Deep Learning-Augmented ECG Analysis for Screening and Genotype Prediction of Congenital Long QT Syndrome.

Importance: Congenital long QT syndrome (LQTS) is associated with syncope, ventricular arrhythmias, and sudden death. Half of patients with LQTS have a normal or borderline-normal QT interval despite LQTS often being detected by QT prolongation on resting electrocardiography (ECG). Objective: To develop a deep learning-based neural network for identification of LQTS and differentiation of genotypes (LQTS1 and LQTS2) using 12-lead ECG. Design, Setting, and Participants: This diagnostic accuracy study used ECGs from patients with suspected inherited arrhythmia enrolled in the Hearts in Rhythm Organization Registry (HiRO) from August 2012 to December 2021. The internal dataset was derived at 2 sites and an external validation dataset at 4 sites within the HiRO Registry; an additional cross-sectional validation dataset was from the Montreal Heart Institute. The cohort with LQTS included probands and relatives with pathogenic or likely pathogenic variants in KCNQ1 or KCNH2 genes with normal or prolonged corrected QT (QTc) intervals. Exposures: Convolutional neural network (CNN) discrimination between LQTS1, LQTS2, and negative genetic test results. Main Outcomes and Measures: The main outcomes were area under the curve (AUC), F1 scores, and sensitivity for detecting LQTS and differentiating genotypes using a CNN method compared with QTc-based detection. Results: A total of 4521 ECGs from 990 patients (mean [SD] age, 42 [18] years; 589 [59.5%] female) were analyzed. External validation within the national registry (101 patients) demonstrated the CNN's high diagnostic capacity for LQTS detection (AUC, 0.93; 95% CI, 0.89-0.96) and genotype differentiation (AUC, 0.91; 95% CI, 0.86-0.96). This surpassed expert-measured QTc intervals in detecting LQTS (F1 score, 0.84 [95% CI, 0.78-0.90] vs 0.22 [95% CI, 0.13-0.31]; sensitivity, 0.90 [95% CI, 0.86-0.94] vs 0.36 [95% CI, 0.23-0.47]), including in patients with normal or borderline QTc intervals (F1 score, 0.70 [95% CI, 0.40-1.00]; sensitivity, 0.78 [95% CI, 0.53-0.95]). In further validation in a cross-sectional cohort (406 patients) of high-risk patients and genotype-negative controls, the CNN detected LQTS with an AUC of 0.81 (95% CI, 0.80-0.85), which was better than QTc interval-based detection (AUC, 0.74; 95% CI, 0.69-0.78). Conclusions and Relevance: The deep learning model improved detection of congenital LQTS from resting ECGs and allowed for differentiation between the 2 most common genetic subtypes. Broader validation over an unselected general population may support application of this model to patients with suspected LQTS.

Sequential Intracardiac Activation Time Mapping of Arrhythmias Without Fiducial Time References.

Sequential local activation time (LAT) mapping of intracardiac electrograms' activations requires a stable reference signal to align recording phases. OBJECTIVE: This work's purpose is to develop an LAT mapping approach that does not rely on a time-alignment reference (TAR). METHODS: To create an LAT map in absence of TAR (TARLess), the coordinates and LATs of recording electrodes are collected sequentially; a bank of candidate functions (CFs) is constructed that contains constant binary level CFs and non-linear functions of recording points' coordinates. Finally, a subset of CFs is linearly combined to create an activation time function with output matching electrodes' LATs. Synthetic and clinical data were deployed to validate TARLess. A simple two-dimensional computer model was used to create 30 different wavefront collision scenarios in a region with spatial conduction heterogeneities. Furthermore, sequential recordings were collected from seven atrial fibrillation patients during stimulation from one or two sites, after sinus rhythm was achieved post catheter ablation. RESULTS: We showed that TARLess maps are similar to the one that uses TAR; for the 20 clinical maps, the mean absolute difference between measured LAT with the TAR and TARLess approach was 5.2 ±2.0 milliseconds. CONCLUSION: We developed a novel method to create an LAT map of sequential recordings without using any TAR and showed that it can create accurate maps even during the collision of multiple wavefronts. SIGNIFICANCE: TARLess mapping does not require a reference catheter which could lead to reduction in ablation procedure duration, cost, and potential complications.

Machine Learning for Predicting Postoperative Atrial Fibrillation After Cardiac Surgery: A Scoping Review of Current Literature.

