Real-world validation of smartphone-based photoplethysmography for rate and rhythm monitoring in atrial fibrillation.

AIMS: Photoplethysmography- (PPG) based smartphone applications facilitate heart rate and rhythm monitoring in patients with paroxysmal and persistent atrial fibrillation (AF). Despite an endorsement from the European Heart Rhythm Association, validation studies in this setting are lacking. Therefore, we evaluated the accuracy of PPG-derived heart rate and rhythm classification in subjects with an established diagnosis of AF in unsupervised real-world conditions. METHODS AND RESULTS: Fifty consecutive patients were enrolled, 4 weeks before undergoing AF ablation. Patients used a handheld single-lead electrocardiography (ECG) device and a fingertip PPG smartphone application to record 3907 heart rhythm measurements twice daily during 8 weeks. The ECG was performed immediately before and after each PPG recording and was given a diagnosis by the majority of three blinded cardiologists. A consistent ECG diagnosis was exhibited along with PPG data of sufficient quality in 3407 measurements. A single measurement exhibited good quality more often with ECG (93.2%) compared to PPG (89.5%; P < 0.001). However, PPG signal quality improved to 96.6% with repeated measurements. Photoplethysmography-based detection of AF demonstrated excellent sensitivity [98.3%; confidence interval (CI): 96.7-99.9%], specificity (99.9%; CI: 99.8-100.0%), positive predictive value (99.6%; CI: 99.1-100.0%), and negative predictive value (99.6%; CI: 99.0-100.0%). Photoplethysmography underestimated the heart rate in AF with 6.6 b.p.m. (95% CI: 5.8 b.p.m. to 7.4 b.p.m.). Bland-Altman analysis revealed increased underestimation in high heart rates. The root mean square error was 11.8 b.p.m. CONCLUSION: Smartphone applications using PPG can be used to monitor patients with AF in unsupervised real-world conditions. The accuracy of AF detection algorithms in this setting is excellent, but PPG-derived heart rate may tend to underestimate higher heart rates.

The MADIT-ICD benefit score helps to select implantable cardioverter-defibrillator candidates in cardiac resynchronization therapy.

AIMS: The aim of this study is to evaluate whether the MADIT-ICD benefit score can predict who benefits most from the addition of implantable cardioverter-defibrillator (ICD) to cardiac resynchronization therapy (CRT) in real-world patients with heart failure with reduced ejection fraction (HFrEF) and to compare this with selection according to a multidisciplinary expert centre approach. METHODS AND RESULTS: Consecutive HFrEF patients who received a CRT for a guideline indication at a tertiary care hospital (Ziekenhuis Oost-Limburg, Genk, Belgium) between October 2008 and September 2016, were retrospectively evaluated. The MADIT-ICD benefit groups (low, intermediate, and high) were compared with the current multidisciplinary expert centre approach. Endpoints were (i) sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) and (ii) non-arrhythmic mortality. Of the 475 included patients, 165 (34.7%) were in the lowest, 220 (46.3%) in the intermediate, and 90 (19.0%) in the highest benefit group. After a median follow-up of 34 months, VT/VF occurred in 3 (1.8%) patients in the lowest, 9 (4.1%) in the intermediate, and 13 (14.4%) in the highest benefit group (P < 0.001). Vice versa, non-arrhythmic death occurred in 32 (19.4%) in the lowest, 32 (14.6%) in the intermediate, and 3 (3.3%) in the highest benefit group (P = 0.002). The predictive power for ICD benefit was comparable between expert multidisciplinary judgement and the MADIT-ICD benefit score: Uno's C-statistic 0.69 vs. 0.69 (P = 0.936) for VT/VF and 0.62 vs. 0.60 (P = 0.790) for non-arrhythmic mortality. CONCLUSION: The MADIT-ICD benefit score can identify who benefits most from CRT-D and is comparable with multidisciplinary judgement in a CRT expert centre.

Atrial fibrillation screening with photo-plethysmography through a smartphone camera.

