Delineation of conduction gaps of linear lesions during atrial fibrillation ablation using ultra-high-density mapping.

AIMS: Linear lesions are routinely created by radiofrequency catheter ablation. Unwanted electrical conduction gaps can be produced and are often difficult to ablate. This study aimed to clarify the characteristics of conduction gaps during atrial fibrillation ablation by analysing bidirectional activation maps using a high-density mapping system (RHYTHMIA). METHODS AND RESULTS: This retrospective study included 31 patients who had conduction gaps along pulmonary vein (PV) isolation or box ablation lesions. Activation maps were sequentially created during pacing from the coronary sinus and PV to reveal the earliest activation site, defined by the entrance and exit. The locations, length between the entrance and exit (gap length), and direction were analysed. Thirty-four bidirectional activation maps were drawn: 21 were box isolation lesions (box group), and 13 were PV isolation lesions (PVI group). Among the box group, nine conduction gaps were present in the roof region and 12 in the bottom region, while nine in right PV and four in left PV among the PVI group. Gap lengths in the roof region were longer than those in the bottom region (26.8 ± 11.8 vs. 14.5 ± 9.8 mm; P = 0.022), while those in right PV tended to longer than those in left PV (28.0 ± 15.3 vs. 16.8 ± 8.0 mm, P = 0.201). CONCLUSION: The entrances and exits of electrical conduction gaps were separated, especially in the roof region, indicating that epicardial conduction might contribute to gap formation. Identifying the bidirectional conduction gap might indicate the location and direction of epicardial conduction.

Visualization of the electrophysiologically defined junction between the superior vena cava and right atrium.

INTRODUCTION: An electrical superior vena cava (SVC) isolation from the right atrium (RA) sometimes can be challenging. For a safe and efficient SVC isolation, we aimed to visualize the accurate position of the SVC-RA junction on a three-dimensional (3D) mapping system using the decremental conduction properties of the SVC-RA junction in patients with atrial fibrillation (AF). METHODS: This study consisted of 15 consecutive AF patients (11 males, age 59 ± 10 years). A 3D mapping catheter was positioned in the SVC-RA junction region while delivering a single extra-stimulus from the right atrial appendage (RAA), to discriminate the RA and SVC potentials. The electrophysiological SVC-RA junction was defined as the most proximal points where the SVC potentials were recorded, which were tagged on the 3D mapping system around the SVC-RA junction, where radiofrequency energy applications were applied. RESULTS: Around the SVC-RA junction, 9 ± 2 points were tagged on the 3D mapping system. The highest and lowest SVC-RA junction points were located on the anterior wall and posterior wall, respectively. The difference in the level between the highest and lowest SVC-RA junction points was 16.2 ± 6.3 mm. A successful SVC isolation was obtained in all patients without any complications. CONCLUSION: The plane of the electrophysiologically defined SVC-RA junction was not perpendicular to the body axis, but slanted due to the anterior side being higher. Recognizing the precise location of the SVC-RA junction would contribute to a safe and efficacious SVC isolation.

Anatomical changes in the pulmonary veins and left atrium after cryoballoon ablation.

BACKGROUND: The anatomical changes in pulmonary veins (PVs) after cryoballoon ablation (CBA) are unclear. We aimed to determine the morphological changes in the PVs and left atrium (LA) along with the predictive factors for clinical PV stenosis. METHODS: We analyzed data of 320 PVs from 80 patients who underwent CBA for atrial fibrillation (age: 62 ± 10 years, 59 males). All patients underwent pre- and post-procedural cardiac computed tomography. We defined clinical PV stenosis when the cross-sectional area decreased by more than 50%. RESULTS: The average ostial PV area and LA volume decreased significantly after CBA (pre- vs post-CBA; 2.4 ± 1.0 cm2 vs 2.3±1.1 cm2 , P < .001, 75.0 ± 23.2 cm3 vs 70.7 ± 21.9 cm3 , P < .001, respectively). There was a significant correlation between the reduction rates of the PV area and those of LA volume (R = 0.411, P < .001). The larger preoperative PV area and greater reduction in LA volume were associated with advanced PV narrowing. Clinical PV stenosis was observed in six PVs, was more common in females (male vs female; 0.8% vs 4.8%, P = .043), and tended to be more frequent in left PVs (left PVs vs right PVs; 3.1% vs 0.6%: P = .107), irrespective of the LA volume reduction. CONCLUSIONS: The significant reduction of the ostial PV area occurred after CBA, which correlated with the reduction rate of LA volume. The narrowing of the PV was partly produced by the LA volume reduction. Clinical PV stenosis was more common in females and tended to be more frequent in left PVs.