Postoperative atrial fibrillation (POAF) occurs in up to 20% to 55% of patients who underwent cardiac surgery. Machine learning (ML) has been increasingly employed in monitoring, screening, and identifying different cardiovascular clinical conditions. It was proposed that ML may be a useful tool for predicting POAF after cardiac surgery. An electronic database search was conducted on Medline, EMBASE, Cochrane, Google Scholar, and ClinicalTrials.gov to identify primary studies that investigated the role of ML in predicting POAF after cardiac surgery. A total of 5,955 citations were subjected to title and abstract screening, and ultimately 5 studies were included. The reported incidence of POAF ranged from 21.5% to 37.1%. The studied ML models included: deep learning, decision trees, logistic regression, support vector machines, gradient boosting decision tree, gradient-boosted machine, K-nearest neighbors, neural network, and random forest models. The sensitivity of the reported ML models ranged from 0.22 to 0.91, the specificity from 0.64 to 0.84, and the area under the receiver operating characteristic curve from 0.67 to 0.94. Age, gender, left atrial diameter, glomerular filtration rate, and duration of mechanical ventilation were significant clinical risk factors for POAF. Limited evidence suggest that machine learning models may play a role in predicting atrial fibrillation after cardiac surgery because of their ability to detect different patterns of correlations and the incorporation of several demographic and clinical variables. However, the heterogeneity of the included studies and the lack of external validation are the most important limitations against the routine incorporation of these models in routine practice. Artificial intelligence, cardiac surgery, decision tree, deep learning, gradient-boosted machine, gradient boosting decision tree, k-nearest neighbors, logistic regression, machine learning, neural network, postoperative atrial fibrillation, postoperative complications, random forest, risk scores, scoping review, support vector machine.

Right atrial collision time (RACT): A novel marker of propensity for typical atrial flutter.

INTRODUCTION: The risk of typical atrial flutter (AFL) is increased proportionately to right atrial (RA) size or right atrial scarring that results in reduced conduction velocity. These characteristics result in propagation of a flutter wave by ensuring the macro re-entrant wave front does not meet its refractory tail. The time taken to traverse the circuit would take account of both of these characteristics and may provide a novel marker of propensity to develop AFL. Our goal was to investigate right atrial collision time (RACT) as a marker of existing typical AFL. METHODS: This single-centre, prospective study recruited consecutive typical AFL ablation patients that were in sinus rhythm. Controls were consecutive electrophysiology study patients >18 years of age. While pacing the coronary sinus (CS) ostium at 600 ms, a local activation time map was created to locate the latest collision point on the anterolateral right atrial wall. This RACT is a measure of conduction velocity and distance from CS to a collision point on the lateral right atrial wall. RESULTS: Ninety-eight patients were included in the analysis, 41 with atrial flutter and 57 controls. Patients with atrial flutter were older, 64.7 ± 9.7 versus 52.4 ± 16.8 years (<.001), and more often male (34/41 vs. 31/57 [.003]). The AFL group mean RACT (132.6 ± 17.3 ms) was significantly longer than that of controls (99.1 ± 11.6 ms) (p < .001). A RACT cut-off of 115.5 ms had a sensitivity and specificity of 92.7% and 93.0%, respectively for diagnosis of atrial flutter. A ROC curve indicated an AUC of 0.96 (95% CI: 0.93-1.0, p < .01). CONCLUSION: RACT is a novel and promising marker of propensity for typical AFL. This data will inform larger prospective studies.

Association of the Timing and Extent of Cardiac Implantable Electronic Device Infections With Mortality.

