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.

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.

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.

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.

Implantable loop recorder detection of atrial fibrillation to prevent stroke (The LOOP Study): a randomised controlled trial.

BACKGROUND: It is unknown whether screening for atrial fibrillation and subsequent treatment with anticoagulants if atrial fibrillation is detected can prevent stroke. Continuous electrocardiographic monitoring using an implantable loop recorder (ILR) can facilitate detection of asymptomatic atrial fibrillation episodes. We aimed to investigate whether atrial fibrillation screening and use of anticoagulants can prevent stroke in individuals at high risk. METHODS: We did a randomised controlled trial in four centres in Denmark. We included individuals without atrial fibrillation, aged 70-90 years, with at least one additional stroke risk factor (ie, hypertension, diabetes, previous stroke, or heart failure). Participants were randomly assigned in a 1:3 ratio to ILR monitoring or usual care (control) via an online system in permuted blocks with block sizes of four or eight participants stratified according to centre. In the ILR group, anticoagulation was recommended if atrial fibrillation episodes lasted 6 min or longer. The primary outcome was time to first stroke or systemic arterial embolism. This study is registered with ClinicalTrials.gov, NCT02036450. FINDINGS: From Jan 31, 2014, to May 17, 2016, 6205 individuals were screened for inclusion, of whom 6004 were included and randomly assigned: 1501 (25·0%) to ILR monitoring and 4503 (75·0%) to usual care. Mean age was 74·7 years (SD 4·1), 2837 (47·3%) were women, and 5444 (90·7%) had hypertension. No participants were lost to follow-up. During a median follow-up of 64·5 months (IQR 59·3-69·8), atrial fibrillation was diagnosed in 1027 participants: 477 (31·8%) of 1501 in the ILR group versus 550 (12·2%) of 4503 in the control group (hazard ratio [HR] 3·17 [95% CI 2·81-3·59]; p<0·0001). Oral anticoagulation was initiated in 1036 participants: 445 (29·7%) in the ILR group versus 591 (13·1%) in the control group (HR 2·72 [95% CI 2·41-3·08]; p<0·0001), and the primary outcome occurred in 318 participants (315 stroke, three systemic arterial embolism): 67 (4·5%) in the ILR group versus 251 (5·6%) in the control group (HR 0·80 [95% CI 0·61-1·05]; p=0·11). Major bleeding occurred in 221 participants: 65 (4·3%) in the ILR group versus 156 (3·5%) in the control group (HR 1·26 [95% CI 0·95-1·69]; p=0·11). INTERPRETATION: In individuals with stroke risk factors, ILR screening resulted in a three-times increase in atrial fibrillation detection and anticoagulation initiation but no significant reduction in the risk of stroke or systemic arterial embolism. These findings might imply that not all atrial fibrillation is worth screening for, and not all screen-detected atrial fibrillation merits anticoagulation. FUNDING: Innovation Fund Denmark, The Research Foundation for the Capital Region of Denmark, The Danish Heart Foundation, Aalborg University Talent Management Program, Arvid Nilssons Fond, Skibsreder Per Henriksen, R og Hustrus Fond, The AFFECT-EU Consortium (EU Horizon 2020), Læge Sophus Carl Emil Friis og hustru Olga Doris Friis' Legat, and Medtronic.

Differences in Inpatient Insertable Cardiac Monitor Placement after Ischemic Stroke.

