Charakterisierung der Vorhofflimmerlast mittels Wearables.

The characterization of atrial fibrillation (AF) according to current guidelines categorically refers to the differentiation between paroxysmal, persistent, and permanent AF. A more precise characterization of AF, including the evaluation of AF burden, is playing an increasingly significant role in both scientific research and clinical practice. Digital devices, especially those with the capability of passive (semi-)continuous recording, can contribute to a more accurate quantification of AF burden. Particularly in patients with an already established diagnosis of AF, the evaluation of AF burden can be used to monitor the success of antiarrhythmic therapy including antiarrhythmic drugs or pulmonary vein isolation. However, important questions remain unanswered: In addition to a uniform, evidence-based definition of AF burden, clinically relevant cut-offs for AF burden and resulting therapeutic consequences (e.g., subclinical AF) need to be elaborated. Furthermore, the establishment and evaluation of care structures for assessing and integrating AF burden in clinical care, especially by incorporating data from wearable medical devices, should take place.

Early atrial fibrillation recurrence post catheter ablation: Analysis from insertable cardiac monitor in the era of optimized radiofrequency ablation.

BACKGROUND: Early recurrence of atrial tachyarrhythmia (ERAT) is associated with ablation-induced proarrhythmogenic inflammation; however, existing studies used intermittent monitoring or nonoptimized radiofrequency (RF) applications (noncontiguous or without ablation index target value). OBJECTIVE: The purpose of this study was to investigate the relationship between ERAT and late recurrence based on insertable cardiac monitor (ICM) data. METHODS: We compiled data from Close-To-Cure and Close Maze studies, which enrolled patients who underwent RF ablation for paroxysmal or persistent atrial fibrillation (AF). All patients were implanted with an ICM 2-3 months before ablation. RESULTS: We studied 165 patients (104 with paroxysmal AF, 61 with persistent AF). Over the 1-year follow-up period, 41 of the patients experienced late recurrence. The risk of late recurrence was higher in patients experiencing ERAT (hazard ratio [HR] 6.2; 95% confidence interval [CI] 3.0-13.0), with negative and positive predictive values of 90.5% and 45.7%, respectively. Median burden of AF during the blanking period was significantly higher in patients with late recurrence (7.9% [0.0%-99.6%]) compared to those without recurrence (0.0% [0.0%-6.0]; P <.001). For each 1% increase in AF burden during the blanking period, late recurrence increased by 4.6% (HR 1.046; 95% CI 1.035-1.059). The best tradeoff for predicting AF from ERAT occurrence was AF burden of 0.6% and last ERAT at 64 days. CONCLUSION: In patients ablated for paroxysmal and persistent AF with a durable RF lesion set and implanted with a continuous monitoring device, postablation early AF recurrence and burden significantly predict late recurrence. The post-AF ablation blanking period should be reduced to 2 months.

The Beneficial Role of Telemedicine for Arrhythmic Risk Stratification in Asymptomatic Brugada Syndrome: An Exemplary Case Report.

Telemedicine and remote monitoring devices, including implantable loop recorders (ILR), are increasingly adopted in the cardiologic setting. These are valuable tools in the arrhythmic stratification of patients at risk of sudden cardiac death, providing a tailored therapeutic management to prevent lethal arrhythmias. We report a case of an asymptomatic 18-year-old boy with a family history of syncope and cardiac arrest, who had a diagnosis of Brugada syndrome with an inducible type 1 pattern and carrier of a missense mutation of the SCN5A gene. In light of the risk factors, although not recommended by current guidelines, we decided to proceed with the implantation of an ILR with remote monitoring service. A few months later, an episode of asymptomatic sustained polymorphic ventricular tachycardia was promptly observed by the remote monitoring, leading to a timely implantation of a subcutaneous cardiac implantable defibrillator.

Multimodality imaging in patients with implantable loop recorders: Tips and tricks.

An implantable loop recorder (ILR) is a leadless rectangular device used for prolonged electrocardiographic monitoring for up to 3 years. This miniaturized device, inserted subcutaneously, allows clinicians to investigate possible cardiac rhythm disturbances in patients suffering from recurrent unexplained syncope. As the age of the population increases rapidly and the number of ILR patients amplifies, the clinical significance of ILRs is undeniable. Although radioopaque and easily seen on plain chest radiographs and other imaging modalities, ILRs may represent a challenge for clinicians and radiologists to recognize their classic appearance and differentiate them from numerous other cardiac devices. This article aims to summarize current literature on ILRs, their basic function, types, and indications for implantation, but most of all, it aims to familiarize clinicians and radiologists with common imaging features of these devices, safety issues, and artifact-reducing methods. Specifically, this review discusses the typical appearance of ILRs on major diagnostic imaging modalities, including chest X-ray, mammography, ultrasonography, computed tomography, and magnetic resonance imaging (MRI). Furthermore, optimization strategies to mitigate image artifacts and safety issues regarding MRI are discussed.