Importance: Cardiac implantable electronic device (CIED) infection is a potentially devastating complication with an estimated 12-month mortality of 15% to 30%. The association of the extent (localized or systemic) and timing of infection with all-cause mortality has not been established. Objective: To evaluate the association of the extent and timing of CIED infection with all-cause mortality. Design, Setting, and Participants: This prospective observational cohort study was conducted between December 1, 2012, and September 30, 2016, in 28 centers across Canada and the Netherlands. The study included 19 559 patients undergoing CIED procedures, 177 of whom developed an infection. Data were analyzed from April 5, 2021, to January 14, 2023. Exposures: Prospectively identified CIED infections. Main Outcomes and Measures: Time-dependent analysis of the timing (early [≤3 months] or delayed [3-12 months]) and extent (localized or systemic) of infection was performed to determine the risk of all-cause mortality associated with CIED infections. Results: Of 19 559 patients undergoing CIED procedures, 177 developed a CIED infection. The mean (SD) age was 68.7 (12.7) years, and 132 patients were male (74.6%). The cumulative incidence of infection was 0.6%, 0.7%, and 0.9% within 3, 6, and 12 months, respectively. Infection rates were highest in the first 3 months (0.21% per month), reducing significantly thereafter. Compared with patients who did not develop CIED infection, those with early localized infections were not at higher risk for all-cause mortality (no deaths at 30 days [0 of 74 patients]: adjusted hazard ratio [aHR], 0.64 [95% CI, 0.20-1.98]; P = .43). However, patients with early systemic and delayed localized infections had an approximately 3-fold increase in mortality (8.9% 30-day mortality [4 of 45 patients]: aHR, 2.88 [95% CI, 1.48-5.61]; P = .002; 8.8% 30-day mortality [3 of 34 patients]: aHR, 3.57 [95% CI, 1.33-9.57]; P = .01), increasing to a 9.3-fold risk of death for those with delayed systemic infections (21.7% 30-day mortality [5 of 23 patients]: aHR, 9.30 [95% CI, 3.82-22.65]; P < .001). Conclusions and Relevance: Findings suggest that CIED infections are most common within 3 months after the procedure. Early systemic infections and delayed localized infections are associated with increased mortality, with the highest risk for patients with delayed systemic infections. Early detection and treatment of CIED infections may be important in reducing mortality associated with this complication.

Half-Normal Saline vs Normal Saline for Cavotricuspid Isthmus-Dependent Atrial Flutter Ablation.

Background: Cavotricuspid isthmus (CTI) ablation requires permanent bidirectional block to prevent recurrence of typical atrial flutter (AFL). Catheter irrigation with half-normal saline (HNS) produces larger and deeper lesions in experimental models compared with normal saline (NS). This study was performed to compare the clinical efficacy and safety of HNS vs NS irrigation for typical AFL ablation. Methods: Sixty patients undergoing catheter ablation of typical AFL were randomized 1:1 to NS or HNS irrigation. Endpoints included time to CTI block, acute reconnection, incidence of steam pops, and recurrence of AFL during follow-up. Results: Baseline characteristics were comparable between both arms. The mean age of the patients was 68.5 ± 8.2 years, 20% were female, and 32% had atrial fibrillation before being enrolled. Bidirectional CTI block was obtained in all patients with no difference in time to CTI block between groups (6.4 ± 4.4 minutes vs 7.6 ± 4.5 minutes, respectively; P = 0.15). There was a trend to less acute reconnection in the HNS group compared with NS (13.3% vs 26.6%; P = 0.46). Steam pops occurred in 4 patients using HNS vs none in the NS group, but no major complications were observed. During the follow-up, rate of AFL recurrence was similar between groups (6.7% with HNS vs 10% with NS; P = 0.5). There was no difference in time to recurrence (7.6 ± 6.9 vs 4.9 ± 4.5 months; P = 0.6). Conclusions: In this small pilot randomized controlled trial, there was no significant difference between HNS and NS for CTI ablation; however, HNS may increase the incidence of steam pops.

