Feasibility and Diagnostic Value of Recording Smartwatch Electrocardiograms in Neonates and Children.

OBJECTIVE: The objective of this study was to evaluate the agreement of smartwatch-derived single-lead electrocardiogram (ECG) recordings with 12-lead ECGs for diagnosing electrocardiographic abnormalities. STUDY DESIGN: A 12-lead ECG and an ECG using Apple Watch were obtained in 110 children (aged 1 week to 16 years) with normal (n = 75) or abnormal (n = 35) 12-lead ECGs (atrioventricular block [7], supraventricular tachycardia [SVT] {5}, bundle branch block [12], ventricular preexcitation [6], long QT [5]). In children aged <6 years, the ECG recording was performed with the active participation of an adult who applied the neonate or child's finger to the crown of the watch. In older children, tracings were obtained after brief teaching without adult guidance. All 12-lead ECGs were independently evaluated by 2 blinded cardiologists. Apple Watch ECGs were independently evaluated by another blinded cardiologist. RESULTS: In 109 children (99.1%), the smartwatch tracing was of sufficient quality for evaluation. Smartwatch tracings were 84% sensitive and 100% specific for the detection of an abnormal ECG. All 75 normal tracings were correctly identified. Of the 35 children with abnormalities on 12-lead ECGs, 5 (14%) were missed, most often because of baseline wander and artifacts. Rhythm disorders (atrioventricular block or SVT) and bundle branch blocks were correctly detected in most cases (11 of 12 and 11 of 12, respectively); preexcitation and long QT was detected in 4 of 6 and 4 of 5, respectively. CONCLUSION: Smartwatch ECGs recorded with parental assistance in children aged up to 6 years and independently in older children have the potential to detect clinically relevant conditions.

Implantation of a leadless pacemaker in young adults.

AIMS: Leadless pacing has emerged as an alternative to conventional transvenous pacemakers to mitigate the risks of pocket- and lead-related complications but its use remains controversial in young adults mostly because experience in this patient population is limited. We sought to examine the feasibility and safety of implanting leadless single chamber pacemakers in young adults. METHODS: This multicenter, retrospective, observational study sought to evaluate the safety, efficacy, and electrical performance of the Micra VR Transcatheter Pacemaker System (Medtronic) in patients between 18 and 40 years who underwent implantation of a leadless pacemaker for any indication at the university medical centers of Bordeaux, Clermont-Ferrand, Toulouse, and Tours (France), between 2015 and 2021. The primary safety endpoint was freedom from system-related or procedure-related major complications at 6 months. The primary efficacy endpoint was the combination of a low (≤2 V) and stable (increase within 1.5 V) pacing capture threshold at 6 months. RESULTS: Leadless pacemaker implantation was successful in all 35 patients. At 6 months, safety endpoint was met for 35 (100%) and efficacy endpoint for 34 (97%) patients. During a follow-up of 26 ± 15 months (range: 6-60 months), Safety endpoint remained 100% and efficacy endpoint was 94%. Leadless pacemaker retrieval was not required in any patient. Approximately one-third of patients (n = 13, 37%) had >40% ventricular pacing burdens at 1 year, including all 10 patients with a complete AV block but also 3 patients with normal AV conduction during implantation. One patient reported symptoms of pacemaker syndrome which was confirmed using Holter recording and successfully treated using reprogramming. CONCLUSION: In this observational study, leadless pacemakers demonstrated favorable short- and intermediate-term safety and effectiveness in young adults.

Clinical and echocardiographic evolution of patients with arrhythmogenic cardiomyopathy before heart transplantation.

BACKGROUND: Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiomyopathy characterized by fibrofatty myocardial replacement, and accurate diagnosis can be challenging. The clinical course of patients expressing a severe phenotype of the disease needing heart transplantation (HTx) is not well described in the literature. Therefore, this study aims to describe the clinical and echocardiographic evolution of patients with ACM necessitating HTx. METHODS: We retrospectively studied all patients who underwent HTx in our institution between 1998 and 2019 with a definite diagnosis of ACM according to the explanted heart examination. RESULTS: Ten patients with confirmed ACM underwent HTx. Only four of them had a diagnosis of ACM before HTx. These patients were 28 ± 15 years old at the time of their first symptoms. Patients received a diagnosis of heart failure (HF) after 5.9 ± 8.7 years of symptom evolution. The mean age at transplantation was 40 ± 17 years old. All the patients experienced ventricular tachycardia (VT) at least once before their HTx and 50% were resuscitated after sudden death. The mean left ventricular ejection at diagnosis and before transplantation was similar (32% ± 21% vs. 35.0% ± 19.3%, p = NS). Right ventricular dysfunction was present in all patients at the time of transplantation. CONCLUSION: Patients with ACM necessitating HTx show a high burden of ventricular arrhythmias and frequently present a biventricular involvement phenotype, making early diagnosis challenging. HF symptoms are the most frequent reason leading to the decision to transplant.

