Pulsed field ablation in patients with complex consecutive atrial tachycardia in conjunction with ultra-high density mapping: Proof of concept.

INTRODUCTION: Catheter-ablation (CA) of consecutive left atrial tachycardias (LAT) can be challenging. Pulsed field ablation (PFA) yields a novel nonthermal CA technology for treatment of atrial fibrillation (AF). There is no data regarding PFA of LAT. This study sought to investigate PFA of consecutive LAT following prior CA of AF. METHODS: Consecutive patients with LAT underwent ultrahigh-density (UHDx) mapping. Subsequent to identification of the AT mechanism, PFA was performed at the assumed critical sites for LAT maintenance. Continuous ablation lines were performed if required and evaluated with pre- and post-PFA HDx-mapping. RESULTS: Fifteen patients (age 70 ± 10, male 73%) who underwent 3.6 ± 2 prior AF-CA procedures were included. The total mean procedure and fluoroscopy times were 141 ± 43 and 18 ± 10 min, respectively. All 19 of 19 (100%) LAT were successfully ablated with PFA. Two AT located at the right atria required RF-ablation. LAT were identified as localized reentry (n = 1) and macro-reentry LAT (n = 18) and targeted with PFA. All LAT terminated with PFA either to sinus rhythm (9/15) or a secondary AT (6/15 and subsequently to SR); 63% (12/19) terminated with the first PFA-application. All lines (13 roof, 11 anterior, 1 mitral) were blocked. LA-posterior-wall isolation (LAPWI) was successfully achieved when performed (10/10). AF/AT free survival was 80% (12/15) after 153 [88-207] days of follow-up. No procedure-related complications occurred. CONCLUSION: PFA of consecutive LAT is feasible and safe. Successful creation of ablation lines and LAPWI can be achieved in a short time. PFA may offer the opportunity for effective ablation of atrial arrhythmias beyond AF.

Pulsed-field ablation combined with ultrahigh-density mapping in patients undergoing catheter ablation for atrial fibrillation: Practical and electrophysiological considerations.

BACKGROUND: Pulsed-field ablation (PFA) yields a novel ablation technology for atrial fibrillation (AF). PFA lesions promise to be highly durable, however clinical data on lesion characteristics are still limited. OBJECTIVE: This study sought to investigate PFA lesion creation with ultrahigh-density (UHDx) mapping. METHODS: Consecutive AF patients underwent PFA-based pulmonary vein isolation (PVI) using a multispline catheter (Farwave, Farapulse Inc.). Additional ablation, including left atrial posterior wall isolation (LAPWI) and mitral isthmus ablation (MI) were performed in a subset of persistent AF patients. The extent of PFA-lesions and decrease of LA-voltage were assessed with pre- and post PFA UHDx-mapping (Orion™ catheter and Rhythmia™ 3D-mapping system, Boston Scientific). RESULTS: In 20 patients, acute PVI was achieved in 80/80 PVs, LAPW isolation in 9/9 patients, MI ablation in 2/2 (procedure time: 123 ± 21.6 min, fluoroscopy time: 19.2 ± 5.5 min). UHDx-mapping subsequent to PVI revealed early PV-reconnection in five case (5/80, 6.25%). Gaps were located at the anterior-superior PV ostia and were successfully targeted with additional PFA. Repeat UHDx mapping after PFA revealed a significant decrease of voltage along the PV ostia (1.67 ± 1.36 mV vs. 0.053 ± 0.038 mV, p < .0001) with almost no complex electrogram-fractionation at the lesion border zones. PFA-catheter visualization within the mapping system was feasible in 17/19 (84.9%) patients and adequate in 92.9% of ablation sites. CONCLUSION: For the first time illustrated by UHDx mapping, PFA creates wide antral circumferential lesions and homogenous LAPW isolation with depression of tissue voltage to a minimum. Although with a low incidence, early PV reconnection can still occur also in the setting of PFA.

Specific electrogram characteristics impact substrate ablation target area in patients with scar-related ventricular tachycardia-insights from automated ultrahigh-density mapping.

INTRODUCTION: Substrate-based catheter ablation approaches to ventricular tachycardia (VT) focus on low-voltage areas and abnormal electrograms. However, specific electrogram characteristics in sinus rhythm are not clearly defined and can be subject to variable interpretation. We analyzed the potential ablation target size using automatic abnormal electrogram detection and studied findings during substrate mapping in the VT isthmus area. METHODS AND RESULTS: Electrogram characteristics in 61 patients undergoing scar-related VT ablation using ultrahigh-density 3D-mapping with a 64-electrode mini-basket catheter were analyzed retrospectively. Forty-four complete substrate maps with a mean number of 10319 ± 889 points were acquired. Fractionated potentials detected by automated annotation and manual review were present in 43 ± 21% of the entire low-voltage area (<1.0 mV), highly fractionated potentials in 7 ± 8%, late potentials in 13 ± 15%, fractionated late potentials in 7 ± 9% and isolated late potentials in 2 ± 4%, respectively. Highly fractionated potentials (>10 ± 1 fractionations) were found in all isthmus areas of identified VT during substrate mapping, while isolated late potentials were distant from the critical isthmus area in 29%. CONCLUSION: The ablation target area varies enormously in size, depending on the definition of abnormal electrograms. Clear linking of abnormal electrograms with critical VT isthmus areas during substrate mapping remains difficult due to a lack of specificity rather than sensitivity. However, highly fractionated, low-voltage electrograms were found to be present in all critical VT isthmus sites.