Contexte: Pour prévenir la récurrence d'un flutter auriculaire (flutter) typique, l'ablation de l'isthme cavotricuspidien exige un bloc de conduction bidirectionnel permanent. Dans des modèles expérimentaux, l'irrigation par cathéter au moyen d'un soluté demi-salin produit des lésions plus larges et plus profondes, comparativement à un soluté physiologique salin. La présente étude a été réalisée dans le but de comparer l'efficacité clinique et l'innocuité de l'irrigation au moyen d'un soluté demi-salin à celles de l'irrigation par un soluté physiologique salin dans les cas d'ablation d'un flutter. Méthodologie: Soixante patients soumis à une ablation d'un flutter typique par cathéter ont été répartis au hasard dans un rapport de 1:1 en deux groupes d'irrigation, soit par soluté demi-salin, soit par soluté physiologique salin. Les critères d'évaluation de l'étude étaient les suivants : temps écoulé jusqu'au bloc de l'isthme cavotricuspidien, reconnexion aiguë, jet de vapeur sonore (steam pop) et récidive de flutter durant le suivi. Résultats: Les caractéristiques initiales étaient comparables dans les deux groupes. Les patients avaient une moyenne d'âge de 68,5 ± 8,2 ans, 20 % étaient des femmes et 32 % présentaient une fibrillation auriculaire avant leur admission à l'étude. Un bloc bidirectionnel dans l'isthme cavotricuspidien a été obtenu chez tous les patients, sans différence entre les groupes en ce qui a trait au temps écoulé jusqu'à l'obtention du bloc isthmique (6,4 ± 4,4 minutes vs 7,6 ± 4,5 minutes, respectivement; p = 0,15). Une tendance vers un nombre plus faible de cas de reconnexion aiguë a été notée dans le groupe d'irrigation par soluté demi-salin, comparativement au soluté physiologique salin (13,3 % vs 26,6 %; p = 0,46). Un jet de vapeur sonore est survenu chez 4 patients recevant un soluté demi-salin contre aucun dans le groupe sous soluté physiologique salin, mais aucune complication importante n'a été relevée. Durant le suivi, le taux de récidive de flutter a été similaire dans les deux groupes (6,7 % sous soluté demi-salin vs 10 % sous soluté physiologique salin; p = 0,5). Aucune différence n'a été notée pour ce qui est du temps écoulé jusqu'à la survenue d'une récidive (7,6 ± 6,9 vs 4,9 ± 4,5 mois; p = 0,6). Conclusions: Dans cette petite étude pilote contrôlée et avec répartition aléatoire, aucune différence significative n'a été observée entre le soluté demi-salin et le soluté physiologique salin pour l'ablation de l'isthme; toutefois, le soluté demi-salin augmenterait la fréquence des cas de jet de vapeur sonore.

Characterization of arrhythmia substrate to ablate persistent atrial fibrillation (COAST-AF): Randomized controlled trial design and rationale.

BACKGROUND: Atrial low voltage area (LVA) catheter ablation has emerged as a promising strategy for ablation of persistent atrial fibrillation (AF). It is unclear if catheter ablation of atrial LVA increases treatment success rates in patients with persistent AF. OBJECTIVE: The primary aim of this trial is to assess the potential benefit of adjunctive catheter ablation of atrial LVA in addition to pulmonary vein isolation (PVI) in patients with persistent AF, when compared to PVI alone. The secondary aims are to evaluate safety outcomes, the quality of life and the healthcare resource utilization. METHODS/DESIGN: A multicenter, prospective, parallel-group, 2-arm, single-blinded randomized controlled trial is under way (NCT03347227). Patients who are candidates for catheter ablation for persistent AF will be randomly assigned (1:1) to either PVI alone or PVI + atrial LVA ablation. The primary outcome is 18-month documented event rate of atrial arrhythmia (AF, atrial tachycardia or atrial flutter) post catheter ablation. Secondary outcomes include procedure-related complications, freedom from atrial arrhythmia at 12 months, AF burden, need for emergency department visits/hospitalization, need for repeat ablation for atrial arrhythmia, quality of life at 12 and 18 months, ablation time, and procedure duration. DISCUSSION: Characterization of Arrhythmia Mechanism to Ablate Atrial Fibrillation (COAST-AF) is a multicenter randomized trial evaluating ablation strategies for catheter ablation. We hypothesize that catheter ablation of atrial LVA in addition to PVI will result in higher procedural success rates when compared to PVI alone in patients with persistent AF.

Long-term Outcomes in Treated Lyme Carditis.

Lyme disease is the most reported tick-borne illness in North America. Lyme carditis (LC) is an early-disseminated manifestation of Lyme disease, most commonly presenting as symptomatic high-degree atrioventricular block (AVB) which resolves with appropriate antibiotic therapy. However, long-term outcomes of treated LC have not previously been described. We present a series of 7 patients (median 28 years, 6 male) with serologically confirmed LC treated with a standard protocol developed at our center including antibiotics and pre-discharge stress test to assess AV node stability. At a mean follow-up of 20.8 months, all patients were asymptomatic, had resumed normal activities, and were free of conduction abnormalities. None required permanent pacing. Our study supports avoidance of permanent pacing for LC if conduction is stable at discharge.

Electrocardiographic predictors of atrial fibrillation in patients with cryptogenic stroke.

