Results from a nationwide atrial fibrillation screening effort in Belgium

Introduction

Atrial Fibrillation (AF) is associated with an increased risk of stroke that can be mitigated with anticoagulation therapy. Opportunistic screening for AF for primary stroke prevention is recommended in subjects above 65. However, the paroxysmal and asymptomatic nature of AF hampers early detection with a single time point screening. Multiple time point measurements are superior to single time point measurements for the detection of AF. New technologies such as photoplethysmography (PPG) enable large scale AF screening with repetitive measurements at low-cost using only a smartphone.

Purpose

To explore an entirely online AF screening program in subjects with an elevated stroke risk.

Methods

The Belgian Heart Rhythm Association launched a digital marketing campaign, to promote AF screening during “The Belgian Week of the Heart Rhythm”. Candidates were referred to an online questionnaire to calculate their CHADS-VASC score. Subjects older than 18 with a CHADS-VASC score of 2 or more were allowed to enter the screening program. AF screening was performed with a PPG-based smartphone application. A 60-second PPG trace is captured by placing a fingertip on the smartphone's camera. The smartphone application analyses the PPG trace with an artificial intelligence software. Subjects were instructed to perform measurement twice daily and while experiencing symptoms over the course of 7 days. Measurements were classified as AF or non-AF by the algorithm and were reviewed by medical technicians.

Results

Of the 12.602 candidates who completed the questionnaire, 6.020 subjects met the inclusion criteria and were offered screening. However, only 2.111 (35%) participated in the screening program. The mean age of participants was 63±11 years, 37.3% was male, median CHADS-VASC was 2 (2–3). 257 participants (12.2%) were previously known with AF. In total 25.362 PPG recordings of 60 seconds were performed of which 258 demonstrated AF. AF was detected in 56 participants (2.7%). This was a new finding in 36 participants (1.7%) meaning that 64.3% of participants demonstrating AF were not previously known with AF. The number needed to screen was 58.6 to detect AF in a population without a history of AF and the number needed to invite was 167.2. Only 20 participants (7.8%) with a history of AF demonstrated AF during the screening program.

Conclusions

AF screening in subjects with an elevated stroke risk is feasible with an entirely online screening program without the need for medical hardware or medical personnel with an acceptable number needed to screen. However, this approach failed to target subjects in the highest age groups and since almost two thirds of the subjects interested in the screening program failed to commence screening, approaches to increase this response (specifically in high-risk groups) needs to be explored.

Funding Acknowledgement

Type of funding sources: None.

Patient motivation and adherence to an on-demand app-based heart rate and rhythm monitoring infrastructure for atrial fibrillation management through teleconsultation. TeleCheck-AF project results

Funding Acknowledgements

Type of funding sources: None.

Background

TeleCheck-AF is a mobile health (mHealth) infrastructure developed to provide remote management and comprehensive care to patients with atrial fibrillation (AF) during the Covid disease-19 pandemic lockdown within cardiology centers in Europe. TeleCheck-AF integrates an on-demand photoplethysmography-based heart rate/rhythm monitoring application supported a scheduled teleconsultation.

Purpose

The current sub-study of the TeleCheck-AF project aimed to provide the first real-world dataset on patient adherence and motivation to a standardized mHealth application integrated in remote AF management.

Methods

Patients were instructed to perform 60-second app-based heart rate/rhythm recordings three times daily and in case of symptoms for seven consecutive days prior to teleconsultation. Motivation was defined as number of days in which the expected number of measurements (≥three/day) were performed per number of days over the entire prescription period. Adherence was defined as number of performed measurements per number of expected measurements over the entire prescription period.

