Catheter ablation is a widely used treatment modality for various cardiac tachyarrhythmias, including atrial and ventricular arrhythmias. Although it is generally considered safe, the procedure carries potential complications, with coronary artery injury being one of the most significant. The aim of this systematic review was to assess the incidence, mechanisms, contributing factors, diagnostic strategies, and preventive measures related to coronary artery injury in patients undergoing catheter ablation, including radiofrequency catheter ablation, cryoablation, and pulsed-field ablation.

Background: The primary prevention of atrial fibrillation (AF), which increases mortality through complications including stroke and heart failure, is important. Excessive salt intake and low potassium intake are risk factors for cardiovascular disease; however, their association with AF remains inconclusive. This study investigated the association between sodium- and potassium-related urinary markers and AF prevalence.

Methods and Results: Data from the Tohoku Medical Megabank Project Community-based Cohort Study were used in this cross-sectional study. The urinary sodium-to-potassium (Na/K) ratio and estimated 24-h sodium and potassium excretion were calculated using spot urine samples and categorized into quartiles (Q1–Q4). The prevalence of AF was the primary outcome. Of the 26,506 participants (mean age 64.8 years; 33.2% males) included in this study, 630 (2.4%) had AF. Using Q1 as the reference group, the odds ratios for AF prevalence in Q4 were 1.35 (95% confidence interval [CI] 1.07–1.73) and 1.59 (95% CI 1.20–2.12) for 24-h estimated urinary Na/K ratio and estimated 24-h sodium excretion, respectively. Estimated 24-h potassium excretion was not associated with AF prevalence.

Conclusions: AF prevalence was positively associated with the urinary Na/K ratio and estimated 24-h urinary sodium excretion, but not with estimated 24-h urinary potassium excretion. Although further prospective studies are warranted, the findings of this study suggest that salt intake may be a modifiable risk factor for AF.

Background: The HELT-E₂S₂score, a novel risk stratification system, was developed to determine the incidence of ischemic stroke in Japanese patients with non-valvular atrial fibrillation (NVAF). It has been suggested that the HELT-E₂S₂score is more useful than the CHADS₂and CHA₂DS₂-VASc scores for Japanese patients with NVAF. This study determined the incidence of ischemic stroke in patients with NVAF and cardiac implantable electronic devices (CIEDs) and assessed the validity of the HELT-E₂S₂score in this population.

Methods and Results: We retrospectively analyzed the database of the CIED clinic of Chiba University Hospital and investigated the incidence of ischemic stroke according to the HELT-E₂S₂score. Of the 730 consecutive patients who were followed-up at the CIED clinic, those without NVAF were excluded, leaving 362 patients in this study (mean [±SD] follow-up period, 64±48 months; mean age, 73±16 years; 65% male). The mean CHADS₂and CHA₂DS₂-VASc scores were 1.8±1.2 and 2.8±1.6 points, respectively. During follow-up, 31 (8.6%) patients experienced ischemic stroke. The c-statistic for the HELT-E₂S₂score was 0.719 (95% confidence interval [CI] 0.657–0.795), which was higher than the c-statistics for the CHADS₂(0.704; 95% CI 0.647–0.768; P=0.025) and CHA₂DS₂-VASc (0.700; 95% CI:0.621–0.747; P=0.0097) scores.

Conclusions: Risk stratification for ischemic stroke using the HELT-E₂S₂score is valid in Japanese patients with NVAF and CIEDs.

Background: Recurrence after ablation for atrial fibrillation (AF) may occur in patients in whom atrial remodeling progresses. Atrial conduction time is a marker of remodeling. This study investigated whether atrial conduction time is related to postoperative recurrence.

