Rates of pulmonary vein reconnection at repeat ablation for recurrent atrial fibrillation and its impact on outcomes among females and males.

BACKGROUND: Several studies have demonstrated that females have a higher risk of arrhythmia recurrence after pulmonary vein (PV) isolation for atrial fibrillation (AF). There are limited data on sex-based differences in PV reconnection rates at repeat ablation. We aimed to investigate sex-based differences in electrophysiological findings and atrial arrhythmia recurrence after repeat AF ablation METHODS: We conducted a retrospective study of 161 consecutive patients (32% female, age 65 ± 10 years) who underwent repeat AF ablation after index PV isolation between 2010 and 2022. Demographics, procedural characteristics and follow-up data were collected. Recurrent atrial tachycardia (AT)/AF was defined as any atrial arrhythmia ≥30 s in duration. RESULTS: Compared to males, females tended to be older and had a significantly higher prevalence of prior valve surgery (10 vs. 2%; P = .03). At repeat ablation, PV reconnection was found in 119 (74%) patients. Males were more likely to have PV reconnection at repeat ablation compared to females (81 vs. 59%; P = .004). Excluding repeat PV isolation, there were no significant differences in adjunctive ablation strategies performed at repeat ablation between females and males. During follow-up, there were no significant differences in freedom from AT/AF recurrence between females and males after repeat ablation (63 vs. 59% at 2 years, respectively; P = .48). CONCLUSIONS: After initial PV isolation, significantly fewer females have evidence of PV reconnection at the time of repeat ablation for recurrent AF. Despite this difference, long-term freedom from AT/AF was similar between females and males after repeat ablation.

Early Stroke and Mortality After Percutaneous Left Atrial Appendage Occlusion in Patients With Atrial Fibrillation.

BACKGROUND: Percutaneous endocardial left atrial appendage occlusion (LAAO) is an alternative therapy for stroke prevention in patients with atrial fibrillation who are poor candidates for oral anticoagulants. Oral anticoagulation is generally discontinued 45 days following successful LAAO. Real-world data on early stroke and mortality following LAAO are lacking. METHODS: Using International Classification of Diseases, Tenth Revision, Clinical-Modification codes, we performed a retrospective observational registry analysis to examine the rates and predictors of stroke, mortality, and procedural complications during index hospitalization and 90-day readmission among 42 114 admissions in the Nationwide Readmissions Database for LAAO between 2016 and 2019. Early stroke and mortality were defined as events occurring during index admission or 90-day readmission. Data on timing of early strokes post-LAAO were collected. Multivariable logistic regression modeling was used to ascertain predictors of early stroke and major adverse events. RESULTS: LAAO was associated with low rates of early stroke (0.63%), early mortality (0.53%), and procedural complications (2.59%). Among patients who had readmissions with strokes after LAAO, the median time from implant to readmission was 35 days (interquartile range, 9-57 days); 67% of readmissions with strokes occurred <45 days postimplant. Between 2016 and 2019, the rates of early stroke after LAAO significantly decreased (0.64% versus 0.46% P-for-trend <0.001), while early mortality and major adverse event rates were unchanged. Peripheral vascular disease and a history of prior stroke were independently associated with early stroke after LAAO. Early post-LAAO stroke rates were similar between low, medium, and high LAAO volume tertile centers. CONCLUSIONS: In this contemporary real-world analysis, the early stroke rate after LAAO was low, with the majority occurring within 45 days of device implantation. Despite an increase in LAAO procedures between 2016 and 2019, there with a significant decline in early strokes after LAAO during that period.

Initial experience with stylet-driven versus lumenless lead delivery systems for left bundle branch area pacing.