Results

Data from 990 consecutive patients with diagnosed AF (median age 64 [57-71] years, 39% female) from 10 centers that included the highest number of patients (≥25) were analyzed. Patients with both optimal motivation (100%) and adherence (≥100%) constituted 28% of the study population and had a lower percentage of recordings in sinus rhythm (90 [53-100%] vs 100 [64-100%], P<0.001) compared to others. Age and diabetes were predictors of both optimal motivation and adherence (odds ratio [OR] 1.02, 95% coincidence interval [95% CI] 1.01-1.04, P<0.001 and OR, 0.49, 95% CI 0.28-0.86, P=0.013, respectively). Patients with 100% motivation also had ≥100% adherence. Independent predictors for optimal adherence alone were age (OR 1.02, 95% CI 1.00-1.04, P=0.014), female sex (OR 1.70, 95% CI 1.29-2.23, P<0.001), previous AF ablation (OR 1.35, 95%CI 1.03-1.07, P=0.028).

Conclusion

In the TeleCheck-AF project, older age and diabetes were predictors of optimal patient motivation and adherence to app-based heart rate/rhythm monitoring. Therefore, physicians, nurses and allied health specialists involved in the management and care for patients with AF should not be discouraged to provide a mHealth infrastructure to elderly patients. Patient engagement improves mHealth adherence/motivation, hence, it is crucial to tailor the mHelath intervention to the needs and preferences of the patient.

Performance of an artificial intelligence algorithm to detect atrial fibrillation on a 24-hour continuous photoplethysmography recording using a smartwatch: ACURATE study

Background

In the awakening era of mobile health, wearable devices capable of detecting atrial fibrillation (AF) are on the rise. Smartwatches and wristbands are equipped with photoplethysmography (PPG) technology that enables (semi)continuous rhythm monitoring. These devices have been pioneered already in a few screening trials. However, such devices are being spread among consumers at a pace that is not paralleled by the evidence supporting their clinical performance. This imbalance reflects the urgent need for validation studies.

Purpose

To determine the diagnostic performance of an artificial intelligence algorithm to detect AF using photoplethysmography acquired by a smartwatch.

Methods

One hundred patients (≥18 years) without a pacemaker-dependent heart rhythm who were referred to a university hospital or a large tertiary hospital for elective 24-hour ECG Holter monitoring were asked to wear a continuous PPG monitoring smartwatch (i.e. Samsung GWA2 or Empatica E4) simultaneously with the Holter. All activities of daily life were allowed. The ECG trace and PPG waveform were synchronised and fragmented in one-minute fragements. The one-minute ECG fragments were labelled as AF, non-AF, or insufficient quality based on the routine clinical interpretation of the 24-hour Holter (i.e. software + physician overreading). The one-minute PPG fragments were analysed by an artificial intelligence (AI) algorithm (i.e. FibriCheck) and were given the same labels. Diagnostic metrics of the PPG AI algorithm were calculated with respect to the ECG interpretation, for all fragments with sufficient quality for both PPG and ECG.

Results

Four patients had to be excluded due to technical error (3 Holter errors, 1 smartwatch error). The mean age in the remaining study population (n=96) was 59±16 years, 51 (53%) were men and 15 (15.6%) were known with permanent AF. In this population, simultaneous ECG and PPG monitoring was recorded for 115,245 one-minute fragments. Fragments of insufficient quality for ECG (n=1,454; 1.3%), PPG (n=25,704; 22.3%) or both (n=15,362; 13.3%) were excluded. PPG fragments were more frequently of insufficient quality (p<0.001). AF was present in 10,255 (14.1%) of the resulting 72,725 high-quality one-minute fragments. The sensitivity of PPG to detect AF was 93.4% (CI 92.9% - 93.8%). The specificity of PPG to exclude AF was 98.4% (CI 98.3% - 98.5%). As a result, the overall accuracy of the PPG algorithm on one-minute fragment level was 97.7% (CI 97.6%- 97.8%).