BACKGROUND AND PURPOSE: Cryptogenic stroke accounts for 30% of ischemic stroke and in such patients, cardiac monitoring leads to increased detection of AF, increased utilization of anticoagulation, and decreased risk of recurrent stroke. We aim to identify differences in inpatient utilization of implantable cardiac monitors (ICMs) in patients with ischemic stroke. METHODS: This is an analysis of the National Inpatient Sample. We included all ischemic stroke hospitalizations nation-wide between Jan 1st 2016 and Dec 31st 2018. We excluded patients with history of atrial fibrillation or atrial flutter. We compared survey weighted baseline demographics and characteristics between patients who received an inpatient ICM versus those who didn't using logistic regression models. RESULTS: We identified a weighted total 1,069,395 patients who met the inclusion criteria; 2.2% received an inpatient ICM. In multivariable analyses, factors associated with decreased odds of inpatient ICM placement including Black race (OR 0.76 95% CI 0.68 - 0.84, p < 0.001), residence in a micropolitan area (OR 0.79 95% CI 0.67 - 0.94, p = 0.008), hospital region [Midwest (OR 0.74 95% CI 0.61 - 0.90, p = 0.002), South (OR 0.68 95% CI 0.57 - 0.81, p < 0.001), and West (OR 0.37 95% CI 0.29 - 0.45, p < 0.001)], hospital bed size [small (OR 0.38 95% CI 0.39-0.46, p < 0.001) and medium hospital bed size (OR 0.73 95% CI 0.63 - 0.84, p < 0.001)], insurance status [Medicaid (OR 0.86 95% CI 0.76 - 0.98, p = 0.02) and self-pay (OR 0.51 95% CI 0.41 - 0.62, p < 0.001)], and non-teaching hospital (OR 0.52 95% CI 0.47 - 0.60, p < 0.001). CONCLUSIONS: There are important differences in inpatient ICM placement in patients with ischemic stroke highlighting disparities in inpatient care for patients hospitalized with ischemic stroke. More studies are needed to validate our findings.

Comprehensive Evaluation of Rhythm Monitoring Strategies in Screening for Atrial Fibrillation: Insights From Patients at Risk Monitored Long Term With an Implantable Loop Recorder.

BACKGROUND: Stroke is an increasing health problem worldwide. Atrial fibrillation (AF) is a major risk factor for stroke, and the attention given to AF screening is rising, as new monitoring technologies emerge. We aimed to evaluate the performance of a large panel of screening strategies and to assess population characteristics associated with diagnostic yield. METHODS: Individuals with stroke risk factors but without AF were recruited from the general population to undergo screening with an implantable loop recorder. New-onset AF lasting ≥6 minutes was adjudicated by senior cardiologists. After continuous monitoring for >3 years, complete day-to-day heart rhythm data sets were reconstructed for every participant, including exact time of onset and termination of all AF episodes. Random sampling was applied to assess the sensitivity and negative predictive value of screening with various simulated screening strategies compared with the implantable loop recorder. The diagnostic yield across strategies and population subgroups was compared by use of nonparametric tests. RESULTS: The rhythm data sets comprised 590 participants enduring a total of 659 758 days of continuous monitoring and 20 110 AF episodes. In these data, a single 10-second ECG yielded a sensitivity (and negative predictive value) of 1.5% (66%) for AF detection, increasing to 8.3% (67%) for twice-daily 30-second ECGs during 14 days and to 11% (68%), 13% (68%), 15% (69%), 21% (70%), and 34% (74%) for a single 24-hour, 48-hour, 72-hour, 7-day, or 30-day continuous monitoring, respectively. AF detection further improved when subsequent screenings were performed or when the same monitoring duration was spread over several periods compared with a single period (eg, three 24-hour monitorings versus one 72-hour monitoring; P<0.0001 for all comparisons). The sensitivity was consistently higher among participants with age ≥75 years, male sex, CHADS2 score >2, or NT-proBNP (N-terminal pro-B-type natriuretic peptide) ≥40 pmol/L and among participants with underlying ≥24-hour AF episodes compared with shorter AF (P<0.0001 for all screening strategies). CONCLUSIONS: In screening for AF among participants with stroke risk factors, the diagnostic yield increased with duration, dispersion, and number of screenings, although all strategies had low yield compared with the implantable loop recorder. The sensitivity was higher among participants who were older, were male, or had higher NT-proBNP. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02036450.

Rationale and design of a large population study to validate software for the assessment of atrial fibrillation from data acquired by a consumer tracker or smartwatch: The Fitbit heart study.

