Machine learning based detection of T-wave alternans in real ambulatory conditions.

BACKGROUND AND OBJECTIVE: T-wave alternans (TWA) is a fluctuation in the repolarization morphology of the ECG. It is associated with cardiac instability and sudden cardiac death risk. Diverse methods have been proposed for TWA analysis. However, TWA detection in ambulatory settings remains a challenge due to the absence of standardized evaluation metrics and detection thresholds. METHODS: In this work we use traditional TWA analysis signal processing-based methods for feature extraction, and two machine learning (ML) methods, namely, K-nearest-neighbor (KNN) and random forest (RF), for TWA detection, addressing hyper-parameter tuning and feature selection. The final goal is the detection in ambulatory recordings of short, non-sustained and sparse TWA events. RESULTS: We train ML methods to detect a wide variety of alternant voltage from 20 to 100 µV, i.e., ranging from non-visible micro-alternans to TWA of higher amplitudes, to recognize a wide range in concordance to risk stratification. In classification, RF outperforms significantly the recall in comparison with the signal processing methods, at the expense of a small lost in precision. Despite ambulatory detection stands for an imbalanced category context, the trained ML systems always outperform signal processing methods. CONCLUSIONS: We propose a comprehensive integration of multiple variables inspired by TWA signal processing methods to fed learning-based methods. ML models consistently outperform the best signal processing methods, yielding superior recall scores.

Implantable loop recorders in patients with Brugada syndrome: the BruLoop study.

BACKGROUND AND AIMS: Available data on continuous rhythm monitoring by implantable loop recorders (ILRs) in patients with Brugada syndrome (BrS) are scarce. The aim of this multi-centre study was to evaluate the diagnostic yield and clinical implication of a continuous rhythm monitoring strategy by ILRs in a large cohort of BrS patients and to assess the precise arrhythmic cause of syncopal episodes. METHODS: A total of 370 patients with BrS and ILRs (mean age 43.5 ± 15.9, 33.8% female, 74.1% symptomatic) from 18 international centers were included. Patients were followed with continuous rhythm monitoring for a median follow-up of 3 years. RESULTS: During follow-up, an arrhythmic event was recorded in 30.7% of symptomatic patients [18.6% atrial arrhythmias (AAs), 10.2% bradyarrhythmias (BAs), and 7.3% ventricular arrhythmias (VAs)]. In patients with recurrent syncope, the aetiology was arrhythmic in 22.4% (59.3% BAs, 25.0% VAs, and 15.6% AAs). The ILR led to drug therapy initiation in 11.4%, ablation procedure in 10.9%, implantation of a pacemaker in 2.5%, and a cardioverter-defibrillator in 8%. At multivariate analysis, the presence of symptoms [hazard ratio (HR) 2.5, P = .001] and age >50 years (HR 1.7, P = .016) were independent predictors of arrhythmic events, while inducibility of ventricular fibrillation at the electrophysiological study (HR 9.0, P < .001) was a predictor of VAs. CONCLUSIONS: ILR detects arrhythmic events in nearly 30% of symptomatic BrS patients, leading to appropriate therapy in 70% of them. The most commonly detected arrhythmias are AAs and BAs, while VAs are detected only in 7% of cases. Symptom status can be used to guide ILR implantation.

Monitoring of Remotely Reprogrammable Implantable Loop Recorders With Algorithms to Reduce False-Positive Alerts.