AIMS: This cross-sectional study was set up to assess the feasibility of mass screening for atrial fibrillation (AF) with only the use of a smartphone. METHODS AND RESULTS: A local newspaper published an article, allowing to subscribe for a 7-day screening period to detect AF. Screening was performed through an application that uses photo-plethysmography (PPG) technology by exploiting a smartphone camera. Participants received instructions on how to perform correct measurements twice daily, with notifications pushed through the application's software. In case of heart rhythm irregularities, raw PPG signals underwent secondary offline analysis to confirm a final diagnosis. From 12 328 readers who voluntarily signed up for screening (49 ± 14 years; 58% men), 120 446 unique PPG traces were obtained. Photo-plethysmography signal quality was adequate for analysis in 92% of cases. Possible AF was detected in 136 individuals (1.1%). They were older (P < 0.001), more frequently men (P < 0.001), and had higher body mass index (P = 0.004). In addition, participants who strictly adhered to the recommended screening frequency (i.e. twice daily) were more often diagnosed with possible AF (1.9% vs. 1.0% in individuals who did not adhere; P = 0.008). Symptoms of palpitations, confusion, and shortness of breath were more frequent in case of AF (P < 0.001). The cumulative diagnostic yield for possible AF increased from 0.4% with a single heart rhythm assessment to 1.4% with screening during the entire 7-day screening period. CONCLUSION: Mass screening for AF using only a smartphone with dedicated application based on PPG technology is feasible and attractive because of its low cost and logistic requirements.

Genotype-phenotype relationship and risk stratification in loss-of-function SCN5A mutation carriers.

INTRODUCTION: Loss-of-function (LoF) mutations in the SCN5A gene cause multiple phenotypes including Brugada Syndrome (BrS) and a diffuse cardiac conduction defect. Markers of increased risk for sudden cardiac death (SCD) in LoF SCN5A mutation carriers are ill defined. We hypothesized that late potentials and fragmented QRS would be more prevalent in SCN5A mutation carriers compared to SCN5A-negative BrS patients and evaluated risk markers for SCD in SCN5A mutation carriers. METHODS: We included all SCN5A loss-of-function mutation carriers and SCN5A-negative BrS patients from our center. A combined arrhythmic endpoint was defined as appropriate ICD shock or SCD. RESULTS: Late potentials were more prevalent in 79 SCN5A mutation carriers compared to 39 SCN5A-negative BrS patients (66% versus 44%, p = .021), while there was no difference in the prevalence of fragmented QRS. PR interval prolongation was the only parameter that predicted the presence of a SCN5A mutation in BrS (OR 1.08; p < .001). Four SCN5A mutation carriers, of whom three did not have a diagnostic type 1 ECG either spontaneously or after provocation with a sodium channel blocker, reached the combined arrhythmic endpoint during a follow-up of 44 ± 52 months resulting in an annual incidence rate of 1.37%. CONCLUSION: LP were more frequently observed in SCN5A mutation carriers, while fQRS was not. In SCN5A mutation carriers, the annual incidence rate of SCD was non-negligible, even in the absence of a spontaneous or induced type 1 ECG. Therefore, proper follow-up of SCN5A mutation carriers without Brugada syndrome phenotype is warranted.

Prognostic value of electrocardiographic time intervals and QT rate dependence in hypertrophic cardiomyopathy.

INTRODUCTION: Preventing sudden cardiac death (SCD) is one of the main goals in hypertrophic cardiomyopathy (HCM). Many variables have been proposed, however the European and American guidelines do not incorporate any ECG or Holter monitoring derived variables other than the presence of ventricular arrhythmia in their risk stratification models. In the present study we evaluated electrocardiographic parameters in risk stratification of HCM. METHODS AND RESULTS: Novel electrocardiographic parameters including the index of cardio-electrophysiological balance (iCEB), individualized QT correction (QTi) and QT rate dependence were evaluated along with established risk factors. A composite endpoint of SCD was defined as out of hospital cardiac arrest, appropriate ICD shock and sustained ventricular tachycardia. Cox regression analysis was used to evaluate predictors of SCD. Out of the 466 HCM patients, 31 reached the composite endpoint during a follow up of 75 ±â€¯86 months. In a multivariate model, nor iCEB, QTi or QT rate dependence were predictors of SCD. Only male gender (p < 0.01; OR 13.1; CI 1.74-98.83), negative T waves in the inferior leads (p = 0.04; OR 2.51; CI 1.03-6.13) and familial sudden death (p < 0.01; OR 3.03; CI 1.39-6.59) were significant predictors. On top of either the ESC risk score or the 3 traditional 'American risk factors', only male gender was a significant predictor of SCD. CONCLUSION: No ECG or Holter monitoring parameters added in risk stratification for SCD in HCM. However, male gender and negative T waves in the inferior leads are promising novel markers to evaluate in larger cohorts.