BACKGROUND: Empiric anticoagulation is not routinely indicated in patients with cryptogenic stroke without documentation of atrial fibrillation (AF). Therefore, identification of patients at increased risk of AF from this vulnerable group is vital. OBJECTIVES: To identify electrocardiographic (ECG) predictors of AF in patients with cryptogenic stroke or transient ischemic attack (TIA) undergoing insertion of an implantable cardiac monitor (ICM). METHODS: In this single-center study, 48 patients with cryptogenic stroke or TIA had an ICM implanted for detection of AF between January 2013 and September 2019. Patients with and without AF were compared in terms of p-wave duration and a novel index (MVP score). RESULTS: During a mean follow-up of 16 ± 14 months, AF was detected in seven patients (15%). Diagnosis of AF was made after a mean of 10 ± 14 months, with time to first AF detection ranging between 1 and 40 months. Patients with AF had a longer p-wave duration (136 ± 9 ms vs. 116 ± 10 ms; p = .0001) and a higher MVP score (4.5 ± 1.2 vs. 2.0 ± 0.9, p = .0001) than those without AF. Advanced interatrial block (IAB) was observed in 43% of patients with ICM evidence of AF and 0% of those without AF (p = .002). Age, LA size or LVEF were not predictors of AF. CONCLUSION: An increased p-wave duration, advanced IAB and high MVP score are associated with AF occurrence in patients with cryptogenic stroke. Identifying patients with these markers may be helpful as they may benefit from more exhaustive and prolonged monitoring.

Impact of Choice of Prophylaxis on the Microbiology of Cardiac Implantable Electronic Device Infections: Insights From the Prevention of Arrhythmia Device Infection Trial (PADIT).

BACKGROUND: The Prevention of Arrhythmia Device Infection Trial (PADIT) investigated whether intensification of perioperative prophylaxis could prevent cardiac implantable electronic device (CIED) infections. Compared with a single dose of cefazolin, the perioperative administration of cefazolin, vancomycin, bacitracin, and cephalexin did not significantly decrease the risk of infection. Our objective was to compare the microbiology of infections between study arms in PADIT. METHODS: This was a post hoc analysis. Differences between study arms in the microbiology of infections were assessed at the level of individual patients and at the level of microorganisms using the Fisher exact test. RESULTS: Overall, 209 microorganisms were reported from 177 patients. The most common microorganisms were coagulase-negative staphylococci (CoNS; 82/209 [39.2%]) and S. aureus (75/209 [35.9%]). There was a significantly lower proportion of CoNS in the incremental arm compared with the standard arm (30.1% vs 46.6%; P = .04). However, there was no significant difference between study arms in the frequency of recovery of other microorganisms. In terms of antimicrobial susceptibility, 26.5% of microorganisms were resistant to cefazolin. CoNS were more likely to be cefazolin-resistant in the incremental arm (52.2% vs 26.8%, respectively; P = .05). However, there was no difference between study arms in terms of infections in which the main pathogen was sensitive to cefazolin (77.8% vs 64.3%; P = .10) or vancomycin (90.8% vs 90.2%; P = .90). CONCLUSIONS: Intensification of the prophylaxis led to significant changes in the microbiology of infections, despite the absence of a decrease in the overall risk of infections. These findings provide important insight on the physiopathology of CIED infections. TRIAL REGISTRATION: NCT01002911.

Substrate Characterization and Outcomes of Ventricular Tachycardia Ablation in TTN (Titin) Cardiomyopathy: A Multicenter Study.

[Figure: see text].

Moving average and standard deviation thresholding (MAST): a novel algorithm for accurate R-wave detection in the murine electrocardiogram.