Conclusion

Continuous out-of-hospital PPG monitoring using a smartwatch in combination with an AI algorithm can accurately discriminate between AF and non-AF rhythms in a heterogenous patient population. PPG quality is more often affected than ECG quality during daily life activities.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Research Foundation-Flanders, Strategic Basic Research Fund

Assessment of heart rate agreement on continuous photoplethysmography monitoring using a smartwatch versus beat-to-beat synchronized ECG monitoring

Background

In the awakening era of mobile health, wearables equipped with photoplethysmography (PPG) technology to monitor the heart rate (HR) and rhythm are on the rise. Smartwatches and wristbands enable HR monitoring for consumers at massive scale. Unfortunately, once consumers become patients, physicians are limited by insufficient evidence to support the clinical use of PPG based wearables. Accurate identification of heartbeats is the first step in the interpretation of PPG traces and should be validated.

Purpose

To assess the agreement between continuous PPG monitoring using a smartwatch and continuous ECG Holter monitoring in the identification of heartbeats and calculation of the HR.

Methods

One hundred patients (≥18 years) without a pacemaker-dependent heart rhythm who were referred to a university hospital and a large tertiary hospital for elective 24-hour ECG Holter monitoring were asked to wear a continuous PPG monitoring smartwatch (i.e. Samsung GWA2 or Empatica E4) simultaneously with the 24-hour Holter monitor. All activities of daily life were allowed. The ECG trace and PPG waveform were synchronised and fragmented in one-minute fragments. The one-minute ECG fragments were labelled as AF, non-AF, or insufficient quality based on the routine clinical interpretation (i.e. software + physician overreading), and the average HR during each fragment was calculated by Holter algorithm. The PPG fragments were analysed by an artificial intelligence (AI) algorithm (i.e. FibriCheck) that labelled fragments as sufficient or insufficient quality, identified the number of heartbeats and calculated the HR. The agreement between the HR on ECG and PPG in sufficient quality tracings was analysed with linear regression, Pearson's product-moment correlation and Bland-Altman analysis. A subanalysis was performed for AF rhythm and non-AF rhythms.

Results

A total of 72,725 simultaneous ECG and PPG one-minute fragments were recorded in 96 patients, after excluding 4 patients (due to 3 Holter and 1 smartwatch technical error) and 42,520 minutes (36.9%) of insufficient quality (ECG 1,454 (1.3%); PPG 25,704 (22.3%), ECG and PPG 15,362 (13.3%)). The correlation (r=0.935) between ECG and PPG HR was statistically significant (CI 0.934–0.936; P<0.001), with a mean difference between ECG and PPG of 0.8bpm. The lower and upper limit boundary (LLB and ULB; defined as ±1.96 SD) were −8.0bpm and 9.7bpm, respectively, i.e. 95% of PPG measurements identified the HR within 8bpm below or 10bpm above the ECG reference. The mean difference between ECG and PPG HR in the AF subgroup (n=10,255 (14.1%)) was 0.9bpm (LLB −8.4bpm; ULB 10.2bpm) and 0.8bpm in the non-AF subgroup (LLB −0.8bpm; ULB 9.6bpm).

Conclusion

The AI algorithm analysing continuous out-of-hospital PPG tracings can annotate heartbeats and assess HR without a clinically significant bias compared to continuous ECG monitoring, both during AF and non-AF rhythms in a heterogenous patient population.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Research Foundation-Flanders, Strategic Basic Research Fund Correlation plot & Bland-Altman plot

Evaluation of the device independent nature of a photoplethysmography-deriving smartphone app

Funding Acknowledgements

Type of funding sources: None.

Background

Smartphone apps using photoplethysmography (PPG) technology enable digital heart rhythm monitoring through their built-in camera, without the need for additional, specific, or costly hardware. This may positively impact the availability and scalability of remote monitoring. However, the diversity of smartphone specifications on the consumer market may raise concerns regarding the robustness of AF detection algorithms between various devices.

Purpose

To study the device independency of AF detection performance by a PPG-based smartphone application.