Methods and Results: This study enrolled 441 patients with AF (median age 69 years; 144 women; paroxysmal/non-paroxysmal AF=231/210) who underwent initial radiofrequency catheter ablation at Mie University Hospital between January 2018 and December 2022. The interval from the earliest potential in the right atrium (RA) to the latest potential in the coronary sinus (CS) was measured using a BeeAT catheter during sinus rhythm after ablation. The primary endpoint was AF recurrence or atrial tachycardia lasting >30 s in the 1 year after ablation. Recurrence was observed in 44 patients. Patients were categorized into 2 groups according to recurrence. The RA-CS interval was significantly longer in the recurrence group (122.5±17.7 vs. 98.5±17.7 ms; P<0.001). In Cox regression analysis, the RA-CS interval was independently associated with recurrence (hazard ratio 1.05; 95% confidence interval [CI] 1.03–1.07; P<0.001). The cut-off value for the RA-CS interval was 111 ms (area under the curve=0.845; 95% CI 0.785–0.905). The recurrence rate was significantly higher in patients with an RA-CS interval ≥111 vs. <111 ms.

Conclusions: The RA-CS interval time was an independent predictor of recurrence after AF ablation.

Background: Landiolol is a short-acting, intravenously administered β₁-adrenergic receptor blocker that can rapidly control heart rate in refractory and urgent fatal arrhythmias (ventricular fibrillation [VF] and hemodynamically unstable ventricular tachyarrhythmia [VT]). This indication was approved in Japan in 2019 based on results of the J-Land II clinical trial. We conducted post-marketing surveillance (PMS) to assess the safety and effectiveness of landiolol in real-world settings in Japan.

Methods and Results: This PMS examined the safety, focusing on adverse drug reactions (ADRs) related to the safety specifications (_SS), namely hypotension-decreased blood pressure_SS, bradycardia_SS, and heart failure_SS, and effectiveness (physician-rated) in patients treated with landiolol for the target indication. Among 253 registered patients, 13.0% experienced ADRs related to the safety specifications: bradycardia_SS(7.1%), hypotension-decreased blood pressure_SS(6.7%), and heart failure_SS(1.2%). Serious ADRs related to the safety specifications occurred in 6.7% of patients, including those related to bradycardia_SS(3.2%), hypotension-decreased blood pressure_SS(3.2%), and heart failure_SS(1.2%). The effectiveness of landiolol within 48 h after starting treatment was rated as effective (52.4%), slightly effective (27.0%), not effective (18.7%), and indeterminate (2.0%).

Conclusions: The safety profile of landiolol in this PMS was similar to that observed in a prior clinical trial, and no new safety signals were identified. Landiolol is an option for treating refractory and potentially fatal VF or hemodynamically unstable VT.

Background: Ventricular arrhythmia (VA) is an independent risk factor for adverse outcomes in patients with left ventricular hypertrabeculation (LVHT). This study explored the predictive value of biomarkers for VAs in LVHT.

Methods and Results: This cohort study retrospectively enrolled 265 LVHT patients (mean [±SD] age 44.2±17.0 years, 65.7% male) with data available for N-terminal pro B-type natriuretic peptide, big endothelin-1, high-sensitivity C-reactive protein, uric acid, and free fatty acid. The primary outcome was a composite of non-sustained ventricular tachycardia, sustained ventricular tachycardia, ventricular fibrillation, and appropriate implantable cardioverter defibrillator therapy. Over a median follow-up of 4.34 years, 82 (30.9%) patients experienced VAs. Multivariable Cox regression analysis revealed that baseline concentrations of big endothelin-1 were independently associated with the occurrence of VAs (hazard ratio 1.513; 95% confidence interval 1.136–2.013; P=0.005). Restricted cubic spline analysis showed that susceptibility to VAs increased markedly with increases in big endothelin-1 concentrations. Subgroup analysis revealed that LVHT patients with big endothelin-1 concentrations >0.63 pmol/L should be closely monitored for VAs, particularly when higher concentrations are accompanied by cardiomyopathies, left ventricular (LV) end-diastolic diameters ≥60 mm, or LV ejection fraction <50%. Individuals with elevated big endothelin-1 concentrations and isolated hypertrabeculation in the LV lateral wall had a significantly greater risk of VAs (log-rank P=0.002).

Conclusions: Big endothelin-1 concentrations and the location of hypertrabeculation can help with risk stratification for VAs in LVHT.

Background: The effect of paced-QRS (p-QRS) duration on long-term outcomes is unclear, so we assessed the association between p-QRS duration and cardiac events.