BACKGROUND: Early detection of atrial fibrillation or flutter (AF) may enable prevention of downstream morbidity. Consumer wrist-worn wearable technology is capable of detecting AF by identifying irregular pulse waveforms using photoplethysmography (PPG). The validity of PPG-based software algorithms for AF detection requires prospective assessment. METHODS: The Fitbit Heart Study (NCT04380415) is a single-arm remote clinical trial examining the validity of a novel PPG-based software algorithm for detecting AF. The proprietary Fitbit algorithm examines pulse waveform intervals during analyzable periods in which participants are sufficiently stationary. Fitbit consumers with compatible wrist-worn trackers or smartwatches were invited to participate. Enrollment began May 6, 2020 and as of October 1, 2020, 455,699 participants enrolled. Participants in whom an irregular heart rhythm was detected were invited to attend a telehealth visit and eligible participants were then mailed a one-week single lead electrocardiographic (ECG) patch monitor. The primary study objective is to assess the positive predictive value of an irregular heart rhythm detection for AF during the ECG patch monitor period. Additional objectives will examine the validity of irregular pulse tachograms during subsequent heart rhythm detections, self-reported AF diagnoses and treatments, and relations between irregular heart rhythm detections and AF episode duration and time spent in AF. CONCLUSIONS: The Fitbit Heart Study is a large-scale remote clinical trial comprising a unique software algorithm for detection of AF. The study results will provide critical insights into the use of consumer wearable technology for AF detection, and for characterizing the nature of AF episodes detected using consumer-based PPG technology.

Patch monitors for arrhythmia monitoring in patients for suspected inherited arrhythmia syndrome.

INTRODUCTION: Patients undergoing evaluation for an inherited arrhythmia syndrome undertake a series of ambulatory investigations including 24-h Holter monitor, exercise treadmill testing (ETT), and others. Patch monitors may simplify the evaluation, providing accurate arrhythmia evaluation and QT assessment. METHODS AND RESULTS: Patients referred for evaluation of an inherited arrhythmia syndrome underwent standard investigations, including 12-lead electrocardiography (ECG), 24-h Holter monitoring, ETT, along with supplemental monitoring using a 7-day ECG patch monitor. Heart rates (HR), corrected QT intervals (QTc), and ectopic burden were compared across monitoring modalities. Among 35 patients that wore the patch monitor, the median age was 39 years (54% male). There was intermediate correlation between resting HR across modalities (r = .58-.66) and poor correlation of peak HR (r = .27-.39). There was intermediate correlation between resting QTc intervals across modalities (r = .72-.77) but negligible correlation between QTc intervals at peak HR across modalities (r = -.01 to -.06). There was good correlation in PAC and PVC ectopic burden across the Holter and patch monitor. CONCLUSION: Patch monitors may simplify the evaluation of patients for an inherited arrhythmia syndrome and provide resting QT assessment over time. However, QTc interval comparison at peak HRs remains variable, and may be limited by the single-lead ECG vector when using the patch monitor. Apart from QTc intervals at peak HR, patch monitors demonstrated good correlation with the ECG and Holter monitor for other parameters.

Relationship between diabetes mellitus and atrial fibrillation prevalence in the Polish population: a report from the Non-invasive Monitoring for Early Detection of Atrial Fibrillation (NOMED-AF) prospective cross-sectional observational study.