INTRODUCTION: Left bundle branch area pacing (LBBP) has emerged as an alternative method for conduction system pacing. While initial experience with delivery systems for stylet-driven and lumenless lead implantation for LBBP has been described, data comparing outcomes of stylet-driven versus lumenless lead implantation for LBBP are limited. In this study, we compare success rates and outcomes of LBBP with stylet-driven versus lumenless lead delivery systems. METHODS: Eighty-three consecutive patients (mean age 74.1 ± 11.2 years; 56 [68%] male) undergoing attempted LBBP at a single institution were identified. Cases were grouped by lead delivery systems used: stylet-driven (n = 53) or lumenless (n = 30). Baseline characteristics and procedural findings were recorded and compared between the cohorts. Intermediate term follow-up data on ventricular lead parameters were also compared. RESULTS: Baseline characteristics were similar between groups. Successful LBBP was achieved in 77% of patients, with similar success rates between groups (76% in stylet-driven, 80% in lumenless, p = 0.79), and rates of adjudicated LBB capture and other paced QRS parameters were also similar. Compared with the lumenless group, the stylet-driven group had significantly shorter procedure times (90 ± 4 vs. 112 ± 31 min, p = 0.004) and fluoroscopy times (10 ± 5 vs. 15 ± 6 min, p = 0.003). Ventricular lead parameters at follow-up were similar, and rates of procedural complications and need for lead revision were low in both groups. CONCLUSION: Delivery systems for stylet-driven and for lumenless leads for LBBP have comparable acute success rates. Long-term follow-up of lead performance following use of the various delivery systems is warranted.

Reduction of left ventricular global longitudinal strain in patients with permanent pacemakers as a predictor of heart failure and mortality outcomes.

INTRODUCTION: Frequent right ventricular (RV) pacing is associated with cardiomyopathy. The impact of RV pacing on left ventricular (LV) global longitudinal strain (GLS) and clinical outcomes is unclear. METHODS: We analyzed GLS via two-dimensional speckle tracking and LV ejection fraction (EF) on pre- and post-implantation transthoracic echocardiograms of patients undergoing dual chamber pacemaker implantation. We collected long-term data on strain, LVEF, and clinical outcomes. RESULTS: One hundred and ten patients (mean age 76 ± 12 years; 59 [54%] female) were followed for mean 23 ± 17 months. Mean baseline LVEF was 58 ± 11% and mean GLS was -17 ± 4%. Twenty-four (22%) patients had an absolute decrease in LVEF > 10% and 43 (39%) patients had a relative reduction of GLS > 15%. Among patients with a reduction of GLS, a larger proportion of patients had RV pacing burden ≥20% (67% vs. 46%; p = .048). Compared to patients without GLS reduction, more patients with a reduction in GLS reached a composite endpoint of HF hospitalization, CRT upgrade or death (47% vs. 16%; p = .001). CONCLUSION: Reduction in LV GLS was seen in nearly four in 10 patients undergoing pacemaker implantation and was significantly associated with increased RV pacing burden. LV GLS reduction was associated with increased risk of adverse outcomes. LV GLS may have utility in predicting outcomes among patients with RV pacing.

Differences between cardiac implantable electronic device envelopes evaluated in an animal model.

INTRODUCTION: Cardiac implantable electronic device (CIED) pocket related problems such as infection, hematoma, and device erosion cause significant morbidity and the clinical consequences are substantial. Bioabsorbable materials have been developed to assist in the prevention of these complications but there has not been any direct comparison of these adjunctive devices to reduce these complications. We sought to directly compare the TYRX absorbable antibacterial and CanGaroo extracellular matrix (ECM) envelopes in an animal model susceptible to these specific CIED-related complications (i.e., skin erosion and infection). METHODS AND RESULTS: Sixteen mice undergoing implantation with biopotential transmitters were divided into three groups (no envelope = 4, TYRX = 5, and CanGaroo = 7) and monitored for device-related complications. Following 12 weeks of implantation, gross and histological analysis of the remaining capsules was performed. Three animals in the CanGaroo group (43%) had device erosion compared to none in the TYRX group. The remaining capsules excised at 12 weeks were qualitatively thicker following CanGaroo compared to TYRX and no envelope and histological evaluation demonstrated increased connective tissue with CanGaroo. CONCLUSION: CanGaroo ECM envelopes did not reduce the incidence of device erosion and were associated with qualitatively thicker capsules and connective tissue staining at 12 weeks compared to no envelope or TYRX. Further studies regarding the use of these envelopes to prevent device erosion and their subsequent impact on capsule formation are warranted.

A hybrid endocardial-epicardial biventricular implantable cardioverter-defibrillator to circumvent the tricuspid valve.

The development of pacing and defibrillator systems that do not involve hardware traversing the tricuspid annulus can be desirable in order to minimize lead-related complications such as tricuspid regurgitation. Occasionally, primary tricuspid valve pathology (ie, infectious endocarditis, nonbacterial thrombotic endocarditis, and carcinoid disease) or congenital heart disease prohibits use of transvenous leads and alternative strategies are required to provide pacing or defibrillation. We describe such a case in which a biventricular implantable cardioverter defibrillator was implanted using a hybrid system involving endocardial and epicardial components.

