Background and Objectives: Cardiac arrhythmia is highly prevalent in hypertrophic cardiomyopathy (HCM), but its relation to genotype has not been well established.We investigated the arrhythmia manifestations according to genotype in HCM patients. Methods: This single-center, retrospective study included 119 patients with HCM who underwent genetic testing using a next-generation sequencing panel. Incidence of cardiac arrhythmias and long-term outcomes were analyzed according to the presence of pathogenic variants (PVs). Results: PVs related to HCM were identified in 45 (37.8%) patients. Presentation of sustained ventricular tachycardia (VT) prior to HCM diagnosis was more prevalent in the PV-positive group. During a median follow-up of 45.9 months, the incidence of sustained VT was significantly higher in the PV-positive group (11.1% vs. 1.4%, hazard ratio, 8.71; 95% confidence interval, 1.02–74.61). A new implantable cardioverter defibrillator insertion rate was comparable in the 2 groups, but appropriate shocks were delivered in only 4 patients in the PV-positive group (8.9% vs. 0%, P = 0.037). Incidence of bradyarrhythmias requiring pacemaker and new-onset atrial fibrillation (AF) was not significantly different between the 2 groups. Among 56 patients with AF, there was no significant difference in treatment strategies in the 2 groups. However, sinus rhythm was maintained over the last 6 months of follow-up in 4/17 (23.5%) patients in the PV-positive group and 24/39 (61.5%) patients in the PV-negative group (P = 0.031). Conclusions Patients with PVs related to HCM exhibited higher incidence of life-threatening VTs. While overall AF incidence was similar between the groups, the presence of PVs was significantly associated with poorer rhythm outcomes of AF.

Background and Objectives: Circulating microRNAs (miRNAs) have been proposed as potential biomarkers in atrial fibrillation (AF) and heart failure (HF), but their role in patients with AF and heart failure with preserved ejection fraction (HFpEF) remains uncertain. Methods: We measured serum levels of 4 candidate miRNAs (miR-21, miR-146a, miR-146b, and miR-328) using quantitative polymerase chain reaction in 45 patients with persistent AF and HFpEF and five non-AF arrhythmia controls (Healthy). Expression levels were normalized to miR-16 and expressed as fold change (2−ΔCt ). Baseline (V1) and 3–6 months follow-up (V2) samples were analyzed, and comparisons were performed using non-parametric tests. Results: At baseline, none of the 4 miRNAs differed significantly between AF patients and Healthy controls; miR-21, 1.24 ± 0.55 vs. 1.15 ± 0.32 (P = 0.57); miR-146a, 0.66 ± 0.35 vs. 0.65 ± 0.06 (P = 0.71); miR-146b, 0.12 ± 0.07 vs. 0.11 ± 0.01 (P = 0.90); and miR-328, 0.08 ± 0.05 vs. 0.07 ± 0.03 (P = 0.95), all P > 0.5. Baseline comparisons were analyzed using relative expression values (2−ΔCt , normalized to miR-16), while longitudinal changes between V1 and V2 were assessed using fold change (2−ΔΔCt ). No significant longitudinal changes were observed across treatment groups. Conclusions In patients with persistent AF and HFpEF/HF with mildly reduced ejection fraction, circulating miR-21, miR-146a, miR-146b, and miR-328 showed no significant differences compared with the non-AF arrhythmia control group and did not change after 6 months of renin-angiotensin-aldosterone system-targeted therapy. These pilot data suggest that the short-term utility of biomarkers is limited and warrants validation in larger, randomized cohorts.

Background: Left bundle branch area pacing (LBBAP) provides physiologic ventricular activation but requires deep lead penetration into the interventricular septum, which can rarely cause various complications.Case presentation: A 57-year-old woman with high-degree atrioventricular block underwent dual-chamber pacemaker implantation with stylet-driven LBBAP via the left axillary vein. Within hours, she developed nausea, vomiting, and frequent ventricular premature contractions with non-sustained ventricular tachycardia, while remaining hemodynamically stable. Transthoracic echocardiography revealed a well-circumscribed echo lucent mass in the mid interventricular septum (15.6 × 24.7 mm) consistent with hematoma, without pericardial effusion or left ventricular outflow tract obstruction. In the absence of clinical deterioration, a conservative strategy with close rhythm monitoring and serial echocardiography was chosen. The hematoma regressed progressively with near-complete resolution at two weeks, and the patient remained asymptomatic with stable lead function at 6-month follow-up. Conclusions Interventricular septal hematoma is a rare complication of LBBAP that may present predominantly with ventricular arrhythmia. In hemodynamically stable patients without mechanical compromise, careful surveillance can allow successful conservative management without surgical intervention.

