BACKGROUND AND OBJECTIVES:Thermal energy-based catheter ablation techniques, including cryoballoon ablation (CBA) and radiofrequency ablation (RFA), are widely utilized for rhythm control in patients with atrial fibrillation. However, direct comparisons of CBA and RFA using real-world data are limited. This study aims to evaluate the short- and long-term outcomes of CBA and RFA. METHODS:A total of 4,868 patients who underwent procedures between January 2018 and July 2022 were selected from the Korean CBA Registry and a multicenter RFA cohort. The primary outcome was the atrial tachyarrhythmia recurrence. To reduce selection bias, 1:1 propensity score matching (PSM) was performed, yielding 1,843 patients in each group. RESULTS:After PSM, RFA demonstrated significantly lower recurrence rates compared with CBA at both 1 year (20.9% vs. 27.9%; hazard ratio [HR], 0.69; 95% confidence interval [CI], 0.61-0.79) and 3 years (31.9% vs. 35.2%; HR, 0.72; 95% CI, 0.65-0.81). In multivariable Cox regression analysis, RFA was independently associated with lower recurrence risk, with a 30% relative risk reduction at 1 year (HR, 0.70; 95% CI, 0.61-0.80) and a 27% relative risk reduction at 3 years (HR, 0.73; 95% CI, 0.65-0.81). When cavotricuspid isthmus (CTI) ablation was performed in addition to pulmonary vein isolation (PVI), recurrence rates were comparable between RFA and CBA. CONCLUSIONS:In this large, multicenter real-world cohort, RFA consistently demonstrated more favorable short- and long-term outcomes than CBA, even after PSM and multivariable adjustment. However, outcomes were comparable when CTI ablation was additionally performed, underscoring the importance of procedural strategies beyond PVI.

INTRODUCTION:Patient characteristics and predictors of early (ERAT) and late (LRAT) recurrence of atrial tachyarrhythmia by atrial fibrillation (AF) type after cryoballoon ablation (CBA) remain poorly defined. METHODS:Using the Korean Heart Rhythm Cryoballoon Registry (12 centers, 2018-2022), 2051 patients undergoing CBA for drug-refractory AF were stratified by AF type. ERAT was defined as atrial tachyarrhythmia within the 3-month blanking period and LRAT as recurrence beyond 3 months. Independent predictors of ERAT (all patients) and LRAT (patients without ERAT) were identified. RESULTS:ERAT occurred in 631 patients (30.8%; 17.6% in paroxysmal and 40.4% in persistent AF). Among 1420 patients without ERAT, LRAT occurred in 311 (21.9%; 16.7% paroxysmal, 27.2% persistent). In paroxysmal AF, coronary artery disease (HR 1.60; 95% CI, 1.00-2.56; p = 0.048) and LA enlargement (HR 1.07; 95% CI, 1.04-1.10; p < 0.001) predicted ERAT, whereas hypertrophic cardiomyopathy (HR 5.01; 95% CI, 2.20-11.42; p < 0.001) and LA enlargement (HR 1.04; 95% CI, 1.01-1.08; p = 0.019) predicted LRAT. In persistent AF, AF duration (HR 1.04; 95% CI, 1.02-1.06; p < 0.001) and LA enlargement (HR 1.03; 95% CI, 1.02-1.04; p < 0.001) predicted ERAT, and LA enlargement (HR 1.03; 95% CI, 1.01-1.05; p = 0.010) independently predicted LRAT. CONCLUSION:Predictors of ERAT and LRAT differed between patients with paroxysmal and those with persistent AF. LA enlargement was the most consistently shared predictor across recurrence phenotypes.