Evaluation of Index of Cardio-Electrophysiological Balance (iCEB) as a New Biomarker for the Identification of Patients at Increased Arrhythmic Risk.

BACKGROUND: Recently a new risk marker for drug-induced arrhythmias called index of cardio-electrophysiological balance (iCEB), measured as QT interval divided by QRS duration, was evaluated in an animal model. It was hypothesized that iCEB is equivalent to the cardiac wavelength λ (λ = effective refractory period (ERP) x conduction velocity) and that an increased or decreased value of iCEB would potentially predict an increased susceptibility to TdP or non-TdP mediated VT/VF, respectively. METHODS: First, the correlation between QT interval and ERP was evaluated by invasively measuring ERP during a ventricular stimulation protocol in humans (N = 40). Then the effect of administration of sotalol and flecainide on iCEB was measured in 40 patients with supraventricular tachycardias. Finally iCEB was assessed in carriers of a long QT syndrome (LQTS, N = 70) or Brugada syndrome (BrS, N = 57) mutation and compared them with genotype negative family members (N = 65). RESULTS: The correlation between QT interval and ERP was established (Pearson R(2) = 0.25) which suggests that iCEB≈ERPxCV≈QT/QRS. Sotalol administration increased iCEB (+ 0.23; P = 0.01), while it decreased with the administration of flecainide (-0.21, P = 0.03). In the LQTS group iCEB was increased (5.22 ± 0.93, P < 0.0001) compared to genotype negative family members (4.24 ± 0.5), while it was decreased in the BrS group (3.52 ± 0.43, P < 0.0001). CONCLUSIONS: Our data suggest that iCEB (QT/QRS) is a simple but effective ECG surrogate of cardiac wavelength. iCEB is increased in situations that predispose to TdP and is decreased in situations that predispose to non-TdP mediated VT/VF. Therefore, iCEB might serve as a noninvasive and readily measurable marker to detect increased arrhythmic risk.

Left ventricular four-dimensional rotational angiography with low radiation dose through interphase registration.

AIMS: Ventricular tachycardia ablations could benefit from four-dimensional (4D) (dynamic 3D) visualization of the left ventricle (LV) as roadmap for anatomy-guided procedures. Our aim was to develop an algorithm that combines information of several cardiac phases to improve signal-to-noise ratio in low-dose, noisy rotational angiography [three-dimensional rotational angiography (3DRA)] image datasets, enabling semi-automatic segmentation and generation of 4D rotational angiography (4DRA) LV surface models. METHODS AND RESULTS: We developed a novel slow pacing protocol for low-dose 4DRA imaging and applied interphase registration (IPR) to improve contrast-to-noise ratio (CNR) such that 4D LV segmentation could be achieved using a single iso-intensity value (ISO). The method was applied to construct four-phase dynamic LV models from five porcine experiments. Optimal choice of IPR and ISO parameters and resulting LV model accuracy were assessed by comparison with 'groundtruth' manual LV delineations using surface distance measures [root mean square distance (RMSD), Hausdorff distance (HD), fraction of surface distances ≤3 mm (d3 mm)]. Using IPR with optimized parameters, CNR improved by 88% (P < 0.0001) and increased segmentation accuracy was proven irrespective of ISO. Significant improvement was achieved in RMSD [mean at optimal ISO: -28.3% (95% confidence interval (CI) -21.7 to -35.0, P < 0.0001)], HD [-21.4% (95% CI -18.6 to -24.1, P < 0.0001)], and d3 mm [+7.8% (95% CI +4.6 to +10.9, P < 0.0001)]. An average d3 mm of 95.6 ± 2.8% was reached at optimal ISO. Time to generate a 4D model was ±11.5 min with IPR vs. ±22 min without. CONCLUSION: Interphase registration significantly improves 4DRA image quality and facilitates semi-automatic segmentation, resulting in clinically useful accuracy despite low-dose image acquisition protocols, while shortening 4D model generation time. This opens the prospect of 4D imaging in clinical settings.

