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Aims This study aimed to identify factors for attention leading to future pacing device implantation (PDI) and reveal the necessity of prophylactic PDI or implantable cardioverter-defibrillator (ICD) implantation in transthyretin amyloid cardiomyopathy (ATTR-CM) patients. Methods and results This retrospective single-center observational study included consecutive 114 wild-type ATTR-CM (ATTRwt-CM) and 50 hereditary ATTR-CM (ATTRv-CM) patients, neither implanted with a pacing device nor fulfilling indications for PDI at diagnosis. As a study outcome, patient backgrounds were compared with and without future PDI, and the incidence of PDI in each conduction disturbance was examined. Furthermore, appropriate ICD therapies were investigated in all 19 patients with ICD implantation. PR-interval ≥220 msec, interventricular septum (IVS) thickness ≥16.9 mm, and bifascicular block were significantly associated with future PDI in ATTRwt-CM patients, and brain natriuretic peptide ≥35.7 pg/mL, IVS thickness ≥11.3 mm, and bifascicular block in ATTRv-CM patients. The incidence of subsequent PDI in patients with bifascicular block at diagnosis was significantly higher than that of normal atrioventricular (AV) conduction in both ATTRwt-CM [hazard ratio (HR): 13.70, P = 0.019] and ATTRv-CM (HR: 12.94, P = 0.002), whereas that of patients with first-degree AV block was neither (ATTRwt-CM: HR: 2.14, P = 0.511, ATTRv-CM: HR: 1.57, P = 0.701). Regarding ICD, only 2 of 16 ATTRwt-CM and 1 of 3 ATTRv-CM patients received appropriate anti-tachycardia pacing or shock therapy, under the number of intervals to detect for ventricular tachycardia of 16–32. Conclusions According to our retrospective single-center observational study, prophylactic PDI did not require first-degree AV block in both ATTRwt-CM and ATTRv-CM patients, and prophylactic ICD implantation was also controversial in both ATTR-CM. Larger prospective, multi-center studies are necessary to confirm these results.

Mitochondrial cardiomyopathy can be described as a condition characterized by abnormal heart-muscle structure and/or function, secondary to mutations in nuclear or mitochondrial DNA. Its severity can range from subclinical to critical conditions. We presented three cases of mitochondrial cardiomyopathy with m.3243A > G mutation and compared the clinical manifestations with the histological findings for each of these cases. All cases showed cardiac hypertrophy, juvenile-onset diabetes mellitus, and hearing loss. Case 1 (43-year-old male) showed less cardiac involvement and shorter duration of mitochondrial disease-related symptoms than case 2 (67-year-old female) and case 3 (51-year-old male), who showed the most advanced cardiac condition and longest duration from the manifestation of heart failure. The histological findings revealed that cardiomyocytes from case 1 showed no hypertrophy and mitochondrial degeneration in electron microscopy. Alternatively, cases 2 and 3 showed hypertrophy in their cardiomyocytes, and mitochondrial degeneration (e.g. onion-like lesions, swollen cristae, and lamellar bodies) was most apparent in case 3. These results suggested that mitochondrial degeneration, as evaluated by electron microscopy, might be correlated with impaired heart function in patients with mitochondrial cardiomyopathy.

Background The impact of intra-atrial conduction delay on the recurrence of atrial tachyarrhythmia after radio frequency catheter ablation (RFCA) has not been fully elucidated. Methods We retrospectively analyzed 155 AF patients who were sinus rhythm at the start of RFCA. The conduction time from the onset of the earliest atrial electrogram at the high right atrium (HRA) to the end of the latest electrogram at the coronary sinus (CS) during sinus rhythm was defined as HRA-CS conduction time. Pulmonary vein isolation (PVI) was performed followed by linear roof lesion and complex fractionated atrial electrogram (CFAE) ablation until AF termination. We evaluated atrial tachyarrhythmia recurrence 12 months after RFCA. Results The follow-up data were available for 148 patients. The recurrence of atrial tachyarrhythmia was noted in 28 (18.9%) patients. Atrial tachyarrhythmia recurrence patients had longer HRA-CS conduction times (151.3 ± 22.1 ms vs 160.1 ± 32.6 ms, p = .017). The patients were divided into the long or short HRA-CS conduction time group. The Kaplan–Meier analysis revealed that the long HRA-CS conduction time group held a higher risk of atrial tachyarrhythmia recurrence (log-rank test, p = .019). The multivariable Cox hazard analysis revealed that a long HRA-CS conduction time was a significant risk factor for the recurrence of atrial tachyarrhythmia, despite a long AF duration, persistent AF, and larger left atrial diameter (LAD) were not statistically significant. Conclusions The HRA-CS conduction time was the primary influencing factor that predicted the recurrence of atrial tachyarrhythmia after catheter ablation.