Advances in implantable radio-telemetry or diverse biologging devices capable of acquiring high-resolution ambulatory electrocardiogram (ECG) or heart rate recordings facilitate comparative physiological investigations by enabling detailed analysis of cardiopulmonary phenotypes and responses in vivo. Two priorities guiding the meaningful adoption of such technologies are: (1) automation, to streamline and standardize large dataset analysis, and (2) flexibility in quality-control. The latter is especially relevant when considering the tendency of some fully automated software solutions to significantly underestimate heart rate when raw signals contain high-amplitude noise. We present herein moving average and standard deviation thresholding (MAST), a novel, open-access algorithm developed to perform automated, accurate, and noise-robust single-channel R-wave detection from ECG obtained in chronically instrumented mice. MAST additionally and automatically excludes and annotates segments where R-wave detection is not possible due to artefact levels exceeding signal levels. Customizable settings (e.g. window width of moving average) allow for MAST to be scaled for use in non-murine species. Two expert reviewers compared MAST's performance (true/false positive and false negative detections) with that of a commercial ECG analysis program. Both approaches were applied blindly to the same random selection of 270 3-min ECG recordings from a dataset containing varying amounts of signal artefact. MAST exhibited roughly one quarter the error rate of the commercial software and accurately detected R-waves with greater consistency and virtually no false positives (sensitivity, Se: 98.48% ± 4.32% vs. 94.59% ± 17.52%, positive predictivity, +P: 99.99% ± 0.06% vs. 99.57% ± 3.91%, P < 0.001 and P = 0.0274 respectively, Wilcoxon signed rank; values are mean ± SD). Our novel, open-access approach for automated single-channel R-wave detection enables investigators to study murine heart rate indices with greater accuracy and less effort. It also provides a foundational code for translation to other mammals, ectothermic vertebrates, and birds.

Predicting adverse cardiovascular outcomes in post-coronary artery bypass grafting patients using novel ECG frequency analysis of the QRS complex.

BACKGROUND: A novel metric called Layered Symbolic Decomposition frequency (LSDf) has been shown to be an independent predictor of ventricular arrhythmia and mortality in patients receiving implantable cardioverter-defibrillator (ICD) devices. This novel index studies the fragmentation of the QRS complex. However, its generalizability to predict cardiovascular events for other cardiac procedures is unknown. Herein, we investigated the applicability of LSDf as a predictive measure for major adverse cardiovascular events (MACE) in patients receiving coronary artery bypass grafting (CABG). METHODS AND RESULTS: One hundred ninety-five patients had high-resolution ECG recorded prior to CABG surgery in 2012/2013 and were followed for a mean duration of 7.32 ± 0.32 years for postoperative cardiovascular outcomes. These outcomes were described as a modified composite of MACE defined as hospitalization for heart failure, ventricular tachycardia, ventricular fibrillation, and cardiovascular death including stroke and cardiac arrest. One hundred seventy-two patients were included for analysis and 18 patients experienced a postoperative cardiovascular outcome. These patients had significantly increased age (71.3 vs. 64.6 years, p = .007), prolonged QRS duration (113.22 vs. 97.35 ms, p = .003), reduced left ventricular ejection fraction (42.7% vs. 56.5%, p < .001), and lower LSDf percent (13.5% vs. 16.9%, p = .002). Patients with an LSDf below 13.25% were 4.8 (OR 1.7-13.5, p < .001) times more likely to experience a MACE and up to 19.4 (OR 4.2-90.3, p < .001) times more likely to experience a MACE when older than 70 years and an ejection fraction below 50%. CONCLUSION: Layered Symbolic Decomposition frequency may be an applicable metric to predict long-term cardiovascular outcomes in patients with ischemic heart disease.

Differences in Healthcare Use Between Patients With Persistent and Paroxysmal Atrial Fibrillation Undergoing Catheter-Based Atrial Fibrillation Ablation: A Population-Based Cohort Study From Ontario, Canada.

Background Patients with persistent atrial fibrillation (AF) undergoing catheter-based AF ablation have lower success rates than those with paroxysmal AF. We compared healthcare use and clinical outcomes between patients according to their AF subtypes. Methods and Results Consecutive patients undergoing AF ablation were prospectively identified from a population-based registry in Ontario, Canada. Via linkage with administrative databases, we performed a retrospective analysis comparing the following outcomes between patients with persistent and paroxysmal AF: healthcare use (defined as AF-related hospitalizations/emergency room visits), periprocedural complications, and mortality. Multivariable Poisson modeling was performed to compare the rates of AF-related and all-cause hospitalizations/emergency room visits in the year before versus after ablation. Between April 2012 and March 2016, there were 3768 consecutive patients who underwent first-time AF ablation, of whom 1040 (27.6%) had persistent AF. The mean follow-up was 1329 days. Patients with persistent AF had higher risk of AF-related hospitalization/emergency room visits (hazard ratio [HR], 1.21; 95% CI, 1.09-1.34), mortality (HR, 1.74; 95% CI, 1.15-2.63), and periprocedural complications (odds ratio, 1.36; 95% CI, 1.02-1.75) than those with paroxysmal AF. In the overall cohort, there was a 48% reduction in the rate of AF-related hospitalization/emergency room visits in the year after versus before ablation (rate ratio [RR], 0.52; 95% CI, 0.48-0.56). This reduction was observed for patients with paroxysmal (RR, 0.45; 95% CI, 0.41-0.50) and persistent (RR, 0.74; 95% CI, 0.63-0.87) AF. Conclusions Although patients with persistent AF had higher risk of adverse outcomes than those with paroxysmal AF, ablation was associated with a favorable reduction in downstream AF-related healthcare use, irrespective of AF type.