Targeted capture sequencing in a large LQTS family reveals a new pathogenic mutation c.2038delG in KCNH2 initially missed due to allelic dropout.

We present a new mutation in KCNH2 (c.2038delG) resulting in a frameshift and premature truncation of the IKr channel protein in a large LQTS family with several sudden death cases. This mutation was initially missed by mutation scanning with DHPLC due to allelic dropout and only retrieved after repeat genetic testing with targeted capture and massive parallel sequencing. There was full penetrance of this mutation, only if an individualized QT correction derived from 24-hour Holter data was used. This case again underscores the importance of repeat genetic testing in robust cases of LQTS that remained genotype negative with mutation scanning techniques.

Heart rate turbulence predicts ICD-resistant mortality in ischaemic heart disease.

AIMS: In high-risk patients, implantable cardioverter-defibrillators (ICDs) can convert the mode of death from arrhythmic to pump failure death. Therefore, we introduced the concept of 'ICD-resistant mortality' (IRM), defined as death (a) without previous appropriate ICD intervention (AI), (b) within 1 month after the first AI, or (c) within 1 year after the initial ICD implantation. Implantable cardioverter-defibrillator implantation in patients with a high risk of IRM should be avoided. METHODS AND RESULTS: Implantable cardioverter-defibrillator patients with ischaemic heart disease were included if a digitized 24 h Holter was available pre-implantation. Demographic, electrocardiographic, echocardiographic, and 24 h Holter risk factors were collected at device implantation. The primary endpoint was IRM. Cox regression analyses were used to test the association between predictors and outcome. We included 130 patients, with a mean left ventricular ejection fraction (LVEF) of 33.6 ± 10.3%. During a follow-up of 52 ± 31 months, 33 patients died. There were 21 cases of IRM. Heart rate turbulence (HRT) was the only Holter parameter associated with IRM and total mortality. A higher New York Heart Association (NYHA) class and a lower body mass index were the strongest predictors of IRM. Left ventricular ejection fraction predicted IRM on univariate analysis, and was the strongest predictor of total mortality. The only parameter that predicted AI was non-sustained ventricular tachycardia. CONCLUSION: Implantable cardioverter-defibrillator implantation based on NYHA class and LVEF leads to selection of patients with a higher risk of IRM and death. Heart rate turbulence may have added value for the identification of poor candidates for ICD therapy. Available Holter parameters seem limited in their ability to predict AI.

Predictors of 30-day and 1-year mortality after transvenous lead extraction: a single-centre experience.

AIMS: Owing to the increasing use of cardiac implantable electronic devices, there is a growing need for safe and effective techniques to manage device-related complications and lead dysfunction. Lead extraction remains a challenging procedure with inherent risks. We present the 30-day and long-term outcomes of lead extractions in the University Hospitals Leuven. METHODS AND RESULTS: We report a retrospective cohort study of 176 patients admitted to the University Hospitals Leuven between January 2005 and December 2011, for the transvenous extraction of 295 leads. Indications for extraction were lead dysfunction and device upgrade in 84 (47.7%), pocket infection in 61 (34.7%), and systemic infection in 31 patients (17.6%). Extraction was successful in 95.5% of patients with complete removal of the leads or only a minor fragment remaining. One fatal peri-procedural complication occurred. Thirty-day mortality was 3.4% (n = 6). Systemic infection was the only significant predictor of 30-day mortality [odds ratio (OR) 29.706; P = 0.029]. A lower level of haemoglobin prior to extraction also tended to be related with a higher mortality, but this was not significant (OR 2.024; P = 0.082). One-year mortality was 8.5% (n = 15). Systemic infection (OR 9.727; P = 0.009), a lower level of haemoglobin (OR 1.597; P = 0.05), and a higher level of ureum (OR 1.021; P = 0.017) prior to extraction were significant predictors of 1-year mortality. Systemic infection was associated with significantly higher 30-day (19%), 1-year (32%), and long-term (39%) mortality rates. CONCLUSION: Lead extraction can be safely and successfully performed in the majority of patients, with limited life-threatening complications. However, lead extraction because of systemic infection is associated with a significantly higher risk of short- and long-term mortality.

