Single-lead electrocardiogram Artificial Intelligence model with risk factors detects atrial fibrillation during sinus rhythm.

AIMS: Guidelines recommend opportunistic screening for atrial fibrillation (AF), using a 30 s single-lead electrocardiogram (ECG) recorded by a wearable device. Since many patients have paroxysmal AF, identification of patients at high risk presenting with sinus rhythm (SR) may increase the yield of subsequent long-term cardiac monitoring. The aim is to evaluate an AI-algorithm trained on 10 s single-lead ECG with or without risk factors to predict AF. METHODS AND RESULTS: This retrospective study used 13 479 ECGs from AF patients in SR around the time of diagnosis and 53 916 age- and sex-matched control ECGs, augmented with 17 risk factors extracted from electronic health records. AI models were trained and compared using 1- or 12-lead ECGs, with or without risk factors. Model bias was evaluated by age- and sex-stratification of results. Random forest models identified the most relevant risk factors. The single-lead model achieved an area under the curve of 0.74, which increased to 0.76 by adding six risk factors (95% confidence interval: 0.74-0.79). This model matched the performance of a 12-lead model. Results are stable for both sexes, over ages ranging from 40 to 90 years. Out of 17 clinical variables, 6 were sufficient for optimal accuracy of the model: hypertension, heart failure, valvular disease, history of myocardial infarction, age, and sex. CONCLUSION: An AI model using a single-lead SR ECG and six risk factors can identify patients with concurrent AF with similar accuracy as a 12-lead ECG-AI model. An age- and sex-matched data set leads to an unbiased model with consistent predictions across age groups.

Initial experience of left bundle branch area pacing using stylet-driven pacing leads: A multicenter study.

BACKGROUND: Left bundle branch area pacing (LBBAP) has been performed exclusively using lumen-less pacing leads (LLL) with fixed helix design. This registry study explores the safety and feasibility of LBBAP using stylet-driven leads (SDL) with extendable helix design in a multicenter patient population. METHODS: This study prospectively enrolled consecutive patients who underwent LBBAP for bradycardia pacing or heart failure indications at eight Belgian hospitals. LBBAP was attempted using SDL (Solia S60; Biotronik) delivered through dedicated delivery sheath (Selectra3D). Implant success, complications, procedural, and pacing characteristics were recorded at implant and follow-up. RESULTS: The study enrolled 353 patients (mean age 76 ± 39 years, 43% female). The mean number of implants per center was 25 (range: 5-162). Overall, LBBAP with SDL was successful in 334/353 (94%), varying from 93% to 100% among centers. Pacing response was labeled as left bundle branch pacing in 73%, whereas 27% were labeled as myocardial capture. Mean paced QRS duration and stimulus to left ventricular activation time measured 126 ± 21 ms and 74 ± 17. SDL-LBBAP resulted in low pacing thresholds (0.6 ± 0.4 V at 0.4 ms), which remained stable at 12 months follow-up (0.7 ± 0.3, p = .291). Lead revisions for SDL-LBBAP occurred in 5 (1.4%) patients occurred during a mean follow up of 9 ± 5 months. Five (1.4%) septal coronary artery fistulas and 8 (2%) septal perforations occurred, none of them causing persistent ventricular septal defects. CONCLUSION: The use of SDL to achieve LBBAP is safe and feasible, characterized by high implant success in low and high volume centers, low complication rates, and stable low pacing thresholds.

Treatment patterns in anticoagulant therapy in patients with newly diagnosed atrial fibrillation in Belgium: results from the GARFIELD-AF registry.