BACKGROUND: Implantable loop recorders (ILRs) are increasingly placed for arrhythmia detection. However, historically, ≈75% of ILR alerts are false positives, requiring significant time and effort for adjudication. The LINQII and LUX-Dx are remotely reprogrammable ILRs with dual-stage algorithms using artificial intelligence to reduce false positives, but their utility in routine clinical practice has not been studied. METHODS AND RESULTS: We identified patients with the LINQII and LUX-Dx who were monitored by the Veterans Affairs National Cardiac Device Surveillance Program between March and June 2022. ILR programming was customized on the basis of implant indication. All alerts and every 90-day scheduled transmissions were manually reviewed. ILRs were remotely reprogrammed, as appropriate, after false-positive alerts or 2 consecutive same-type alerts, unless there was ongoing clinical need for that alert. Outcomes were total number of transmissions and false positives. We performed medical record review to determine if patients experienced any adverse clinical events, including hospitalization and mortality. Among 117 LINQII patients, there were 239 total alerts, 43 (18.0%) of which were false positives. Among 105 LUX-Dx patients, there were 300 total alerts, 115 (38.3%) of which were false positives. LINQIIs were reprogrammed 22 times, resulting in a decrease in median alerts/day from 0.13 to 0.03. LUX-Dx ILRs were reprogrammed 52 times, resulting in a decrease from 0.15 to 0.01 median alerts/day. There were no adverse clinical events that could have been identified by superior or earlier arrhythmia detection. CONCLUSIONS: ILRs with artificial intelligence algorithms and remote reprogramming ability are associated with reduced alert burden because of higher true-positive rates than prior ILRs, without missing potentially consequential arrhythmias.

Novel application of convolutional neural networks for artificial intelligence-enabled modified moving average analysis of P-, R-, and T-wave alternans for detection of risk for atrial and ventricular arrhythmias.

BACKGROUND: T-wave alternans (TWA) analysis was shown in >14,000 individuals studied worldwide over the past two decades to be a useful tool to assess risk for cardiovascular mortality and sudden arrhythmic death. TWA analysis by the modified moving average (MMA) method is FDA-cleared and CMS-reimbursed (CAG-00293R2). OBJECTIVE: Because the MMA technique is inherently suitable for dynamic tracking of alternans levels, it was selected for development of artificial intelligence (AI)-enabled algorithms using convolutional neural networks (CNN) to achieve rapid, efficient, and accurate assessment of P-wave alternans (PWA), R-wave alternans (RWA), and TWA. METHODS: The novel application of CNN algorithms to enhance MMA analysis generated efficient and powerful pattern-recognition algorithms for highly accurate alternans quantification. Algorithm reliability and accuracy were verified using simulated ECGs achieving R2 ≥ 0.99 (p < 0.01) in response to noise inputs and artifacts that emulate real-life conditions. RESULTS: Accuracy of the new AI-MMA algorithms in TWA analysis (n = 5) was significantly improved over unsupervised, automated MMA output (p = 0.036) and did not differ from conventional MMA analysis with expert overreading (p = 0.21). Accuracy of AI-MMA in PWA analysis (n = 45) was significantly improved over unsupervised, automated MMA output (p < 0.005) and did not differ from conventional MMA analysis with expert overreading (p = 0.89). TWA and PWA by AI-MMA were correlated with conventional MMA output over-read by an expert reader (R2 = 0.7765, R2 = 0.9504, respectively). CONCLUSION: This novel technique for AI-MMA analysis could be suitable for use in diverse in-hospital and out-of-hospital monitoring systems, including cardiac implantable electronic devices and smartwatches, for tracking atrial and ventricular arrhythmia risk.

Atrial Fibrillation Detection and Ischemic Stroke Recurrence in Cryptogenic Stroke: A Retrospective, Multicenter, Observational Study.

BACKGROUND: Atrial fibrillation (AF) is known to be a strong risk factor for stroke. However, the risk of stroke recurrence in patients with cryptogenic stroke with AF detected after stroke by an insertable cardiac monitor (ICM) is not well known. We sought to evaluate the risk of ischemic stroke recurrence in patients with cryptogenic stroke with and without ICM-detected AF. METHODS AND RESULTS: We retrospectively reviewed patients with cryptogenic stroke who underwent ICM implantation at 8 stroke centers in Japan. Cox regression models were developed using landmark analysis and time-dependent analysis. We set the target sample size at 300 patients based on our estimate of the annualized incidence of ischemic stroke recurrence to be 3% in patients without AF detection and 9% in patients with AF detection. Of the 370 patients, 121 were found to have AF, and 110 received anticoagulation therapy after AF detection. The incidence of ischemic stroke recurrence was 4.0% in 249 patients without AF detection and 5.8% in 121 patients with AF detection (P=0.45). In a landmark analysis, the risk of ischemic stroke recurrence was not higher in patients with AF detected ≤90 days than in those without (hazard ratio, 1.47 [95% CI, 0.41-5.28]). In a time-dependent analysis, the risk of ischemic stroke recurrence did not increase after AF detection (hazard ratio, 1.77 [95% CI, 0.70-4.47]). CONCLUSIONS: The risk of ischemic stroke recurrence in patients with cryptogenic stroke with ICM-detected AF, 90% of whom were subsequently anticoagulated, was not higher than in those without ICM-detected AF.

