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Exercise associated deaths (EADs) in horses are a problem for the equestrian industry. Sudden death (SD) is responsible for approximately 20% of EADs. The underlying cause of SD is suspected to be cardiovascular disease but often cannot be determined post-mortem. User-friendly cardiac monitors are needed for large scale investigations of arrhythmias associated with SD in horses. We hypothesised that novel wearable devices would provide exercising electrocardiograms (ECGs) of sufficient diagnostic quality for this purpose. Diagnostic quality of ECGs generated by two wearable devices (W2nd™ and Polar Equine™) were compared to simultaneous recordings with a telemetry unit (Televet™) in 5 Thoroughbreds completing 43 separate submaximal exercise tests on a high-speed treadmill. Maximal heart rate (HRmax) generated by mobile applications (HRmaxapp), HRmax after manual correction (HRmaxcorr), percentage of diagnostic ECGs (%diag) at the gallop, and overall quality assessed by visual analogue scale (VAS) were assessed by a blinded observer. HRmaxcorr did not differ significantly between groups. HRmaxapp was significantly lower for W2nd (166.8/min, 95% confidence interval (CI): 160.5-173.1/min) but did not differ significantly between Televet (178.8/min 95% CI: 165.8-191.1/min) and Polar (181.3/min, 95% CI: 174.5-188.1/min). HRmaxcorr was accurate and precise in all runs. HRmaxapp was within a priori limits of agreement in 16/23 W2nd and 18/19 Polar recordings. %diag was significantly lower (77.1%, 95% CI: 67.4-86.8) for W2nd than Polar (100%, 95% CI: 89.9-110.3). VAS was lower for W2nd (46.2, 95% CI: 35.5-57.0) than Polar (90.6, 25% CI: 79.4-101.9). In conclusion, wearable devices appear to be promising tools for investigation of equine exercising arrhythmias in large-scale studies.

Internet of Things technology is discussed as the basis for constructing a global communications system for cardiac monitoring. The advantages of this technology and trends in its development are identified, and the potential for its widespread introduction into online cardiac monitoring devices is presented. The technical requirements of the Internet of Things are discussed, along with current problems of a general nature related mainly to supporting secure and reliable communications.

Atrial fibrillation (AF) comes to attention clinically during an evaluation of symptoms, an evaluation of its adverse outcomes, or because of incidental detection during a routine examination or electrocardiogram. However, a notable number of additional individuals have AF that has not yet been clinically apparent or suspect-subclinical AF (SCAF). SCAF has been recognized during interrogation of pacemakers and defibrillators. More recently, SCAF has been demonstrated in prospective studies with long-term monitors-both external and implanted. The REVEAL AF trial enrolled a demographically "enriched" population that underwent monitoring for up to 3 years with an insertable cardiac monitor. SCAF was noted in 40% by 30 months. None of these patients had AF known before the study; however, some had nonspecific symptoms common to patients with known AF. The current study assessed whether patients with versus without such symptoms were more likely to have SCAF detected. We found that only palpitations had an association with AF detection when controlling for other baseline symptoms (hazard ratio 1.61 (95% confidence interval 1.12 to 2.32; p = 0.011). No other prescreening symptoms evaluated were associated with an increased likelihood of SCAF detection although patients without detected SCAF had an even higher frequency of symptoms than those with detected SCAF. Thus, REVEAL AF demonstrated that the presence of palpitations is associated with an increased likelihood of SCAF whereas other common symptoms are not; and, symptoms, per se, may more likely be consequent to associated disorders than they are a direct consequence of SCAF.

Background Direct-to-consumer devices allow patients to record electrocardiograms (ECG) and detect atrial fibrillation (AF). Clinical adoption of these devices has been limited owing to the lack of efficient workflow. Objective To assess a new care model for following patients after AF ablation that uses a smartphone ECG coupled with a novel cloud-based platform. Methods This was a pilot study to describe AF detection, healthcare utilization, use of additional ECGs and cardiac monitors, and changes in anxiety after AF ablation. Patients presenting 3–4 months after early successful AF ablation were randomized into a control group with standard clinical follow-up or a self-monitoring group using smartphone ECG (Kardia Mobile, KM) coupled with a cloud-based platform (KardiaPro, KP) that alerted the physician when AF was detected and followed for 6 months Results A total of 100 patients were randomized: 51 to the KM/KP group and 48 to the control group (1 withdrew). AF was detected in 18 patients (18.2%), 11 (21.6%) in the KM/KP group and 7 (14.6%) in the control group (P = .42). AF detection occurred at a median of 68 and 91 days in the KM/KP and control groups, respectively (P = .93). These differences were not statistically significant. Healthcare utilization and changes in anxiety were similar between the groups. More patients required additional ECGs or cardiac monitors in the control group (27.1%) compared to the KM/KP group (5.9%) (P = .004). Conclusions Smartphone ECG with a cloud-based platform can be incorporated into the care of post–AF ablation patients without increasing anxiety and with less need for additional traditional monitors.

Aim: The study assesses the burden and costs of recurring unexplained syncope and injuries and the effectiveness of implantable loop recorders. Methods: The English national hospital database (Hospital Episode Statistics) was retrospectively analyzed. Results: 12,002 patients were identified with repeated syncope hospitalizations. 25% of patients were hospitalized at least once again for syncope, 9% of the patients were hospitalized at least once for an injury, causing substantial costs. In the second analysis: 10,902 patients implanted with an implantable cardiac monitor were tracked. By year 3, hospitalizations due to syncope had dropped by 60% versus pre-implantable cardiac monitor (ICM) levels. Conclusion: This study shows a high rate of recurrent syncope admissions and a parallel burden of hospitalizations for injuries. Use of an ICM appears to reduce syncope hospitalizations.

Introduction: There is limited data on the experience with insertable cardiac monitors (ICMs) in patients with Brugada syndrome. Objective: To evaluate the outcome of ICM in symptomatic patients with Brugada syndrome who are at suspected low risk of sudden cardiac death (SCD). Methods: We conducted a prospective single-center cohort study including all symptomatic patients with Brugada syndrome who received an ICM (Reveal LINQ) between July 2014 and October 2019. The main indication for monitoring was to exclude ventricular arrhythmias as the cause of symptoms and to establish a symptom-rhythm relationship. Results: A total of 20 patients (mean age, 39 ± 12 years; 55% male) received an ICM during the study period. Nine patients (45%) had a history of syncope (presumed nonarrhythmogenic), and 5 patients had a recent syncope (n = 3), pulmonary vein isolation, and oral anticoagulation for atrial fibrillation (n = 1), electrophysiological study for risk stratification (n = 1), and pacemaker implantation for atrioventricular block (n = 1). Conclusions: An ICM can be used to exclude ventricular arrhythmias in symptomatic patients with Brugada syndrome at low risk of SCD. Furthermore, an ICM-detected arrhythmia changed clinical management in 20% of patients.

Background Little is known about the decision-making process for insertable cardiac monitors (ICM) in those with suspected arrhythmias. Objective The purpose of this qualitative study was to describe how individuals make a decision to insert an ICM. Methods A qualitative descriptive design was used. Data were analyzed using content analysis and constant comparison. NVivo 10 was used for data grouping and patterns. Results Participants (N = 12) ranged in age from 41to 95. Most (n = 7) had the device inserted because of syncope or atrial fibrillation (AF), and others (n = 5) for cryptogenic stroke. Three categories emerged: pre-decision, definitive decision, and deliberated decision. Event symptoms, including physical, cognitive and emotional, and trust emerged as factors in decision-making. Conclusions Those who perceived their experience as life-threatening, trusted the healthcare provider and assented to the ICM insertion. Conversely, those who perceived symptoms as episodic, used other strategies to resolve symptoms prior to making the decision for insertion.