Methods

Patients from the cardiology department were consecutively enrolled. Patients were handed 7 iOS models and 1 Android model and were asked to consecutively perform one PPG measurement per device. A 12-lead electrocardiogram (ECG) was collected during the same consultation and interpreted by a cardiologist as reference diagnosis. To allow an objective comparison across the devices, patients who failed to perform one successful measurement on each device were excluded. Additional exclusions were atrial flutter rhythms and insufficient quality results. Sensitivity, specificity and accuracy were calculated with respect to the reference diagnosis. McNemar’s analysis was used for the head-to-head comparison of the sensitivity and specificity of the proprietary algorithm on the different smartphone devices.

Results

A total of 150 patients participated in the study with a median CHA2DS2-VASc score of 3 (interquartile range: 1-5). The median age of the study population was 70 (interquartile range: 56-79) years. In total, 54.7% of the population was male and the AF-prevalence was 35.3%. After the exclusion of patients with atrial flutter (n = 14) and patients who did not successfully perform a PPG measurement on each device (n = 5), diagnostic-grade results of 131 patients were used to calculate the performance of the proprietary algorithm. The sensitivity and specificity of the AF detection algorithm ranged from 90.9% (95% CI 75.7-98.1) to 100.0% (95% CI 91.0-100) and 94.5% (95% CI 86.6-98.5) to 100.0% (95% CI 94.6-100), respectively. The overall accuracy across the devices ranged from 94.4% (95% CI 88.3-97.9) to 99.0% (95% CI 94.6-100). Head-to-head comparisons of the results did not reveal significant differences in sensitivity (P = 0.125-1.000) or specificity (P = 0.375-1.000) of the proprietary AF detection algorithm among the different devices.

Conclusion

This study demonstrated the device-independent nature of the PPG-deriving smartphone application with respect to 12-lead ECG diagnosis.

The accuracy of physician interpretation of PPG vs single-lead ECG vs 12-lead ECG for the detection of atrial fibrillation

Funding Acknowledgements

Type of funding sources: None.

Introduction

The increasing availability of smartphones has enabled rhythm monitoring in large populations using standalone photoplethysmography (PPG) apps or singe-lead electrocardiography (ECG) with add-on devices. Current guidelines note that when atrial fibrillation (AF) is suspected by an automated algorithm, confirmation on an ECG tracing is required. The use of PPG alone to establish the diagnosis is not generally accepted, even when overread. The performance of physicians to discriminate between sinus rhythm (SR) and AF based on PPG alone is unknown.

Purpose

To study the performance of physicians to detect AF based on PPG vs single-lead ECG vs 12-lead ECG, and to explore the incremental value of a tachogram, Poincaré plot, and algorithm output to the interpretation of the PPG waveform by physicians.

Methods

PPG, single-lead ECG and 12-lead ECG data were simultaneously recorded in 30 patients. Diagnostic reference was the 12-lead ECG, read by two cardiologists. Cardiologists, electrophysiologists and cardiology fellows were invited to analyse the data of 30 patients (10 in SR, 10 in SR with extrasystoles and 10 in AF) through online surveys and classify the readings as ‘SR’, ‘ectopic/missed beats’, ‘AF’, ‘flutter’ or ‘unreadable’. For dichotomous analysis, ‘unreadable’ was reclassified as incorrect, the other options were reclassified as AF ‘present’ or ‘absent’. In the first survey, PPG data were presented subsequently as a waveform, stepwise adding the tachogram and Poincaré plot, and algorithm information. In the next two surveys, the single-lead and 12-lead ECG traces were presented. Sensitivity and specificity for all presentations were calculated with respect to the reference diagnosis. Diagnostic performances were compared with the Obuchowski-Rockette’s ANOVA approach with Jackknife covariance estimation and Benjamini-Hochberg correction.