Background: AF, anticoagulation, NOACs, changing patterns of prescription. Methods: We describe baseline data and treatment patterns of patients recruited in Belgium in the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF). Recruitment began when novel oral anticoagulants (NOACs) were introduced and provides a unique picture of changing treatment patterns over time. 1713 patients with a new (≤6 weeks duration) diagnosis of non-valvular atrial fibrillation (NVAF) and at least one investigator-defined stroke risk factor were recruited between May 2012 and August 2016, and will be prospectively followed for at least 2 years. Results: Overall, anticoagulant use in Belgium was higher than in the rest of Europe: 80.1% of patients received an anticoagulant ± antiplatelet (AP) therapy (14.5% on vitamin K antagonists; 65.6% on NOAC), 10.7% AP therapy and 9.3% no antithrombotic therapy. Over time, we observed an increase in anticoagulant use and a decrease in AP use for stroke prevention. NOAC use in Belgium was the highest of Europe at the study start, with many countries catching up later. In high stroke risk patients (CHA2DS2-VASc ≥2), anticoagulants were used in 84.3%, leaving 15.7% unprotected. In low risk patients (CHA2DS2-VASc 0-1) anticoagulants were overused (58.7%). Factor Xa inhibitors were used more frequently than direct thrombin inhibitors. Conclusion: Guideline adherence on stroke prevention was higher in Belgium than in the rest of Europe, and increased over time. NOAC use in Belgium was the highest of Europe at the study start, with many countries catching up later. Possible reasons are discussed. Clinical Trial Registration: http://www.clinicaltrials.gov . Unique identifier: NCT01090362.

Flutter ablation with remote magnetic navigation: comparison between the 8-mm tip, the irrigated tip and a manual approach.

INTRODUCTION: Remote magnetic navigated ablation has proven its feasibility in a large group of arrhythmias. Until now only scarce data are available on the use for atrial flutter. In this study we compared remote magnetic navigation (RMN), using non-irrigated and irrigated tip catheters, to manual radiofrequency ablation for ablating typical atrial flutter. METHODS: The 3 study groups consisted of 17 patients treated with RMN 8-mm tip; 14 patients with RMN irrigated tip; and 24 patients with a manual 8-mm tip. The primary outcome was the number of patients in whom bidirectional isthmus block could be obtained with < or = 15 applications. Secondary end points were the median number of applications needed, the need to switch to a manual irrigated tip catheter, the procedural and fluoroscopy times. RESULTS: There was no significant difference in the primary end point (RMN 8 mm-tip group: 59%, RMN irrigated tip group: 64% and manual group: 83%). The median number of applications needed to obtain block was higher in the RMN groups compared to the manual group. In 5 patients from the RMN 8-mm tip group, 1 in the RMN irrigated tip group and 1 in the manual group, a switch to a manually irrigated tip catheter was performed.There was no difference in fluoroscopy time, but procedural time was significantly longer in the RMN groups compared to the manual group (P= 0.03). CONCLUSIONS: The use of magnetic navigation for the ablation of atrial flutter is feasible but not superior to a manual approach. There was no difference concerning the primary end point of acute success within 15 applications. Overall, more applications were needed and procedure times were longer with RMN but RMN with the irrigating tip is promising.

Mapping and isolation of the pulmonary veins using the PVAC catheter.

OBJECTIVES: We aimed to investigate the feasibility, efficacy, and safety of the pulmonary vein ablation catheter (PVAC) catheter (a novel multielectrode catheter using duty-cycled bipolar and unipolar radiofrequency energy, Medtronic, Minneapolis, MN, USA) to completely isolate the pulmonary veins (PVs). METHODS: Twenty-seven patients (60 +/- 8 years) with paroxysmal atrial fibrillation (AF) underwent PV isolation with the PVAC catheter. PVAC was used for both mapping and isolation of the PVs (PVAC-guided ablation). After PVAC ablation, presence/absence of PV potentials (PVP) was verified using a conventional circular mapping catheter. In case of residual PVP on the circular catheter, PVAC ablation was continued. RESULTS: After PVAC-guided ablation 99 of 106 PVs (93%) and 21 of 27 patients (78%) were proven to be isolated. Failure to isolate was due to a mapping failure in four right-sided PVs and a true ablation failure in three right-sided PVs. After continued PVAC ablation, 103 of 106 PVs (97%) and 25 of 27 patients (93%) were shown to be isolated. The total procedural time from femoral vein access to complete catheter withdrawal was 176 +/- 25 minutes. The actual dwelling-time of the PVAC within the left atrium was 102 +/- 37 minutes. Esophageal T degrees rise to >38.5 degrees occurred in nine of 19 monitored patients (47%). CONCLUSIONS: (1) PVAC-guided ablation (i.e., mapping and ablation with a single catheter) results in isolation of all PVs in 73% of the patients. (2) An additional circular mapping catheter is required to increase complete isolation rate to 93% of the patients. (3) Given the esophageal T degrees rise in almost 50% of patients, safety precautions are needed.

