OBJECTIVE: Implantable loop recorders (ILR) are increasingly used in cardiac rhythm monitoring and diagnostic work-up of unexplained syncope. ILR battery longevity, according to manufacturers\' product performance specifications, typically ranges between 2 and 4 years, but real-world data in this population are lacking.
METHODS: This monocentric, prospective, observational study included consecutive patients with unexplained syncope undergoing ILR implantation between October 2007 and 2019. The main purpose was to determine real-world battery longevity of ILRs. Diagnostic yield and relationship between arrhythmogenic diagnosis and duration of ILR monitoring were explored.
RESULTS: The study included 309 patients (59 years [38-73], 49% female) with ILR implantation for unexplained syncope. Median battery longevity was 42 [40-45] months. A total of 99.5% of ILRs reached prespecified battery longevity. The time to end-of-life varied by up to 33 months among the same ILR models. Overall arrhythmogenic diagnostic yield counted 27% (73% sick sinus syndrome, 20% atrioventricular block, and 7% ventricular tachycardia). Median time to diagnosis was 10 [2-25] months, with the latest event at 43 months. The cumulative diagnostic yield for arrhythmogenic event explaining syncope was 4.2%, 6.1%, 9.4%, 14.6%, 19.4%, and 26.7% at 1, 2, 6, 12, 24, and 48 months, respectively. In univariate analysis, first degree AV block and prolonged HV time on EP study were predictors of diagnosis, while QRS duration abnormality borderline missed significance.
CONCLUSIONS: Real-world battery longevity of ILRs matched industry projected longevity in 99.5% of patients implanted with ILR for unexplained syncope. A battery longevity of minimum 3.5 years is recommended to maximize the diagnostic yield in this population.

BACKGROUND: Most studies of device-detected atrial fibrillation (AF) have recommended indefinite anticoagulation once a patient crosses a particular threshold for AF duration or burden. However, durations and burdens are known to fluctuate over time, but little is known about the magnitude of spontaneous fluctuations and the potential impact on anticoagulation decisions.
OBJECTIVE: To quantify spontaneous fluctuations in AF duration and burden in patients with implantable loop recorders (ILRs) METHODS: We reviewed all ILR interrogations for patients with non-permanent AF at our institution from 2018 to 2023. We excluded patients treated with rhythm control. The duration of longest AF episode at each interrogation was classified as < 6, 6-24, and > 24 h, and the AF burden reported at each interrogation was classified as < 2%, 2%-11.4%, and > 11.4%.
RESULTS: Out of 156 patients, the mean age at ILR implant was 70.9 ± 12.5 years, CHA2DS2-VASc score was 4.2 ± 1.8, duration of ILR follow-up was 23.4 ± 11.2 months, and number of ILR interrogations per patient was 18.0 ± 8.9. The duration of longest AF episode at any point during follow-up was < 6 , 6-24 , and > 24 h in 110, 30, and 16 patients, respectively. Among the 30 patients with a longest AF episode of 6-24 h at some point during follow-up, out of 594 total ILR interrogations, only 75 (12%) showed a longest episode of 6-24 h. In the remaining 519 interrogations, the longest episode was < 6 h. In patients with a longest episode of > 24 h at any point during follow-up (n = 16), only 47 out of 320 total ILR interrogations (15%) showed an episode of > 24 h. When evaluating AF burden, 96, 38, and 22 patients had maximum reported AF burdens of < 2%, 2%-11.4%, and > 11.4% at any point during ILR follow-up. Among those with a maximum burden of 2%-11.4% at some point during follow-up (n = 38), out of 707 ILR interrogations, only 76 (11%) showed a burden of 2%-11.4%. In the remaining 631 interrogations, the burden was < 2%. In the 22 patients with a burden > 11.4% at some point during follow-up, only 80 out of 480 interrogations (17%) showed a burden of > 11.4%. In 65% of interrogations, the burden was < 2%.
CONCLUSIONS: Significant, spontaneous fluctuations in AF burden and duration are common in patients with ILRs. Even in patients with AF episodes of 6-24 h or > 24 h at some point during follow-up, the vast majority of interrogations show episodes of < 6 h. Similarly, in patients with burdens of 2%-11.4% or > 11.4% at some point during follow-up, the vast majority of interrogations show burdens of < 2%. More data are needed to determine whether crossing an AF burden or duration threshold once is sufficient to merit lifelong anticoagulation or whether spontaneous fluctuations in AF burden and duration should impact anticoagulation decisions.