BACKGROUND:Left bundle branch area pacing (LBBAP) is a physiologic pacing strategy encompassing heterogeneous pacing subtypes. However, predictors of clinically significant tricuspid regurgitation (TR) after LBBAP, particularly according to pacing subtype, remain unclear. OBJECTIVE:To identify the incidence and predictors of significant TR following LBBAP. METHODS:We retrospectively analyzed patients from 31 centers who underwent successful LBBAP between 2021 and 2024 and had no or mild TR at baseline. LBBAP was categorized as left bundle branch pacing, left fascicular pacing, and left ventricular septal pacing (LVSP). The primary outcome was incident TR, defined as new-onset moderate-or-greater TR on follow-up echocardiography performed 6-12 months after the index procedure. Multivariable logistic regression was performed to identify predictors of incident TR. RESULTS:Among 523 patients (mean age, 72.5 ± 11.9 years; 45.5% male), 35 (6.7%) developed incident TR during 1-year follow-up. Compared with patients without incident TR, those with incident TR had a significantly higher prevalence of atrial fibrillation (AF), higher baseline TR maximal velocity (Vmax), longer baseline QRS duration, and a higher frequency of LVSP. On multivariable analysis, AF (odds ratio [OR], 12.55; 95% confidence interval [CI], 3.18-49.55), LVSP (OR, 9.08; 95% CI, 2.35-35.12), baseline TR Vmax of ≥2.8 m/second (OR, 4.19; 95% CI, 1.20-14.60), and baseline QRS duration of ≥120 ms (OR, 3.80; 95% CI, 1.01-14.32) were independently associated with incident TR. CONCLUSION:Incident TR occurred in 6.7% of patients following successful LBBAP. LVSP, prevalent AF, elevated TR Vmax, and prolonged QRS duration were independent predictors of incident TR.

Background Direct oral anticoagulants (DOACs) are the cornerstone of thromboembolic prevention in patients with atrial fibrillation, venous thromboembolism, or other cardiovascular conditions. However, DOAC use is associated with an increased risk of bleeding, with gastrointestinal (GI) bleeding being the most common site of major bleeding. Proton pump inhibitors (PPIs) are reasonably used during combined antithrombotic therapy or based on individual bleeding risk; nonetheless, evidence supporting their benefit in patients receiving DOAC therapy remains limited. Methods The Gastrointestinal protection Using proton-pump inhibitor in pAtients who RequireD Oral AntiCoagulants (GUARD-OAC) trial is a prospective, multicenter, open-label, randomized controlled trial evaluating the GI protective effect of PPI coadministration with DOAC. Eligible participants are patients with cardio- or cerebrovascular disease requiring long-term anticoagulation (≥ 1 year), who are currently receiving or initiating DOAC therapy, and have a HAS-BLED score of ≥ 1. The primary outcome is a composite of upper GI clinical events, including bleeding, symptomatic gastroduodenal ulcer, persistent pain of presumed GI origin with underlying multiple erosive disease, obstruction, or perforation. The secondary outcomes are the individual components of the primary outcome, GI symptoms or signs, cardiovascular or all bleeding events, and all-cause mortality. Assuming a 40% relative risk reduction of the primary outcome in the PPI plus DOAC group compared to the DOAC alone group, a total of 3,846 patients will be enrolled and followed for one year. A Clinical Events Committee will adjudicate clinical outcomes and adverse events for causality and attribution, and an independent Data Safety Monitoring Board will oversee the study. The GUARD-OAC trial is funded by the Ministry of Health & Welfare, Republic of Korea. Conclusions The GUARD-OAC trial is the first randomized controlled trial exploring the efficacy of PPI cotherapy in patients receiving DOACs, providing evidence that may inform future guidelines on GI protection in this population. Trial registration Clinical Research Information Service, Identifier KCT0006848