Robotics for catheter ablation of cardiac arrhythmias: Current technologies and practical approaches.

Robotic technology has emerged as an important tool to facilitate catheter ablation of arrhythmias. Robotic cardiac electrophysiology technology includes remote magnetic navigation and manual robotic navigation. Robotics can confer advantages with respect to ease of catheter manipulation in anatomically challenging spaces, minimization of fluoroscopic exposure to both patients and operators, and reduction in operator fatigue. This review provides a comprehensive summary of robotic electrophysiology technology, its practical applications and its safety and efficacy for targeting cardiac arrhythmias.

Outcomes and mortality associated with atrial arrhythmias among patients hospitalized with COVID-19.

INTRODUCTION: The impact of atrial arrhythmias on coronavirus disease 2019 (COVID-19)-associated outcomes are unclear. We sought to identify prevalence, risk factors and outcomes associated with atrial arrhythmias among patients hospitalized with COVID-19. METHODS: An observational cohort study of 1053 patients with severe acute respiratory syndrome coronavirus 2 infection admitted to a quaternary care hospital and a community hospital was conducted. Data from electrocardiographic and telemetry were collected to identify atrial fibrillation (AF) or atrial flutter/tachycardia (AFL). The association between atrial arrhythmias and 30-day mortality was assessed with multivariable analysis. RESULTS: Mean age of patients was 62 ± 17 years and 62% were men. Atrial arrhythmias were identified in 166 (15.8%) patients, with AF in 154 (14.6%) patients and AFL in 40 (3.8%) patients. Newly detected atrial arrhythmias occurred in 101 (9.6%) patients. Age, male sex, prior AF, renal disease, and hypoxia on presentation were independently associated with AF/AFL occurrence. Compared with patients without AF/AFL, patients with AF/AFL had significantly higher levels of troponin, B-type natriuretic peptide, C-reactive protein, ferritin and d-dimer. Mortality was significantly higher among patients with AF/AFL (39.2%) compared to patients without (13.4%; p < .001). After adjustment for age and co-morbidities, AF/AFL (adjusted odds ratio [OR]: 1.93; p = .007) and newly detected AF/AFL (adjusted OR: 2.87; p < .001) were independently associated with 30-day mortality. CONCLUSION: Atrial arrhythmias are common among patients hospitalized with COVID-19. The presence of AF/AFL tracked with markers of inflammation and cardiac injury. Atrial arrhythmias were independently associated with increased mortality.

Inpatient hospital procedural volume and outcomes following catheter ablation of atrial fibrillation.

INTRODUCTION: The real-world distribution of hospital atrial fibrillation (AF) ablation volume and its impact on outcomes are not well-established. We sought to examine patient characteristics, complications, and readmissions after AF ablation stratified by hospital procedural volume. METHODS AND RESULTS: Using the nationally representative inpatient Nationwide Readmissions Database, we evaluated 54 597 admissions for AF ablation between 2010 and 2014. Hospitals were categorized according to tertiles of annual AF ablation volume. Index complications, 30-day readmissions, and early mortality were examined. Multivariable logistic regression was performed to assess the predictors of adverse outcomes. Between 2010 and 2014, low volume tertile hospitals accounted for 79.3% of hospitals performing AF ablations. When stratified by first, second, and third volume tertiles, complication and early mortality rates were higher in low volume centers (8.9% and 0.67% vs 6.1% and 0.33%, vs 4.5% and 0.16%, respectively; P < .001). Patients undergoing AF ablation at low volume centers were older and had a higher prevalence of congestive heart failure, coronary artery disease, and other comorbidities. Low volume hospitals were associated with increased cardiac perforation (adjusted odds ratio [aOR], 4.79; P < .001), vascular complications (aOR 1.49; P < .001), and any complication (aOR 2.06; P < .001) during index admission as well as increased early mortality (aOR 2.43; P = .039). CONCLUSIONS: Among patients hospitalized for AF ablation, low inpatient AF ablation hospital volume was associated with worse outcomes following ablation, which was exacerbated by a greater comorbidity burden among patients at these centers.