Self-terminating AF depends on electrical remodeling while persistent AF depends on additional structural changes in a rapid atrially paced sheep model.

The development of atrial fibrillation (AF) is associated with electrical and structural remodeling. The aim of this study was to assess the contribution of electrical and structural remodeling to the development of AF in a rapid atrially paced ovine model with and without His bundle ablation and to determine the role of the angiotensin pathway and matrix metalloproteinases in this process. Thirty-five sheep were rapidly paced in the atrium and were randomized to undergo His bundle ablation (HBA) (21 sheep; HBA sheep) or not (14 sheep; non-HBA sheep). After HBA the ventricles were paced at 80 bpm. Both groups were subdivided to receive active treatment (quinapril+losartan) or placebo. Sheep were followed for 15 weeks. Inducible AF was defined as a rapid irregular atrial rhythm lasting >1 min. Inducible AF was considered to be persistent if during further follow-up no sinus rhythm (SR) was documented anymore. The inducibility of AF with atrial tachypacing was not different between the 4 groups. On the other hand, non-HBA sheep developed persistent AF significantly earlier than HBA sheep (p=0.028). They had elevated ventricular rates, diminished atrial MMP-2, increased TIMP-2 expression, and more extensive atrial fibrosis. Active treatment in these sheep significantly lowered AT-II (p=0.018), prevented atrial fibrogenesis (p<0.001) and slowed the development of persistent AF (p=0.049). Electrical remodeling is sufficient to induce AF, while structural changes are needed for persistent AF. Fibrosis development in our model is the result of an increased expression of AT-II in combination with changes in MMP expression. Inhibition of the angiotensin pathway suppresses atrial fibrosis and the development of persistent AF.

Long-term symptomatic benefit after radiofrequency catheter ablation for atrial flutter despite a high incidence of post-procedural atrial fibrillation.

OBJECTIVE: A high proportion of patients develops atrial fibrillation (AF) after ablation for atrial flutter (AFL). Radiofrequency ablation for AFL therefore would only be useful if it leads to a better quality of life despite this high incidence of AF post-ablation. METHODS: All patients who underwent AFL ablation in our centre before March 2002 (n=203) were contacted by letter a median of 2.3 years after their ablation. Sixty-eight percent answered the questionnaire polling the perceived benefits of the procedure. The results were stratified according to the presenting arrhythmia before the ablation: only AFL, predominantly AFL, predominantly AF or class Ic-III AFL. RESULTS: Despite a 60% incidence of AF, 84% considered the procedure to be beneficial during the 1st year and 77% during the 2nd year post-ablation. Patients with predominantly AF before the procedure showed significantly less overall improvement than the 3 other groups (50% and 33% after I year and 2 years, p< 0.01) and a smaller reduction in palpitations (50% and 29% after I year and 2 years, p < 0.01). The benefit of an ablation was also significantly less in patients who developed AF post-ablation than in patients who were completely arrhythmia free (75% versus 98% 1st year, 58% versus 91% 2nd year; p 0.01); nevertheless 75% of these patients reported fewer palpitations and 56% tolerated symptoms better than before. CONCLUSIONS: Despite a high incidence of AF after AFL ablation, the majority of patients considered the intervention beneficial. Only in patients with predominantly AF before ablation the procedure does not seem beneficial.

Endurance sports is a risk factor for atrial fibrillation after ablation for atrial flutter.