Copyright © 2019 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:. To compare the benefits, harm and the atrial high-rate episode (AHRE) detection rate of implantable cardiac monitors against conventional methods (such as electrocardiogram, ambulatory Holter monitors, event monitors and real-time telemetry) in participants with embolic stroke of unknown source.

Sudden cardiac death (SCD) risk stratification in hypertrophic cardiomyopathy (HCM) currently relies on arrhythmic burden quantification by 24 or 48-hour Holter monitoring. Whether this approach adequately captures arrhythmic burden, compared with longer-term continuous monitoring, is unclear. We sought to assess the long-term incidence of nonsustained ventricular tachycardia (NSVT) in HCM patients at low or moderate SCD risk, using implantable cardiac monitors (ICMs) paired with a novel Bluetooth-enabled 2-way communication platform.This prospective, single-arm, observational study enrolled 33 HCM patients. Patients were implanted with an Abbott (Chicago, IL) Confirm Rx ICM and monitored using a protocolized care pathway.A total of 20 patients (60.6%) had ≥ 1 episode of NSVT recorded on the ICM, the majority of whom had previous Holter monitors that did not identify NSVT (60%, n = 12). A total of 71 episodes of NSVT were detected. Median time to first NSVT detection was 76.5 days (range: 0-553 days). A total of 19 patients underwent primary prevention implantable cardioverter defibrillator implantation during an average follow-up of 544 days (range: 42-925 days). A total of 172,112 automatic transmissions were received, and 65 (0.04%) required clinical follow-up. A total of 325 manual transmissions were received and managed. A total of 14 manual transmissions (4.3%) required follow-up, whereas 311 (95.7%) were managed solely with a text message.Surveillance and reporting systems utilizing 2-way communication enabled by novel ICMs are feasible and allow remote management of patients with HCM. Prolonged monitoring with ICMs identified more patients with nonsustained arrythmias than did standard Holter monitoring. In many cases, this information impacted both SCD risk stratification and patient management.La stratification du risque de mort cardiaque subite (MCS) dans la cardiomyopathie hypertrophique (CMH) dépend actuellement de la quantification de la charge arythmique par une surveillance Holter de 24 ou 48 heures. Il n’est pas clair si cette approche permet d’évaluer adéquatement la charge arythmique, comparativement à une surveillance continue à plus long terme. Nous avons cherché à évaluer la fréquence à long terme de la tachycardie ventriculaire non soutenue (TVNS) chez des patients atteints de CMH à risque faible ou modéré de MCS, au moyen de moniteurs cardiaques implantables (MCI) couplés à une nouvelle plate-forme de communication bidirectionnelle utilisable avec Bluetooth.Cette étude par observation prospective comportant un seul groupe a été menée auprès de 33 patients atteints de CMH. Les patients ont reçu un MCI Confirm Rx d’Abbott (Chicago, États-Unis) et ont été surveillés dans le cadre d’un parcours de soins reposant sur un protocole.Au total, 20 patients (60,6 %) ont eu au moins un épisode de TVNS enregistré par le MCI. La majorité de ces patients portaient déjà un moniteur Holter qui n’a pas décelé de TVNS (60 %, n = 12). Au total, 71 épisodes de TVNS ont été détectés. Le temps médian écoulé avant la première détection de TVNS était de 76,5 jours (fourchette : 0-553 jours). Au total, 19 patients se sont fait poser un défibrillateur cardioverteur implantable en prévention primaire pendant un suivi moyen de 544 jours (fourchette : 42-925 jours). En tout, 172 112 transmissions automatiques ont été reçues, et 65 (0,04 %) ont nécessité un suivi clinique. Par ailleurs, 325 transmissions manuelles ont été reçues et traitées. De ce nombre, 14 transmissions (4,3 %) ont nécessité un suivi, tandis que 311 (95,7 %) ont été traitées uniquement au moyen d’un message texte.Les systèmes de surveillance et de signalement utilisant une communication bidirectionnelle rendue possible grâce aux nouveaux MCI sont réalisables et permettent une prise en charge à distance des patients atteints d’un CMH. La surveillance prolongée par un MCI a permis de déceler plus d’arythmies non soutenues que la surveillance Holter type. Dans de nombreux cas, ces renseignements ont eu un effet positif tant sur la stratification du risque de MCS que sur la prise en charge des patients.

The authors have requested that this preprint be removed from Research Square.

The use of insertable cardiac monitors (ICM) has been increasing because of their ability to provide long-term electrocardiographic monitoring and symptom correlation. Indications for implantation include evaluation of cryptogenic stroke, unexplained syncope, intermittent palpitations, and atrial fibrillation. When the ICM needs to be removed because of battery depletion and/or diagnostic revelation, its removal can be challenging because of its small size and the capsule that forms around the proximal end of the device. A simple technique is described that takes advantage of the ICM design to facilitate its successful extraction.

Background TIA (Transient Ischaemic Attack) is a transient episode of neurologic dysfunction. Patients with a TIA have a high early risk of recurrent stroke. These patients need urgent initial evaluation with brain imaging, neurovascular imaging and cardiac evaluation. We conducted retrospective audit in our Acute Medical Unit (AMU) to assess waiting time and type of investigations completed as per TIA guidelines Methods All consecutive admissions with suspected TIAs were evaluated on length of stay, type of imaging tests obtained and how long they awaited for these tests. This was assessed by reviewing discharge summaries, and times and dates of scans on hospital imaging system. Results There was a total of 28 patients admitted to AMU with suspected TIA’s. Of these, 16 were female and 12 were male. Mean age was 70. All patients had CT brain done on admission, two out of 28 had to wait more than 12 hours. 25 out of 28 (89%) patients got US Carotid Dopplers, and two had CT intracranial angiograms. Average waiting time for US Carotid Dopplers was 33 hours, shortest wait was 6 hours and longest was 72 hours. 14 out of 24 (58%) had inpatient heart monitoring (24h telemetry or 24h Holter) two were excluded with known atrial fibrillation, one had PPM in situ and one refused monitoring. Average length of stay in AMU was 3 days. Conclusion Patients admitted to AMU with suspected TIAs had relevant imaging and tests completed as per guidelines. 89 % had US Carotid Dopplers which were on average done 33h from admission. 58% of patients had inpatient heart monitoring. The average length of stay was 3 days but three patients stayed in AMU for up to 5 days. Protected imaging slots for AMU would expedite investigations and reduce inpatient stay.