Breast MRI in patients with implantable loop recorder: initial experience.

OBJECTIVES: To investigate the feasibility of breast MRI exams and guided biopsies in patients with an implantable loop recorder (ILR) as well as the impact ILRs may have on image interpretation. MATERIALS AND METHODS: This retrospective study examined breast MRIs of patients with ILR, from April 2008 to September 2022. Radiological reports and electronic medical records were reviewed for demographic characteristics, safety concerns, and imaging findings. MR images were analyzed and compared statistically for artifact quantification on the various pulse sequences. RESULTS: Overall, 40/82,778 (0.049%) MRIs during the study period included ILR. All MRIs were completed without early termination. No patient-related or device-related adverse events occurred. ILRs were most commonly located in the left lower-inner quadrant (64.6%). The main artifact was a signal intensity (SI) void in a dipole formation in the ILR bed with or without areas of peripheral high SI. Artifacts appeared greatest in the cranio-caudal axis (p < 0.001), followed by the anterior-posterior axis (p < 0.001), and then the right-left axis. High peripheral rim-like SI artifacts appeared on the post-contrast and subtracted T1-weighted images, mimicking suspicious enhancement. Artifacts were most prominent on diffusion-weighted (p < 0.001), followed by T2-weighted and T1-weighted images. In eight patients, suspicious findings were found on MRI, resulting in four additional malignant lesions. Of six patients with left breast cancer, the tumor was completely visible in five cases and partially obscured in one. CONCLUSION: Breast MRI is feasible and safe among patients with ILR and may provide a significant diagnostic value, albeit with localized, characteristic artifacts. CLINICAL RELEVANCE STATEMENT: Indicated breast MRI exams and guided biopsies can be safely performed in patients with implantable loop recorder. Nevertheless, radiologists should be aware of associated limitations including limited assessment of the inner left breast and pseudo-enhancement artifacts. KEY POINTS: • Breast MRI in patients with an implantable loop recorder is an infrequent, feasible, and safe procedure. • Despite limited breast visualization of the implantable loop recorder bed and characteristic artifacts, MRI depicted additional lesions in 8/40 (20%) of cases, half of which were malignant. • Breast MRI in patients with an implantable loop recorder should be performed when indicated, taking into consideration typical associated artifacts.

Correlation between the electrocardiogram amplitude detected by an implantable cardiac monitor and the implantation depth.

INTRODUCTION: Implantable cardiac monitors (ICMs) primarily use R-R intervals in subcutaneous electrocardiograms (ECGs) to detect arrhythmias. Therefore, reliable detection of R-wave amplitude by an ICM is vital. Since ICMs detect subcutaneous ECGs, the impact of the implantation depth should be assessed. METHODS AND RESULTS: This study investigated the influence of ICM depth on R-wave (ICM-R) amplitude on an ECG generated by an ICM (JOT Dx; Abbott). Overall, 58 patients who underwent ICM implantation at Kamagaya General Hospital from May 2022 to April 2023 were retrospectively reviewed. The depth-position was measured using ultrasound imaging after implantation. The depth of the ICM did not show any correlation with ICM-R amplitude (r = -.0141, p = .294). However, the distance between the ICM and the heart surface showed a significant correlation with ICM-R amplitude (r = -.581, p < .001). Body weight (r = -.0283, p = .033) and body mass index (r = -.0342, p = .009) were associated with ICM-R amplitude. S wave in the V1 -lead was also associated with ICM-R amplitude (r = .481, p < .001). After multivariate analysis, the distance between the ICM and heart surface and the S wave in V1 were independent determinants for the ICM-R amplitude. CONCLUSION: The ICM-R amplitude may be higher with the ICM implanted deeper.

[Anti-motion Artifact Performance Test System for Ambulatory ECG Monitoring Equipment].