Methods and Results: We enrolled 187 patients (103 males, mean age: 77±12 years) who underwent pacemaker implantation between 2018 and 2021. During the median follow-up period of 972 days (761–1,292 days), 18 patients experienced cardiac events (1 cardiac death, 17 heart failure hospitalizations). The p-QRS duration was longer in the cardiac event group than in the noncardiac event group (162±17 vs. 148±17 ms, P=0.005). Receiver operating characteristic curve analysis identified 149 ms as the optimal cutoff value for predicting cardiac events (area under the curve, 0.72). Kaplan-Meier analysis showed better outcomes for mid-range p-QRS duration (≤149 ms, n=89) compared with long p-QRS duration (>149 ms, n=98) (P=0.005). Multivariate Cox hazard analysis indicated a good outcome with mid-range p-QRS duration (hazard ratio: 0.28, 95% confidence interval: 0.06–0.88, P=0.029).

Conclusions: A p-QRS duration of ≤149 ms was associated with a reduction in cardiac events. Therefore, it may serve as a target index of success in right ventricular pacing.

Background: The early repolarization pattern (ERP) is associated with cardiovascular death, but its connection with arrhythmias remains unknown. This study evaluated relationships between ERP and incident arrhythmias, including ventricular arrhythmias, bradyarrhythmias, and atrial fibrillation (AF)/flutter (Afl).

Methods and Results: We analyzed 14,679 middle-aged (45–64 years) participants from the Atherosclerosis Risk in Communities cohort, a prospective population-based study in the US. Participants were monitored for ERP status at baseline and at 3 subsequent follow-up visits. We examined associations between incident arrhythmias and baseline ERP, time-varying ERP, time-updated ERP, and changes in ERP over time using Cox models to estimate hazard ratios (HRs) adjusted for potential confounders. Over a 20-year follow-up, there were 1,252 ventricular arrhythmias, 890 bradyarrhythmias, and 2,202 cases of AF. Time-updated ERP was associated with increased HRs for ventricular arrhythmias (1.55; 95% confidence interval [CI] 1.35–1.77), bradyarrhythmias (1.76; 95% CI 1.48–2.08), and AF (1.25; 95% CI 1.10–1.43). Time-varying ERP also showed associations with these outcomes. Compared with individuals with consistently normal electrocardiogram results, those with new-onset or persistent ERP had increased risks of incident arrhythmias. In subjects with time-updated ERP, anterior leads and J wave amplitudes ≥0.2 mV were associated with a higher incidence of arrhythmias.

Conclusions: Several types of ERP, including time-varying, time-updated, new-onset, and consistent, are associated with the incidence of arrhythmias in the middle-aged biracial (Black and White) population.

Background: The aim of this was to develop an atrial fibrillation (AF) risk score using items usually included in Japanese governmental health check-ups.

Methods and Results: We analyzed data from 6,476 Japanese participants registered in the Suita Study. At baseline, the participants were aged ≥30 years and were free from AF. Cox regression analysis was used to identify AF risk factors, and a 0–100 score was developed to predict AF events within 10 years. Within a median follow-up of 14.6 years, 278 participants developed AF. The risk score incorporated age [<50 years (16 points for men, 0 for women), 50–59 years (26 points for men, 14 for women), 60–69 years (41 points for men, 37 for women), ≥70 years (54 points for men, 51 for women)], current smoking with a smoking index >500 (7 points), heavy alcohol consumption (8 points), body mass index ≥25 kg/m²(6 points), hypertension (7 points), urinary proteins (4 points), glutamic-pyruvic transaminase >50 IU/dL (4 points), and cardiovascular disease history (10 points). The 10-year AF event probabilities were 7.1%, 8.4%, 10.8%, and 15.9% for scores of 47–54, 55–58, 59–69, and ≥70, respectively.

Conclusions: The new risk score to predict AF uses items similar to those used in Japanese governmental health check-ups.

Background: The prevalence of congenital long QT syndrome (LQTS) (1 : 2,000) is based on genetic testing and ECG data, but the prevalence of electrocardiographically determined prolonged corrected QT interval (pQTc) in infants is unclear.