BACKGROUND: The global burden of atrial fibrillation (AF) and diabetes mellitus (DM) is constantly rising, leading to an increasing healthcare burden of stroke. AF often remains undiagnosed due to the occurrence in an asymptomatic, silent form, i.e., silent AF (SAF). The study aims to evaluate the relationships between DM and AF prevalence using a mobile long-term continuous ECG telemonitoring vest in a representative Polish and European population ≥ 65 years for detection of AF, symptomatic or silent. METHODS: A representative sample of 3014 participants from the cross-sectional NOMED-AF study was enrolled in the analyses (mean age 77.5, 49.1% female): 881 (29.2%) were diagnosed with DM. AF was screened using a telemonitoring vest for a mean of 21.9 ± 9.1days. RESULTS: Overall, AF was reported in 680 (22.6%) of the whole study population. AF prevalence was higher among subjects with concomitant DM (DM+) versus those without DM (DM-) [25%, 95% CI 22.5-27.8% vs 17%; 95% CI 15.4-18.5% respectively, p < 0.001]. DM patients were commonly associated with SAF [9%; 95% CI 7.9-11.4 vs 7%; 95% CI 5.6-7.5 respectively, p < 0.001], and persistent/permanent AF [12.2%; 95% CI 10.3-14.3 vs 6.9%; 95% CI 5.9-8.1 respectively, p < 0.001] compared to subjects without DM. The prolonged screening was associated with a higher percentage of newly established AF diagnosis in DM+ vs DM- patients (5% vs 4.5% respectively, p < 0.001). In addition to shared risk factors, DM+ subjects were associated with different AF and SAF independent risk factors compared to DM- individuals, including thyroid disease, peripheral/systemic thromboembolism, hypertension, physical activity and prior percutaneous coronary intervention/coronary artery bypass graft surgery. CONCLUSIONS: AF affects 1 out of 4 subjects with concomitant DM. The higher prevalence of AF and SAF among DM subjects than those without DM highlights the necessity of active AF screening specific AF risk factors assessment amongst the diabetic population. TRIAL REGISTRATION: NCT03243474.

The predictive role of early recurrences of atrial arrhythmias after pulmonary vein cryoballoon ablation. Is blanking period an outdated concept? Insights from 12-month continuous cardiac monitoring.

BACKGROUND: Early recurrences of atrial arrhythmias (ERAA) after atrial fibrillation (AF) catheter ablation do not predict procedural failure. A well-demarcated homogeneous lesion delivered by cryoballoon is less arrhythmogenic, and the recommended three-months blanking period may not refer to cryoballoon ablation (CBA). OBJECTIVE: We aimed to evaluate the predictive role of ERAA after second-generation CBA using an implantable loop recorder. METHODS: This prospective observational study enrolled 100 patients (58 males, median age 58) with paroxysmal/persistent AF undergoing pulmonary vein (PV) CBA using second-generation cryoballoon with simultaneous ECG loop recorder implantation. The duration of follow-up was 12 months, with scheduled visits at 3, 6 and 12 months. RESULTS: 99 patients from 100 completed the 12-month follow-up period. ERAA occurred in 31.3 % of patients. 83.9 % of patients with ERAA also developed late recurrences. The 12-month freedom from AF in patients with ERAA was significantly lower than in those without ERAA (p < 0.0001). Non-paroxysmal AF and longer arrhythmia history were associated with increased risk of both early (HR 3.27; 95 % CI 1.32-8.08; p = 0.010 and HR 1.0147; 95 % CI 1.008-1.086; p = 0.015, respectively) and late recurrences (HR 3.89; 95 % CI 1.67-9.04; p = 0.002 and HR 1.0142; 95 % CI 1.007-1.078; p = 0.019, respectively) of AF. ERAA were another predictor for procedural failure (HR 15.2; 95 % CI (6.42-35.99; p = 0.019). CONCLUSIONS: ERAA occurred in the third of the patients after PV second-generation CBA and are strongly associated with procedural failure. Longer duration of AF history and persistent AF are independent predictors of AF's early and late recurrence.

Patients' and family members' perspectives on arrhythmias and sudden death in dialysis: the HeartLink focus groups pilot study.

BACKGROUND: Patients receiving dialysis face a high risk of cardiovascular disease, arrhythmia and sudden cardiac death. Few patients, however, are aware of this risk. Implantable cardiac monitors are currently available for clinical use and can continuously monitor cardiac rhythms without the need for transvenous leads. Our goal was to gauge patients' and family members' perceptions of these risks and to identify their concerns about cardiac monitors. METHODS: Two 90-minute focus groups were conducted: one with patients receiving in-center hemodialysis and one with their family members. Trained moderators assessed: (1) knowledge of cardiovascular disease; (2) cardiovascular disease risk in dialysis; (3) risk of death due to cardiovascular disease; (4) best ways to convey this risk to patients/families; and (5) concerns about cardiac monitors. The sessions were audiotaped, transcribed, and independently analyzed by two reviewers to identify core themes. Emblematic quotations were chosen to illustrate the final themes. RESULTS: Nine adult patients and three family members participated. Patients felt education was inadequate and had little knowledge of arrhythmias. Patients'/families' concerns regarding cardiac monitors were related to adverse effects, the notification process, and cosmetic effects. Patients/families felt that nephrologists, not dialysis staff, would be the best source for education. CONCLUSIONS: The preliminary data from this small study population suggest that patients/families are not well aware of the high risk of arrhythmia and sudden cardiac death in dialysis. Further investigation is required to gauge this awareness among patients/families and to assess their impressions of implantable cardiac monitors for arrhythmia detection and management.