Close-coupled pacing to identify the "functional" substrate of ventricular tachycardia: Long-term outcomes of the paced electrogram feature analysis technique.

BACKGROUND: The conduction delay and block that compose the critical isthmus of macroreentrant ventricular tachycardia (VT) is partly "functional" in that they only occur at faster cycle lengths. Close-coupled pacing stresses the myocardium's conduction capacity and may reveal late potentials (LPs) and fractionation. Interest has emerged in targeting this functional substrate. OBJECTIVE: The purpose of this study was to assess the feasibility and efficacy of a functional substrate VT ablation strategy. METHODS: Patients with scar-related VT undergoing their first ablation were recruited. A closely coupled extrastimulus (ventricular effective refractory period + 30 ms) was delivered at the right ventricular apex while mapping with a high-density catheter. Sites of functional impaired conduction exhibited increased electrogram duration due to LPs/fractionation. The time to last deflection was annotated on an electroanatomic map, readily identifying ablation targets. RESULTS: A total of 40 patients were recruited (34 [85%] ischemic). Median procedure duration was 330 minutes (interquartile range [IQR] 300-369), and ablation time was 49.4 minutes (IQR 33.8-48.3). Median functional substrate area was 41.9 cm2 (IQR 22.1-73.9). It was similarly distributed across bipolar voltage zones. Noninducibility was achieved in 34 of 40 patients (85%). Median follow-up was 711 days (IQR 255.5-972.8), during which 35 of 39 patients (89.7%) did not have VT recurrence, and 3 of 39 (7.5%) died. Antiarrhythmic drugs were continued in 53.8% (21/39). CONCLUSION: Functional substrate ablation resulted in high rates of noninducibility and freedom from VT. Mapping times were increased considerably. Our findings add to the encouraging trend reported by related techniques. Randomized multicenter trials are warranted to assess this next phase of VT ablation.

Risk Factors for Infections Involving Cardiac Implanted Electronic Devices.

BACKGROUND: Cardiac implantable electronic device infection is a major complication that usually requires device removal. PADIT (Prevention of Arrhythmia Device Infection Trial) was a large cluster crossover trial of conventional versus incremental antibiotics. OBJECTIVES: This study sought to investigate independent predictors of device infection in PADIT and develop a novel infection risk score. METHODS: In brief, over 4 6-month periods, 28 centers used either conventional or incremental prophylactic antibiotic treatment in all patients. The primary outcome was hospitalization for device infection within 1 year (blinded endpoint adjudication). Multivariable logistic prediction modeling was used to identify the independent predictors and develop a risk score for device infection. The prediction models were internally validated with bootstrap methods. RESULTS: Device procedures were performed in 19,603 patients, and hospitalization for infection occurred in 177 (0.90%) within 1 year of follow-up. The final prediction model identified 5 independent predictors of device infection (prior procedures [P], age [A], depressed renal function [D], immunocompromised [I], and procedure type [T]) with an optimism-corrected C-statistic of 0.704 (95% confidence interval: 0.660 to 0.744). A PADIT risk score ranging from 0 to 15 points classified patients into low (0 to 4), intermediate (5 to 6) and high (≥7) risk groups with rates of hospitalization for infection of 0.51%, 1.42%, and 3.41%, respectively. CONCLUSIONS: This study identified 5 independent predictors of device infection and developed a novel infection risk score in the largest cardiac implantable electronic device trial to date, warranting validation in an independent cohort. The 5 independent predictors in the PADIT score are readily adopted into clinical practice. (Prevention of Arrhythmia Device Infection Trial [PADIT Pilot]; NCT01002911).