Background and Objectives: Atrial septal defect (ASD) often accompanies atrial fibrillation (AF). AF is usually treated with radiofrequency catheter ablation (RFCA) before transcatheter ASD closure. However, there is still no established consensus on the treatment of AF after transcatheter ASD closure, as the deployed occluder makes access to the left atrium during RFCA more challenging. We report 9 cases of totally thoracoscopic ablation (TTA) for atrial tachyarrhythmia following transcatheter ASD closure. Methods: From 2012 to 2021, 9 patients underwent TTA for atrial tachyarrhythmia that developed or recurred after transcatheter ASD closure. TTA, a type of video-assisted thoracoscopic surgery, was performed to achieve transmural ablation of the atria. Results: Seven patients had been diagnosed with atrial tachyarrhythmia before transcatheter ASD closures; 3 had undergone RFCA, and 4 had received direct-current cardioversion.All 9 patients were in sinus rhythm at the time of transcatheter ASD closure. During a mean follow-up of 44.9 ± 39.4 months after closure, atrial tachyarrhythmia developed or recurred in all patients. After TTA, every patient was discharged without atrial tachyarrhythmia. The mean follow-up duration after TTA was 58.7 ± 41.1 months. Atrial arrhythmia recurred in 2 patients; in one, sinus rhythm was restored after post-TTA RFCA. A cerebral infarction occurred in one patient despite maintaining sinus rhythm after TTA. N-terminal pro brain natriuretic peptide levels significantly decreased after TTA (P = 0.021). Conclusions TTA can be performed without interference from the ASD occluder and therefore represents a safe and feasible treatment option for AF after transcatheter ASD closure.

Background and Objectives: Primary prevention (PP) implantable cardioverter-defibrillator (ICD) therapy for ischemic cardiomyopathy (ICM) is underused in Asian countries, including South Korea. Both clinical and hospital factors may influence appropriate ICD use. We evaluated whether determinants of PP ICD implantation differ by hospital implantation volume. Methods: In this prospective, multicenter observational registry (blinded for review), patients eligible for PP ICD were enrolled. Factors associated with ICD implantation—clinical characteristics and hospital-level systems—were examined across 4 large-volume hospitals (≥ 15 implants during the study) and 12 small-volume hospitals (< 15). Multivariable logistic regression identified independent predictors. Results: Among 3,083 ICM patients (2,403 men; median age 70 years), PP ICD implantation rates were 10.8% in large-volume and 5.7% in small-volume hospitals. Across groups, male sex and chronic kidney disease independently predicted ICD implantation. Regarding hospital factors, non-monetary incentives for referral were the sole independent predictor in large-volume centers (odds ratio [OR], 3.55; 95% confidence interval [CI], 2.07–6.10;P < 0.001). In small-volume centers, heart failure conferences (OR, 12.73; 95% CI, 1.72–94.37;P = 0.013), structured education systems (OR, 11.72; 95% CI, 2.45–56.12; P = 0.02), and pacemaker clinics (OR, 11.4; 95% CI, 2.24–58.39; P = 0.003) were independently associated with implantation. Conclusions Clinical predictors of PP ICD use were consistent across hospital volumes, but hospital-level determinants differed. Referral incentives characterized large-volume centers, whereas conferences, education systems, and pacemaker clinics were key in smallvolume centers. Tailored institutional strategies by hospital volume may help close the PP ICD underuse gap and improve evidence-based implementation.

Background: and Objective: Obstructive sleep apnea (OSA) is increasingly recognized as a risk factor for cardiovascular diseases. However, long-term population-based evidence across a broad range of cardiovascular outcomes, particularly conduction system disorders, remains limited. We investigated the 15-year cardiovascular outcomes in patients with OSA using a large-scale nationwide cohort. Methods: This retrospective cohort study used the Korean National Health Insurance Service database, including 547,749 patients diagnosed with OSA and 2,282,415 matched controls between 2002 and 2020. Following exclusion criteria and 1:1 propensity score matching, 541,812 individuals were included in each group. The primary outcomes were incidence of atrial fibrillation (AF), premature beats, ventricular arrhythmias, atrioventricular (AV) block, sinus node dysfunction, heart failure, ischemic heart disease (IHD), and stroke. Cumulative incidence was assessed using Kaplan-Meier survival curves. Hazard ratios (HRs) were estimated using Cox proportional hazards models adjusted for relevant covariates. Results: Over a 15-year follow-up period, the OSA group exhibited significantly higher incidence rates for all cardiovascular outcomes than controls. In the matched cohort, adjusted HR were elevated for AF (1.82 [1.77–1.87]), premature beats (2.25 [2.17–2.34]), ventricular arrhythmias (1.81 [1.64–1.99]), AV block (1.81 [1.64–1.99]), sinus node dysfunction (2.22 [1.96–2.50]), heart failure (1.43 [1.39–1.48]), IHD (1.54 [1.52–1.56]), and stroke (1.20 [1.18–1.22]) (all P < 0.0001). Conclusions OSA was independently associated with an increased long-term risk of various cardiovascular outcomes, including arrhythmias, ischemic events, and conduction system disorders. This supports the importance of early identification and longitudinal management of cardiovascular risk in this population.