Characteristics and health-status outcomes in patients with atrial fibrillation detected via health screening.

BACKGROUND: Early detection of atrial fibrillation (AF) is important. Japan has a universal screening system, and regular health screening (HS) is available to support AF detection without a hospital visit. However, health-related outcomes and other characteristics of HS-detected and conventionally diagnosed AF remain unknown. HYPOTHESIS: That the characteristics and health-related outcomes of patients with HS-detected AF may differ from those of patients whose AF was detected by other procedures. METHODS: In total, 3318 consecutive newly referred AF cases were enrolled; demographic characteristics and health-related and clinical outcomes were compared between two groups created based on the mode of AF detection (the HS and non-HS groups). Health-related outcomes were assessed using the AF Effect on QualiTy-of-life (AFEQT) questionnaire at baseline and after 1 year of follow-up. RESULTS: AF was detected by HS in 25.0% of patients; these patients had lower CHADS2 scores (1.01 vs. 1.50, p < .001), higher prevalence of persistent AF (odds ratio, 95% confidence interval; 2.21, 1.88-2.60) and asymptomatic presentation (3.19, 2.71-3.76), and better baseline QoL scores (83.6 vs. 75.0; p < .001). Catheter ablation was more frequently performed in the HS group at follow-up (44.4% vs. 34.1%; p < .001). At 1-year follow-up, the AFEQT scores of the HS group were significantly better in most subdomains. CONCLUSIONS: In the Japanese registry, AF was detected via HS in 25% of patients referred to specialty centers for management. Notably, the overall health status of patients with HS-detected AF improved after medical interventions, including catheter ablations.

Prognostic Implications and Efficacy of Catheter Ablation by Atrial Fibrillation Type.

Background Catheter ablation (CA) for atrial fibrillation (AF) is preferred for paroxysmal AF (PAF) but selectively performed in patients with persistent AF (PersAF). This study aimed to investigate the prognostic differences and consequences of CA based on the AF type. Methods and Results Data from a multicenter AF cohort study were analyzed, categorizing patients as PAF or PersAF according to AF duration (≤7 or >7 days, respectively). A composite of all-cause death, heart failure hospitalization, stroke, and bleeding events during 2-year follow-up and changes in the Atrial Fibrillation Effect on Quality-of-life score were compared. Additionally, propensity score matching was performed to compare clinical outcomes of patients with and without CA in both AF types. Among 2788 patients, 51.6% and 48.4% had PAF and PersAF, respectively. Patients with PersAF had a higher incidence of the composite outcome (12.8% versus 7.2%; P<0.001) and smaller improvements in Atrial Fibrillation Effect on Quality-of-life scores than those with PAF. After adjusting for baseline characteristics, PersAF was an independent predictor of adverse outcomes (adjusted hazard ratio, 1.35 [95% CI, 1.30-1.78], P=0.031) and was associated with poor improvements in Atrial Fibrillation Effect on Quality-of-life scores. Propensity score matching analysis showed that the CA group had significantly fewer adverse events than the medication group among patients with PAF (odds ratio, 0.31 [95% CI, 0.18-0.68]; P=0.002). Patients with PersAF showed a similar but nonsignificant trend. Conclusions PersAF is a risk factor for worse clinical outcomes, including patients' health status. CA is associated with fewer adverse events, although careful consideration is required based on the AF type.