Orally Inhaled Flecainide for Conversion of Atrial Fibrillation to Sinus Rhythm: INSTANT Phase 2 Trial.

BACKGROUND: INSTANT (INhalation of flecainide to convert recent-onset SympTomatic Atrial fibrillatioN to sinus rhyThm) was a multicenter, open-label, single-arm study of flecainide acetate oral inhalation solution (FlecIH) for acute conversion of recent-onset (≤48 hours) symptomatic atrial fibrillation (AF) to sinus rhythm. OBJECTIVES: This study investigated the efficacy and safety in 98 patients receiving a single dose of FlecIH delivered via oral inhalation. METHODS: Patients self-administered FlecIH over 8 minutes in a supervised medical setting using a breath-actuated nebulizer and were continuously monitored for 90 minutes using a 12-lead Holter. RESULTS: Mean age was 60.5 years, mean body mass index was 27.0 kg/m2, and 34.7% of the patients were women. All patients had ≥1 AF-related symptoms at baseline, and 87.8% had AF symptoms for ≤24 hours. The conversion rate was 42.6% (95% CI: 33.0%-52.6%) with a median time to conversion of 14.6 minutes. The conversion rate was 46.9% (95% CI: 36.4%-57.7%) in a subpopulation that excluded predose flecainide exposure for the current AF episode. Median time to discharge among patients who converted was 2.5 hours, and only 2 patients had experienced AF recurrence by day 5. In the conversion-no group, 44 (81.5%) patients underwent electrical cardioversion by day 5. The most common adverse events were related to oral inhalation of flecainide (eg, cough, oropharyngeal irritation/pain), which were mostly of mild intensity and limited duration. CONCLUSIONS: The risk-benefit of orally inhaled FlecIH for acute cardioversion of recent-onset AF appears favorable. FlecIH could provide a safe, effective, and convenient first-line therapeutic option. (INhalation of Flecainide to Convert Recent Onset SympTomatic Atrial Fibrillation to siNus rhyThm [INSTANT]; NCT03539302).

Arrhythmia monitoring and outcome after myocardial infarction (BIO|GUARD-MI): a randomized trial.

Objectives: Cardiac arrhythmias predict poor outcome after myocardial infarction (MI). We studied if arrhythmia monitoring with an insertable cardiac monitor (ICM) can improve treatment and outcome. Design: BIO|GUARD-MI was a randomized, international open-label study with blinded outcome assessment. Setting: Tertiary care facilities monitored the arrhythmias, while the follow-up remained with primary care physicians. Participants: Patients after ST-elevation (STEMI) or non-ST-elevation MI with an ejection fraction >35% and a CHA2DS2-VASc score ≥4 (men) or ≥5 (women). Interventions: Patients were randomly assigned to receive or not receive an ICM in addition to standard post-MI treatment. Device-detected arrhythmias triggered immediate guideline recommended therapy changes via remote monitoring. Main outcome measures: MACE, defined as a composite of cardiovascular death or acute unscheduled hospitalization for cardiovascular causes. Results: 790 patients (mean age 71 years, 72% male, 51% non-STEMI) of planned 1,400 pts were enrolled and followed for a median of 31.6 months. At 2 years, 39.4% of the device group and 6.7% of the control group had their therapy adapted for an arrhythmia [hazard ratio (HR) = 5.9, P < 0.0001]. Most frequent arrhythmias were atrial fibrillation, pauses and bradycardia. The use of an ICM did not improve outcome in the entire cohort (HR = 0.84, 95%-CI: 0.65-1.10; P = 0.21). In secondary analysis, a statistically significant interaction of the type of infarction suggests a benefit in the pre-specified non-STEMI subgroup. Risk factor analysis indicates that this may be connected to the higher incidence of MACE in patients with non-STEMI. Conclusions: The burden of asymptomatic but actionable arrhythmias is large in post-infarction patients. However, arrhythmia monitoring with an ICM did not improve outcome in the entire cohort. Post-hoc analysis suggests that it may be beneficial in non-STEMI patients or other high-risk subgroups. Clinical Trial Registration: [https://www.clinicaltrials.gov/ct2/show/NCT02341534], NCT02341534.

