A focal atrial tachycardia (FAT) with low inducibility can be challenging to treat with catheter ablation. A 17-year-old female had previously undergone an unsuccessful ablation due to low inducibility of the tachycardia. During the second session, an activation map with a few FAT was insufficient to identify the earliest activation site. However, by employing a novel pace mapping technique using dual chamber unipolar electrograms as a reference, we accurately identified the FAT origin and successfully performed the ablation. This technique may enable effective ablation with fewer radiofrequency applications in FAT where the earliest excitation site cannot be clearly identified.

Introduction: In the COVID-19 era, demand is growing for remote ECG monitoring systems with less or no in-person contact. However, the practical usage of wearable ECG devices has been little studied in Japan. This study aimed to report our initial experience of using the postal system in the delivery of the self-wearable ECG device (Duranta) and long-term ECG monitoring in outpatient care. Methods:　　 The Duranta is small, light (35 g), and easy to attach to the chest with two patch electrodes. Real-time ECG data were automatically transmitted to a cloud server via iPhones. The devices were packed in prepaid envelopes that could be put in any postbox for delivery between the hospital and patients’ homes. Results: Twenty-five patients (61 ± 17 years) were enrolled. The median distance to the hospital from the patients’ homes was 10 km (range: 1.1–183). The patients had no difficulties with either the postal delivery or wearing the ECG devices. A total of 57 hours (range: 20–179) of ECG monitoring per patient was performed, and the data were successfully transmitted to the hospital. The median percentage of noise/artifact burden during the ECG monitoring was 0.9%. Arrhythmic events were observed in 8 patients. Most patients were satisfied with the ECG system and delivery via the postal service. Conclusion: The use of a postal delivery of a wearable ECG device could work in clinical practice with to achieve less or no in-person contact. This system can be applicable for telehealth, home care, and arrhythmia screening.

Background: Some of atrial fibrillation (AF) drivers are found in lesser late-gadolinium enhancement (LGE) areas, as well as heterogenous ones. The atrial wall thickness (AWT) has been reported to be important as a possible AF substrate. However, the AWT and degree of LGEs as an AF substrate has not been fully validated in humans. Objective: The purpose of this study was to evaluate the impact of the AWT in lesser LGE areas on AF drivers. Methods: A total of 287 segments in 15 persistent AF patients were assessed. AF drivers were defined as non-passively activated areas (NPAs), where rotational activation was frequently observed, and were detected by the novel real-time phase mapping (ExTRa Mapping). Lesser LGE areas were defined as areas with a volume ratio of the enhancement voxel of <10%. The AWT was defined as the minimum distance from the manually determined endocardium to the epicardial border on the LGE-MRI. Results: NPAs were found in 20 (18.0%) of 131 lesser LGE areas where the AWT was significantly thicker than that in the passively activated areas (PAs) (2.46±0.26 vs. 2.20±0.25 mm, p<0.001). However, NPAs were found in 61 (21.3%) of 287 LGE areas where the AWT was similar to that of the PAs (2.24±0.24 vs. 2.22±0.25 mm, p=0.58). An ROC curve analysis yielded an optimal cutoff value of 2.24 mm for predicting the presence of an NPA in lesser LGE areas. Conclusion: The location of AF drivers in lesser LGE areas might be more accurately identified by evaluating the AWT.

Atrial tachycardia (AT) in the right atrium often occurs following open-heart surgery. Catheter ablation for these AT is challenging and can lead to unintended conduction block. We performed late-gadolinium enhancement magnetic resonance imaging prior to catheter ablation and predicted wavefront propagation during SR as well as the slow conduction zone

Atrial tachycardia (AT) in the right atrium often occurs following open-heart surgery. Catheter ablation for these AT is challenging and can lead to unintended conduction block. We performed late-gadolinium enhancement magnetic resonance imaging (LGE-MRI) prior to catheter ablation and predicted wavefront propagation during SR as well as the slow conduction zone during tachycardia. LGE-MRI may assist predicting the conduction disturbance and reducing the risk of unexpected sinus exit block.

Background: A computational model demonstrated that atrial fibrillation (AF) rotors could be distributed in patchy fibrotic tissue and play an important role in AF drivers. However, this was not validated in humans. Objective: The purpose of this study was to evaluate the fibrotic tissue properties of AF rotors in patients with persistent AF. Methods: A total of 287 segments in 15 patients with persistent AF (longstanding persistent AF in 9 patients) that underwent AF ablation were assessed. Non-passively activated areas (NPAs), where rotational activation (AF rotor) was frequently observed, were detected by the novel real-time phase mapping (ExTRa Mapping). Atrial fibrosis was detected by late-gadolinium enhancement magnetic resonance imaging (LGE-MRI), and the fibrotic heterogeneity and density were assessed by the entropy (LGE-entropy) and volume ratio of the enhancement voxel (LGE-volume ratio), respectively. Results: NPAs were found in 61 (21%) of 287 segments and were mostly found around the pulmonary vein antrum. A receiver operating characteristic curve analysis yielded an optimal cutoff value of 5.7 and 10% for the LGE-entropy and LGE-volume ratio, respectively. The incidence of NPAs was significantly higher at segments with an LGE-entropy of >5.7 and LGE-volume ratio of >10% than at the other segments (38 [30%] of 126 vs. 23 [14%] of 161 segments, p = 0.001). No NPAs were found at segments with an LGE-volume ratio of >50% regardless of the LGE-entropy. Conclusion: AF rotors are mostly distributed in relatively weak and much more heterogenous fibrotic tissue.

Background: Computer simulation model demonstrated that atrial fibrillation (AF) driver attached to the patchy fibrosis assessed by late gadolinium enhancement magnetic resonance imaging (LGE-MRI). However, it has not been well elucidated in patients with persistent AF. The aim of this study is to investigate whether radiofrequency (RF) application on the patchy LGE site (PLS) could terminate AF or convert to atrial tachycardia (AT) and improve the rhythm outcome. Methods: A total of 31consecutive persistent AF patients with PLS were enrolled (PLS ablation group, mean age: 69 ± 8 years, mean left atrial diameter: 42 ± 6 mm). AF direct termination or AT conversion during RF application on the PLS were defined as favorable response. The rhythm outcome was compared between the PLS ablation group and the propensity matched conventional ablation group. Results: Favorable response was found in 15 (48%) of 31 patients (AF termination in 7, AT conversion in 8 patients). AF recurrence at 12 months follow-up was significantly less in the PLS group as compared to the control group (4 (13%) of 31 patients vs. 11 (35%) of 31 patients, log-rank p = 0.019). In patients with favorable response, AT recurred in 1 (7%) of 15 patients but AF. Conclusions: The PLS ablation could terminate AF or convert to AT in half of the patients and improve the rhythm outcome as compared to the conventional ablation. No AF recurrence was documented in patients with a favorable response.