Clinical outcomes of catheter ablation for atrial fibrillation, atrial flutter, and atrial tachycardia in wild-type transthyretin amyloid cardiomyopathy: a proposed treatment strategy for catheter ablation in each arrhythmia.

AIMS: Wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM) is often accompanied by atrial fibrillation (AF), atrial flutter (AFL), and atrial tachycardia (AT), which are difficult to control because beta-blockers and antiarrhythmic drugs can worsen heart failure (HF). This study aimed to investigate the outcomes of catheter ablation (CA) for AF/AFL/AT in patients with ATTRwt-CM and propose a treatment strategy for CA. METHODS AND RESULTS: A cohort study was conducted on 233 patients diagnosed with ATTRwt-CM, including 54 who underwent CA for AF/AFL/AT. The background of each arrhythmia and the details of the CA and its outcomes were investigated. The recurrence-free rate of AF/AFL/AT overall in ATTRwt-CM patients with multiple CA was 70.1% at 1-year, 57.6% at 2-year, and 44.0% at 5-year follow-up, but CA significantly reduced all-cause mortality [hazard ratio (HR): 0.342, 95% confidence interval (CI): 0.133-0.876, P = 0.025], cardiovascular mortality (HR: 0.378, 95% CI: 0.146-0.981, P = 0.045), and HF hospitalization (HR: 0.488, 95% CI: 0.269-0.889, P = 0.019) compared with those without CA. There was no recurrence of the cavotricuspid isthmus (CTI)-dependent AFL, non-CTI-dependent simple AFL terminated by one linear ablation, and focal AT originating from the atrioventricular (AV) annulus or crista terminalis eventually. Twelve of 13 patients with paroxysmal AF and 27 of 29 patients with persistent AF did not have recurrence as AF. However, all three patients with non-CTI-dependent complex AFL not terminated by a single linear ablation and 10 of 13 cases with focal AT or multiple focal ATs originating beyond the AV annulus or crista terminalis recurred even after multiple CA. CONCLUSION: The outcomes of CA for ATTRwt-CM were acceptable, except for multiple focal AT and complex AFL. Catheter ablation may be aggressively considered as a treatment strategy with the expectation of improving mortality and hospitalization for HF.

Clinical, electrocardiographic, and echocardiographic parameters associated with the development of pacing and implantable cardioverter-defibrillator indication in patients with transthyretin amyloid cardiomyopathy.

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.

Comparison of electron microscopic findings and clinical presentation in three patients with mitochondrial cardiomyopathy caused by the mitochondrial DNA mutation m.3243A > G.

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.

Analysis of the preferable site and stability of rotational reentry: its role for the maintenance of atrial fibrillation.

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 < 0.001) and Intermittent-RR (n = 22, p < 0.001). The intervals involved in RR occupied only 22.4% of total activation time. There was no significant difference in the prevalence of AF termination nor AF/atrial tachycardia recurrence between RR and non-RR Groups (46 vs. 9 patients, p = 0.317, and 13 vs. 1 patients, p = 0.271) and between patients in whom radiofrequency lesion was involved in RR and those was not (24 vs. 22 patients, p = 0.210, and 6 vs. 7 patients, p = 0.506). In conclusion, most RRs were observed transiently and often shifted its locations. Radiofrequency lesion delivered within RR site did not correlate with AF termination nor recurrence, suggesting that RR is not a driving source during AF.

Improvement of Vascular Endothelial Function Reflects Nonrecurrence After Catheter Ablation for Atrial Fibrillation.