Insertable cardiac monitors (ICM) are used in patients with suspected or known cardiac arrhythmias; the resulting diagnosis can lead to therapeutic interventions such as a pacemaker (PPM) or defibrillator (ICD) implant. We investigated the incidence of these implants in a large, real-world, cohort of ICM patients. The Optum© EHR de-identified database was used to identify patients with cardiovascular diseases, an ICM implant, ≥180 days of follow-up before and after ICM implant, and no previous history of a PPM or ICD. The Kaplan-Meier (KM) incidence estimates for device implants following an ICM implant were determined. A total of 19,173 patients with an ICM implant were identified. During a mean follow-up of 40 months, either a PPM or ICD was implanted in 21% of patients. A device was implanted in 25% of patients with history of syncope compared with 15% in patients with another indication for ICM implant (p

Several external cardiac monitors (ECMs) have recently been developed. These have never been compared to ‘gold standard’ monitoring with concurrently implanted DDDRP pacemakers. The accuracy of AF detection of Zio XT Monitor (ZM), NUUBO Vest (NV) and Carnation Ambulatory Monitor (CAM) compared with Novacor ‘R’ Test 4 (RT) in patients (pts) with DDDRP PPM advanced Holters as the comparator, was evaluated. Twenty-one pts. with AF and a DDDRP PPM, each acting as their own control subject, wore every ECM for 2 weeks in randomized order. PPM downloads were performed at application and removal. Device ECGs were compared for AF burden and individual AF episodes with PPM Holters. Pt acceptability, wear time, costs and time expenditure were evaluated. RT AF burden was less accurate than the ZM, NV or CAM (p

Background: The Implantable Cardiac Monitor (ICM) is an invaluable tool for detecting cardiac arrhythmias by providing physicians. Critical to the success of ICMs depends on how quickly and accurately the data can be transmitted to a physician’s office after an arrhythmic event. Then, the clinical event can be analyzed and the treatment will be provided accordingly. However, no reports have been published as to how efficiently the ICM data is transmitted. Methods: There is a retrospective review of 520 patients who received a Medtronic Reveal LINQTM between 2/01/2015 and 6/01/2017. The time from the arrhythmic event to the time of physician notification was calculated and reason for delay was noted. Results: One hundred and twenty patients out of 520 patients (23%) had arrhythmic events transmitted over a mean follow up of 14 ± 4 months. The mean time between cardiac events and physician notification was 15 ± 8 days. Sixty-three percent (63%) of data transmission delay (defined as >24 hours) was due to the MyCareLinkTM Monitor not being in proximity to the patient. Connection failure between the monitor and the network accounted for 34% of data transmission delay. Conclusion: Significant delay in data transmission from Medtronic Reveal LINQTM cardiac monitor occurs frequently impacting patient care. Newer generations of the implantable cardiac monitors utilize Bluetooth technology, enabling immediate transfer of data from ICM to a patient’s cellular phone and subsequently to their physician’s office. This technology could potentially improve efficiency and reliability eliminating the issues of proximity and connectivity.

Funding Acknowledgements Type of funding sources: None. Background The insertable cardiac monitor (ICM) is an essential tool for the ambulatory diagnosis of arrhythmias. However, definitive diagnoses still rely on time-consuming, manual adjudication of electrograms (EGMs) transmitted to the patient care network. This EGM review burden may be minimized by automatically selecting a subset of EGMs for fast review without delaying the diagnosis. Purpose Develop EGM selection strategies to reduce the EGM review burden without delaying diagnoses. Methods A retrospective analysis of 1,000 randomly selected Abbott Confirm Rx devices with 90+ days of remote transmission history was performed, regardless of transmission frequency, and all EGMs were adjudicated as either true or false positive (TP, FP). Up to 3 EGMs per day per arrhythmia type were prioritized for review based on ventricular rate and episode duration, with rules specific to each arrhythmia type: atrial fibrillation (AF), tachycardia, bradycardia, and pause. The resulting reduction in EGM review burden and TP days (patient-days with at least 1 TP EGM), as well as any diagnostic delay from the first transmitted TP, were calculated relative to reviewing all transmitted EGMs. Results In this population and transmission period, at least one AF, tachycardia, bradycardia, and pause EGM was transmitted by 424, 343, 190, and 325 unique devices, respectively, with a total of 35,723, 12,239, 19,752, and 28,002 EGMs, and a total of 6,163, 1,572, 1,438, and 646 TP days. For these patients with ≥1 EGM, the median [IQR] EGM transmission rate was 2.6 [0.7, 11.6], 1.1 [0.4, 4.7], 2.1 [0.6, 10.7], and 3.4 [0.6, 29.9] EGMs/patient/month, respectively. The optimal EGM selection strategy reduced this EGM review burden by 43%, 67%, 76%, and 50%, while only missing 3.4%, 2.2%, 0.3%, and 0.2% of TP days, respectively. Ultimately, 97%, 99%, 99%, and 99% of devices with a TP AF, tachycardia, bradycardia, or pause EGM exhibited no diagnostic delay vs. reviewing all transmitted EGMs. Conclusion EGM prioritization rules for selecting up to 3 episodes/day significantly reduced EGM burden across all patients, not just "frequent fliers," with no delay-to-diagnosis in >97% of patients who exhibited a true arrhythmia. Implementing these rules on the patient care network may improve clinical workflow and ICM patient management. Abstract Figure.

Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Medtronic Background Remote monitoring is guideline-recommended to manage cardiac implantable electronic device (CIED) patients. With the continuous growth of implanted patients, clinic workload to review transmissions is increasing. Outsourcing initial data review and triage to an external monitoring center could be a valuable option for more efficient allocation of staff time, as high-skilled healthcare professionals can focus on patients in need rather than non-actionable data. Purpose The objective was to estimate the potential clinic staff time saved when outsourcing part of remote transmission review. Methods A previous time and motion evaluation described workflow tasks and time required for remote transmission review (4 EU sites, 674 observations). From real-world experience with a third-party monitoring service, the steps that can be outsourced were determined considering existing clinic-driven protocols for triage and transmission escalation. Staff time required with and without the monitoring service was thus modeled and compared. Results Outsourcing to an external monitoring center can reduce clinic staff time between 77.4% and 84.7% depending on device type. Absolute time savings range from 32.7 to 82.6 hours per year per 100 patients for therapeutic devices, and 301.3 hours for insertable cardiac monitor (ICM) patients, due to the higher frequency of transmissions in diagnostic devices. Conclusion Time to review remote transmissions can become overwhelming for clinics as growing CIED population often outpaces available staffing resources. Outsourcing initial review and triage to an external monitoring center (ensuring quality and regulatory compliance) can be an efficient option to save dedicated staff and facility time for other crucial healthcare activities. Clinic Staff Time Savings Per YearPacemakerICDCRTICMTRANSMISSIONS PER PATIENT PER YEARGreen (no further review required when outsourcing)3.04.35.020.8Yellow/Red (medical action/decision required)0.60.80.93.8ANNUAL STAFF TIME PER PATIENT, minutesNo outsourcing25.346.658.5219.7Outsourcing to monitoring center5.77.78.938.9ANNUAL STAFF TIME PER 100 PATIENTS, hoursNo outsourcing42.277.697.4366.2Outsourcing to monitoring center9.612.914.964.8TIME SAVED PER 100 PATIENTS, hours (%)32.7 (77.4%)64.7 (83.4%)82.6 (84.7%)301.3 (82.3%)Abstract Figure. Outsourcing Remote Transmission Review

Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Biotronik SE & Co.KG OnBehalf BIO|CONCEPT.BIOMONITOR III study group, BIO|MASTER.BIOMONITOR III study group, BIO|STREAM-ICM study group Background Implantable Cardiac Monitors (ICM) provide continuous long-term heart rhythm monitoring. The new ICM BIOMONITOR III / IIIm (BM III) is provided with a single-step insertion tool. Purpose To report on the insertion procedure of the BM III in a large real-world patient population. Methods The BM III combines a low cross-section (4.5 x 8.5 mm) with an extended ICM length (77 mm, including flexible antenna). It is inserted into subcutaneous tissue with an ‘injection’ tool that forms the pocket and delivers the device in a single step. We report results of the insertion procedure from a pooled data set from the BIO|CONCEPT BM III (completed) and the BIO|MASTER BM III and BIO|STREAM-ICM (ongoing) studies. Results From 54 investigational sites in 11 countries, 455 insertions were reported (including 39 BM IIIm). The patients were 63 ± 16 years old, had a BMI of 27.6 ± 5.4, and 43% were women. The indications were syncope or pre-syncope (57%), cryptogenic stroke (23%), management of AF (11%) or other (9%). Insertions took 1.7 ± 1.8 minutes until removal of the insertion tool, 4.7 ± 3.4 minutes until wound closure, and 7.1 ± 5.6 minutes including wound cleaning. The wound was sutured (79%) or closed with staples (10%) or adhesive strips (10%). General anaesthesia was used in 8% of the patients and antibiotic prophylaxis in 50% (44% systemic and 6% local). Insertions took place in the catheter laboratory (62%), operating theatre (22%) or in a consultation room (16%) without specific precautional equipment. The insertion site was parallel to the heart"s long axis (56%), parasternal (39%), in the 2nd/3rd intercostal space (3.5%), axillary (0.9%) or at the clavicula (0.7%). The device was repositioned in one case (0.2%). 13 adverse events were reported in connection to the insertion procedure. 5 cases of device pocket bleeding or hematoma occurred. In 5 further cases, the device migrated, posing the risk of extrusion, or actually extruded. Three of these cases used only adhesive strips or no wound closure at all. In two cases, an incorrect usage of the incision tool and substantial subcutaneous fatty tissue may have contributed. One device was damaged by a 200 J defibrillation shock with a shock electrode placed over the device. One patient suffered from dyspnoea, possibly due to psychogenic hyperventilation. One patient had a vasovagal syncope due to pain after an insertion with insufficient local anaesthesia. No infections were reported until the day of analysis, which was more than 30 days after insertion in 92% of all cases. Conclusion The new BM III was inserted in typically less than 5 minutes until wound closure. A relevant number of insertions took place in a consultation room. Prophylactic antibiotics may be unnecessary, because no pocket infections were reported, although no antibiotic prophylaxis was used in one half of all cases (N = 229). In summary, the insertion with the new tool is fast and has a low risk of complications.

Background: Emergency care is an essential part of a health system. Ecuador has recognized emergency medicine as a specialty and has two emergency medicine residency training programs. However, little has been published about emergency department characteristics and capabilities in Ecuador. Objective: We described the characteristics and capabilities of emergency departments (EDs) in Quito, Ecuador, in 2017, using the National Emergency Department Inventory (NEDI) survey. Methods: The 23-item survey included questions pertaining to ED characteristics, including: visit volume, physical and administrative structure, clinical capabilities, technological resources, and consult personnel availability. This study included all EDs in Quito operating 24 hours/day, 7 days/week, and serving all patients seeking care. One representative from each ED was asked to complete the survey based on calendar year 2017. Findings: Thirty EDs met the inclusion criteria, and 26 completed the survey (87% response). The median number of ED beds was 17 (range 2–61). Median annual visit volume was 22,580 (range 1,680 to 129,676). All but two EDs provided care for both children and adults. Cardiac monitors were available in 88% of EDs, CT scanners in 68%, and rooms for respiratory isolation in 31%. Most EDs could manage patients with general medicine (92%), general surgery (92%), and gynecology (88%) emergencies 24/7. Fewer were able to provide hand surgery (45%) and dental (28%) care 24/7. Typical length of stay was 1–6 hours in 65% and >6 hours in 31% of EDs. Half of EDs reported operating at full capacity and 27% reported operating over their capacity. When compared to private EDs, government EDs (public and social security) had a higher mean number of visits per year (50,090 government vs. 13,968 private, p < 0.001), higher mean number of ED beds (36 government vs. 9 private, p = 0.002), and higher length of stay (58% of patient stays > 6 hours in government EDs vs. 86% of patient stays 1–6 hours in private EDs, p = 0.009). Conclusions: EDs in Quito varied widely with respect to annual visit volume, ability to treat different pathologies 24/7, and resources. Most EDs are functioning at or over capacity, and a substantial number have long lengths of stay. Further research and investment in emergency care could help increase the capacity and efficiency of EDs in Ecuador.

While previous generations of insertable cardiac monitors (ICMs) required a bedside monitor for remote monitoring (RM), the Confirm Rx™ ICM (Abbott, Chicago, IL, USA) utilizes Bluetooth®, Wi-Fi/cellular technology, and a smart device to connect to the RM system. We aimed to characterize compliance, connectivity, and event transmission timing with the Confirm Rx™ ICM RM system. The study cohort included American patients who received the Confirm Rx™ ICM with SharpSense™ technology within three months of release (May-July 2019). Compliance with RM was quantified as the proportion of patients registering the patient app on their smart device and transmitting at least once. Connectivity was measured as the median number of days between consecutive transmissions per patient. Event transmission time was measured from episode detection to availability on the Merlin.net™ RM system (Abbott). Time from transmission until review by a clinician was examined. Values for device connectivity, episode transmission timing, and clinician view times were reported as median [first quartile, third quartile]. Of 5,666 patients who received a Confirm Rx™ ICM, 97% registered their patient app and 92% transmitted data at least once. Among those utilizing RM (aged 66 ± 15 years; 49% female), connectivity occurred every 1.5 [1.2, 2.4] days, or 4.7 times per week. Patient-reported symptoms were transmitted to Merlin.net™ within 2.9 [2.1, 3.8] minutes of event onset and viewed by the clinician within 0.9 [0.4, 3.1] days, while device-detected episodes without symptoms were transmitted within 18.5 [11.2, 36.5] hours and then viewed within 0.8 [0.3, 2.5] days. This real-world study demonstrated excellent patient compliance with the smartphone-based RM paradigm enabled by Confirm Rx™, suggesting the suitability of this technology for future cardiac implantable devices.

Title: Diagnostic Accuracy and Safety of Confirm RxTM Insertable Cardiac Monitor in Pediatric Patients Purpose: ICMs are efficacious in establishing symptom-rhythm correlation in cases of infrequent and unpredictable symptoms. Confirm RxTM devices recently were upgraded with SharpSenseTM – an algorithm for detecting arrhythmias. The purpose of this study is to assess the diagnostic capabilities of the Confirm RxTM device pre- and post-implementation of SharpSenseTM, …