BACKGROUND: Implantable loop recorder (ILR) allows rhythm-monitoring up to 3 years. They are recommended in patients with recurrent syncope and for the detection of atrial fibrillation (AF) in patients with cryptogenic thromboembolic events. AF and syncope occur more often in elderly patients. However, data in this cohort is limited.
RESULTS: All patients ≥ 80 years undergoing ILR-implantation between 2011 and 2022 in our center were included. Permanent pacemaker implantation (PPI) and oral anticoagulation due AF were defined as primary endpoints. Forty-five patients ≥ 80 years were included, 33 because of recurrent syncope and 12 because of suspected AF. The average follow up (FU) was 17.6 months. Overall in 22 patients, ILR-implantation led to a therapeutic consequence (48.9%). In the 12 patients who underwent ILR-implantation for detection of AF, AF was detected in nine patients (75%). In the 33 elderly patients who received ILR-implantation after syncope, 11 underwent PPI during FU (33.3%). One patient accidentally removed the ILR himself via the implantation-wound, and no other ILR-related complications were observed.
CONCLUSIONS: ILR are effective and safe in elderly patients. AF was often found in patients with suspected AF, especially in patients after catheter ablation of only documented atrial flutter (AFlu). PPI-rate was high in patients with recurrent syncope and ILR-implantation. Further investigations are necessary to determine whether PPI may be considered in elderly patients with syncope even in the absence of a bifascicular block.

OBJECTIVE: Subclinical thyroid dysfunction is a marker for atrial fibrillation (AF) and stroke risk. This study explored the effects of AF screening according to thyroid-stimulating hormone (TSH) levels.
METHODS: An AF screening trial (the LOOP study) was analyzed post-hoc according to baseline TSH. The primary outcome was stroke or systemic embolism (SE). Secondary outcomes included major bleeding, all-cause death, and the combination of stroke, SE, and cardiovascular death.
RESULTS: TSH measurement was available in 6003 of 6004 trial participants, 1500 randomized to implantable loop recorder (ILR) screening for AF and anticoagulation upon detection vs. 4503 to usual care; mean age was 74.7±4.1 years and 2836 (47%) were women. AF detection was approximately triple for ILR vs usual care across TSH tertiles (adjusted p-interaction=0.44). In the first tertile, screening was associated with decreased risk of the primary outcome (hazard ratio 0.52 [0.30-0.90]; p=0.02) and stroke, SE, or cardiovascular death (hazard ratio 0.54 [0.34-0.84]; p=0.006) compared to usual care, while no effect was observed among participants with higher TSH (adjusted p-interaction 0.03 and 0.01, respectively). There was no effect on other outcomes. Analyses of continuous TSH or excluding those with abnormal TSH or thyroid medication showed similar results.
CONCLUSIONS: AF screening and subsequent treatment was associated with decreased stroke risk among participants with low TSH, though the yield of screening was similar across TSH levels. TSH may be useful as a marker to indicate benefit from AF screening vs. overdiagnosis and overtreatment. These findings should be considered exploratory and warrant further study.
BACKGROUND: ClinicalTrials.gov, identifier: NCT0203645.

BACKGROUND: The aim of this study was to investigate the clinical implication of incidentally induced atrial fibrillation (AF) during programmed electrical stimulation (PES) in patients with left ventricular systolic dysfunction (≤40%) after an acute myocardial infarction (MI).
METHODS: In this study, we included 231 patients from the Cardiac Arrhythmias and RIsk Stratification after Myocardial InfArction (CARISMA) study with left ventricular ejection fraction ≤40% and no prior history of AF. These patients underwent PES 6 weeks post-MI as part of the study protocol. Patients all received an implantable cardiac monitor (ICM) 3-21 days post-MI and were continuously monitored for cardiac arrhythmias for 2 years. Induction of AF was unwanted but reported if this incidentally occurred.
RESULTS: A total of 61 patients (26%) developed AF within 2 years of follow-up, in which n = 10 (29%) had incidental AF during PES at baseline. The overall risk of AF was not significantly increased in patients with incidental AF (n = 34) during PES compared to patients without incidental AF (n = 197) (HR 1.6 [0.9-3.0], p = 0.14). The risk of bradyarrhythmia (HR = 0.2 [0.0-1.2], p = 0.07), ventricular arrhythmias (HR = 0.7 [0.1-5.8], p = 0.77), and major cardiovascular events (MACE) (HR 0.5 [0.2-1.7], p = 0.28) was not significantly different in patients with versus without incidental AF.
CONCLUSIONS: Incidentally induced AF during PES in post-MI patients with reduced LVEF was not significantly associated with a higher risk of long-term atrial fibrillation, other cardiac arrhythmias, or major cardiac events.
BACKGROUND: NCT00145119.