Background The clinical implication of vascular endothelial dysfunction in patients with atrial fibrillation (AF) remains unclear. This study aimed to elucidate the correlation between changes in vascular endothelial function assessed by reactive hyperemia-peripheral arterial tonometry and the effect of sinus rhythm restoration after catheter ablation (CA) for AF. Methods and Results Consecutive 214 patients who underwent CA for AF were included in this single center, retrospective study. The natural logarithmic transformed reactive hyperemia-peripheral arterial tonometry index (LnRHI) of all patients was measured before CA as well as 3 and 6 months after CA. LnRHI in sinus rhythm was significantly higher than that in AF before CA. Multivariate logistic regression analysis revealed that the presence of AF was an independent risk factor for lowering of LnRHI (odds ratio, 4.092; P=0.002) before CA. The LnRHI was significantly improved 3 and 6 months after CA in patients without AF recurrence. Multivariate Cox hazard analysis revealed that changes in LnRHI from before to 3 months after CA independently correlated with recurrence of AF (hazard ratio, 0.106; P=0.001). Receiver operating characteristic analysis showed the decrease in LnRHI levels from before to 3 months after CA as a significant marker that suspects AF recurrence (area under the curve, 0.792; log-rank test, P<0.001). Conclusions The presence of AF was independently correlated with the impaired vascular endothelial function assessed by the reactive hyperemia-peripheral arterial tonometry. Long-term sinus rhythm restoration after CA for AF might contribute to the improvement of vascular endothelial function, which may reflect the nonrecurrence of AF.

Analysis of the driving mechanism in paroxysmal atrial fibrillation: comparison of the activation sequence between the left atrial body and pulmonary vein.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Elongation of the high right atrium to coronary sinus conduction time predicts the recurrence of atrial fibrillation after radiofrequency catheter ablation.

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.

Slow Potential at the Entrance of the Slow Conduction Zone in the Reentry Circuit of a Verapamil-Sensitive Atrial Tachycardia Originating From the Atrioventricular Annulus.

BACKGROUND: Slow conduction zone in a verapamil-sensitive reentrant atrial tachycardia originating from atrioventricular annulus is composed of calcium channel-dependent tissue. We examined whether there was a slow potential (SP) at the entrance of the slow conduction zone. METHODS AND RESULTS: We first identified the pacing site from where manifest entrainment and orthodromic capture of the earliest atrial activation site were demonstrated in 40 atrioventricular annulus patients with atrioventricular annulus. Radiofrequency energy was then delivered 2 cm proximal to the earliest atrial activation site in the direction of entrainment pacing site and gradually advanced toward the earliest atrial activation site until atrial tachycardia termination to localize the entrance of the slow conduction zone. Electrogram characteristics were analyzed at successful and unsuccessful ablation sites. During sinus rhythm, SP was observed at all 40 successful sites, but was observed at only 12 unsuccessful sites (P<0.0001). During sinus rhythm, there was no significant difference in electrogram amplitude nor width of atrial electrogram between successful and unsuccessful sites (0.407±0.281 versus 0.487±0.447 mV [P=0.1989] and 37.0±9.2 versus 38.9±8.0 ms [P=0.1773]); however, SP amplitude and width at successful sites were significantly greater than those at unsuccessful sites (0.110±0.049 versus 0.025±0.046 mV [P<0.0001] and 38.8±13.4 versus 8.1±13.2 ms [P<0.0001]). During atrial tachycardia, SP amplitude was significantly attenuated (0.088±0.042 versus 0.110±0.049 mV, P<0.001) and SP width was significantly prolonged (47.8±14.1 versus 38.8±13.4 ms, P<0.0001) at successful sites. CONCLUSIONS: SP was observed during sinus rhythm at the entrance of the slow conduction zone; however, SP amplitude was attenuated and SP width was prolonged during atrial tachycardia, suggesting that SP reflects the characteristics of calcium channel-dependent tissue involved in atrioventricular annulus reentry circuit.

Analysis for the primary predictive factor for the incidence of esophageal injury after ablation of atrial fibrillation.

BACKGROUND: Esophageal injury (EI) is a serious complication that occurs after catheter ablation of atrial fibrillation (AF), however predictable factor of EI is unclear. METHODS: 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. RESULTS: 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, p<0.001). The area under a receiver operating characteristic curve using SD-CT as a predictive marker in EI patients was 0.988 (p<0.001). 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. CONCLUSIONS: 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.

Refractory Hypotension after Cardioversion in a Patient with Atrial Fibrillation and Congestive Heart Failure.

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.