Purpose Electrical artefacts are frequent in implantable cardiac monitors (ICMs). We analyzed the subcutaneous electrogram (sECG) provided by an ICM with a long sensing vector and factors potentially affecting its quality. Methods Consecutive ICM recipients underwent a follow‐up where demographics, body mass index (BMI), implant location, and surface ECG were collected. The sECG was then analyzed in terms of R‐wave amplitude and P‐wave visibility. Results A total of 84 patients (43% female, median age 68 [58‐76] years) were enrolled at 3 sites. ICMs were positioned with intermediate inclination (n = 44, 52%), parallel (n = 35, 43%), or perpendicular (n = 5, 6%) to the sternum. The median R‐wave amplitude was 1.10 (0.72‐1.48) mV with P waves readily visible in 69.2% (95% confidence interval, CI: 57.8%‐79.2%), partially visible in 23.1% [95% CI: 14.3%‐34.0%], and never visible in 7.7% [95% CI: 2.9%‐16.0%] of patients. Men had higher R‐wave amplitudes compared to women (1.40 [0.96‐1.80] mV vs 1.00 [0.60‐1.20] mV, P = .001), while obese people tended to have lower values (0.80 [0.62‐1.28] mV vs 1.10 [0.90‐1.50] mV, P = .074). The P‐wave visibility reached 86.2% [95% CI: 68.3%‐96.1%] in patients with high‐voltage P waves (≥0.2 mV) at surface ECG. The sECG quality was not affected by implant site. Conclusion In ordinary clinical practice, ICMs with long sensing vector provided median R‐wave amplitude above 1 mV and reliable P‐wave visibility of nearly 70%, regardless of the position of the device. Women and obese patients showed lower but still very good signal quality., Electrical artefacts are frequent in implantable cardiac monitors (ICMs). We analysed the subcutaneous electrogram (sECG) provided by an ICM with a long sensing vector and factors potentially affecting its quality. In ordinary clinical practice, ICMs with long sensing vector provided median R wave amplitude above 1 mV and reliable P wave visibility of nearly 70%, regardless of the position of the device. Women and obese patients showed lower but still very good signal quality.

Introduction: African American (AA) patients have a higher incidence of stroke but lower prevalence of atrial fibrillation (AF). Studies involving long term monitoring with implantable cardiac monitors (ICM) for AF after cryptogenic stroke are limited by the under-representation of the AA population. Objective: We sought to assess racial differences in the diagnosis of AF by implantable cardiac monitors in patients with cryptogenic stroke. Methods: We performed a retrospective chart review study at Methodist University Hospital, University of Tennessee Health Science Center, Memphis TN. We included patients with cryptogenic stroke who received an ICM from September 2014 to June 2019 to assess for AF. Race and additional demographic characteristics were obtained from the electronic medical records. Interrogation reports from the ICMs were obtained by remote monitoring as well as clinic visits. Fisher exact and student t test were used to compare demographic data as well as the incidence of AF in these patients. Results: A total of 219 patients with cryptogenic stroke who underwent ICM implantation were included, of which 129 (58.9%) were AA. In the AA cohort, the patients were significantly younger than (62.3 versus 65.8 years; p =0.04) and had a significantly higher prevalence of hypertension (92.2% versus 68.5%; p p =0.04). Upon a mean follow up of 10.6 months, a total of 39 patients (17.8%) were diagnosed with AF on ICM monitoring. The mean time to the incidence of AF was 7.4 months. There was no significant difference in the incidence of AF in the AA population (17.8%) as compared to the rest of the population (17.8%) ( p =1.00). Conclusion: In this single center study of patients with cryptogenic stroke who underwent long term monitoring with ICM, there was no significant difference in the incidence of AF between AA and the rest of the population. We conclude that ICM’s have an equally important role in AF detection in AA patients as in the general population with cryptogenic stroke.

Introduction: Although implantable cardiac monitors (ICM) improve atrial fibrillation (AF) detection relative to Holters or other extended ambulatory cardiac monitors (EACMs) (e.g., 30-day event monitors or outpatient telemetry) in clinical trials, data are limited on their performance in the community setting. We investigated AF detection in ischemic stroke patients and subsequent initiation of oral anticoagulation (OAC) in a real-world setting. Methods: We identified patients with ischemic stroke (2010-2015) in IBM MarketScan, a national prospectively acquired data set in whom Holters, EACMs, or ICMs were ordered. We further selected patients with no prior history of AF or OAC and continuous database enrollment 6 mos pre- and 24 mos post monitoring. Propensity score matching (PSM) was used to adjust for baseline characteristics differences between monitoring types. Logrank test was used to compare the Kaplan-Meier (KM) curves for AF detection and OAC initiation in patients with AF. Results: A total of 6,287 patients were analyzed: 4,107 Holter (age 63±14 yrs, 46% female, 28% coronary artery disease [CAD], 71% hypertension [HTN]), 1,829 EACM (age 61±14 yrs, 49% female, 27% CAD, 73% HTN), and 351 implanted with ICM (age 63±13 yrs, 51% female, 38% CAD, 82% HTN). After 1:1 PSM, the Holter-ICM cohort comprised of 664 patients and the EACM-ICM cohort comprised of 676 patients. In the Holter-ICM pair, 2 yr AF diagnoses rate was 14.5% for Holter vs 38.3% for ICM (logrank p Conclusion: In community patients with ischemic stroke with no history of AF or prior OAC, rates of OAC initiation are comparable between monitoring types when AF is detected, and ICM outperforms Holter and EACM for the detection of AF.

Intro: Tools for baseline prediction of catheter ablation outcome are instrumental to treatment management that best balances positive outcomes against risk of treatment complications. To date, many such predictive models exist in the literature; yet, it is unclear which should be adopted as no study has compared all using a single dataset. Goals: examine 8 published models using a single dataset with expert-annotated data recorded by implanted monitors. Methods: We collected data from a cohort of ~350, acquired from a randomized clinical trial blinded to ablation outcome. Based on a 2020 review, we shortlisted 12 models for baseline prediction of recurrences recorded between days 91-365 post ablation per standard. Models that use postoperative data, thus unsuited for baseline prediction, were excluded. Four models were further dropped from this work as their required variables (e.g. normalized atrial area) are unavailable in our cohort. Results: There was no missing variable; 34% were female and 53% of patients experienced recurrence. Figure reports each model’s performance with metrics as sensitivity (SEN), specificity (SPEC), positive predictive value (PPV), negative predictive value (NPV), area under receiver operating characteristic curve (AUC), positive and negative clinical utility indices (SENxPPV; SPECxNPV, resp.). The digit after each model name indicates the cut-off used (some studies used different cut-offs). Models are presented in rank-order by utility indices. All evaluated scores achieved AUC Conclusions: Our results reinforce statements of previous reviews that many published models are lacking and that there remains a need to develop and validate models for prediction of AFR post ablation.

Introduction: Insertable Cardiac Monitors (ICM) aid in the diagnosis and monitoring of arrhythmias, however, reviewing the data is labor intensive and time consuming. Hypothesis: We hypothesized that new algorithms (ALG) and indication tailored programming (ITP) could reduce device-based alerts and clinician review time. Methods: Baseline data was obtained from a real-world de-identified Reveal LINQ TruRhythm ICMs database. The arrhythmia alerts and manual transmissions per patient/month was queried in this Control Group of patients with ≥3 months of follow-up. The effect of ALG and ITP was computed and applied to the Control Group. For practical purposes, the results were extrapolated to a 200 ICM clinic. Annualized clinic review time was estimated by assuming the staff time per transmission was 12.9 min., based on prior study. ALG improvements included: 1) Reject noise, loss of contact, and small R-waves for Pauses, 2) Require rapid onset for Tachy, 3) Limit nighttime episodes for Brady, and 4) Eliminate manual patient transmissions. ITP changes included: 1) Patients without Syncope: Pause ≥ 5 sec., Brady ≥ 12 beats and not during night, 2) Patients for AF Monitoring: AF ≥ 6 min. Results: The dataset consisted of 248,603 ICMs inserted for Syncope (36%), AF Diagnosis (35%), AF Monitoring (17%), and Other (12%) with an avg. of 1.1 years of follow-up (total 265,938 yrs). Applied to a 200 ICM clinic size, ALG and ITP reduced arrhythmia alerts by 32% (Control: 2,445 to ALG and ITP: 1,655 per clinic/yr). Using the new data transmission scheme eliminated 360 manual transmissions per clinic/yr.(Panel A) In total, the projected annual transmission volume (alerts + manuals in Panel A) and corresponding clinic review time (Panel B) dropped by 41% (247 hrs/yr = 13.1% full-time employee). Conclusion: Improved ALG and ITP can significantly reduce the volume of ICM alerts and consequently clinician review time impacting the management efficiency of this patient population.