BACKGROUND:Identifying the risks related to the complications of electrical cardioversion (ECV) can alert the determinaton of rhythm control in patients with atrial fibrillation (AF). METHODS:We retrospectively reviewed 1,058 patients who underwent ECV for persistent or long-standing persistent AF/atrial flutter (AFL) from multiple centers. Patients were classified into the no-complication (1,023 patients) and complication (35 patients) groups based on the following major complications: stroke and/or systemic embolism (SSE), myocardial infarction, major bleeding, implantation of cardiac implantable electronic devices, ventricular tachycardia/fibrillation, and death at 1 year follow-up after ECV. RESULTS:Compared with the no-complication group, the complication group exhibited a higher proportion of female patients (37% vs. 22%), as well as a higher proportion of patients with older age (67 ± 11 vs. 61 ± 10 years), diabetes mellitus (DM) (49% vs. 24%), heart failure (HF) (49% vs. 30%), SSE (23% vs. 9%), high CHA₂DS₂-VASc (CV) score (3.6 ± 1.8 vs. 2.2 ± 1.4), low left ventricular ejection fraction (LVEF) (50 ± 16% vs. 58 ± 21%), and high left atrial volume index (LAVI) (51 ± 26 vs. 40 ± 20 mL/m²). Class I and III antiarrhythmics were less prescribed in the complication group than in the no-complication group (57% vs. 76%). Univariate analysis for complications revealed age (≥ 65 years), female sex, DM, HF, SSE, LVEF (< 50%), LAVI (≥ 40 mL/m²), CV score (≥ 3), bradycardia on Holter (< 60/min), and no antiarrhythmics as risk factors. Among these, multivariate analysis revealed clinical significance of female sex and SSE. CONCLUSION:Female sex and a history of SSE were the most important risk factors of complications in patients with persistent or long-standing persistent AF/AFL who underwent ECV.

BACKGROUND/AIMS:Identifying clinical risk factors of failed electrical cardioversion (ECV) for persistent or long-standing persistent atrial fibrillation (AF) can guide selection of rhythm control. METHODS:A total of 1058 patients who underwent ECV for persistent or long-standing persistent AF at multiple centres were retrospectively reviewed. Patients were divided into three groups: group 1 maintained sinus rhythm (SR) for >1 year, group 2 maintained SR ≤1 year after ECV, and group 3 had failed ECV. SR maintenance was assessed via regular electrocardiography follow-ups or Holter. RESULTS:Group 1, 2 and 3 comprised 315 (30%), 654 (62%), and 89 (8%) patients, respectively. The mean patient age was 61 ± 10 years, with males accounting for 78% (824). Group 3 showed longer AF duration, female dominance, high proportion of patients with history of coronary artery disease (CAD) and heart failure (HF), and increased left atrium (LA) diameter, LA volume index (LAVI), cardiac size, and cardiothoracic ratio. Univariate analysis revealed that AF duration (≥50 months), female sex, history of CAD and HF, increased LA diameter (≥ 45 mm) and LAVI (≥ 45 mL/m2), and no antiarrhythmics were risk factors of failed ECV for persistent or long-standing persistent AF. Among them, AF duration (≥50 months), history of HF, and increased LAVI showed clinical significance in the multivariate analysis. CONCLUSIONS:Longer AF duration, history of HF, and increased LAVI were strongly associated with failed ECV in patients with persistent or long-standing persistent AF.

BACKGROUND AND OBJECTIVES:The optimal sedation strategy for cryoablation in atrial fibrillation (AF) remains uncertain. We aimed to compare the safety and efficacy outcomes between deep sedation (DS) and general anesthesia (GA) in patients undergoing cryoablation. METHODS:We analyzed 2,068 patients from the Korean Heart Rhythm Society Cryoablation Registry who underwent cryoablation for AF between 2018 and 2022. Patients were grouped based on anesthesia method: DS (n=1,390) and GA (n=678). Propensity score matching (1:1) was performed to adjust for baseline differences. The primary outcomes included any recurrence of atrial tachyarrhythmias (ATs) after a 3 month blanking period and procedure-related major complications. RESULTS:The study included 2,068 patients (average age: 61.7±9.7 years; 76.3% male; 57.9% with persistent AF). In the matched cohort, AT recurrence rates were comparable between DS and GA groups (47.1% [n=220] vs. 53.1% [n=225]; p=0.99) during a mean follow-up of 1.2 years. The incidence of major complications was also similar between groups both before (2.8% [n=39] vs. 2.4% [n=16]; p=0.66) and after matching (2.3% [n=15] vs. 2.1% [n=14]; p=1.00). Subgroup analysis based on body mass index (≥30 vs. <30) revealed no significant differences in efficacy and safety outcomes between the DS and GA groups. CONCLUSIONS:DS provides a comparable safety and efficacy profile to GA for cryoablation in patients with AF. These findings support the use of DS as a feasible and practical alternative to GA in routine clinical practice.