Cardiac three-dimensional rotational angiography can be performed with low radiation dose while preserving image quality.

AIMS: The effective radiation dose (ED) of three-dimensional rotational angiography (3DRA) is 5-8 mSv, leading to reticence on its use. We evaluated the potential of 3DRA with a reduced number of frames (RNF) and a reduced dose per frame. METHODS AND RESULTS: Three-dimensional rotational angiography was performed in 60 patients (52.5 ± 9.6 years, 16 females) referred for ablation in the right (RA; n = 10) and left atrium (LA; n = 50). In a simulation group (n = 20), the effect of dropping frames from a conventional 248 frames 3DRA LA acquisition was simulated. In a prospective group (n = 40), RNF 3DRA were acquired of LA (n = 30) and RA (n = 10) with 67 frames (0.24 Gy/frame) and 45 frames (0.12 µGy/frame), respectively. Accuracy was evaluated qualitatively and quantitatively. Effective radiation dose was determined by Monte Carlo simulation on every frame. In the simulation group, surface errors increased minimally and non-significantly when reducing frames from 248 to 124, 83, 62, 50, 42, and 31: 0.49 ± 0.51, 0.52 ± 0.46, 0.61 ± 0.49, 0.62 ± 0.47, 0.71 ± 0.48, and 0.81 ± 0.47 mm, respectively (Pearson coefficient 0.20). All 3D LA images were clinically useful, even with only 31 frames. In the prospective group, good or optimal 3D image quality was achieved in 80% of LA and all of RA reconstructions. These accurate models were obtained with ED of 2.6 ± 0.4 mSv for LA and 1.2 ± 0.5 mSv for RA. CONCLUSION: Three-dimensional rotational angiography is possible with a significant reduction in ED (to the level of prospectively gated cardiac computed X-ray tomography) without compromising image quality. Low-dose 3DRA could become the preferred online 3D imaging modality for pulmonary vein isolation and other anatomy-dependent ablations.

Foetal presentation of long QT syndrome.

Long-QT syndrome is a rare, inherited cardiac channelopathy that is characterized by arrhythmia, syncope and sudden cardiac death. Foetal symptoms are very rare and prenatal diagnosis is difficult. We report on a foetal presentation of long-QT syndrome with severe hydrops and a chaotic heart rhythm at 32 weeks of gestation. Postnatal electrocardiography showed runs of polymorphic ventricular tachycardia and an extremely prolonged-QT segment (QTc of 640 ms). The initial approach of overdrive pacing, followed by the combined therapy of a beta blocker, a sodium channel blocker (mexiletine) and potassium suppletion proved successful in maintaining a stable sinus rhythm. The girl was doing well at eight months of followup. In this patient a timely diagnosis and effective management after birth have been life-saving.The intrauterine manifestation of foetal atrioventricular dissociation and ventricular arrhythmia should raise suspicion of congenital long-QT syndrome.

Individualized QT interval (QTi) is a powerful diagnostic tool in long QT syndrome: results from a large validation study.