Background P-wave visibility is useful for diagnosis of atrial arrhythmias via insertable cardiac monitors (ICM). Purpose To compare the sensing capability of ICM with different vector length: Medtronic REVEAL LINQ (45mm) vs. Biotronik Biomonitor BMIII (75mm). Methods We accessed de-identified remote monitoring transmissions from n=40 patients with BMIII from Biotronik for comparison with n=80 gender- and body mass index (BMI)-matched patients with REVEAL LINQ. Digital measurement of calibrated ICM electrograms was performed using DigitizeIt© (V2.3.3, Germany) of 5 consecutive P-QRS complexes by 3 investigators independently. P-wave amplitude was measured from baseline to peak and R-wave amplitude was measured from peak-to-peak. Further, we evaluated the impact of BMI on P-wave visibility. Results Patients in both groups are well matched for gender and BMI (53% male, mean BMI 26.7 kg/m2; both p=NS). P-wave and R-wave amplitude were 89% & 20% larger in the BMIII vs. LINQ (0.072±0.039 vs. 0.038±0.022mV, p=0.0001; & 0.83±0.42 vs. 0.69±0.45mV, p=0.095 respectively; Figure). Consequently, the P/R-wave ratio was 44% greater for the BMIII (p=0.002). Multivariate regression analysis showed that increasing BMI, female gender and LINQ were independently associated with lower P-wave amplitude (all P Conclusion The longer ICM sensing vector of BMIII yielded considerable larger P-wave amplitude than LINQ, that was not impacted by increasing BMI. Better P-wave visibility may improve clinical decision-making after device-detected arrhythmias while further studies are needed to determine its impact on clinical outcomes. P-wave visibility comparison of ICMs Funding Acknowledgement Type of funding source: None

Background Atrial fibrillation (AF) is a well-known risk factor for ischemic stroke with a reported increased incidence range of 2.5 to 5-fold. However, it is not well established whether treatment of cryptogenic stroke patients with AF detected by insertable cardiac monitors (ICM) reduces the risk of recurrent stroke. Objective To compare recurrent stroke rates between cryptogenic stroke patients who have AF detected by ICMs and thus started on oral anticoagulation (OAC) treatment and those without detected AF. Methods We performed a retrospective analysis of consecutive patients who received an ICM for the purpose of AF monitoring following a cryptogenic stroke between July 2015 and March 2019. Patients with prior documented AF history were excluded. We calculated the rates of AF detection and OAC initiation. We also compared recurrent stroke rates between patients with and without AF detected. Results A total of 298 cryptogenic stroke patients receiving an ICM and home remote monitoring were studied (mean age: 77 SD: 11.7; Female/Male: 147 (49%)/151; virtual CHA2DS2-VASc: 4.96 SD: 1.28). AF was newly detected in 91 (29.6%) patients over a mean follow-up of 46 months. Of these patients 68 (72.4%) were started on OAC, 12 (15.3%) were already on OAC and 11 (12.2%) remained not anticoagulated. Of the total patients evaluated, 22 patients (7.3%) developed recurrent strokes for an annualized stroke rate of 1.926%. Of those, 8 occurred among the 91 patients with newly detected AF, for an annualized stroke rate of 1.72%. The remining 14 recurrent strokes occurred among the 207 patients without AF detected, for an annualized stroke rate of 1.76%; (p=0.87). One recurrent stroke occurred in an AF patient not anticoagulated due to a prior bleeding event. No hemorrhagic strokes were reported in the AF-OAC group. Conclusion Our study found that newly AF was detected by ICM in almost 1/3 (29%) of cryptogenic stroke patients (consistent with previous studies), and the vast majority of them (88%) accordingly received oral anticoagulation. There was not a significant difference in recurrent stroke rates among patients with AF detected on OAC and those without AF detected. This suggests that rigorous arrhythmia monitoring with ICMs can help identify cryptogenic stroke patients with new AF and initiate oral anticoagulation accordingly, to reduce their risk of recurrent stroke to background levels. Annualized Stroke Risk Funding Acknowledgement Type of funding source: None

Background/Introduction The primary goal of monitoring for atrial fibrillation (AF) after cryptogenic stroke (CS) is secondary stroke prevention. Therefore, long-term monitoring of CS patients with insertable cardiac monitors (ICMs) is likely important to ensure appropriate secondary stroke prevention therapy, regardless of when AF is detected after the index event. However, long-term data on the incidence and duration of AF from real-world populations are sparse. Purpose To investigate the long-term incidence and duration of AF episodes in real-world clinical practice among a large population of patients with ICMs placed for AF detection following CS. Methods We included patients from a large device manufacturer's database who received an ICM for the purpose of AF detection following CS and were monitored for up to 3 years. All detected AF episodes (≥2 minutes) were adjudicated. We quantified the AF detection rate for various episode duration thresholds using Kaplan-Meier survival estimates, analyzed the maximum duration of AF episodes, and measured the time to initial AF detection. Results A total of 1247 patients (65.3±13.0 years, 53% male) were included and followed for 763±362 days. AF episodes (n=5456) were detected in 257 patients, resulting in a median frequency of 5 episodes [IQR 2–19] per patient. At 3 years, the AF detection rate for episodes ≥2 minutes was 24.2%. The AF detection rates at 3 years for episodes ≥6 minutes, ≥30 minutes, and ≥1 hour were 22.4%, 20.6%, and 19.1%, respectively. The median duration of the longest detected AF episode was 4.4 [IQR 1.2–13.9] hours and the median time to AF detection was 129 [IQR 45–354] days. Conclusion AF episodes were detected via ICMs in approximately one-quarter of CS patients within 3 years of follow-up. More than 75% of patients with AF detected had episodes lasting ≥1 hour and half had episodes lasting ≥4 hours. Detection of the first AF episode typically occurred beyond the range of conventional ambulatory monitors. Long-term surveillance of CS patients is likely important given the appreciable incidence, frequency, and duration of these AF episodes. Funding Acknowledgement Type of funding source: None

Background The population with cardiac implantable electronic devices (CIEDs) is growing, creating workload for device clinics to manage these patients. However, the CIED follow-up workflow is poorly understood. This study sought to characterize the workflow and staff time for CIED patient management. Methods A time and motion workflow evaluation was performed in 6 U.S. CIED clinics, which manage an average of 4,217 patients. Each task involved in CIED management was repeatedly timed, including all manufacturers, during 1 business week at each clinic. Mean staff time for a remote transmission and an in-person visit were calculated, including all clinical and administrative (e.g: scheduling, documentation) activities related to the encounter. Annual staff time for follow-up of 1 patient was modeled using CIED transmission data for the 6 clinics, guidelines for CIED follow-up, and published literature. Results 124 clinic visits and 1,374 remote monitoring activities were observed. Staff time required per remote transmission ranged from 12.1–13.4 minutes (depending on the CIED type), and time per visit was 43.4–51.0 minutes. Including all remote and in-person follow-ups, the estimated total staff time per year to manage one pacemaker, ICD, CRT, and ICM patient was 2.3, 2.4, 2.4, and 9.3 hours, respectively (Table 1). Conclusion CIED clinic workflow is complex and requires significant staff time. Remote monitoring is an efficient complement to in-office visits, allowing for continuous follow-up of patients. Future research should examine heterogeneity in clinic processes to identify the most efficient workflow. Funding Acknowledgement Type of funding source: Private company. Main funding source(s): Medtronic