Risk stratification of patients with left atrial appendage thrombus prior to catheter ablation of atrial fibrillation: An approach towards an individualized use of transesophageal echocardiography.

INTRODUCTION: The need for transesophageal echocardiography (TEE) before catheter ablation of atrial fibrillation (CA-AF) is still being questioned. The aim of this study is to analyze patients' (patients) risk factors of left atrial appendage thrombus (LAAT) prior to CA-AF in daily clinical practice, according to oral anticoagulation (OAC) strategies recommended by current guidelines. METHODS AND RESULTS: All patients scheduled for CA-AF from 01/2015 to 12/2016 in our center were included and either treated with NOACs (novel-OAC; paused 24-hours preablation) or continuous vitamin K antagonists (INR 2.0-3.0). All patients received a preprocedural TEE at the day of ablation. Two groups were defined: (1) patients without LAAT, (2) patients with LAAT. The incidence of LAAT was 0.78% (13 of 1,658 patients). No LAAT was detected in patients with a CHA2 DS2 -VASc score of ≤1 (n = 640 patients) irrespective of the underlying AF type. Independent predictors for LAAT are: higher CHA2 DS2 -VASc scores (odds ratio [OR] 1.54, 95%-confidence interval [CI]: 1.07-2.23, P = 0.0019), a history of nonparoxysmal AF (OR 7.96, 95%-CI: 1.52-146.64, P = 0.049), hypertrophic cardiomyopathy (HCM; OR 9.63, 95% CI: 1.36-43.05, P = 0.007), and a left ventricular ejection fraction (LVEF) < 30% (OR 8.32, 95% CI: 1.18-36.29, P = 0.011). The type of OAC was not predictive (P = 0.70). CONCLUSIONS: The incidence of LAAT in patients scheduled for CA-AF is low. Therefore, periprocedural OAC strategies recommended by current guidelines seem feasible. Preprocedural TEE may be dispensed in patients with a CHA2 DS2 -VASc score ≤1. However, a CHA2 DS2 -VASc score ≥2, reduced LVEF, HCM, or history of nonparoxysmal AF are independently associated with an increased risk for LAAT.

Acute and long-term effects of fingolimod on heart rhythm and heart rate variability in patients with multiple sclerosis.

BACKGROUND: Fingolimod can lead to increased risk of cardiac events such as bradycardia or atrioventricular (AV) block. OBJECTIVE: Evaluate acute and long-term effects of fingolimod on heart rhythm (HR), heart rate variability (HRV) and development of AV-blocks. METHODS: In 64 patients with relapsing-remitting multiple sclerosis Holter ECG monitoring (HEM) and HRV analysis were performed 24h before, six h during and 72h after initiation of fingolimod. We additionally analyzed a 24h HEM after a follow up of ≥ three months. RESULTS: Heart rate (HR) decreased significantly (p < 0.001) under fingolimod treatment with nadir at five hours after starting and maintained decreased for 72h. Five (7.8%) patients suffered from new-onset AV-block requiring cessation of treatment. In four of five patients (80%), the AV-block could only be documented in the 72h-HEM with a median time of occurrence at 14h. The mean heart rate was still significant lower after a mean follow up time of 14.1 ± 9.6 months (85.0 ± 9.8 vs. 75.3 ± 16.2 bpm; p = 0.002) in comparison to baseline. CONCLUSION: The treatment with fingolimod leads to an increase of vagal activation which persists even after 14 months of treatment. These changes did not return to baseline levels on treatment with fingolimod. Based on our data an additional at least 24h hour-HEM after the initiation of fingolimod therapy should be considered.

Heart rate turbulence and deceleration capacity for risk prediction of serious arrhythmic events in Marfan syndrome.

OBJECTIVE: Marfan syndrome (MFS) is associated with a substantial risk for ventricular arrhythmia and sudden cardiac death (SCD). We used heart rate turbulence (HRT) and deceleration capacity (DC), to evaluate the risk stratification for these patients. METHODS: We enrolled 102 patients [45 male (44.1 %), age 40.5 ± 14.6 years] with MFS. Blood samples were obtained to determine N-terminal pro-brain natriuretic peptide (NT-proBNP) levels. Transthoracic echocardiography studies were conducted to evaluate heart function parameters and a 24-h holter ECG was performed. An analysis of two HRT parameters, turbulence onset (TO) and turbulence slope (TS), and DC was performed. Therefore, optimal cut-off values were calculated. Primary endpoint was the combination of SCD, ventricular arrhythmia and arrhythmogenic syncope. Secondary endpoint was total mortality. RESULTS: During a follow-up of 1145 ± 491 days, 12 (11.7 %) patients reached the primary and 8 (7.8 %) patients the secondary endpoint. Patients reaching the primary were significantly older, had a higher burden of premature ventricular complexes and NT-proBNP levels and lower values of LVEF, DC and HRT TS. Multivariate analysis identified NT-proBNP (HR 1.25, 95 % CI 1.01-1.56, p = .04) and the abnormal HRT (abnormal TS and/or TO (HR 7.04, 95 % CI 1.07-46.27, p = .04) as independent risk predictor of arrhythmogenic events. CONCLUSION: Patients with Marfan syndrome are at risk for severe ventricular arrhythmias and SCD. Abnormal HRT parameters and NT-proBNP values are independent risk factors for arrhythmogenic events and SCD. The assessment of these tools may help predicting SCD patients with MFS.