Results

Sixty-five physicians completed the PPG survey and analysed the PPG waveforms with 88.8% sensitivity and 86.3% specificity for AF. The diagnostic metrics significantly increased to 95.5% sensitivity (P < 0.001) and 92.5% specificity (P < 0.001) after providing the tachogram and Poincaré plot. Fifty-seven physicians completed both ECG surveys and analysed the single-lead ECG outputs with 91.2% sensitivity and 93.9% specificity, while 12-lead ECG outputs were analysed with 93.9% sensitivity and 98.6% specificity. Hence, qualitative analysis of a PPG waveform with tachogram and Poincaré plot had a similar diagnostic performance to detect AF compared to single-lead ECG analysis and a similar sensitivity (P = 0.792) but lower specificity (P = 0.035) compared to 12-lead ECG.

Conclusions

PPG rhythm recordings, analysed by physicians as a waveform in combination with the corresponding tachogram and Poincaré plot, achieve similar diagnostic accuracy as single-lead ECG to detect AF. Abstract Figure.

P5694Outcomes of patients with arrhythmogenic right ventricular cardiomyopathy after ventricular tachycardia ablation without an implantable cardioverter-defibrillator: a multicenter international study

Background

In arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D), implantable cardioverter-defibrillators (ICD) after an episode of sustained monomorphic ventricular tachycardia (MVT) are currently recommended in most situations. However, radiofrequency catheter ablation (RCA) is effective in reducing recurrent VT and whether MVT is a surrogate of sudden cardiac death is debated when other risk factors are lacking.

Purpose

To report the outcomes of patients with ARVC/D who underwent RCA of well-tolerated MVT without a back-up ICD.

Methods

Patients with a definite ARVC/D diagnosis according to the 2010 Task Force revised criteria who underwent RCA of well-tolerated MVT at 9 tertiary centers across 5 countries, without an ICD prior to RCA and in the 3 following months were retrospectively included. Patients presenting with syncope or electrical storm, and patients with left ventricular ejection fraction <50% were excluded. Similar patients implanted with an ICD prior or without RCA in the same period served as controls.

Results

Sixty-five patients [median age 46.1 years, range (19.5–73.8), 75% males] underwent RCA of MVT between 2003 and 2016. Familial history of ARVC/D was found in 11% of patients. Epsilon-waves were present in 19% and T-waves inversion beyond V2 in 43%. A right ventricular (RV) ejection fraction ≤40% or fractional area change ≤33% was found in 14 (25%) patients. Median left ventricular ejection fraction was 61% (50–70). Clinical presentation was palpitations in 81% of patients and near-syncope in 14%. Prior to RCA, patients were on beta-blockers alone in 18%, class I drugs in 37% and amiodarone in 9%, while 15% of patients were free any antiarrhythmic medication. Only 1 patient (2%) had >1 clinical VT morphology. Median VT rate was 180 (110–270). An epicardial approach was used in 31% patients. The clinical VT was inducible in 84% of patients. The median number of targeted RV site was 1 (1–3) (RV outflow tract in 72%). Full acute success defined inability to induce any VT was achieved in 72% of patients. During a median follow-up time of 49 month (1.4–162), there was no death or aborted cardiac arrest. Survival without VT recurrence was estimated at 82%, 71% and 60%, 12-, 36- and 60-months after RCA. No VT recurrence was observed among patient who had undergone an epicardial ablation. Among patients with VT recurrence, 6 (35%) did not receive an ICD, and 14 (70%) underwent redo RCA. An ICD was implanted in 10 patients, including 5 for VT recurrence. Fifty-eight patients constituted the control group, and 64% had appropriate ICD interventions during follow-up.

Conclusions

Despite a significant rate of VT recurrence, selected patients with ARVC/D who underwent RCA for stable MVT without an ICD did not experience any arrhythmic death. Further prospective studies are mandatory to precise the respective places of ICD and RCA in the management of ARVC/D patients with well-tolerated MVT.

Acknowledgement/Funding

None

Can the tricyanomethanide anion improve CO2 absorption by acetate-based ionic liquids?