Background Hypertrophic cardiomyopathy (HCM) is a heterogeneous disease associated with arrhythmias. Non‐sustained ventricular tachycardia (NSVT) is a risk factor for sudden cardiac death and part of the current risk stratification. Furthermore, atrial fibrillation (AF), which increases the risk of stroke, is believed to be common in HCM patients. Routine ambulatory monitoring captures the rhythm only periodically over 24–48 h; thus, the true burden of arrhythmia is unknown. The insertable cardiac monitor (ICM) should help determine a more realistic arrhythmia assessment in HCM patients. Objective The purpose of this study was to ascertain the incidence of NSVT, AF, and bradycardia in unselected HCM patients by the use of an ICM. Methods Thirty adults, mean age 49.9 ± 12.3 years, 25 (83.3%) males were implanted with a Confirm Rx ICM. The monitoring application was installed on the patient's smartphone, which allowed for patient activation in case of symptoms. The ICM was programmed as follows: ventricular tachycardia (VT) ≥ 160 beats per minute (bpm) for ≥8 intervals, AF ≥ 2 min of duration, and bradycardia ≤ 40 bpm or pause ≥ 3.0 s. Results The mean calculated 5‐year risk was 2.3%, and 29/30 of the patients had a risk

OnBehalf 1.Department of Cardiology, Ghent University Hospital, Ghent, Belgium Introduction Insertable cardiac monitors (ICM) allow automatic arrhythmia detection but the diagnostic performance can be hampered by poor R-wave sensing leading to false positive recordings. Purpose This study assesses the prevalence and predictors of R-wave under- and oversensing among different ICM types. Methods Patients implanted with an ICM at the University Hospital of Ghent between January 2017 and August 2018 were included. All ICM tracings recorded at ICM interrogation or transmitted by remote monitoring were reviewed for inadequate R-wave sensing leading to false arrhythmia alerts. Inadequate R wave sensing was defined as undersensing due to sudden reduction in R wave amplitude or oversensing due to the occurrence of artefacts. Patient and implant characteristics were retrieved from the medical record and implant reports. Results The study screened 135 patients (age 59 ± 19 years, 44% female) implanted with different ICM types: Reveal XT and LINQ n = 92 (68%), Confirm and Confirm Rx n = 35 (26%), BioMonitor n = 8 (6%). ICM analysis was conducted in 112 patients (83%). Overall, false arrhythmia alerts due to inadequate R wave sensing occurred in 22 (20%) of the patients. Among these 22 patients, false diagnosis of bradycardia or pauses were documented in 64%, false high ventricular rates in 14% and false atrial fibrillation alerts in 22% of the patients. Of interest, in an additional 7 (6%) patients significant changes in R wave sensing occurred, although not causing false arrhythmic alerts. Occurrence of R-wave changes occurred in 19% of Reveal, 17% of Confirm and 50% of BioMonitor ICMs (p = not significant). Occurrence of R-wave changes among the different types of ICMs were not related to age, sex, BMI, time of the day, heart frequency or implant R-wave sensing. Conclusion Poor R wave sensing, leading to false arrhythmia detection, occurred in a significant number of ICM, and seems to occur independent of ICM type, patient or implant characteristics. Abstract Figure.

Atrial fibrillation is a leading cause of ischemic stroke. Stroke risk can be reduced with oral anticoagulation. Current guidelines recommend that decisions regarding anticoagulation after ablation be based solely on preprocedural risk. Factors that favor stopping oral anticoagulationafter atrial fibrillation ablation include lower CHA2DS2-VASc score, lesser extent of atrial cardiopathy as defined by atrial size, and fibrosis and higher bleeding risk. More extensive monitoring with insertable cardiac monitors, smart devices, and frequent pulse checks provide greater sensitivity for recurrence. The authors' strategy for managing oral anticoagulation after atrial fibrillation ablation is provided.

Background: Diagnosing cardiac pauses that could produce syncopal episodes is clinically important to guide appropriate therapy. However, the infrequent nature of these episodes can make their detection a challenge with conventional monitoring (CM) strategies with short-term ECG monitors. We simulated several CM strategies and analyzed the sensitivity to diagnose patients with pause arrhythmias compared to continuous monitoring with an insertable cardiac monitor (ICM). Methods: CM was simulated from syncope patients’ ICM data by assuming the 1st detected true pause episode (≥5s) was symptomatic and prompted further evaluation. Based on published literature, 32% of patients were assumed to be admitted for 3 days of inpatient monitoring followed by CM of varying durations (24 or 48 hrs, and 14, 30 or 60 days) beginning at random within the next week; the other 68% were assumed to be discharged home, with CM of varying durations beginning at random within the next week. Subsequent true pause episodes in patients remaining undiagnosed with CM triggered additional rounds of CM, with simulations repeated 1,000 times. Longer pause definitions of ≥6-8s were also evaluated. ECG diagnosis was considered successful if a pause episode occurred simultaneous to CM. Results: A total of 105 true pause episodes from 44 patients (mean±SD age 66±17, 48% male) were detected by ICM, during 505±333 days of continuous follow-up. Patients experienced an average of 2.4±2.7 pause episodes ≥5s during follow-up. Relative to ICM-diagnosed patients, the mean sensitivity of CM to capture an ECG diagnosis for these pause episodes during follow-up ranged from 13.8% (on average, 6.1 of 44 patients) with 24-hr holter to 30.2% with two 30-day monitors (13.3 of 44 patients) (Figure). Sensitivity further decreased for pause durations of ≥6-8s, due to the less frequent occurrence of these episodes and consequently lower likelihood of capture with CM. Average days of follow-up without a diagnosis was 109 days with ICM versus a range of 384-452 days with CM modalities. Conclusion: Of syncope patients diagnosed with pause arrhythmias via ICM, the vast majority would go undiagnosed via CM strategies and therefore may not be optimally managed for syncope prevention. The cost-effectiveness of these strategies requires further study.

Atrial fibrillation (AF) has been associated with increased morbidity and mortality, even when symptoms are absent and the arrhythmia is unrecognized (e.g., subclinical AF [SCAF]). Despite substantial evidence demonstrating an association between AF and adverse outcomes, the role of mass screening for previously unrecognized SCAF, such that its individual and population risks may be reduced by prophylactic therapy, remains uncertain. Many AF screening strategies exist, from pulse palpation and single-use devices to implanted cardiac monitors; however, existing guidelines are insufficient in specifying who to screen and for how long. In general, higher age, more (and more severe) comorbidities, and longer monitoring periods are associated with greater detection of SCAF. Herein we review the significance of previously unrecognized SCAF and current status of SCAF detection methods. We then propose a clinical approach to help clinicians incorporate AF screening into their practice. In conclusion, we report that SCAF may not be rare, that inserted cardiac monitors have the highest yield of SCAF detection, that clinical concern regarding SCAF is appropriate, but that evidence for therapy mandates is still being collected.