Acute pacing threshold elevation during simultaneous Micra leadless pacemaker implantation and AV node ablation: Clinical cases, computer model and practical recommendations.

BACKGROUND: In patients with refractory atrial fibrillation (AF), atrioventricular nodal (AVN) ablation and permanent pacemaker implantation is recommended. The Micra Transcatheter Pacing System (Micra) is a single chamber leadless pacemaker (LPM) and thus offers the possibility of AV node (AVN) ablation in the same procedure. Pacing threshold (PT) elevation after radiofrequency (RF) ablation is a potential complication. METHODS: We conducted a single center retrospective cohort study. Patients implanted with a Micra (n = 84) and concomitant or delayed AVN ablation (n = 12) from 2014 to 2022 were included. Two cases of acute Micra PT elevation immediately following RF AVN ablation required device retrieval and implantation of a new Micra. Procedural characteristics and electrophysiological parameters were analyzed, and a computer model was performed to determine factors responsible for acute PT elevations. RESULTS: A total of 84 patients were included. Mean age was 74 ± 10 and 48% were women. Twelve patients (14%) underwent AVN ablation. Two patients had acute PT elevation requiring device retrieval despite no direct contact of the ablation catheter with the Micra. Computer modeling shows that significant dissipated power due to electrical field coupling can occur at the tip or ring electrode if the catheter is not kept at a safe distance (≥35 mm) from the Micra when a maximum power of 100 W is delivered. CONCLUSION: Concurrent AVN ablation and Micra implantation is safe in most patients. To prevent acute PT elevation, keeping a safe distance of ≥35 mm from the tip and ring electrodes of the Micra and using lower power output may prevent this complication.

Accuracy of stroke volume measurement with phase-contrast cardiovascular magnetic resonance in patients with aortic stenosis.

BACKGROUND: Phase contrast (PC) cardiovascular magnetic resonance (CMR) in the ascending aorta (AAo) is widely used to calculate left ventricular (LV) stroke volume (SV). The accuracy of PC CMR may be altered by turbulent flow. Measurement of SV at another site is suggested in the presence of aortic stenosis, but very few data validates the accuracy or inaccuracy of PC in that setting. Our objective is to compare flow measurements obtained in the AAo and LV outflow tract (LVOT) in patients with aortic stenosis. METHODS: Retrospective analysis of patients with aortic stenosis who had CMR and echocardiography. Patients with mitral regurgitation were excluded. PC in the AAo and LVOT were acquired to derive SV. LV SV from end-systolic and end-diastolic tracings was used as the reference measure. A difference ≥ 10% between the volumetric method and PC derived SVs was considered discordant. Metrics of turbulence and jet eccentricity were assessed to explore the predictors of discordant measurements. RESULTS: We included 88 patients, 41% with bicuspid aortic valve. LVOT SV was concordant with the volumetric method in 79 (90%) patients vs 52 (59%) patients for AAo SV (p = 0.015). In multivariate analysis, aortic stenosis flow jet angle was a strong predictor of discordant measurement in the AAo (p = 0.003). Mathematical correction for the jet angle improved the concordance from 59 to 91%. Concordance was comparable in patients with bicuspid and trileaflet valves (57% and 62% concordance respectively; p = 0.11). Accuracy of SV measured in the LVOT was not influenced by jet eccentricity. For aortic regurgitation quantification, PC in the AAo had better correlation to volumetric assessments than LVOT PC. CONCLUSION: LVOT PC SV in patients with aortic stenosis and eccentric jet might be more accurate compared to the AAo SV. Mathematical correction for the jet angle in the AAo might be another alternative to improve accuracy.

The use of smartwatch electrocardiogram beyond arrhythmia detection.