Background: The role of pulsed-field ablation (PFA) in convergent procedure for atrial fibrillation (AF)/atrial tachycardia remains unclear.Case presentation: We describe a case of a patient who developed pulmonary vein (PV)-left atrium macroreentrant tachycardia following the epicardial portion of convergent procedure for AF and subsequently underwent successful endocardial ablation using a pentaspline PFA system. Conclusions The application of PFA successfully terminated the tachycardia and eliminated the PV potentials, thereby completing the convergent ablation procedure.

Background: Our case highlights the challenging nature of left para-Hisian premature ventricular contractions (PVCs) catheter ablation (CA) and proves that sometimes the compromise between successful ablation and inadvertent atrioventricular (AV) block is the only viable solution for the patient.Case presentation: The case shows an improvement of left ventricular function combining heart failure therapy and CA of the PVC. However, a complete AV block—although with a junctional escape rhythm—could not be avoided. Conclusions The main “take-away” lesson from this case is the importance of prediction of PVC site of origin during preprocedural planning. This is helpful to plan the anatomical approach required for mapping and ablation of these PVCs and to appreciate the risk of the procedure.

Background and Objectives: Hypertrophic cardiomyopathy (HCM) increases the risk of sudden cardiac death. Despite international guidelines for sudden death prevention and implantable cardiac defibrillator (ICD) use, clinical practices vary. This study assessed the practices and opinions of Korean cardiologists on HCM management, focusing on ICD use and reimbursement policies. Methods: A structured electronic survey was distributed to members of the Korean Society of Cardiology, covering HCM management, ICD preferences, and reimbursement policies. Results: A total of 119 cardiologists participated, with most being arrhythmia specialists (56.3%) and university professors (81.5%). Cardiac magnetic resonance imaging and genetic testing were underutilized (30.3% and 11.8%, respectively). Beta-blocker-refractory premature ventricular complexes were primarily managed with continued medical therapy (77.3%). ICD preferences varied by physician specialty and patient age, with subcutaneous ICDs preferred in younger patients and dual-chamber ICDs in older patients. Nearly half of respondents believed ICD reimbursement criteria required revision. Conclusions Significant variability in HCM management exists among Korean cardiologists, influenced by restrictive reimbursement criteria rather than clinical guidelines. Updated reimbursement policies and improved access to advanced diagnostics are needed to align with international standards and optimize patient care.

Background and Objectives: Until now, apical hypertrophic cardiomyopathy (HCM) has been considered to have a benign prognosis in terms of cardiovascular mortality. The prevalence of sudden cardiac arrest and the current status of implantable cardioverter-defibrillator (ICD) implantations in patients with apical HCM remain to be elucidated. Methods: Between July 2001 and May 2021, 96 HCM patients who had undergone ICD implantations from 3 tertiary hospitals were reviewed. We evaluated the prevalence of apical HCM and the indication for an ICD implantation. Results: Fifteen patients (15.6%) had apical HCM and 81 (84.4%) the non-apical type including septal (n = 56) and diffuse (n = 25) types, respectively. Sixty-four patients (66.7%) received ICD implantations for primary prevention and 32 (33.3%) for secondary prevention.Among those with apical HCM, 7 patients (46.7%) presented with an aborted sudden cardiac death or documented ventricular fibrillation, therefore, they received ICD implantations for secondary prevention. The proportion of secondary prevention ICD implantations did not significantly differ between apical and non-apical HCM subtypes (46.7% [7/15] vs. 30.9% [25/81], P = 0.233). Conclusions The proportion of secondary prevention ICD implantations did not differ significantly by HCM subtype. ICD implantations should be considered for high-risk patients with apical HCM.