Mitochondrial cardiomyopathy can be described as a condition characterized by abnormal heart-muscle structure and/or function, secondary to mutations in nuclear or mitochondrial DNA. Its severity can range from subclinical to critical conditions. We presented three cases of mitochondrial cardiomyopathy with m.3243A G mutation and compared the clinical manifestations with the histological findings for each of these cases. All cases showed cardiac hypertrophy, juvenile-onset diabetes mellitus, and hearing loss. Case 1 (43-year-old male) showed less cardiac involvement and shorter duration of mitochondrial disease-related symptoms than case 2 (67-year-old female) and case 3 (51-year-old male), who showed the most advanced cardiac condition and longest duration from the manifestation of heart failure. The histological findings revealed that cardiomyocytes from case 1 showed no hypertrophy and mitochondrial degeneration in electron microscopy. Alternatively, cases 2 and 3 showed hypertrophy in their cardiomyocytes, and mitochondrial degeneration (e.g. onion-like lesions, swollen cristae, and lamellar bodies) was most apparent in case 3. These results suggested that mitochondrial degeneration, as evaluated by electron microscopy, might be correlated with impaired heart function in patients with mitochondrial cardiomyopathy.

It remains unclear whether AF is maintained by rotor. We evaluated the significance of rotor during atrial fibrillation (AF). Prevalence, location, and stability of rotational reentry (RR) in the left atrium were clarified by endocardial non-contact mapping in 66 AF patients. RR was classified into three categories: RR continued at stable site (Stable-RR), RR observed intermittently at the same site (Intermittent-RR), and RR observed at different locations (Different-RR). Catheter ablation was performed in a stepwise fashion (linear roof lesion and complex fractionated atrial electrogram ablation following pulmonary vein isolation) until AF termination and elucidated the consequence of radiofrequency lesion delivered within RR site on AF termination and recurrence. One hundred and nineteen RRs were observed. There were 54 patients with RR (RR Group) and 22 patients without RR (Non-RR Group). Prevalence of Different-RR (n = 81) was significantly higher than Stable-RR (n = 16, p

Esophageal injury (EI) is a serious complication that occurs after catheter ablation of atrial fibrillation (AF), however predictable factor of EI is unclear.Among 308 patients who underwent AF ablation, upper gastrointestinal tract endoscopy was performed the next day after ablation to examine for EI. To define the primary factor that predicts EI, patients' characteristics, number and amount of radiofrequency energy applied to the posterior wall, ablation procedure, and the shortest distance between esophagus and posterior left atrium measured on contrast computed tomography (SD-CT) were analyzed.EI was found in 27 patients (8.8%). There were no significant differences in the patient characteristics, number and amount of radiofrequency energy applied to posterior wall or ablation procedure between patients with (Injury Group) and without EI (Non-Injury Group). However, SD-CT in the Injury Group was significantly shorter than that in Non-Injury Group (2.3±0.6mm vs 4.1±0.9mm, p0.001). The area under a receiver operating characteristic curve using SD-CT as a predictive marker in EI patients was 0.988 (p0.001). When the cut-off value of SD-CT was set at 2.9mm, the sensitivity and specificity for EI diagnosis were 92.3% and 96.8%, and the positive predictive value and negative predictive value were 0.75 and 0.99, respectively.EI observed after catheter ablation of AF was closely associated with the SD-CT. Patients with SD-CT below 2.9mm have a potential risk of EI and thus must be strictly followed.