Aims: Diagnosis of Long QT syndrome (LQTS) is based on prolongation of the QT interval corrected for heart rate (QTc) on surface ECG and genotyping. However, up to 25% of genotype positive patients have a normal QTc interval. We recently showed that individualized QT interval (QTi) derived from 24 h holter data and defined as the QT value at the intersection of an RR interval of 1,000 ms with the linear regression line fitted through QT-RR data points of each individual patient was superior over QTc to predict mutation status in LQTS families. This study aimed to confirm the diagnostic value of QTi, fine-tune its cut-off value and evaluate intra-individual variability in patients with LQTS. Methods: From the Telemetric and Holter ECG Warehouse, 201 recordings from control individuals and 393 recordings from 254 LQTS patients were analysed. Cut-off values were obtained from ROC curves and validated against an in house LQTS and control cohort. Results: ROC curves indicated very good discrimination between controls and LQTS patients with QTi, both in females (AUC 0.96) and males (AUC 0.97). Using a gender dependent cut-off of 445 ms in females and 430 ms in males, a sensitivity of 88% and specificity of 96% were achieved, which was confirmed in the validation cohort. No significant intra-individual variability in QTi was observed in 76 LQTS patients for whom at least two holter recordings were available (483 ± 36 ms vs. 489 ± 42 ms, p = 0.11). Conclusions: This study confirms our initial findings and supports the use of QTi in the evaluation of LQTS families. Using the novel gender dependent cut-off values, a high diagnostic accuracy was achieved.

Reduced Left Atrial Appendage Flow Is Associated With Future Atrial Fibrillation After Cryptogenic Stroke.

BACKGROUND: Hemostasis within the left atrial appendage (LAA) is a common cause of stroke, especially in patients with atrial fibrillation (AF). Although LAA flow provides insights into LAA function, its potential for predicting AF has yet to be established. The aim of this study was to explore whether LAA peak flow velocities early after cryptogenic stroke are associated with future AF on prolonged rhythm monitoring. METHODS: A total of 110 patients with cryptogenic stroke were consecutively enrolled and underwent LAA pulsed-wave Doppler flow assessment using transesophageal echocardiography within the early poststroke period. Velocity measurements were analyzed offline by an investigator blinded to the results. Prolonged rhythm monitoring was conducted on all participants via 7-day Holter and implantable cardiac monitoring devices, with follow-up conducted over a period of 1.5 years to determine the incidence of AF. The end point of AF was defined as irregular supraventricular rhythm with variable RR interval and no detectable P waves lasting ≥30 sec during rhythm monitoring. RESULTS: During a median follow-up period of 539 days (interquartile range, 169-857 days), 42 patients (38%) developed AF, with a median time to AF diagnosis of 94 days (interquartile range, 51-487 days). Both LAA filling velocity and LAA emptying velocity (LAAev) were lower in patients with AF (44.3 ± 14.2 and 50.7 ± 13.3 cm/s, respectively) compared with patients without AF (59.8 ± 14.0 and 76.8 ± 17.3 cm/sec, respectively; P < .001 for both). LAAev was most strongly associated with future AF, with an area under the receiver operating characteristic curve of 0.88 and an optimal cutoff value of 55 cm/sec. Age and mitral regurgitation were independent determinants of reduced LAAev. CONCLUSIONS: Impaired LAA peak flow velocities (LAAev < 55 cm/sec) in patients with cryptogenic stroke are associated with future AF. This may facilitate the selection of appropriate candidates for prolonged rhythm monitoring to improve its diagnostic accuracy and implementation.

Detecting Paroxysmal Atrial Fibrillation From an Electrocardiogram in Sinus Rhythm: External Validation of the AI Approach.