A pandemic response to home delivery for ambulatory ECG monitoring: Development and validation.

In response to the COVID-19 pandemic, a protocol was designed for mail-out devices and educational materials created to teach patients how to install a device for 2 weeks of continuous ambulatory ECG monitoring. We compared data collection from two sequential patient populations; one who received standard device application in the same clinic in the months before the pandemic response, and another, who received their device by mail for self-installation. Patients received a single phone call when the device was mailed and were able to contact the manufacturer as needed for support. A total of 47 devices were assessed from each group. Each group was similar in age (70 vs 65 years), and clinical indication for monitoring. Noise signal magnitude (22.34 vs 26.28%), symptom based manual activation (10 vs 8 events) and APB/recorded hour burden measurements (37.05 vs 23.36%) were similar in both groups (all comparisons were statistically non-significant). Both groups had a similar mean of hours recorded (240.37 vs. 245.05 h). Zero patient kits were lost, and all reports were delivered. Overall, it was found that a mail-delivered home-based recording platform can be reliably used to acquire clinical data with similar data quality and patient compliance as a conventional in-clinic model for long term ambulatory ECG monitoring.

Diagnostic Accuracy and Safety of Confirm Rx™ Insertable Cardiac Monitor in Pediatric Patients.

Insertable cardiac monitors (ICM) are subcutaneously implanted devices that monitor a patient's heart rate and rhythm (Rossano in Pediatrics 112(3):e228, 2003). The diagnostic accuracy and safety of the Confirm RxTM (Abbott, Minneapolis, MN) ICM in pediatric patients is unknown. This is a single center, retrospective, IRB-approved review of patients ≤ 21 years implanted with Confirm RxTM ICMs from 2017 to 2020. Data collected included demographics, indications, presence of P-wave and R-wave amplitude at implantation and follow-up, number/appropriateness of transmissions pre and post implementation of SharpSenseTM technology, reprogramming to improve accuracy, time from implantation to arrhythmia detection, and complications. There were 29 patients (median age: 8 years, 59% females). P-waves were identified in all patients and average R-wave amplitude was 0.85 mV (0.26-1.03 mV). There was no significant difference in R-wave amplitude based on size (BSA ≥ 1.5 m2: 0.76 mV, < 1.5 m2: 0.91 mV) or congenital heart disease (+CHD: 0.86 mV, -CHD: 0.85 mV). Arrhythmias identified were the following: wide complex tachycardia (1), supraventricular tachycardia (4), bradycardia/sinus pause (3), and premature ventricular contraction (1). SharpSenseTM implementation decreased the false-positive rate in device-initiated transmissions (55.4% to 0%, p < 0.00001). Average time from implantation to arrhythmia detection was 2.63 months (range: 0-8.8). A single complication of cellulitis occurred. Confirm RxTM is appropriate for implant in pediatric patients regardless of age, BSA, or CHD. Implementation of SharpSense™ technology dramatically decreased the false-positive rate. Follow-up studies could utilize additional monitoring devices to provide analysis on potential events that the Confirm RxTM ICM missed.

Comparison of Omegawave Device and an Ambulatory ECG for RR Interval Measurement at rest.