Sex-based differences in outcomes, 30-day readmissions, and costs following catheter ablation of atrial fibrillation: the United States Nationwide Readmissions Database 2010-14.

AIMS: Although catheter ablation has emerged as an important therapy for patients with symptomatic atrial fibrillation (AF), there are limited data on sex-based differences in outcomes. We sought to compare in-hospital outcomes and 30-day readmissions of women and men undergoing AF ablation. METHODS AND RESULTS: Using the United States Nationwide Readmissions Database, we analysed patients undergoing AF ablation between 2010 and 2014. Based on ICD-9-CM codes, we identified co-morbidities and outcomes. Multivariable logistic regression and inverse probability-weighting analysis were performed to assess female sex as a predictor of endpoints. Of 54 597 study patients, 20 623 (37.7%) were female. After adjustment for age, co-morbidities, and hospital factors, women had higher rates of any complication [adjusted odds ratio (aOR) 1.39; P < 0.0001], cardiac perforation (aOR 1.39; P = 0.006), and bleeding/vascular complications (aOR 1.49; P < 0.0001). Thirty-day all-cause readmission rates were higher for women compared to men (13.4% vs. 9.4%; P < 0.0001). Female sex was independently associated with readmission for AF/atrial tachycardia (aOR 1.48; P < 0.0001), cardiac causes (aOR 1.40; P < 0.0001), and all causes (aOR 1.25; P < 0.0001). Similar findings were confirmed with inverse probability-weighting analysis. Despite increased complications and readmissions, total costs for AF ablation were lower for women than men due to decreased resource utilization. CONCLUSIONS: Independent of age, co-morbidities, and hospital factors, women have higher rates of complications and readmissions following AF ablation. Sex-based differences and disparities in the management of AF need to be explored to address these gaps in outcomes.

Approach to catheter ablation of left atrial flutters.

Left atrial tachycardias (ATs) most commonly occur after catheter or surgical ablation of atrial fibrillation and in patients with atrial myopathies. Pre-existing scar in the left atrium (LA) can result in complex circuits, sometimes with narrow channels that can be detected with high-resolution mapping. The most common forms of macroreentrant AT from the LA are variants of peri-mitral and roof-dependent reentry. Localized reentrant rhythms occur in the setting of fibrosis that gives rise to slow conduction and may occur adjacent to areas of prior ablation. The approach to treating these ATs involves first identifying the left atrial origin, defining the tachycardia circuit - which can be facilitated by ultrahigh density mapping and entrainment - and selecting a suitable isthmus to target for ablation. An important endpoint in ablating left atrial flutters is to establish and confirm bidirectional line of the block. Challenges in ablating these ATs include the presence of multiple tachycardias, defining circuits with complex activation patterns and achieving durable lines of block, particularly in the lateral mitral isthmus. Progress in treating these arrhythmias has come from new mapping technologies and the recognition of epicardial connections that allow for persistent conduction across ablation lesions. Also, advances in delivering energy to obtain complete transmural lesions promise to improve the long-term success of ablating ATs from the LA.

Effects of focal impulse and rotor modulation-guided ablation on atrial arrhythmia termination and inducibility: Impact on outcomes after treatment of persistent atrial fibrillation.

INTRODUCTION: The role of focal impulse and rotor modulation (FIRM)-guided ablation for the treatment of atrial fibrillation (AF) remains unclear. Previous studies on the FIRM-guided ablation outcomes have been limited by a focus on AF termination as an endpoint and by patient population heterogeneity. We sought to determine differences in rates of AF termination, inducibility, and recurrence in patients with persistent AF undergoing first-time ablation with a FIRM-guided approach compared with patients undergoing conventional ablation. METHODS AND RESULTS: Eight-five consecutive patients (38 FIRM, 47 conventional) with persistent AF undergoing first-time ablation were retrospectively analyzed. There were no significant differences in the rates of AF termination in the FIRM group compared to the conventional group (26% vs 15%; P = .15). Rates of inducible AF after ablation were 37% in the FIRM group and 30% in the conventional group (P = .32). Over a median follow-up of 2.4 years, the rates of freedom from AF were similar between the FIRM and conventional groups (1-year freedom from AF 65% vs 50%, respectively; P = .18). Procedural termination of AF with either FIRM ablation or conventional ablation was not associated with any significant reduction in AF recurrence. CONCLUSION: A FIRM-guided approach was not associated with a significant difference in freedom from AF when compared to conventional ablation. Termination of AF with ablation was not associated with increased freedom from AF. While AF termination using substrate-based ablation may have mechanistic implications for understanding AF rotor physiology, its impact on clinical outcomes remains unclear.