AIMS:This study, using a prospective cohort, evaluated the effectiveness and safety of off-label reduced-dose apixaban vs. the on-label dose in atrial fibrillation (AF) patients meeting a single-dose reduction criterion. METHODS AND RESULTS:The efficAcy and Safety of aPixaban In REal-world practice in Korean frail patients with AF (ASPIRE) study is a multicentre, prospective observational cohort involving AF patients who met a single-dose reduction criterion of apixaban. Patients were divided into two groups: an on-label standard dose (5 mg twice daily) and an off-label reduced dose (2.5 mg twice daily). The primary effectiveness outcome was stroke/systemic embolism (SSE), and the primary safety outcome was major bleeding. Of 1944 patients (mean age 74.3 ± 7.9 years, 56% women), 997 (51%) were receiving off-label reduced-dose apixaban. The off-label reduced-dose group was older, had more comorbidities, higher concomitant antiplatelet use, and higher CHA2DS2-VASc and HAS-BLED scores. During follow-up (1.0 ± 0.2 year), crude incidence rates were 0.9 vs. 0.7 per 100 person-years for SSE and 0.5 vs. 1.0 for major bleeding in the on-label vs. off-label groups. After inverse probability of treatment weighting, the off-label reduced-dose group showed no significant differences in the risk of SSE [hazard ratio (HR) 0.67, 95% confidence interval (CI) 0.28-1.59, P = 0.370] and major bleeding (HR 1.38, 95% CI 0.44-4.35, P = 0.578) compared with the on-label standard dose group. CONCLUSION:In Korean patients with AF meeting a single-dose reduction criterion of apixaban, off-label reduced-dose apixaban showed no significant differences in SSE and major bleeding compared with the on-label standard dose. These findings suggest that individualized anticoagulation strategies, such as reduced-dose apixaban, may be beneficial for patients with a high risk of bleeding.

This study, using a prospective cohort, evaluated the effectiveness and safety of off-label reduced-dose apixaban versus the on-label dose in atrial fibrillation (AF) patients meeting a single dose reduction criterion. The efficAcy and Safety of aPixaban In Real-world practice in Korean frail patients with AF (ASPIRE) study is a multicenter, prospective observational cohort involving AF patients who met a single dose reduction criterion of apixaban. Patients were divided into two groups: on-label standard dose (5 mg twice daily) and off-label reduced dose (2.5 mg twice daily). The primary effectiveness outcome was stroke/systemic embolism (SSE), and the primary safety outcome was major bleeding. Of 1 944 patients (mean age 74.3 ± 7.9 years, 56% women), 997 (51%) were receiving off-label reduced dose apixaban. The off-label reduced dose group was older, had more comorbidities, higher concomitant antiplatelet use, and higher CHA2DS2-VASc and HAS-BLED scores. During follow-up (1.0 ± 0.2 year), crude incidence rates were 0.9 vs. 0.7 per 100 person-years for SSE and 0.5 vs. 1.0 for major bleeding in the on-label vs. off-label groups. After inverse probability of treatment weighting, the off-label reduced dose group showed no significant differences in the risk of SSE (HR 0.67, 95% CI 0.28-1.59, p = 0.370) and major bleeding (HR 1.38, 95% CI 0.44-4.35, p = 0.578) compared to the on-label standard dose group. In Korean patients with AF meeting a single dose reduction criterion of apixaban, off-label reduced-dose apixaban showed no significant differences in SSE and major bleeding compared to the on-label standard dose. These findings suggest that individualized anticoagulation strategies, such as reduced dose apixaban, may be beneficial for patients with a high risk of bleeding.