The aim of this study was to validate the measurements of the beat intervals taken at rest by the Omegawave® device by comparing them to an ambulatory electrocardiogram system. For this purpose, the electrocardiogram was digitally processed, time-aligned, and scrutinized for its suitable use as gold-standard. Rest measurements were made for 10 minutes on 5 different days to 10 men and 3 women (24.8±5.05 years; 71.82±11.02 kg; 174.35±9.13 cm). RR intervals were simultaneously recorded using the Omegawave device and a Holter electrocardiogram. The processing of Holter electrocardiogram signals included the detrending of baseline noise and a high-pass filtering for emphasizing the QRS complexes and attenuating the T waves. After obtaining the RR intervals from the electrocardiogram, those from the Omegawave device were automatically aligned to them with cross-correlation digital processing techniques and compared to check whether both measurements could be considered superimposable. A Bland-Altman analysis was applied to the 5 measurements made for all subjects. The Omegawave device exhibited very strong agreement with a quality-controlled Holter electrocardiogram. Deviations not exceeding 25 ms could be expected in 95% of the cases, which is within manageable ranges both for clinical practice and for sports.

Effect of Long-term Continuous Cardiac Monitoring vs Usual Care on Detection of Atrial Fibrillation in Patients With Stroke Attributed to Large- or Small-Vessel Disease: The STROKE-AF Randomized Clinical Trial.

Importance: Patients with ischemic stroke attributed to large- or small-vessel disease are not considered at high risk for atrial fibrillation (AF), and the AF incidence rate in this population is unknown. Objectives: To determine whether long-term cardiac monitoring is more effective than usual care for AF detection in patients with stroke attributed to large- or small-vessel disease through 12 months of follow-up. Design, Setting, and Participants: The STROKE-AF trial was a randomized (1:1), multicenter (33 sites in the US) clinical trial that enrolled 496 patients between April 2016 and July 2019, with primary end point follow-up through August 2020. Eligible patients were aged 60 years or older or aged 50 to 59 years with at least 1 additional stroke risk factor and had an index stroke attributed to large- or small-vessel disease within 10 days prior to insertable cardiac monitor (ICM) insertion. Interventions: Patients randomized to the intervention group (n = 242) received ICM insertion within 10 days of the index stroke; patients in the control group (n = 250) received site-specific usual care consisting of external cardiac monitoring, such as 12-lead electrocardiograms, Holter monitoring, telemetry, or event recorders. Main Outcomes and Measures: Incident AF lasting more than 30 seconds through 12 months. Results: Among 492 patients who were randomized (mean [SD] age, 67.1 [9.4] years; 185 [37.6%] women), 417 (84.8%) completed 12 months of follow-up. The median (interquartile range) CHA2DS2-VASc (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke or transient ischemic attack, vascular disease, age 65 to 74 years, sex category) score was 5 (4-6). AF detection at 12 months was significantly higher in the ICM group vs the control group (27 patients [12.1%] vs 4 patients [1.8%]; hazard ratio, 7.4 [95% CI, 2.6-21.3]; P < .001). Among the 221 patients in the ICM group who received an ICM, 4 (1.8%) had ICM procedure-related adverse events (1 site infection, 2 incision site hemorrhages, and 1 implant site pain). Conclusions and Relevance: Among patients with stroke attributed to large- or small-vessel disease, monitoring with an ICM compared with usual care detected significantly more AF over 12 months. However, further research is needed to understand whether identifying AF in these patients is of clinical importance. Trial Registration: ClinicalTrials.gov Identifier: NCT02700945.

Effect of Implantable vs Prolonged External Electrocardiographic Monitoring on Atrial Fibrillation Detection in Patients With Ischemic Stroke: The PER DIEM Randomized Clinical Trial.