Regional isolation in the right atrium with disruption of intra-atrial conduction after catheter ablation of atrial tachycardia.

BACKGROUND: Ablation of atrial tachycardia (AT) that occurs after cardiac surgery or prior ablation often requires complex lesion sets. In combination with the pre-existing atrial scar, these lesion sets may result in inadvertent intra-atrial conduction block. This study reports the phenomenon of incidental isolation of right atrial (RA) regions that occurs secondary to AT ablation, which in some cases results in profound bradycardia due to sinus exit block. METHODS AND RESULTS: Intracardiac electrograms were examined in consecutive patients who underwent AT ablation in the RA. Cases of localized isolation of the RA were defined as areas that developed electrical dissociation during ablation. Of 132 patients having ablation in both the RA free wall and the cavotricuspid isthmus (CTI), 10 (7.6%) developed unintentional isolation of the lateral RA. Five of these patients had prior mitral valve surgery, comprising 12.2% of all 41 patients with mitral surgery who underwent ablation in the CTI and the RA free wall. All patients with regional isolation had a pre-existing scar in the lateral wall of the RA. In six patients, isolation of the lateral RA resulted in profound bradycardia due to exit block from the peri-sinus node myocardium. CONCLUSIONS: Complex ablation lesions in patients with prior valve surgery, prior ablation, or atrial myopathy may result in unintended localized conduction block in the RA. In some cases, isolation of the lateral RA can result in complete sinus exit block with profound bradycardia requiring pacemaker implantation.

Mechanistic subtypes of focal right ventricular tachycardia.

Idiopathic sustained focal right ventricular tachycardia (VT) is most frequently due to outflow tract (OT) tachycardia. This arrhythmia is recognized by its characteristic ECG pattern and sensitivity to adenosine. However, there are other forms of idiopathic, focal sustained VT that originate from the right ventricle (RV), which are less well appreciated and easily overlooked. This review will identify the characteristic features and electrophysiologic properties of these forms of RV VT, including those originating from the tricuspid annulus, right ventricular papillary muscles, and moderator band as well as variants of classic RVOT tachycardia and those due to microreentry in the presence of preclinical disease. Recognition of these subtypes of focal RV tachycardia should facilitate targeted therapy.

Comparison of robotic magnetic navigation-guided and manual catheter ablation of ventricular arrhythmias arising from the papillary muscles.

Aims: Due to the complex anatomy of the left ventricular (LV) and right ventricular (RV) papillary muscles (PMs), PM ventricular arrhythmias (VAs) can be challenging to target with ablation. We sought to compare the outcomes of robotic magnetic navigation-guided (RMN) ablation and manual ablation of VAs arising from the LV and RV PMs. Methods and results: We evaluated 35 consecutive patients (mean age 65 ± 12 years, 69% male) who underwent catheter ablation of 38 VAs originating from the LV and RV PMs as confirmed by intracardiac echocardiography. Catheter ablation was initially performed using RMN-guidance in 24 (69%) patients and manual guidance in 11 (31%) patients. Demographic and procedural data were recorded and compared between the two groups. The VA sites of origin were mapped to 20 (53%) anterolateral LV PMs, 14 (37%) posteromedial LV PMs, and 4 (11%) RV PMs Acute successful ablation was achieved for 20 (74%) VAs using RMN-guided ablation and 8 (73%) VAs using manual ablation (P = 1.000). Fluoroscopy times were significantly lower among patients undergoing RMN ablation compared to patients undergoing manual ablation [median 7.3, interquartile range (IQR) 3.9-18 vs. 24 (16-44) min; P = 0.005]. Retrograde transaortic approach was used in 1 (4%) RMN patients and 5 (46%) manual patients (P = 0.005). No procedural complications were seen in study patients. Conclusion: Use of an RMN-guided approach to target PM VAs results in comparable success rates seen with manual ablation but with lower fluoroscopy times and decreased use of transaortic retrograde access.

Eligibility of Pacemaker Patients for Subcutaneous Implantable Cardioverter Defibrillators.