Background/Aims Although an implantable loop recorder (ILR) is a valuable tool for investigation of unexplained syncope, there are limited data regarding time course to diagnosis and predictors of serious arrhythmias as a cause of unexplained syncope. We sought to investigate diagnosis rate by time period after ILR implantation and identify predictors of serious arrhythmias in patients with unexplained syncope. Methods We identified 394 patients who received ILR implantation for unexplained syncope enrolled in the Korean ILR registry. Results Serious arrhythmias were documented in 205 patients (52.0%). One hundred seventy-two patients (43.7%) had sick sinus-node syndrome (SSS), 24 (6.1%) had atrioventricular block, and nine (2.3%) had ventricular arrhythmia. Of these, 48 (23.4%) and 77 (37.6%) were diagnosed within two weeks and one month after ILR implantation, respectively. Median time to diagnosis was 62 days. In multivariable analysis, left atrial volume index (LAVI) ≥ 34 mL/m2 (hazard ratio [HR] 1.582), hypertension (HR 1.788), sinus bradycardia with a heartrate less than 60 beats per minute (HR 1.762), and LAVI ≥ 34 mL/m2 combined with sinus bradycardia (HR 1.911) were independent predictors of SSS. Cumulative detection rate of SSS was significantly higher in patients with LAVI ≥ 34 mL/m2 than those with LAVI < 34 mL/m2 (p < 0.001). Conclusions More than half of patients with unexplained syncope had serious arrhythmias, and more than one-third of these arrhythmias were diagnosed within one month after ILR implantation. LAVI combined with sinus bradycardia may be a useful predictor of SSS as a cause of unexplained syncope.

BACKGROUND AND OBJECTIVES:Cryoballoon ablation (CBA) is considered an effective rhythm control treatment for atrial fibrillation (AF) and is increasing exponentially. However, data regarding the efficacy and safety of CBA in elderly patients are limited. METHODS:A total of 2,652 patients (55.2% with non-paroxysmal AF) from the Korean CBA registry database with follow-up of ≥12-months after de novo CBA were divided into 2 groups based on age (<75 and ≥75 years old). Procedure related complications and clinical outcomes were compared. RESULTS:Compared to the control group (n=2,403), the elderly group (n=249) had female predominance (41.8% vs. 21.1%, p<0.001), a higher CHA₂DS₂-VASc scores (4.0 [3.0-5.0] vs. 2.0 [1.0-3.0]; p<0.001), and a higher prevalence of heart failure (33.3% vs. 21.9%; p<0.001) and chronic kidney disease (42.2% vs. 10.4%; p<0.001). A total of 120 procedure-related minor complications were reported, but no significant difference was observed between the 2 groups (6.4% vs. 4.3%; p=0.18). Recurrence of atrial tachyarrhythmias was observed in 67 patients (27.2%) in the elderly group and 788 patients (33.3%) in the control group. After adjusting for confounding variables, the freedom from atrial tachyarrhythmias during 24-month was similar between the 2 groups (67.0% vs. 62.7%; adjusted hazard ratio, 0.91; 95% confidence interval, 0.62-1.34; p=0.63). CONCLUSIONS:CBA showed a reasonable efficacy and safety profile in elderly population with AF, comparable to that in younger patients.

BACKGROUND AND OBJECTIVES:Atrial fibrillation (AF) occurs in more than 20% of hypertrophic cardiomyopathy (HCM) patients, further increasing the risk of stroke. Although radiofrequency catheter ablation in AF patients with HCM has been performed, data on cryoballoon ablation (CBA) in HCM patients are limited. We evaluated the efficacy and safety of CBA in HCM patients with AF. METHODS:The study included 2,649 patients with AF from the Korean CBA registry database with follow-up >12 months after de novo CBA. The primary efficacy outcome was recurrence of atrial tachyarrhythmias (ATs) ≥30s after a 3-month blanking period. RESULTS:Totals of 1,176 paroxysmal AF (44.4%) and 1,473 persistent atrial fibrillation (PeAF, 55.6%) patients (mean age 61.7 years; 76.7% men) underwent de novo CBA. Compared to non-HCM patients (n=2,590), those with HCM (n=59) had larger left atrium and higher prevalence of heart failure, previous stroke or transient ischemic attack, and PeAF. Procedure-related complications were not statistically different between the 2 groups. During a mean follow-up period of 638±308 days, 875 (33.0%) patients experienced recurrence of ATs (845 [32.6%] non-HCM patients and 30 [50.8%] HCM patients) (p=0.01). The overall AT-free survival rate at 2 years was 45.9% in HCM group and 63.3% in non-HCM group, respectively (p=0.014), whereas there was no significant difference between the two groups in PeAF. CONCLUSIONS:CBA may be an effective rhythm control treatment for patients with AF and HCM, with an AT-free survival rate of approximately 50% at 2-year follow-up and low procedure-related complications.