INTRODUCTION: Sports activity has been associated with the development of atrial arrhythmias. Atrial fibrillation (AF) is frequently observed after successful ablation for atrial flutter. Sports activity as a risk factor for AF development after flutter ablation has not been studied. METHODS: We analyzed outcome in 137 patients (83% men) after ablation for isthmus-dependent atrial flutter (excluding patients with concomitant ablation for atrial tachycardia or fibrillation). Sports activity before and after ablation was evaluated by detailed questionnaires. Endurance sports was defined as (semi-)competitive participation in cycling, running or swimming for > or =3 h/week (and for > or =3 years pre-ablation). Median follow-up was 2.5 years. Survival free of AF was evaluated with Kaplan-Meier curves and log-rank statistics. Multivariate analysis was based on Cox proportional hazard evaluation. RESULTS: Acute ablation success was 99% and flutter recurrence 4.4%. Thirty-one patients (23%) had been regularly engaged in endurance sports before ablation and 19 (14%) continued regular sports activity afterwards. Those performing sports were slightly younger. A history of endurance sports was a significant risk factor for post-ablation AF (univariate HR 1.96 (1.19-3.22), p<0.01, and multivariate HR 1.81 (1.10-2.98), p=0.02). Also continuation of endurance sports activity after ablation showed a trend for increased risk to develop AF despite a relatively small sample size (n=19; multivariate HR 1.68 (0.92-3.06), p=0.08). Cox proportional hazard calculations revealed a 10% and 11% increased risk for AF development per weekly hour sport performed before and after ablation respectively (p<0.01 for both). CONCLUSION: A history of endurance sports activity is associated with the development of AF after ablation of atrial flutter.

Matrix metalloproteinases and atrial remodeling in patients with mitral valve disease and atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is associated with extracellular matrix remodeling involving atrial fibrosis and atrial dilatation. Angiotensin II mediated pathways and matrix metalloproteinases (MMPs) have been implicated in these processes. Our aim was to study atrial structural remodeling and the expression of the angiotensin receptor subtypes and MMPs and their inhibitors (TIMPs) in patients with mitral valve disease with and without AF. METHODS AND RESULTS: Biopsies from right and left atrial appendages (RA and LA) were taken from patients undergoing CABG (n=9, all in sinus rhythm (SR)) or mitral valve surgery (MVS; n=19; 9 with permanent AF and 10 in SR). Patients with MVS and AF had significantly larger atria (versus MVS and SR: p=0.02; versus CABG: p<0.01). The MVS patients had significantly more fibrosis than the control CABG group. Fibrosis was increased in both the AF and SR MVS groups in the LA, but only in the MVS-AF group in the RA. These AF patients had significantly more tricuspid regurgitation than SR patients. MMP-1 was down-regulated in LA of MVS patients (p=0.02) independent of the underlying rhythm (SR or AF; p=0.95). In RA biopsies, MMP-1 was down-regulated only in the MVS and AF group. MMP-9 was down-regulated in the MVS patients compared to CABG both in the RA and LA, and without a difference between the SR and AF groups. Protein expression of AT-1, AT-2, MMP-2, TIMP-1, -2 and -4, TNF-alpha, and TNF-alpha-converting enzyme did not differ significantly between the 3 groups. CONCLUSIONS: Concordant changes between MMP-expression and fibrosis during mitral valve disease, both in LA and RA, suggest involvement of MMPs in structural atrial remodeling. AF itself did not contribute to altered fibrosis or MMP-expression in the LA. The association between AF and RA changes may be precipitated by greater hemodynamic load due to tricuspid regurgitation in these patients.

Importance of measurements at or after the J-point for evaluation of ST-segment deviation and resolution during treatment for acute myocardial infarction.