Anti-motion artifact is one of the most important properties of ambulatory ECG monitoring equipment. At present, there is a lack of standardized means to test the performance of anti-motion artifact. ECG simulator and special conductive leather are used to build the simulator, it is used to simulate human skin, to generate ECG signal input for the ECG monitoring equipment attached to it. The mechanical arm and fixed support are used to build a motion simulation system to fix the conductive leather. The mechanical arm is programmed to simulate various motion states of the human body, so that the ECG monitoring equipment can produce corresponding motion artifacts. The collected ECG signals are read wirelessly, observed, analyzed and compared, and the anti-motion artifact performance of ECG monitoring equipment is evaluated. The test results show that by artificially creating the small difference between the two groups of ambulatory ECG monitoring equipment, the system can accurately test the interference signals introduced under the conditions of controlled movement such as tension and torsion, and compare the advantages and disadvantages. The research shows that the test system can provide convenient and accurate verification means for the research of optimizing anti-motion interference.

Novel algorithms improve arrhythmia detection accuracy in insertable cardiac monitors.

INTRODUCTION: Insertable cardiac monitors (ICMs) are commonly used to diagnose cardiac arrhythmias. False detections in the latest ICM systems remain an issue, primarily due to inaccurate R-wave sensing. New discrimination algorithms were developed and tested to reduce false detections of atrial fibrillation (AF), pause, and tachycardia episodes in ICMs. METHODS: Stored electrograms (EGMs) of AF, pause, and tachycardia episodes detected by Abbott Confirm Rx™ ICMs were extracted from the Merlin.net™ Patient Care Network, and manually adjudicated to establish independent training and testing datasets. New discrimination algorithms were developed to reject false episodes due to inaccurate R-wave sensing, P-wave identification, and R-R interval patterns. The performance of these new algorithms was quantified by false positive reduction (FPR) and true positive maintenance (TPM), relative to the existing algorithms. RESULTS: The new AF detection algorithm was trained on 5911 EGMs from 744 devices, resulting in 66.9% FPR and 97.8% TPM. In the testing data set of 1354 EGMs from 119 devices, this algorithm achieved 45.8% FPR and 97.0% TPM. The new pause algorithm was trained on 7178 EGMs from 1490 devices, resulting in 70.9% FPR and 98.7% TPM. In the testing data set of 1442 EGMs from 340 devices, this algorithm achieved 74.4% FPR and 99.3% TPM. The new tachycardia algorithm was trained on 520 EGMs from 204 devices, resulting in 57.0% FPR and 96.6% TPM. In the testing data set of 459 EGMs from 237 devices, this algorithm achieved 57.9% FPR and 96.5% TPM. CONCLUSION: The new algorithms substantially reduced false AF, pause, and tachycardia episodes while maintaining the majority of true arrhythmia episodes detected by the Abbott ICM algorithms that exist today. Implementing these algorithms in the next-generation ICM systems may lead to improved detection accuracy, in-clinic efficiency, and device battery longevity.

Rationale and design of the NEO-NORMAL-AF study examination of the usefulness of implantable loop recorder for arrhythmia detection including atrial fibrillation in heart failure with non-reduced ejection fraction cases: a pilot study.

INTRODUCTION: The incidence of arrhythmia in heart failure with non-reduced ejection fraction (HFnon-rEF) in patients who have a history of hospitalisation is unclear. The aim of this study is to investigate the usefulness of an implantable loop recorder (ILR) for arrhythmia detection including atrial fibrillation (AF) in HFnon-rEF patients after discharge. METHODS AND ANALYSIS: This is a multicentre single arm study to evaluate the usefulness of ILR for detecting arrhythmia. The eligible patients are HFnon-rEF patients (left ventricular ejection fraction ≥40%) aged ≥20 years with a history of hospitalisation. The ILR will be implanted for qualified patients, and ECGs will be monitored and recorded for 1 year to check for arrhythmias. The primary endpoint is new-onset 6 min or more persistent AF detected by ILR. Secondary endpoints are 30 s or more persistent supraventricular tachycardia and ventricular tachycardia, 3 s or more persistent pause, bradycardia with 40 beats per minutes or lower heart rate, AF burden, all-cause death, cardiovascular death, hospital readmission due to exacerbation of HF, acute coronary syndrome, ischaemic or haemorrhagic stroke, non-pharmacological therapy such as pacemaker implantation and ablation. CONCLUSIONS: This study is expected to provide valuable findings regarding arrhythmia in HFnon-rEF patients, and elucidate a potential new therapeutic approach for HFnon-rEF. TRIAL REGISTRATION NUMBER: This trial has been registered in the Japan Registry of Clinical Trials (jRCT) (Trial Registration: jRCTs052210060).