The chemical reaction of carbon dioxide with 1-alkyl-3-methylimidazolium acetate ionic liquids is not affected by presence of the C(CN)₃⁻ anion, which leads to a faster gas absorption and a higher solubility.

Pulmonary vein triggers, focal sources, rotors and atrial cardiomyopathy: implications for the choice of the most effective ablation therapy

Understanding of the pathophysiological mechanism(s) underlying atrial fibrillation (AF) is the foundation on which current ablation strategies are built. In the vast majority of patients with paroxysmal AF, the ablation procedure should target the pulmonary veins. In patients with nonparoxysmal AF, however, pulmonary vein isolation alone seems to be insufficient to prevent the arrhythmia. Several recent clinical trials have investigated the concept that rotors (re-entry based on a meandering central core from which spiral waves emanate) might be the mechanism responsible for sustaining AF. Ablation of these localized AF sources is an important step towards substrate-driven procedures in persistent AF. Hybrid AF ablation procedures, based on the integration of endocardial transcatheter and epicardial off-pump surgical techniques, have been introduced to overcome their mutual shortcomings. The long-term results are encouraging, especially in currently challenging settings such as nonparoxysmal AF and failed endocardial catheter ablation procedures.

The changing circumstance of atrial fibrillation - progress towards precision medicine

The prevalence of atrial fibrillation (AF) in the general population is between 1% and 2% in the developed world and is higher in men than in women. The arrhythmia occurs much more commonly in the elderly, and the estimated lifetime risk of developing AF is one in four for men and women aged 40 years and above. Projected data from multiple population-based studies in the USA and Europe predict a two- to threefold increase in the number of AF patients by 2060. The high lifetime risk of AF and increased longevity underscore the important public health burden posed by this arrhythmia worldwide. AF has multiple aetiologies and a broad variety of presentations. The primary pathologies underlying or promoting the occurrence of AF vary more than for any other cardiac arrhythmia, ranging from autonomic imbalance to organic heart disease and metabolic disorders, such as diabetes mellitus, metabolic syndrome, hyperthyroidism and kidney disease, and lifestyle factors such as smoking, alcohol consumption and participation in endurance sports. Biomarkers are increasingly being investigated and, together with clinical and genetic factors, will eventually lead to a clinically valuable detailed classification of AF which will also incorporate pathophysiological determinants and mechanisms of the arrhythmia. In turn, this will allow the development and application of precision medicine to this troublesome arrhythmia.

Reversal of ventricular premature beat induced cardiomyopathy by radiofrequency catheter ablation

Frequent monomorphic ventricular premature beats (VPBs) may lead to left ventricular dysfunction. We describe two patients with frequent monomorphic VPBs and dilated cardiomyopathy in whom left ventricular function normalised after elimination of the VPBs by radiofrequency catheter ablation. The recent literature on this topic is summarised and potential candidates for catheter ablation are discussed. (Neth Heart J 2010;18:493-8.).

Computational and experimental investigations of supramolecular assemblies of p-sulfonatocalix[4]arene organized by weak forces

We report the study of the supramolecular assemblies formed by the incorporation of quaternary ammonium cations such as Me4N+ or Et4N+ into host-guest assemblies with p-sulfonatocalix[4]arene in the presence of a lanthanide(III) cation in water. We use microcalorimetry to characterize the formation of these supramolecular assemblies. We obtain a molecular description of these assemblies by performing molecular dynamics simulations over a very large period of time. The structures of these supramolecular complexes have been determined and discussed through specific interaction energy contributions. By combining MD simulations and 1NMR spectroscopy, we highlight a specific behavior of the supramolecular assembly with the Me4N+.

Apical ballooning in relatives

Apical ballooning of the left ventricle was first introduced as takotsubo-like left ventricular dysfunction in 1990 by Satoh and colleagues. The syndrome is characterised by reversible extensive akinesia of the apical and mid-portions of the left ventricle with hypercontraction of the basal segment. For the first time two sisters with this syndrome are reported, suggesting a possible genetic aetiology.