Catheter ablation improves outcomes and quality of life in Japanese patients with early-stage atrial fibrillation: A retrospective cohort study.

BACKGROUND: Catheter ablation is widely used as first-line therapy for patients with impaired quality of life; however, whether catheter ablation improves survival and other outcomes in atrial fibrillation (AF) cases remains unclear. OBJECTIVE: The purpose of this study was to evaluate whether catheter ablation reduces adverse clinical outcomes and improves patients' quality of life using data from a contemporary Japanese multicenter registry of patients with early-stage AF. METHODS: The Keio Interhospital Cardiovascular Studies-Atrial Fibrillation registered 3318 patients with AF newly diagnosed at or referred to participating hospitals between 2014 and 2018. Propensity score matching based on 47 demographic variables was performed. We extracted 823 pairs who underwent catheter ablation or medical therapy alone. The primary outcome was the composite of all-cause death, stroke, bleeding events, and heart failure hospitalization during a 2-year follow-up period. Additionally, the Atrial Fibrillation Effect on QualiΤy-of-Life scores at baseline and 1-year follow-up were evaluated. RESULTS: Within the matched cohort, the median time since AF diagnosis was 0.3 years (interquartile range [IQR] 0.1‒2.3 years), age was 67.0 years (IQR 59.0‒73.0 years), and the CHA2DS2-VASc score was 2.0 (IQR 1.0‒2.0). During a median follow-up period of 730 days (IQR 366‒731 days), patients who underwent catheter ablation had a lower risk of primary outcomes (hazard ratio 0.49; 95% confidence interval 0.30‒0.79; P = .004), with a significantly lower risk of heart failure hospitalization (hazard ratio 0.33; 95% confidence interval 0.14-0.77; P = .010) and improved Atrial Fibrillation Effect on QualiΤy-of-Life scores, than did those who received medical therapy. CONCLUSION: In patients with propensity score-matched, early-stage, real-world AF, catheter ablation was associated with a lower risk of adverse clinical events and improved quality of life as compared with medical therapy.

Change in the local impedance and electrograms recorded by a micro-electrode tip catheter during initial atrial fibrillation ablation.

BACKGROUND: A novel measurement of the local impedance (LI) and electrograms recorded from micro-electrodes on catheter tip has been developed. However, the data during pulmonary vein (PV) ablation is not sufficient. We aimed to investigate the utility of this measurement during initial atrial fibrillation (AF) ablation. METHODS: We investigated 111 representative radiofrequency applications in 7 AF patients without a history of prior ablation (6 males, age 68 [65-72] years, 2 persistent AF). The ablation strategy was PV isolation for paroxysmal AF and single ring box isolation for persistent AF, using MiFi catheter. The correlation of the generator impedance (GI) drop and LI drop after radiofrequency applications and the predictive value of the initial LI elevation before radiofrequency applications for LI drop were analyzed. Also, the LI and GI drop were investigated according to the location of RF applications. RESULTS: The LI drop was higher than GI drop (23.7 [16.4-35.7] and 9.0 [6.0-12.0]; P < .01). There were correlations between the initial LI elevation and LI drop (R 2 = 0.466, P < .01) and between the LI and GI drop (R 2 = 0.263, P < .01). The LI drops significantly differed according to the different anatomical localizations by the Kruskal-Wallis test, although the GI drops did not differ (P < .01 and P = .49, respectively). CONCLUSION: LI drop was associated with initial LI elevation and was larger than GI drop. LI drop was different according to locations, although GI drop was not. These findings might indicate that LI drop would be a more sensitive marker for lesion formation than GI drop.

Symptom Under-Recognition of Atrial Fibrillation Patients in Consideration for Catheter Ablation: A Report From the KiCS-AF Registry.