Intensive heart rhythm monitoring to decrease ischemic stroke and systemic embolism-the Find-AF 2 study-rationale and design.

BACKGROUND: Atrial fibrillation (AF) is one of the most frequent causes of stroke. Several randomized trials have shown that prolonged monitoring increases the detection of AF, but the effect on reducing recurrent cardioembolism, ie, ischemic stroke and systemic embolism, remains unknown. We aim to evaluate whether a risk-adapted, intensified heart rhythm monitoring with consequent guideline conform treatment, which implies initiation of oral anticoagulation (OAC), leads to a reduction of recurrent cardioembolism. METHODS: Find-AF 2 is a randomized, controlled, open-label parallel multicenter trial with blinded endpoint assessment. 5,200 patients ≥ 60 years of age with symptomatic ischemic stroke within the last 30 days and without known AF will be included at 52 study centers with a specialized stroke unit in Germany. Patients without AF in an additional 24-hour Holter ECG after the qualifying event will be randomized in a 1:1 fashion to either enhanced, prolonged and intensified ECG-monitoring (intervention arm) or standard of care monitoring (control arm). In the intervention arm, patients with a high risk of underlying AF will receive continuous rhythm monitoring using an implantable cardiac monitor (ICM) whereas those without high risk of underlying AF will receive repeated 7-day Holter ECGs. The duration of rhythm monitoring within the control arm is up to the discretion of the participating centers and is allowed for up to 7 days. Patients will be followed for at least 24 months. The primary efficacy endpoint is the time until recurrent ischemic stroke or systemic embolism occur. CONCLUSIONS: The Find-AF 2 trial aims to demonstrate that enhanced, prolonged and intensified rhythm monitoring results in a more effective prevention of recurrent ischemic stroke and systemic embolism compared to usual care.

Health warning based on 3R ECG Sample's combined features and LSTM.

Most researches use the fixed-length sample to identify ECG abnormalities based on MIT ECG dataset, which leads to information loss. To address this problem, this paper proposes a method for ECG abnormality detection and health warning based on ECG Holter of PHIA and 3R-TSH-L method. The 3R-TSH-L method is implemented by:(1) getting 3R ECG samples using Pan-Tompkins method and using volatility to obtain high-quality raw ECG data; (2) extracting combination features including time-domain features, frequency domain features and time-frequency domain features; (3) using LSTM for classification, training and testing the algorithm based on the MIT-BIH dataset, and obtaining relatively optimal features as spliced normalized fusion features including kurtosis, skewness and RR interval time domain features, STFT-based sub-band spectrum features, and harmonic ratio features. The ECG data were collected using the self-developed ECG Holter (PHIA) on 14 subjects, aged between 24 and 75 including both male and female, to build the ECG dataset (ECG-H). The algorithm was transferred to the ECG-H dataset, and a health warning assessment model based on abnormal ECG rate and heart rate variability weighting was proposed. Experiments show that 3R-TSH-L method proposed in the paper has a high accuracy of 98.28% for the detection of ECG abnormalities of MIT-BIH dataset and a good transfer learning ability of 95.66% accuracy for ECG-H. The health warning model was also testified to be reasonable. The key technique of the ECG Holter of PHIA and the method 3R-TSH-L proposed in this paper is expected to be widely used in family-oriented healthcare.

Factors affecting electrogram sensing in an insertable cardiac monitor: Insights from surface electrocardiogram mapping analysis.