INTRODUCTION: The subcutaneous implantable cardioverter defibrillator (ICD) has emerged as a viable therapeutic option for patients who are deemed high risk for sudden cardiac death. Previous studies have shown that 7-15% of patients are not candidates for the S-ICD based on their intrinsic QRS/T-wave morphology. Presently, it is not known if the S-ICD can be considered as supplementary therapy in patients who are ventricularly paced. We sought to determine the proportion of ventricularly paced patients who would qualify for an S-ICD. METHODS AND RESULTS: We evaluated 100 patients with transvenous pacemakers/ICDs, including 25 biventricular devices to determine S-ICD candidacy during right ventricular (RV) pacing and biventricular pacing based on the recommended QRS:T-wave ratio screening template. Fifty-eight percent of patients qualified for an S-ICD based on their QRS morphology during ventricular pacing. More patients during biventricular pacing met criteria compared to during RV pacing alone (80% vs. 46%, P <0.01). Patients that were paced from the RV septum were more likely to qualify compared to those paced from the RV apex (67% vs. 37%, respectively, P <0.01). CONCLUSION: While S-ICD implantation may be considered as supplemental therapy in select patients with preexisting transvenous devices, relatively fewer candidates who are paced from the RV apex qualify. QRS morphologies generated from biventricular pacing as well as from septal RV pacing are more likely to screen in based on the recommended S-ICD template.

Recovery of atrioventricular conduction in patients with heart block after transcatheter aortic valve replacement.

INTRODUCTION: Recovery of conduction has been demonstrated in >50% of patients who receive pacemakers (PPMs) for high-degree atrioventricular block (HD-AVB) after transcatheter aortic valve replacement (TAVR). Little information is available about the time course of conduction recovery in these patients and if any features predict early recovery of conduction. METHODS: A retrospective review was performed of patients who underwent TAVR with balloon and self-expanding valves who required PPMs for HD-AVB. Serial PPM interrogations were analyzed to detect recovery of AV conduction. Analysis was performed to identify predictors and timing of conduction recovery. RESULTS: Of a total population of 578 patients, 54 (9%) received PPMs for HD-AVB. In multivariate analysis, predictors of HD-AVB requiring a PPM included age (P = 0.014), right bundle branch block (OR 7.33 [3.64-14.8], P < 0.0001), atrial fibrillation (OR 2.16 [1.16-4.05], P = 0.016), and self-expanding valves (OR 4.19 [2.20-7.97], P < 0.0001). Of the 54 patients who received PPMs, 38 had follow-up sufficient to evaluate AV conduction recovery. Of these, 23 (61%) showed recovery of AV nodal conduction; 20 had already recovered by their first interrogation, a median of 22 days (IQR 14-31) post-PPM placement. There were no statistically significant predictors of AV nodal conduction recovery, including type of valve implanted. CONCLUSIONS: A majority of patients who receive PPMs for HD-AVB after TAVR recover AV conduction during follow-up, and in most patients conduction recovery occurs within weeks. These findings imply that programming to minimize ventricular pacing may be beneficial in a majority of these patients.

Asystole during pacemaker magnet application.

Pacemaker magnet application during surgery for patients who are pacemaker-dependent is often utilized to avoid perioperative inhibition from electromagnetic interference. We present a case during which such routine magnet use resulted in an unexpected response and discuss the limitations and nuances of this common practice.

Prevalence of early repolarization pattern in patients with lone atrial fibrillation.

BACKGROUND: The objective of this study was to test the association of early repolarization pattern (ER) with lone atrial fibrillation (AF). METHODS: Electrocardiograms (ECGs) were analyzed in blinded fashion in a case-control study of 182 patients with lone AF and 182 controls without AF. RESULTS: Patients with lone AF and controls had similar frequencies of ER pattern (15% vs. 19%, p=0.40). In patients <50years of age, there was also no difference in the percentage of patients with ER in the AF and control groups (17% vs. 19%, p=0.60). ER pattern was more common in patients with ECG voltage criteria of left ventricular hypertrophy (LVH), with ER present in 57% of patients with elevated Sokolow-Lyon voltage compared to 14% of those without (p<0.0001). CONCLUSIONS: No association could be identified between the ER pattern and lone AF in young and middle-aged patients. In this age group, ER is substantially more common in patients with elevated Sokolow-Lyon voltage criteria.