The adoption of wearables in medicine has expanded worldwide with a rapidly growing number of consumers and new features capable of real-time monitoring of health parameters such as the ability to record and transmit a single-lead electrocardiogram (ECG). Smartwatch ECGs are increasingly used but current smartwatches only screen for atrial fibrillation (AF). Most of the literature has focused on analyzing the smartwatch ECG accuracy for the detection of AF or other tachycardias. As with the conventional ECG, this tool may be used for many more purposes than only detection of AF. The objectives of this review are to describe the published literature regarding the accuracy and clinical value of recording a smartwatch ECG in other situations than diagnosis of tachycardia and discuss possible techniques to optimize the diagnostic yield.

Left Ventricular Abnormal Substrate in Brugada Syndrome.

BACKGROUND: Slow-conductive structural abnormalities located in the epicardium of the right ventricle (RV) underlie Brugada syndrome (BrS). The extent of such substrate in the left ventricle (LV) has not been investigated. OBJECTIVES: This study sought to characterize the extent of epicardial substrate abnormalities in BrS. METHODS: We evaluated 22 consecutive patients (mean age 46 ± 11 years, 21 male) referred for recurrent ventricular arrhythmias (mean 10 ± 13 episodes) in the setting of BrS. The patients underwent clinical investigations and wide genetic screening to identify SCN5A mutations and common risk variants. High-density biventricular epicardial mapping was performed to detect prolonged (>70 ms) fragmented electrograms, indicating abnormal substrate area. RESULTS: All patients presented with abnormal substrate in the epicardial anterior RV (27 ± 11 cm2). Abnormal substrate was also identified on the LV epicardium in 10 patients (45%), 9 at baseline and 1 after ajmaline infusion, covering 15 ± 11 cm2. Of these, 4 had severe LV fascicular blocks. Patients with LV substrate had a longer history of arrhythmia (11.4 ± 6.7 years vs 4.3 ± 4.3 years; P = 0.003), longer PR (217 ± 24 ms vs 171 ± 14 ms; P < 0.001) and HV (60 ± 12 ms vs 46 ± 5 ms; P = 0.005) intervals, and abnormal substrate also extending into the inferior RV (100% vs 33%; P = 0.001). SCN5A mutation was present in 70% of patients with LV substrate (vs 25%; P = 0.035). SCN5A BrS patients with recurrent ventricular arrhythmias present a higher polygenic risk score compared with a nonselected BrS population (median of differences: -0.86; 95% CI: -1.48 to -0.27; P = 0.02). CONCLUSIONS: A subset of patients with BrS present an abnormal substrate extending onto the LV epicardium and inferior RV that is associated with SCN5A mutations and multigenic variants.

Smartwatch Electrocardiograms for Automated and Manual Diagnosis of Atrial Fibrillation: A Comparative Analysis of Three Models.

AIMS: The diagnostic accuracy of proprietary smartwatch algorithms and the interpretability of smartwatch ECG tracings may differ between available models. We compared the diagnostic potential for detecting atrial fibrillation (AF) of three commercially available smartwatches. METHODS: We performed a prospective, non-randomized, and adjudicator-blinded clinical study of 100 patients in AF and 100 patients in sinus rhythm, patients with atrial flutter were excluded. All patients underwent 4 ECG recordings: a conventional 12-lead ECG, Apple Watch Series 5®, Samsung Galaxy Watch Active 3®, and Withings Move ECG® in random order. All smartwatch ECGs were analyzed using their respective automated proprietary software and by clinical experts who also graded the quality of the tracings. RESULTS: The accuracy of automated AF diagnoses by Apple and Samsung outperformed that of Withings, which was attributable to a higher proportion of inconclusive ECGs with the latter (sensitivity/specificity: 87%/86% and 88%/81% vs. 78%/80%, respectively, p < 0.05). Expert interpretation was more accurate for Withings and Apple than for Samsung (sensitivity/specificity: 96%/86% and 94%/84% vs. 86%/76%, p < 0.05), driven by the high proportion of uninterpretable tracings with the latter (2 and 4% vs. 15%, p < 0.05). CONCLUSION: Diagnosing AF is possible using various smartwatch models. However, the diagnostic accuracy of their automated interpretations varies between models as does the quality of ECG tracings recorded for manual interpretation.