OBJECTIVES: This study sought to investigate whether symptom under-recognition is associated with the application of catheter ablation. BACKGROUND: Atrial fibrillation (AF) symptom burden is frequently under-recognized and may affect the choice of treatment strategies. METHODS: A total of 3,276 patients with AF consecutively registered in a Japanese multicenter database from 2012 to 2017 were analyzed. All patients underwent AF symptom burden assessment via the symptom and daily activities domain within the Atrial Fibrillation Effect on QualiTy-of-life (AFEQT) questionnaire. For the present analysis, 1,173 symptomatic patients (AFEQT score ≤80) with a clinical indication for catheter ablation were included. Under-recognition of symptom burden was defined as no subjective complaints checked by physicians despite self-reported AFEQT scores ≤80. Logistic regression analysis identified the predictors associated with receiving catheter ablation. RESULTS: Of the 1,173 patients (age: 68 ± 12 years, men: 61%) analyzed, 459 underwent catheter ablation (ablation group); they had lower overall AFEQT scores (p < 0.01 for all domains) compared with the nonablation group. At the 1-year follow-up, greater improvement in the AFEQT scores was noted in the ablation group, even after adjusting for clinically relevant factors (+20.0 ± 1.2, +14.2 ± 0.9, respectively; p < 0.001). Notably, 306 (28%) patients met the criteria for symptom under-recognition, which was associated with the nonuse of catheter ablation during follow-up (odds ratio: 0.41; 95% confidence interval: 0.28 to 0.60; p < 0.001). CONCLUSIONS: Under-recognition of AF symptom burden was frequently noted and was associated with less use of catheter ablation. Standardized recognition of symptoms using the application of validated questionnaires may facilitate outcome improvement.

Burden of Mild (<13 g/dl) Anemia in Patients With Atrial Fibrillation (A Report from a Multicenter Registry With Patient-Reported Outcomes).

The prognostic impact of anemia, especially mild anemia, in atrial fibrillation (AF) remains unclear. We examined clinical burdens of mild anemia on the quality of life (QoL) and clinical outcomes of 1,677 AF patients. Patients were divided into a non-anemia (hemoglobin [Hb] ≥13 g/dl for men and Hb ≥12 g/dl for women) and a mild anemia group (10≤ Hb <13 g/dl for men and 10≤ Hb <12 g/dl for women). At baseline, 22.5% of patients (n = 378) had anemia; patients in the mild anemia group had higher CHA2DS2-VASc scores (3.7 vs 2.7; p <0.01) and brain natriuretic peptide levels (253.5 vs 159.6 pg/ml; p <0.01) and were more likely to develop chronic kidney disease (64.2 vs 42.9%; p <0.01) than those in the non-anemia group. During follow-up (mean 1.7 ± 0.4 years), patients with mild anemia had a higher risk of heart failure hospitalization and major bleeding events than those without (12.2 vs 3.8%; p <0.01 and 5.6 vs 2.5%; p <0.01, respectively). Mild anemia was an independent risk factor for heart failure hospitalization (adjusted hazard ratio: 1.67, 95% confidence interval 1.06 to 2.62, p = 0.03) but not for major bleeding (adjusted hazard ratio: 1.44, 95% confidence interval 0.80 to 2.62, p = 0.23). QoL improvement was less likely in the mild anemia group during follow-up, despite the lack of significant differences at baseline. In conclusion, the presence of even mild anemia was associated with increased risks of heart failure hospitalization and poor QoL improvement.

Mexiletine shortens the QT interval in a pedigree of KCNH2 related long QT syndrome.

A 23-year-old female had been suffering from recurrent syncopal episodes during sleep since her childhood. She had a family history of sudden death and her QTc interval was remarkably prolonged to 537 ms A Holter ECG revealed torsade de pointes, corresponding to syncope. She was started on mexiletine and her QTc interval shortened. Her symptoms were controlled after ß-blockers and Ca-blockers were added. A genetic analysis with a next generation sequencer identified a frameshift mutation at the C terminus of the KCNH2 gene. Here we present a type 2 long QT syndrome case in which mexiletine was effective.