Background The ECG is a simple, noninvasive screening method for cardiovascular disease and arrhythmia. The impact of ECG abnormality on mortality is not certain in low‐risk populations. To address this, we evaluated the association between ECG abnormality and mortality. Methods and Results We retrospectively assessed baseline ECG and all‐cause mortality and cardiovascular mortality in 660 383 patients presenting for medical check‐ups. Baseline ECG abnormalities were classified according to the Minnesota Code. Among the total 660 383 participants, 23 609 (3.6%) had major and 110 038 (16.7%) had minor ECG abnormalities. All‐cause mortality occurred in 7751 patients (1.1%) and cardiovascular mortality in 1180 (0.18%) over a median follow‐up period of 8.8 years. Major ECG abnormalities were associated with all‐cause mortality (hazard ratio [HR], 1.11 [95%, 1.03–1.2]) and cardiovascular mortality (HR, 1.92 [95% CI, 1.63–2.27]) compared with no ECG abnormalities. All‐cause mortality was associated with right atrial enlargement (HR, 2.11 [95% CI, 1.1–4.07]), left atrial enlargement (HR, 1.76 [95% CI, 1.1–2.84]), sinus tachycardia (HR, 1.52 [95% CI, 1.15–2.01]), complete atrioventricular block (HR, 2.1 [95% CI, 1.05–4.2]), atrial fibrillation (HR, 1.52 [95% CI, 1.26–1.84]), and left ventricular hypertrophy (HR, 1.15 [95% CI, 1.02–1.3]). Cardiovascular mortality was associated with left atrial enlargement (HR, 4.52 [95% CI, 2.15–9.5]), atrial fibrillation (HR, 3.22 [95% CI, 2.33–4.46]), left ventricular hypertrophy (HR, 1.72 [95% CI, 1.35–2.19]), major Q‐wave abnormality (HR, 1.6 [95% CI, 1.08–2.39]), and major ST‐T abnormality (HR, 1.76 [95% CI, 1.01–3.04]). Conclusions ECG abnormalities, including left atrial enlargement, left ventricular hypertrophy, atrial fibrillation, and major Q‐wave and ST‐T abnormalities, were associated with cardiovascular mortality in a low‐risk population.

INTRODUCTION:Little is known about age and clinical intervention after implantable loop recorder (ILR) insertion. This study investigated the association between age and clinical intervention after ILR implantation. METHODS AND RESULTS:Data were obtained from a multicenter registry of ILR in Korea (2017-2020, n = 795). ILRs were inserted with indications of unexplained syncope, recurrent palpitation, or cryptogenic stroke. The primary outcome was clinically actionable event that was a composite of the newly detected atrial fibrillation (AF), pacemaker or implantable cardioverter defibrillator (ICD) implantation, catheter ablation, and anticoagulation initiation. The mean age was 64.3 years, and the mean follow-up duration was 20.6 months. Clinically actionable events were observed in 322 (40.5%) patients. Compared to younger age (< 50 years), older age (≥ 50 years) showed higher prevalence of newly detected AF (3.7% vs. 15.8%; p = 0.001), pacemaker implantation (11.2% vs. 21.2%; p = 0.022), and initiation of anticoagulation (3.7% vs. 18.6%; p < 0.001). No significant differences were found in ICD implantation (1.9% vs. 1.3%; p = 0.996) or catheter ablation (3.8% vs. 6.0%; p = 0.512). The older age group more frequently experienced clinically actionable events compared to the younger age group (hazard ratio 2.52, 95% confidence interval: 1.86-3.41; p < 0.001). A significant association was found in the increase of age (per 1-year) and the risk of clinically actionable events (adjusted hazard ratio 1.03, 95% confidence interval 1.02-1.04; p < 0.001). CONCLUSION:Advanced age is a significant risk factor for clinical intervention after ILR insertion. ILR should be considered more actively in older patients requiring prolonged rhythm monitoring.