Few recent large-scale studies have evaluated the risks and benefits of continuing oral anticoagulant（OAC）therapy after catheter ablation（CA）of atrial fibrillation（AF）. We used data from the National Database of Health Insurance Claims and Specific Health Checkups of Japan and analyzed patients who underwent CA of AF between April 2014 and March 2021. Patients were divided into two groups according to whether OAC therapy was continued 6 months after the index CA. The primary outcomes were thromboembolism and major bleeding after a landmark period of 6 months. The association between continuing OACs and outcomes was determined according to CHADS₂ score. Of 231,374 patients analyzed, 71％ and 53％ continued OAC therapy at 6 and 12 months, respectively. In the CHADS₂ score ≤ 1 group, the hazard ratio（HR）in the continued OAC group was 0.86（95％ confidence interval［CI］ : 0.74-1.01, p＝0.06）for thromboembolism and 1.51（95％ CI : 1.27-1.80, p＜0.001）for major bleeding. In the CHADS₂ score＝2 group, the hazard ratio（HR）in the continued OAC group was 0.98（95％ CI : 0.78-1.24, p＝0.90）for thromboembolism and 1.35（95％ CI : 1.05-1.72, p＝0.02）for major bleeding. In the CHADS₂ score ≥ 3 group, the HR of the continued OAC group was 0.61（95％ CI : 0.46-0.82, p＝0.001）for thromboembolism and 1.05（95％ CI : 0.71-1.56, p＝0.81）for major bleeding. Discontinuation of OACs may contribute to risk reduction of major bleeding in patients with a lower thromboembolic risk.

In this review, I attempted to interpret previous studies of the genesis of the electrocardiographic T wave（T wave）and its repolarization properties. From the results of these studies, the form of the T wave will be determined by the impulse propagation processes and the distribution of action potential durations（APD）in the cardiac ventricles. To confirm the above thinking, the local refractory periods and the APD distributions, including M cells, have been measured from experimental animal hearts and the human heart. However, further studies including computer simulation studies will be needed to analyze the precise mechanisms of the T waveform. Furthermore, I addressed the repolarization properties related to the T waveform, such as electrotonic interactions between myocytes, and anisotropic propagation of the repolarized wave. Finally, I commented on the classification of the T wave advocated by Abildskov.

Background : Although 24-hour Holter monitoring is essential to investigate the causes of syncope, it has limitations in capturing infrequent arrhythmias. For patients with suspected cardiac syncope or presyncope symptoms, an implantable loop recorder（ILR）, though invasive, may be necessary to enable long-term electrocardiographic recording. Objective : This study aimed to evaluate the diagnostic yield of cardiogenic syncope using a patch type 7-day ECG recorder, with the aim of exploring the potential to reduce the use of implantable loop recorder（ILR）. Methods : The study retrospectively analyzed 118 patients（70 males, 48 females, average age 68 years）who underwent 7-day ECG monitoring to evaluate cardiogenic syncope between April 2019 and March 2023. The incidence and timing of arrhythmias potentially related to syncope（paroxysmal atrial fibrillation, paroxysmal supraventricular tachycardia, non-sustained ventricular tachycardia, sustained ventricular tachycardia, sinus bradycardia, pauses, Mobitz type Ⅱ second-degree AV block and complete AV block）were assessed. Results : Arrhythmias possibly related to syncope were detected in 43 patients（a total of 75 episodes）. Of these, 38 patients（88％）had arrhythmias detected after 24 hours of monitoring. Subsequent treatments included pacemaker implantation in 15 patients（35％）and catheter ablation in 22 patients（51％）. In 36 patients（32％）, catheter ablation or pacemaker implantation was performed without the need for ILR implantation. Conclusion : In patients suspected of cardiogenic syncope or presenting with presyncope symptoms, 7-day ECG monitoring facilitated early diagnosis, potentially avoiding the need for ILR implantation.

［Objective］ Cardiac sympathetic denervation（CSD）is an important strategy in managing refractory ventricular tachycardia（VT）. The original CSD procedure consist of the sympathectomy of the lower half of the stellate ganglion（SG）and T2-T4. Simplifying the existing CSD procedure to minimize surgical invasion without compromising success may be the key to further expanding its clinical application. We performed endoscopic bilateral sympathectomy T2-4 or 5（T2-4 or 5 BCSD）with SG-sparing to reduce surgical invasion because the removal of the SG has the potential to cause Horner syndrome and injury to the brachial plexus, subclavian artery and vein. This study aimed to assess T2-4 or 5 BCSD for untreatable VT. ［Methods］ We enrolled HFrEF patients with VT refractory to multidisciplinary approaches, including catheter ablation. Patient characteristics, procedural outcomes and number of arrhythmic events were evaluated. ［Results］ Five patients with HFrEF（EF 27±10％）underwent T2-4 or 5 BCSD for treatment-resistant VT（VT storm 3, repetitive VT requiring ICD therapy 2）. The CSD procedure was successfully performed without procedure-related complications（mean operative duration 108±24 minutes）. T2-4 or 5 BCSD was effective for suppressing VT in 3 patients. The mean median number of ICD shocks before CSD was 10（range 6-31）and decreased to 0 during available follow-up after CSD. Otherwise, T2-4 or 5 BCSD was ineffective for suppressing VT in 2 patients, while additional BCSD of the lower half of the SG and T5 was effective in preventing VT storm in 1 patient. ［Conclusions］ A T2-4 or 5 BCSD with SG-sparing is a feasible, safe and effective treatment for suppressing refractory VT in HFrEF patients. In some patients, however, removal of the SG is required.

Background : Premature contractions, which sometimes appear with regularity such as bigeminy and trigeminy, is often encountered as an electrocardiographic finding in medical check-ups, but their actual condition and characteristics are not fully investigated. Subjective and Methods : Of the 12-lead ECGs of approximately 50,000 healthy adults in health checkups, 177 cases showing bigeminy, trigeminy, quadrigeminy or quintgeminy（54 supraventricular and 123 ventricular premature contractions ; 120 males, 57 females ; average age of 55.4 ±13.7 years）were identified, and the relationships between the nature, prematurity, and origin of ectopic excitation were examined. Results : 1）Bigeminy was most common in premature atrial contractions（PAC）, while trigeminy was more common in premature ventricular contractions（PVC）. 2）Regarding the nature of extrasystoles, most PAC were judged to be uncompensated, while all bigeminy and most trigeminy or quadrigeminy in PVC were compensatory except several cases of interpolated nature. 3）In terms of prematurity of PAC, coupling interval（CI）tended to show gradual shortening from bigeminy to quadrigeminy, but the prematurity index（PI）was almost constant. On the other hand, the CI of PVC was almost constant regardless of prolongation of PI. 4）Analyzing with QRS morphology of PVC, changes of CI were small, but PI were prolonged from bigeminy to quadrigeminy in any patterns of PVC. Discussion and Conclusions : Although various interesting features and differences were observed in the nature, prematurity, and ectopic foci that exhibit some regular pattern of appearance, it is difficult to determine the detailed mechanism and clinical significance of the systematic appearance of premature contractions from the results of this study alone. Further large-scale studies and basic electrophysiological approaches are needed.