The incidence of atrial fibrillation (AF) in cryptogenic stroke (CS) patients has been studied in carefully controlled clinical trials, but real-world data are limited. We investigated the incidence of AF in clinical practice among CS patients with an insertable cardiac monitor (ICM) placed for AF detection. Patients with CS admitted to our Stroke Unit were included in the study; they received an ICM and were monitored for up to 3 years for AF detection. All detected AF episodes of at least 120 sec were considered. From March 2016 to March 2019, 58 patients (mean age 68.1 ± 9.3 years, 67% male) received an ICM to detect AF after a CS. No patients were lost to follow-up. AF was detected in 24 patients (41%, AF group mean age 70.8 ± 9.4 years, 62% male) after a mean time of 6 months from ICM (ranging from 2 days to 2 years) and 8 months after CS (ranging from 1 month to 2 years). In these AF patients, anticoagulant treatment was prescribed and nobody had a further stroke. In conclusion, AF episodes were detected via continuous monitoring with ICMs in 41% of implanted CS patients. AF in CS patients is asymptomatic and difficult to diagnose by strategies based on intermittent short-term recordings. Therefore, we suggest that ICMs should be part of daily practice in the evaluation of CS patients.

Introduction Implantable cardiac monitor (ICM) is an established tool for the management of unexplained syncope and atrial fibrillation (AF) even if its accuracy of arrhythmia detection may be suboptimal. The aim of this study was to perform an intra-patient comparison of the diagnostic capability of ICM with a dual-chamber PM as a gold standard. Methods We included 19 patients with a previously implanted ICM (BioMonitor 2 Biotronik, Berlin, Germany), who received a dual-chamber PM for standard indications. ICM-detected arrhythmic events in a 6-month follow-up were compared with those detected by the PM and classified by visual inspection of intracardiac electrograms. Results During follow up, ICMs generated 15 false asystole and 39 false bradycardia detections in 5 patients (26.3%) due to recurrent premature ventricular contractions. A total of 34 true high ventricular rate (HVR) episodes were detected by the PM. Of them, 30 (88%) events were also recorded by the ICM, which further detected 14 false HVR snapshots, leading to a sensitivity and positive predictive value of 88% and 68%, respectively. In addition, PM identified 234 true AF episodes. Of them, 225 (96%) events were also detected by the ICM, while 8 (42%) ICMs stored 50 AF episodes classified as false positives. The ICM sensitivity for AF was 96% with a positive predictive value of 82%. Conclusion Our intra-patient comparison with permanent PM confirmed that ICM is an effective tool for cardiac arrhythmias detection. ICM algorithms for AF and HVR detection were highly sensitive with an acceptable rate of false positive episodes.

Insertable cardiac monitors (ICMs) are small, subcutaneously implanted devices offering continuous ambulatory electrocardiogram monitoring with a lifespan up to 3 years. ICMs have been studied and proven useful in selected cases of unexplained syncope and palpitations, as well as in atrial fibrillation (AF) management. The use of ICMs has greatly improved our ability to detect subclinical AF after cryptogenic stroke, and application of this technology is growing. Despite this, current stroke and cardiology society guidelines are lacking in recommendations for monitoring of subclinical AF following cryptogenic stroke, including the optimal timing from stroke event, duration, and method of electrocardiogram monitoring. This focused review outlines the current society guidelines, summarizes the latest evidence, and describes current and future use of ICMs with an emphasis on detection of subclinical AF in patients with cryptogenic stroke.

Background Prophylactic use of direct oral anticoagulants for recurrent stroke prevention in patients with embolic strokes of undetermined source is currently being investigated. It is uncertain whether the bleeding risks associated with prophylactic direct oral anticoagulants use will outweigh any stroke prevention benefit in embolic strokes of undetermined source patients who lack underlying atrial fibrillation. Methods We determined the proportion of cryptogenic stroke patients in the CRYSTAL atrial fibrillation trial who met inclusion criteria for the NAVIGATE embolic stroke of undetermined source and RE-SPECT embolic stroke of undetermined source trials and their atrial fibrillation incidence. Both embolic strokes of undetermined source trials impose requirements on age, modified Rankin Score, antiplatelet use, and type of infarction. Insertable cardiac monitors were used to determine the atrial fibrillation detection rates at 30 days and 3 years using Kaplan–Meier’s estimates. Results Among 441 patients enrolled in the CRYSTAL atrial fibrillation trial, 189 (42.9%) and 236 (53.5%) met the inclusion criteria of the NAVIGATE embolic stroke of undetermined source and RE-SPECT embolic stroke of undetermined source trials, respectively. Atrial fibrillation detection rates at 3 years among insertable cardiac monitors patients eligible for the NAVIGATE embolic stroke of undetermined source and RE-SPECT embolic stroke of undetermined source trials were 35.8% and 33.6% while detection rates at 30 days were 5.6% and 3.5%, respectively. Conclusion Only half of cryptogenic stroke patients in CRYSTAL atrial fibrillation met the inclusion criteria for the ongoing embolic strokes of undetermined source trials. Approximately, two-thirds of patients with embolic strokes of undetermined source do not have any atrial fibrillation despite continuous rhythm monitoring for up to three years. The benefits of prophylactic use of direct oral anticoagulants in the absence of atrial fibrillation is unknown and therefore embolic strokes of undetermined source patients could benefit from prolonged atrial fibrillation monitoring until more robust data are available. ClinicalTrials.gov Registration NCT00924638. https://clinicaltrials.gov/ct2/show/NCT00924638 .

Background: Insertable cardiac monitors (ICM) allow prolonged rhythm monitoring, but the diagnostic performance can be hampered by false positive arrhythmia alerts related to inadequate R‐wave sensing. This study assesses the prevalence and predictors of inadequate R‐wave sensing (both over‐ and undersensing) among different ICM types. Methods: Patients implanted with an ICM at Ghent University Hospital between January 2017 and August 2018 were included. ICM tracings recorded at interrogation or transmitted by remote monitoring were reviewed for inadequate R‐wave sensing leading to false arrhythmia alerts. Patient and implant characteristics were retrieved from the medical records and implant reports. Results: The study screened 135 patients (age 59 ± 19 years, 44% female) implanted with different ICM types: Reveal LINQ™ and XT (Medtronic): n = 92 (68%), Confirm and Confirm Rx (Abbott): n = 35 (26%), and BioMonitor 2 (Biotronik): n = 8 (6%). ICM tracings were analyzed in 112 patients (83%). False arrhythmia alerts occurred in 22 (20%) patients, most frequently related to undersensing (77%). False diagnosis of bradycardia or pause was documented in 64%, false high ventricular rates in 14%, and false atrial fibrillation alerts in 22%. Occurrence of R‐wave changes was not related to patient characteristics or implant R‐wave sensing. A trend toward higher number of inadequate R‐wave sensing seems to occur with nonparasternal implant sites (P = .074). Conclusions: False arrhythmia alerts due to inadequate R‐wave sensing occurred in 20% of ICM patients independent of implant features and patient characteristics.

When black bears cross roads, their HRs increase, indicating heightened alertness to danger. Wildlife reacts to roads in various ways, but it is unknown whether road crossings are stressful. We monitored black bears with cardiac monitors and GPS-collars in Minnesota. On average, bears crossed a road once a day; their HRs increased when 100 m away, and increased more with higher traffic volume, but not enough to suggest roadway interactions were highly stressful.

Implantable cardiac monitors (ICMs) are useful for long-term arrhythmia monitoring in patients with unexplained symptoms. Temporal trends in the use of ICMs in routine clinical practice, a...