Background It has been demonstrated that the short distance between the esophagus and the posterior left atrium (LA) is closely associated with the occurrence of esophageal injury (EI) after catheter ablation of atrial fibrillation (AF). Meanwhile, it has not been fully elucidated whether esophageal temperature monitoring sufficiently prevent EI. Objectives The purpose of this study was to examine the usefulness of esophageal temperature monitoring for avoiding EI. Further we analyzed the relation between the incidence of EI and the distance between the esophagus and the posterior LA measured on the contrast computed tomography (CT). Methods Among 403 patients who underwent catheter ablation of AF, upper gastrointestinal tract endoscopy was performed the next day after ablation to examine for EI. The incidence of EI was compared between 95 patients who used esophageal temperature probe (ETP) (ETP Group) and 308 patients who did not used ETP (Non-ETP Group) during ablation. The shortest distance between esophagus and posterior LA measured on contrast CT (SD-CT) was also compared between the ETP and Non-ETP Groups. Results In all patients, EI was found in 35 patients (8.6%). The SD-CT in patients with EI was significantly lower than that in patients without EI (2.3±0.6 vs 4.1±0.8 mm, p No differences were observed between the two groups in terms of age, body mass index, LA diameter, esophageal course, total number of radiofrequency (RF) energy applications, total amount of RF energy applications, or the location of SD-CT. Also, EI occurred at nealy the same frequency between the ETP Group and Non-ETP Group (8/95 patients; 8.4% vs 27/308 patients; 8.8%, p=0.553). The severity diagnosed as moderate (erosion) in 3 patients and mild (erythema) in 5 patients of ETP Group, and as severe (ulcer) in 23 patients and mild (erythema) in 4 patients of Non-ETP Group. There was no significant difference in the SD-CT between the ETP Group and Non-ETP Group (3.96±0.98 vs 4.19±1.01 mm, p=0.54). However, the SD-CT in patients with EI was significantly shorter than the SD-CT in patients without EI, both in the ETP Group (2.3±0.6 vs 4.1±0.9 mm, p Conclusions The incidence of EI was significantly correlated with SD-CT. Esophageal temperature monitoring did not reduce EI, however, the use of monitoring alleviated the severity of EI, especially in patients with short SD-CT. Acknowledgement/Funding None

It has been shown that most paroxysmal atrial fibrillation (AF) can be terminated by pulmonary vein (PV) isolation alone, suggesting that rapid discharges from PV drive AF. To define the driving mechanism of AF, we compared the activation sequence in the body of left atrium (LA) to that within PV.Endocardial noncontact mapping of LA body (LA group; n = 16) and selective endocardial mapping of left superior PV (LSPV) (PV group; n = 13) were performed in 29 paroxysmal AF patients. The frequency of pivoting activation, wave breakup, and wave fusion observed in LA were compared to those in LSPV to define the driving mechanism of AF. Circumferential ablation lesion around left PV was performed after right PV isolation to examine the effect of linear lesion around PV on AF termination both in LA and PV groups.The frequency of pivoting activation, wave breakup, and wave fusion in PV group were significantly higher than those in LA group (36.5 ± 17.7 vs 5.0 ± 2.2 times/seconds, p 0.001, 10.1 ± 4.3 vs 5.0 ± 2.2 times/seconds, p = 0.004, 18.1 ± 5.7 vs 11.0 ± 5.2, p = 0.002). Especially in the PV group, the frequency of pivoting activation was significantly higher than that of wave breakup and wave fusion (36.5 ± 17.7 vs 10.1 ± 4.3 times/seconds, p 0.001, 36.5 ± 17.7 vs 18.1 ± 5.7 times/seconds, p 0.001). These disorganized activations in LSPV were eliminated by the circumferential ablation lesion around left PV (pivoting activation; 36.5 ± 17.7 vs 9.3 ± 2.3 times/seconds, p 0.001, wave breakup; 10.1±1.3 times/seconds, p = 0.003, wave fusion; 18.1 ± 5.7 vs 5.7 ± 1.8, p 0.001), resulted in AF termination in all patients in both LA and PV groups.Activation sequence within PV was more disorganized than that in LA body. Frequent episodes of pivoting activation rather than wave breakup and fusion observed within PV acted as the driving sources of paroxysmal AF.

A 63-year-old woman with atrial fibrillation visited our hospital due to decompensated heart failure. Because atrial fibrillation was considered a remarkable precipitating factor for heart failure, cardioversion was performed. After cardioversion, refractory hypotension and cardiopulmonary arrest occurred. An arterial blood gas analysis showed marked lactic acidosis. Chronic kidney disease, heart failure, sedatives, and hypoventilation might have contributed to refractory hypotension due to severe acidosis in this case.