BACKGROUND: Fidelity of electrogram sensing may reduce false alerts from an insertable cardiac monitor (ICM). OBJECTIVE: The purpose of this study was to assess the effect of vector length, implant angle, and patient factors on electrogram sensing using surface electrocardiogram (ECG) mapping. METHODS: Twelve separate precordial single-lead surface ECGs were acquired from 150 participants at 2 interelectrode distances (75 and 45 mm), at 3 vector angles (vertical, oblique, and horizontal), and in 2 postures (upright and supine). A subset of 50 patients also received a clinically indicated ICM implant in 1:1 ratio (Reveal LINQ [Medtronic, Minneapolis, MN]/BIOMONITOR III [Biotronik, Berlin, Germany]). All ECGs and ICM electrograms were analyzed by blinded investigators using DigitizeIt software (V2.3.3, Braunschweig, Germany). The P-wave visibility threshold was set at > 0.015 mV. Logistic regression was used to identify factors affecting P-wave amplitude. RESULTS: A total of 1800 tracings from 150 participants (44.5% [n = 68] female; median age 59 [35-73] years) were assessed. The median P- and R-wave amplitudes were 45% and 53% larger with vector lengths of 75 and 45 mm, respectively (P < .001 for both). The oblique orientation yielded the best P- and R-wave amplitudes, while posture change did not affect P-wave amplitude. Mixed effects modeling found that visible P-waves occur more frequently with a vector length of 75 mm than with 45 mm (86% vs 75%, respectively; P < .0001). A longer vector length improved both P-wave amplitude and visibility in all body mass index categories. There was a moderate correlation of P- and R-wave amplitudes from the ICM electrograms to those from surface ECG recordings (intraclass correlation coefficient 0.74 and 0.80, respectively). CONCLUSION: Longer vector length and oblique implant angle yielded the best electrogram sensing and are relevant considerations for ICM implantation procedures.

Cryptogenic stroke as a working diagnosis: the need for an early and comprehensive diagnostic work-up.

In the Nordic Atrial Fibrillation and Stroke (NOR-FIB) study, the causes of ischemic stroke were identified in 43% of cryptogenic stroke patients monitored with implantable cardiac monitor (ICM), but one-third of these patients had non-cardioembolic causes. These results suggest the need for an early and comprehensive diagnostic work-up before inserting an ICM.

New insertable cardiac monitors show high diagnostic yield and good safety profile in real-world clinical practice: results from the international prospective observational SMART Registry.

AIMS: Insertable cardiac monitors (ICMs) are indicated for long-term monitoring of unexplained syncope or palpitations, and for detection of bradycardia, ventricular tachycardia, and/or atrial fibrillation (AF). The aim of our study was to evaluate the safety and clinical value associated with a new generation ICM (Confirm Rx™, Abbott, Illinois, USA), featuring a new remote monitoring system based on smartphone patient applications. METHODS AND RESULTS: The SMART Registry is an international prospective observational study. The main endpoints were ICM safety (incidence of serious adverse device and procedure-related events (SADEs) at 1 month), ICM clinical value (incidence of device-detected true arrhythmias and of clinical diagnoses and interventions), and patient-reported experience measurements (PREMs). A total of 1400 subjects were enrolled. ICM indications included syncope (49.1%), AF (18.8%), unexplained palpitations (13.6%), risk of ventricular arrhythmia (6.6%), and cryptogenic stroke (6.0%). Freedom from SADEs at 1 month was 99.4% (95% Confidence Interval: 98.8-99.7%). In the 6-month monitoring period, the ICM detected true cardiac arrhythmias in 45.7% of patients and led to clinical interventions in a relevant proportion of patients; in particular, a pacemaker implant was performed after bradycardia detection in 8.9% of subjects who received an ICM for syncope and oral anticoagulation therapy was indicated after AF detection in 15.7% of subjects with cryptogenic stroke. PREMs showed that 78.2% of subjects were satisfied with the remote monitoring patient app. CONCLUSION: The evaluated ICM is associated with an excellent safety profile and high diagnostic yield. Patients reported positive experiences associated with the use of their smartphone for the device remote monitoring.

Younger postnatal age is associated with a lower heart rate on Holter monitoring during the first week of life.