BACKGROUND: Atrial fibrillation (AF) may occur asymptomatically and can be diagnosed only with electrocardiography (ECG) while the arrhythmia is present. OBJECTIVES: The aim of this study was to independently validate the approach of using artificial intelligence (AI) to identify underlying paroxysmal AF from a 12-lead ECG in sinus rhythm (SR). METHODS: An AI algorithm was trained to identify patients with underlying paroxysmal AF, using electrocardiographic data from all in- and outpatients from a single center with at least 1 ECG in SR. For patients without AF, all ECGs in SR were included. For patients with AF, all ECGs in SR starting 31 days before the first AF event were included. The patients were randomly allocated to training, internal validation, and testing datasets in a 7:1:2 ratio. In a secondary analysis, the AF prevalence of the testing group was modified. Additionally, the performance of the algorithm was validated at an external hospital. RESULTS: The dataset consisted of 494,042 ECGs in SR from 142,310 patients. Testing the model on the first ECG of each patient (AF prevalence 9.0%) resulted in accuracy of 78.1% (95% CI: 77.6%-78.5%), area under the receiver-operating characteristic curve of 0.87 (95% CI: 0.86-0.87), and area under the precision recall curve (AUPRC) of 0.48 (95% CI: 0.46-0.50). In a low-risk group (AF prevalence 3%), the AUPRC decreased to 0.21 (95% CI: 0.18-0.24). In a high-risk group (AF prevalence 30%), the AUPRC increased to 0.76 (95% CI: 0.75-0.78). This performance was robust when validated in an external hospital. CONCLUSIONS: The approach of using an AI-enabled electrocardiographic algorithm for the identification of patients with underlying paroxysmal AF from ECGs in SR was independently validated.

Smartphone-based atrial fibrillation screening in the general population: feasibility and impact on medical treatment.

Aims: The aim of this study is to determine the feasibility, detection rate, and therapeutic implications of large-scale smartphone-based screening for atrial fibrillation (AF). Methods and results: Subjects from the general population in Belgium were recruited through a media campaign to perform AF screening during 8 consecutive days with a smartphone application. The application analyses photoplethysmography traces with artificial intelligence and offline validation of suspected signals to detect AF. The impact of AF screening on medical therapy was measured through questionnaires. Atrial fibrillation was detected in the screened population (n = 60.629) in 791 subjects (1.3%). From this group, 55% responded to the questionnaire. Clinical AF [AF confirmed on a surface electrocardiogram (ECG)] was newly diagnosed in 60 individuals and triggered the initiation of anti-thrombotic therapy in 45%, adjustment of rate or rhythm controlling strategies in 62%, and risk factor management in 17%. In subjects diagnosed with known AF before screening, a positive screening result led to these therapy adjustments in 9%, 39%, and 11%, respectively. In all subjects with clinical AF and an indication for oral anti-coagulation (OAC), OAC uptake increased from 56% to 74% with AF screening. Subjects with clinical AF were older with more co-morbidities compared with subclinical AF (no surface ECG confirmation of AF) (P < 0.001). In subjects with subclinical AF (n = 202), therapy adjustments were performed in only 7%. Conclusion: Smartphone-based AF screening is feasible at large scale. Screening increased OAC uptake and impacted therapy of both new and previously diagnosed clinical AF but failed to impact risk factor management in subjects with subclinical AF.

Long-term outcome after catheter ablation for left posterior fascicular ventricular tachycardia without development of left posterior fascicular block.

BACKGROUND: Catheter ablation of left posterior fascicular (LPF) ventricular tachycardia (VT) is commonly performed during tachycardia. This study reports on the long-term outcome of patients undergoing ablation of LPF VT targeting the earliest retrograde activation within the posterior Purkinje fiber network during sinus rhythm (SR). METHODS: This study retrospectively analyzed 24 consecutive patients (8 female; mean age 26 ± 11 years) referred for catheter ablation of electrocardiographically documented LPF VT. Programmed stimulation was performed to induce tachycardia, while mapping and ablation was aided by use of a 3D electroanatomical mapping system. Catheter ablation targeted the earliest potential suggestive of retrograde activation within the posterior Purkinje fiber network (retro-PP) recorded along the posterior mid-septal left ventricle during SR if LPF VT was noninducible. RESULTS: Overall, 21/24 (87.5%) patients underwent successful catheter ablation in SR targeting the earliest retro-PP, while 3/24 (12.5%) patients were successfully ablated during tachycardia. In none of the patients, ablation resulted in LPF block. No procedure-related complications occurred. After a median follow-up period of 8.9 (4.8-10.9) years, 22/24 (92%) patients were free from recurrent VT. CONCLUSION: In patients presenting with LPF VT, ablation of the earliest retro-PP along the posterior mid-septal LV during SR results in excellent long-term outcome during a median follow-up period of almost 9 years.