UNASSIGNED: Stroke is the most debilitating outcome of atrial fibrillation (AF). The use of implantable loop recorders increases the detection of AF episodes among patients with embolic stroke of undetermined source. The significance of device-detected AF, or subclinical AF, is unknown. This study aimed to compare the incidence of AF detected by implantable loop recorder in patients with and without embolic stroke of undetermined source.
UNASSIGNED: We retrospectively studied all patients without known AF who were referred to our institution for implantable loop recorder implantation following embolic stroke of undetermined source, syncope, or palpitations from March 2009 to November 2019. The primary endpoint was any detection of AF or atrial flutter by implantable loop recorder. Seven hundred and fifty patients were included and followed up for a mean duration of 731 days (SD 443). An implantable loop recorder was implanted following embolic stroke of undetermined source in 323 and for assessment of syncope, palpitations, or another reason in 427 patients. The incidence of AF was significantly (P < 0.001) higher among patients with embolic stroke of undetermined source compared with the non-embolic stroke of undetermined source group; 48.6% vs. 13.8% (for any duration of AF) and 32.2% vs. 12.4% (for AF lasting ≥30 s) both P < 0.001. Kaplan-Meier analysis showed significantly higher incidence of AF for incremental durations of AF up to >5.5 h, but not >24 h. This was driven by longest AF durations of <6 min and between 5.5 h and 24 h, suggesting a bimodal distribution. In a multivariable Cox regression analysis, embolic stroke of undetermined source independently conferred an almost 5-fold increase in the hazard for any duration of AF.
UNASSIGNED: The incidence of AF is significantly higher amongst embolic stroke of undetermined source vs. non-embolic stroke of undetermined source patients monitored constantly by an implantable loop recorder. A high number of embolic stroke of undetermined source survivors have short-duration AF episodes. Further work is needed to determine the optimal treatment strategy of these AF episodes in embolic stroke of undetermined source.

BACKGROUND: Young (<18 years of age) patients with Brugada syndrome (BrS) are often under-represented in BrS studies and their management, especially related to syncopal episodes, remains unclear.
OBJECTIVE: This study sought to describe the arrhythmia prevalence among young patients with BrS undergoing continuous rhythm monitoring by implantable loop recorder (ILR) and to assess the etiology behind syncope of undetermined origin.
METHODS: A total of 147 patients with BrS with ILR were enrolled in 12 international centers and divided into pediatric (age <12 years; n = 77, 52%) and adolescents (age 13-18 years; n = 70, 48%).
RESULTS: Mean age was 11.3 years, 53 patients (36.1%) were female, and 31 (21.1%) had spontaneous type 1 electrocardiograms. Over a median follow-up of 3.6 years (Q1-Q3: 1.6-4.8 years), an arrhythmic event was recorded in 33 patients (22.4%), mainly of nonventricular origin: 15 atrial (10.2%) and 16 bradyarrhythmic events (10.9%). Ventricular arrhythmias occurred in 4 patients, all with spontaneous BrS, and were fever-related in one-half. Among all patients with recurrence of syncope during follow-up, true arrhythmic syncope was documented in 5 (17.8%), and it was due to bradyarrhythmias or atrial arrhythmias in 3 cases (60%).
CONCLUSIONS: Continuous rhythm monitoring with ILRs in young patients with BrS detects a broad range of arrhythmias. Ventricular arrhythmias occur predominantly in patients with spontaneous type 1 electrocardiograms and during fever. Despite the young age, bradyarrhythmias and atrial arrhythmias are frequent and represent the cause of arrhythmic syncope in 60% of patients. Young patients with BrS with syncope of undetermined origin may benefit from ILR implant.