To evaluate heart rate (HR), the presence of extrasystoles and other Holter findings among healthy newborns, and to collect data for new normal limits for Holter parameters in newborns. For this cross-sectional study, 70 healthy term newborns were recruited to undergo 24-h Holter monitoring. Linear regression analysis was used in HR analyses. The age-specific limits for HRs were calculated using linear regression analysis coefficients and residuals. The mean (SD) age of the infants was 6.4 (1.7) days during the recording. Each consecutive day of age raised the minimum and mean HR by 3.8 beats per minute (bpm) (95% CI: 2.4, 5.2; P < .001) and 4.0 bpm (95% CI: 2.8, 5.2; P < .001), respectively. Age did not correlate with maximum HR. The lowest calculated limit for minimum HR ranged from 56 bpm (aged 3 days) to 78 bpm (aged 9 days). A small number of atrial extrasystoles and ventricular extrasystoles were observed in 54 (77%) and 28 (40%) recordings, respectively. Short supraventricular or ventricular tachycardias were found in 6 newborns (9%). CONCLUSION:  The present study shows an increase of 20 bpm in both the minimum and mean HRs of healthy term newborns between the 3rd and 9th days of life. Daily reference values for HR could be adopted in the interpretation of HR monitoring results in newborns. A small number of extrasystoles are common in healthy newborns, and isolated short tachycardias may be normal in this age group. WHAT IS KNOWN: • The current definition of bradycardia in newborns is 80 beats per minute. • This definition does not fit into the modern clinical setting of continuously monitored newborns, where benign bradycardias are commonly observed. WHAT IS NEW: • A linear and clinically significant increase in heart rate was observed in infants between the ages of 3 and 9 days. • It appears as though lower normal limits for heart rate could be applied to the youngest newborns.

Time of onset of atrial fibrillation and atrial fibrillation progression data from the RACE V study.

AIMS: Atrial fibrillation (AF) progression is associated with adverse outcome, but the role of the circadian or diurnal pattern of AF onset remains unclear. We aim to assess the association between the time of onset of AF episodes with the clinical phenotype and AF progression in patients with self-terminating AF. METHODS AND RESULTS: The Reappraisal of AF: Interaction Between Hypercoagulability, Electrical Remodelling, and Vascular Destabilization in the Progression of AF study included patients with self-terminating AF who underwent extensive phenotyping at baseline and continuous rhythm monitoring with an implantable loop recorder (ILR). In this subanalysis, ILR data were used to assess the development of AF progression and the diurnal pattern of AF onset: predominant (>80%) nocturnal AF, predominant daytime AF, or mixed AF without a predominant diurnal AF pattern. The median follow-up was 2.2 (1.6-2.8) years. The median age was 66 (59-71) years, and 117 (42%) were women. Predominant nocturnal (n = 40) and daytime (n = 43) AF onset patients had less comorbidities compared to that of mixed (n = 195) AF patients (median 2 vs. 2 vs. 3, respectively, P = 0.012). Diabetes was more common in the mixed group (12% vs. 5% vs. 0%, respectively, P = 0.031), whilst obesity was more frequent in the nocturnal group (38% vs. 12% vs. 27%, respectively, P = 0.028). Progression rates in the nocturnal vs. daytime vs. mixed groups were 5% vs. 5% vs. 24%, respectively (P = 0.013 nocturnal vs. mixed and P = 0.008 daytime vs. mixed group, respectively). CONCLUSION: In self-terminating AF, patients with either predominant nocturnal or daytime onset of AF episodes had less associated comorbidities and less AF progression compared to that of patients with mixed onset of AF. CLINICAL TRIAL REGISTRATION: NCT02726698.

Presentation and Prognosis of Excessive Asymptomatic Atrial Ectopy in Children and Adolescents With Structurally and Functionally Normal Hearts.