Methods and Results: Subjects were 10,282 1-month-old infants who participated in 2 prospective ECG screening studies performed in 2010–2011 and 2014–2016. Infants with a QTc ≥0.45 using Bazett’s formula [QTc(B)] at 1-month medical checks were re-examined. pQTc was defined as QTc ≥0.46 on 2 different ECGs in early infancy. Infants with QTc ≥0.50 or progressive prolongation of QTc to 0.50 were defined as at high risk. The prevalence of infants with a pQTc was 11/10,282 (1 : 935; 95% confidence interval, 1 : 588–1 : 2,283). Five infants were diagnosed as at high risk, and all infants had an abrupt increase in QTc(B) values in early infancy, mostly at 6–11 weeks after birth and when medication was started. No infants with a pQTc experienced LQTS-related symptoms. Statistical analysis showed that a cutoff QTc(B) ≥0.45 was optimal for screening infants with a pQTc.

Conclusions: The prevalence of ECG-determined pQTc is approximately 1 : 1,000. An abrupt increase in QTc(B) values occurs in infants at high risk, mostly at 6–11 weeks after birth. A cutoff QTc(B) value ≥0.45 may be appropriate for 1-month-old screening in this population.

Background: Genetic testing for long QT syndrome (LQTS) is useful for diagnosis, risk stratification, and therapeutic strategies. This study investigated the clinical impact of genetic testing for LQTS patients.

Methods and Results: Total 3,851 patients (proband: 2,316 [60%]; female: 2,283 [59%]; median age: 14 years [interquartile range 9–36 years]) diagnosed with LQTS (LQTS score ≥3.5, QTc ≥500 ms, pathogenic variants in LQTS-associated genes, or unexplored syncope with QTc 480–499 ms) were enrolled in this study. Of these patients, 1,146 (29.8%) experienced syncope and 322 (8.5%) experienced ventricular fibrillation (VF) or cardiopulmonary arrest (CPA) at ≤70 years of age. Genetic testing using a next-generation sequencing panel and/or Sanger sequencing was performed for 3,770 (98%) patients, genotype was then identified in the following LQTS-associated genes: KCNQ1 (45%), KCNH2 (34%), SCN5A (8%), KCNE1 (0.1%), KCNE2 (0.03%), KCNJ2 (2.7%), CACNA1C (1.2%), and CALM1,2 (0.3%). Forty-seven (1.2%) patients had double or compound heterozygous variants in LQTS-associated genes, whereas the genotype remained unknown in 220 (5.8%) patients. When comparing phenotype with genotype, QTc was significantly longer in CALM1,2 patients than in others except for CACNA1C, whereas QTc was almost normal in KCNJ2 patients. The incidence of the first cardiac event (syncope, VF/CPA) differed among the genotypes, and prognosis was significantly worse for CALM1,2 patients.

Conclusions: Comprehensive genetic testing, including non-major LQTS genes, is important for diagnosis and risk stratification of LQTS.

Recently, some clinicians have been diagnosing and treating arrhythmias on the basis of electrocardiogram (ECG) devices with low accuracy. In Europe and the US, several statements on the use of ECGs have already been published by related academic societies. In addition, with the relaxation of regulations on media advertising ambulatory/wearable ECG devices, the frequency of use of simple ECG devices by the general public will increase in the future. Therefore, this statement describes the functions and features of non-invasive ambulatory or wearable ECG devices that have been approved as medical devices in Japan (and that can record ECGs remotely), as well as points to note when using them; provides an overview of data storage and security for ambulatory/wearable ECG devices and implantable loop recorders (ILRs), as well as discussing differences between their use and the use of non-invasive ambulatory/wearable ECG devices; and provides classes of recommendation for the use of these devices and their evaluation for each arrhythmia type or condition. We describe lead-based ambulatory ECG devices (classical 24-h Holter ECG monitoring), handheld ECG devices, handheld-based ECG devices using a smartphone, wearable ECG devices (smartwatch and garment ECG devices), and patch ECG devices. In addition, we provide information on methods that are not based on the original ECG, such as photoplethysmography and oscillometric blood pressure measurement, and describe the limitations of their use. We hope that the publication of this statement will lead to the appropriate use of ambulatory/wearable ECG devices in Japan.