The 2018 guidelines of the European Society of Cardiology (ESC) provide improved algorithms for the diagnostics and treatment of syncope. New guidelines on ventricular tachycardia, on the prevention of sudden cardiac death and on cardiomyopathies and pacemakers have refined the recommendations. The detailed medical history and examination are crucial for differentiating between cardiac and noncardiac causes and determining the appropriate treatment. High-risk patients need urgent and comprehensive diagnostics. The basic diagnostics include medical history, physical examination and a 12-lead electrocardiography (ECG). Further tests, such as long-term ECG monitoring, implantable loop recorders and electrophysiological investigations are helpful in unclear cases. The treatment depends on the cause, with pacemaker implantation and implantable cardioverter defibrillators (ICD) being important for cardiac causes, while behavioral measures and medication management have priority for noncardiac syncope.
UNASSIGNED: Die 2018 veröffentlichten Leitlinien der European Society of Cardiology (ESC) bieten verbesserte Algorithmen für die Diagnostik und die Behandlung von Synkopen. Neue Leitlinien zu ventrikulären Tachykardien, zur Prävention des plötzlichen Herztodes sowie zu Kardiomyopathien und Schrittmachertherapie haben die Empfehlungen verfeinert. Die genaue Anamnese und Untersuchung sind entscheidend für die Differenzierung zwischen kardialen und nichtkardialen Ursachen sowie für die Festlegung der Therapie. Bei hohem Risiko ist eine rasche und umfassende Diagnostik notwendig. Die Basisdiagnostik umfasst Anamnese, körperliche Untersuchung und 12-Kanal-EKG(Elektrokardiographie). Weitere Tests wie Langzeit-EKG, implantierbare Ereignisrekorder und elektrophysiologische Untersuchungen sind bei unklaren Fällen hilfreich. Die Therapie richtet sich nach der Ursache, wobei Schrittmacherimplantationen und implantierbare Kardioverter-Defibrillatoren (ICD) bei kardialen Ursachen wichtig sind, während bei nichtkardialen Synkopen Verhaltensmaßnahmen und Medikamentenmanagement im Vordergrund stehen.

Pediatric cardiac symptoms such as palpitations, syncope, or seizure-like episodes pose diagnostic challenges for general pediatricians. These symptoms, though often benign, may reveal underlying arrhythmias or inherited cardiac conditions (ICCs), affecting the quality of life and limiting activity participation. The purpose of this study is to determine the effectiveness and safety of implantable loop recorders (ILRs) in diagnosing and managing arrhythmias in pediatric patients. A retrospective cohort study conducted over an 8-year period from January 2016 to December 2023 in a single pediatric cardiology center. A cohort of 155 pediatric patients (median age 11.4 years) who underwent ILR implantation were selected based on symptoms such as palpitations, chest pain, or syncope, and those with previously recorded arrhythmias or high-risk ICCs. The primary outcomes were the diagnostic yield of ILRs for arrhythmias and subsequent changes in patient management. Diagnostic yield was defined as the detection of relevant arrhythmias, such as pauses of 3 s or longer, high-degree AV block, sinus node dysfunction, supraventricular tachycardia, ventricular tachycardia, or inappropriate sinus tachycardia. The median follow-up period was 2.3 years (845 days). Diagnostic arrhythmias were recorded in 60% of patients with symptom-activated transmissions and 80% of device-activated transmissions. Sinus pauses (37.5%) and VT (30%) were the most common arrhythmias detected. In patients with syncope (n = 76), 30% had relevant arrhythmias. In the palpitations group (n = 20), 35% had relevant arrhythmias. Approximately 80% of patients with ILR-diagnosed arrhythmias underwent targeted management, including medication changes and additional procedures. No significant complications were observed; minor complications occurred in 2.5% of patients.Conclusions: New generation ILRs are effective and safe for diagnosing and managing pediatric arrhythmias, providing significant reassurance to patients and families. Further studies are needed to evaluate the impact of ILRs on quality of life and sports participation in high-risk young patients.

A 75-year-old man with hypertrophic obstructive cardiomyopathy underwent placement of a long-sensing vector implantable loop recorder (ILR) for unexplained syncope. One month later, ILR remote monitoring revealed unstable R-wave amplitudes ranging from very high (>1.9 mV) to very low (<0.2 mV) values. During an in-hospital clinic visit, the only site to establish communication with the ILR was the left posterior axillary area. Chest computed tomography confirmed ILR migration into the anterior costophrenic recess. The device was retrieved with forceps during video thoracoscopy without further complications.
UNASSIGNED: This is the first case report of migration of an implantable loop recorder diagnosed by remote monitoring.