Excessive premature atrial complexes (PACs) in pediatric patients with a structurally normal heart are presumed to be benign and self-resolving, but no studies have confirmed this. Adults with excessive PACs, however, are at increased risk for future sustained atrial arrhythmias and cardiovascular morbidity and mortality. Therefore, we sought to evaluate the clinical course of frequent PACs in asymptomatic children. Patients < 21 years old with numerous asymptomatic PACs (>50/24 hours) were retrospectively selected over a 10-year period. Demographics, clinical characteristics, and results of cardiovascular testing were tabulated. Two groups were defined: those with a significant (>20%) reduction in burden of atrial ectopy versus those with an insignificant (<20%) reduction or increase. Of 6,902 patients, 343 patients (5%) met criteria. Initial median age was 8.3 (interquartile range [IQR] 4.1 to 14) years with comparable male:female ratio. Follow-up Holters were performed on 188 patients (54.8%) at a median interval of 2.2 (IQR 1.3 to 3.6) years. Overall, there was a significant decrease in atrial ectopy burden from 4.2% (IQR 1.9 to 6.5) down to 0.5% (IQR 0.01 to 2.3), with 166 patients (88.3%), demonstrating a decrease of over 20%. Five percent had a small increase, and 6% had an insignificant decrease. None developed cardiac symptoms or sustained supraventricular tachydysrhythmia. Male gender, athletic participation, and discontinuation of stimulant medications were the chief predictors for a reduction of PAC burden on follow-up. Atrial triplets at presentation were associated with a 5.4% increase. In conclusion, this study confirms that excessive asymptomatic childhood PACs with structurally normal hearts are rare and short-term to medium-term prognosis is benign.

Intensive 90-day textile wearable Holter monitoring: an alternative to detect paroxysmal atrial fibrillation in selected patients with cryptogenic stroke.

We aimed to demonstrate the feasibility of 90-day cardiac monitoring with an external Holter device and to find a target population able to benefit from such a technique. Cryptogenic stroke patients were continuously monitored for 90 days with a textile wearable Holter (TWH). Compliance and quality of the monitoring were assessed by the number of hours of ECG stored per month. Mean predictors of pAF, including age, gender, stroke severity, and atrial size (LAVI), were evaluated. One-year follow-up assessed pAF detection outside per protocol monitoring. Out of 224 patients included in 5 stroke centers, 163 patients (72.76%) fulfilled the criteria for the protocol. Median monitoring time was similar among the three months. Per protocol pAF detection reached 35.37% at 90 days. The age (OR 1.095; 95% CI 1.03-1.14) and the LAVI (OR 1.055; 95% CI 1.01-1.09) independently predicted pAF. The cut-off point of 70 years (AUC 0.68) (95% CI 0.60-0.76) predicted pAF with a sensitivity of 75.8% and specificity of 50.5%. The LAVI cut-off point of 28.5 (AUC 0.67) (95% CI 0.56-0.77) had a sensitivity of 63.6% and a specificity of 61.8% to detect pAF. The combination of both markers enhanced the validity of pAF detection sensitivity to 89.6%, with a specificity of 27.59%. These patients had increased risk of pAF during the 90-day monitoring HR 3.23 (χ2 7.15) and beyond 90 days (χ2 5.37). Intensive 90-days TWH monitoring detected a high percentage of pAF. However, a significant number of patients did not complete the monitoring. Patients older than 70 years and with enlarged left atria benefitted more from the protocol.

Preliminary results from the LUX-Dx insertable cardiac monitor remote programming and performance (LUX-Dx PERFORM) study.

Despite the wide adoption of insertable cardiac monitors (ICMs), high false-positive rates, suboptimal signal quality, limited ability to detect atrial flutter, and lack of remote programming remain challenging. The LUX-Dx PERFORM study was designed to evaluate novel technologies engineered to address these issues. Here, we present preliminary results from the trial focusing on the safety of ICM insertion, remote monitoring rates, and the feasibility of remote programming. LUX-Dx PERFORM is a multicenter, prospective, single-arm, post-market, observational study with planned enrollment of up to 827 patients from 35 sites in North America. A preliminary cohort consisting of the first 369 patients who were enrolled between March and October 2021 was selected for analysis. Three hundred sixty-three (363) patients had ICM insertions across inpatient and outpatient settings. The mean time followed was 103.4 ± 61.8 days per patient. The total infection rate was 0.8% (3/363). Interim results show high levels of remote monitoring with a median 94% of days with data transmission (interquartile range: 82-99). Thirteen (13) in-clinic and 24 remote programming sessions were reported in 34 subjects. Reprogramming examples are presented to highlight signal quality, the ability to detect atrial flutter, and the positive impact of remote programming on patient management. Interim results from LUX-Dx PERFORM study demonstrate the safety of insertion, high data transmission rates, the ability to detect atrial flutter, and the feasibility of remote programming to optimize arrhythmia detection and improve clinical workflow. Future results from LUX-Dx PERFORM will further characterize improvements in signal quality and arrhythmia detection.