Importance: The relative rates of detection of atrial fibrillation (AF) or atrial flutter from evaluating patients with prolonged electrocardiographic monitoring with an external loop recorder or implantable loop recorder after an ischemic stroke are unknown. Objective: To determine, in patients with a recent ischemic stroke, whether 12 months of implantable loop recorder monitoring detects more occurrences of AF compared with conventional external loop recorder monitoring for 30 days. Design, Setting, and Participants: Investigator-initiated, open-label, randomized clinical trial conducted at 2 university hospitals and 1 community hospital in Alberta, Canada, including 300 patients within 6 months of ischemic stroke and without known AF from May 2015 through November 2017; final follow-up was in December 2018. Interventions: Participants were randomly assigned 1:1 to prolonged electrocardiographic monitoring with either an implantable loop recorder (n = 150) or an external loop recorder (n = 150) with follow-up visits at 30 days, 6 months, and 12 months. Main Outcomes and Measures: The primary outcome was the development of definite AF or highly probable AF (adjudicated new AF lasting ≥2 minutes within 12 months of randomization). There were 8 prespecified secondary outcomes including time to event analysis of new AF, recurrent ischemic stroke, intracerebral hemorrhage, death, and device-related serious adverse events within 12 months. Results: Among the 300 patients who were randomized (median age, 64.1 years [interquartile range, 56.1 to 73.7 years]; 121 were women [40.3%]; and 66.3% had a stroke of undetermined etiology with a median CHA2DS2-VASc [congestive heart failure, hypertension, age ≥75 years, diabetes, stroke or transient ischemic attack, vascular disease, age 65 to 74 years, sex category] score of 4 [interquartile range, 3 to 5]), 273 (91.0%) completed cardiac monitoring lasting 24 hours or longer and 259 (86.3%) completed both the assigned monitoring and 12-month follow-up visit. The primary outcome was observed in 15.3% (23/150) of patients in the implantable loop recorder group and 4.7% (7/150) of patients in the external loop recorder group (between-group difference, 10.7% [95% CI, 4.0% to 17.3%]; risk ratio, 3.29 [95% CI, 1.45 to 7.42]; P = .003). Of the 8 specified secondary outcomes, 6 were not significantly different. There were 5 patients (3.3%) in the implantable loop recorder group who had recurrent ischemic stroke vs 8 patients (5.3%) in the external loop recorder group (between-group difference, -2.0% [95% CI, -6.6% to 2.6%]), 1 (0.7%) vs 1 (0.7%), respectively, who had intracerebral hemorrhage (between-group difference, 0% [95% CI, -1.8% to 1.8%]), 3 (2.0%) vs 3 (2.0%) who died (between-group difference, 0% [95% CI, -3.2% to 3.2%]), and 1 (0.7%) vs 0 (0%) who had device-related serious adverse events. Conclusions and Relevance: Among patients with ischemic stroke and no prior evidence of AF, implantable electrocardiographic monitoring for 12 months, compared with prolonged external monitoring for 30 days, resulted in a significantly greater proportion of patients with AF detected over 12 months. Further research is needed to compare clinical outcomes associated with these monitoring strategies and relative cost-effectiveness. Trial Registration: ClinicalTrials.gov Identifier: NCT02428140.

Explainable Artificial Intelligence Model for Diagnosis of Atrial Fibrillation Using Holter Electrocardiogram Waveforms.

Atrial fibrillation is a clinically important arrhythmia. There are some reports on machine learning models for AF diagnosis using electrocardiogram data. However, few reports have proposed an eXplainable Artificial Intelligence (XAI) model to enable physicians to easily understand the machine learning model's diagnosis results.We developed and validated an XAI-enabled atrial fibrillation diagnosis model based on a convolutional neural network (CNN) algorithm. We used Holter electrocardiogram monitoring data and the gradient-weighted class activation mapping (Grad-CAM) method.Electrocardiogram data recorded from patients between January 4, 2016, and October 31, 2019, totaling 57,273 electrocardiogram waveform slots of 30 seconds each with diagnostic information annotated by cardiologists, were used for training our proposed model. Performance metrics of our AI model for AF diagnosis are as follows: sensitivity, 97.1% (95% CI: 0.969-0.972); specificity, 94.5% (95% CI: 0.943-0.946); accuracy, 95.3% (95% CI: 0.952-0.955); positive predictive value, 89.3% (95% CI: 0.892-0.897); and F-value, 93.1% (95% CI: 0.929-0.933). The area under the receiver operating characteristic curve for AF detection using our model was 0.988 (95% CI: 0.987-0.988). Furthermore, using the XAI method, 94.5 ± 3.5% of the areas identified as regions of interest using our machine learning model were identified as characteristic sites for AF diagnosis by cardiologists.AF was accurately diagnosed and favorably explained with Holter ECG waveforms using our proposed CNN-based XAI model. Our study presents another step toward realizing a viable XAI-based detection model for AF diagnoses for use by physicians.