BACKGROUND: Determination of ST-segment deviation (STdev) and its resolution (STR) by reperfusion strategies have become important tools in the assessment of patients with acute myocardial infarction (AMI). STdev has been measured at different time-points, i.e. at 20-80 ms after the J-point. There are no data comparing STR at different time-points. METHODS AND RESULTS: STdev was measured using a new computer-assisted workflow. The intraclass correlation coefficients (ICC) for validity and agreement vs. classical manual measurements (n=1020) were both 0.996 (p<0.0001). The reliability indices were 0.991 (95% CI 0.990-0.992) for the manual vs. 0.995 (95% CI 0.995-0.996) for the computer-assisted method, indicating superiority of the latter. 12-lead STdev were determined on ECGs before (baseline) and 180 min after start of thrombolytic therapy, measured both at the J-point (STdev(J)) and 20 ms after the J-point (STdev(J20); n=2400). STdev(J20) was on average 0.01+/-0.03 mV higher than STdev(J) (p<0.0001) with a tendency towards larger differences for higher ST-elevations (p<0.001). Although the average STR calculated from STdev(J20) and STdev(J) was not statistically different in any infarct location group, in 26% of the patients the difference was >10%, and 11% of the patients were classified into another ST-resolution group. Analysing STdev only in the single lead with the highest ST-elevation at baseline (a simplified measurement which may eliminate the confounding effect of ST-depressions) showed an even higher classification discordance (14% of the patients). CONCLUSIONS: The time-point of STdev measurement is an important variable to be accounted for when evaluating ST resolution data. Uncontrolled extrapolation of classification schemes based on STdev(J20) to other time-points cannot be justified.

ST-deviation reconstruction in missing leads on the 12-lead ECG: applicability in studies on ST-segment resolution during thrombolysis.

Quantitative analysis of ST-segment deviations (STdev) and their resolution by treatment (STR; calculated from a combined sum of STdev in multiple leads) are used in trials on reperfusion for myocardial infarction (MI). Unreadable or unavailable electrocardiogram (ECG) leads are a common reason for exclusion, decreasing the statistical power of the trials. We developed mathematical formulas for reconstruction of immeasurable STdev based on STdev from other available leads on the 12-lead ECG. Formulas were deducted from a database of computer-assisted STdev measurements in 2 ECGs (baseline and 180 min after thrombolysis) of 1121 pts. Their accuracy was later evaluated on a second dataset of 377 pts. Acceptable fits could be derived for absent single leads, or for groups of absent limb leads (I-II-III or aVL-aVF). The intraclass correlation coefficient between real and calculated STdev was >or= 0.80 for each (0.77 for V1 in inferior MI). The correlations between STR calculated from original data and from reconstructed STdev were very strong (all intraclass correlation >or=0.97), and discordance in STR subgroup categorization occurred in

Simultaneous creation and evaluation of linear radiofrequency lesions.

BACKGROUND: Catheter based "maze" procedures for atrial fibrillation have been hampered by difficult creation and evaluation of continuous and transmural linear lesions. Our aim was to develop an online evaluation method for effective lesion creation based on conventional techniques and using the multipolar ablation catheter, already in place. METHODS AND RESULTS: We created 15 linear lines in right atria of 13 anesthetized sheep using three multipolar catheter designs (8 x 4 mm 7 Fr, 4 x 6 mm 7 Fr, 8 x 4 mm 3.7 Fr). The lesions were placed on the right posterolateral wall between the orifices of the superior and inferior vena cava. Radiofrequency energy was applied in the temperature-controlled mode to prespecified endpoints (electrogram amplitude decrease to < or = 50%; pacing threshold increase by > or = 100%; split potentials indicating conduction block). Macroscopically transmural and continuous lesions were achieved in only 3 experiments (29 +/- 12 mm x 5 +/- 1 mm), all created by 3.7 Fr octapolar catheters inserted through long sheaths. Preset temperature was reached in 96% of the electrodes (vs. 64% in the non-effective experiments; p < 0.01). Electrogram amplitude decrease (to < or = 50%) and pacing threshold increase (by > or = 100%) did not predict effectiveness. The only criterion that could reliably predict transmural continuous necrosis at histology was the development of split potentials (p < or = 0.05). CONCLUSIONS: Effective creation of linear lesions is difficult. Pliable catheters that conform to the endocardial contour give the best results. The only endpoint that reliably predicted histological transmural continuous necrosis was development of split potentials indicating conduction block.