Incidence and predictors of atrial fibrillation episodes as detected by implantable loop recorder in patients at risk: From the LOOP study.

BACKGROUND: Recent studies have suggested a high prevalence of subclinical atrial fibrillation (AF) in various patient populations, and interest in AF screening has increased. However, knowledge about episode duration is scarce, and risk factors for short or long subclinical AF episodes have yet to be recognized. The aim of the study was to assess AF by long-term continuous screening and to investigate predictors of episodes lasting ≥6 minutes, ≥5.5 hours, or ≥24 hours, respectively. METHODS: A total of 597 patients aged ≥70 years and diagnosed with ≥1 of hypertension, diabetes, previous stroke, or heart failure were recruited from the general population to receive implantable loop recorder with remote monitoring. Exclusion criteria included history of AF or cardiac implantable electronic device. AF episodes were adjudicated by senior cardiologists. RESULTS: During 40 (37; 42) months of continuous monitoring, AF was detected in 209 (35%) of the patients. The cumulative incidences at 3 years were 33.8% (30.2%-37.8%), 16.1% (13.4%-19.4%), and 5.7% (4.1%-7.9%) for AF episodes lasting ≥6 minutes, ≥5.5 hours, and ≥24 hours, respectively. Slower resting sinus rate and higher body mass index, N-terminal prohormone of brain natriuretic peptide, and troponin T at baseline were independently associated with AF detection. Addition of these markers to a model of sex, age, and comorbidities improved prediction of AF episodes ≥24 hours (time-dependent area under the receiver operating characteristic curve 79% vs 65%, P = .037). CONCLUSIONS: A considerable burden of previously unknown AF was detected when long-term monitoring was applied in at-risk patients. Biomarkers were associated with AF incidence and improved prediction of long AF episodes.

Outcomes of convergent atrial fibrillation ablation with continuous rhythm monitoring.

BACKGROUND: Outcomes of catheter ablation for persistent atrial fibrillation (PeAF) are suboptimal. The convergent procedure (CP) may offer improved efficacy by combining endocardial and epicardial ablation. METHODS: We reviewed 113 consecutive patients undergoing the CP at our institution. The cohort was divided into two groups based on the presence (n = 92) or absence (n = 21) of continuous rhythm monitoring (CM) following the CP. Outcomes were reported in two ways. First, using a conventional definition of any atrial fibrillation/atrial tachycardia (AF/AT) recurrence lasting >30 seconds, after a 90 day blanking period. Second, by determining AF/AT burden at relevant time points in the group with CM. RESULTS: Across the entire cohort, 88% had either persistent or long-standing persistent AF, mean duration of AF diagnosis before the CP was 5.1 ± 4.6 years, 45% had undergone at least one prior AF ablation, 31% had impaired left ventricle ejection fraction and 62% met criteria for moderate or severe left atrial enlargement. Mean duration of follow-up after the CP was 501 ± 355 days. In the entire cohort, survival free from any AF/AT episode >30 seconds at 12 months after the blanking period was 53%. However, among those in the CM group who experienced recurrences, mean burden of AF/AT was generally very low (<5%) and remained stable over the duration of follow-up. Ten patients (9%) required elective cardioversion outside the 90 day blanking period, 11 patients (9.7%) underwent repeat ablation at a mean of 229 ± 178 days post-CP and 64% were off AADs at the last follow-up. Procedural complications decreased significantly following the transition from transdiaphragmatic to sub-xiphoid surgical access: 23% versus 3.8% (P = .005) CONCLUSIONS: In a large, consecutive series of patients with predominantly PeAF, the CP was capable of reducing AF burden to very low levels (generally <5%), which appeared durable over time. Complication rates associated with the CP decreased significantly with the transition from transdiaphragmatic to sub-xiphoid surgical access. Future trials will be necessary to determine which patients are most likely to benefit from the convergent approach.