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.

Ultra-high-density mapping of conduction gaps and atrial tachycardias: Distinctive patterns following pulmonary vein isolation with cryoballoon or contact-force-guided radiofrequency current.

INTRODUCTION: The aim of this study was to investigate electrophysiological findings in patients with arrhythmia recurrence undergoing a repeat ablation procedure using ultra-high-density (UHDx) mapping following an index procedure using either contact-force (CF)-guided radiofrequency current (RFC) pulmonary vein isolation (PVI) or second-generation cryoballoon (CB) PVI for treatment of atrial fibrillation (AF). METHODS AND RESULTS: Fifty consecutive patients with recurrence of AF and/or atrial tachycardia (AT) following index CF-RFC PVI (n = 21) or CB PVI (n = 29) were included. A 64-pole mini-basket mapping catheter in combination with an UHDx-mapping system-guided ablation was used. RFC was applied using a catheter tip with three incorporated mini-electrodes. PV reconnection rates were higher after CF-RFC PVI (CF-RFC: 2.5 ± 1.3 PVs vs CB: 1.4 ± 0.9 PVs; P = .0025) and left PVs were more frequently reconnected (CF-RFC: 64% PVs vs CB: 35% PVs; P = .0077). Fractionated signals along the antral index ablation line (FS) were found in 30% of CB-PVI patients (CF-RFC: 9.5% vs CB:30%; P = .098) targeted for ablation. In five cases, FS were a critical part of maintaining consecutive AT. The main AT mechanism found during reablation (n = 45 ATs) was macroreentry (80% [36/45], CF-RFC: 78.9% vs CB: 80.8%; P = 1.0) with a variety of circuits throughout both atria. CONCLUSION: UHDx mapping is sensitive in detecting conduction gaps along the index ablation line. Left PVs are more frequently reconnected after initial CF-RFC PVI. FS are a common finding after CB PVI and can maintain certain forms of ATs. ATs after index PVI are mostly macroreentries with a broad spectrum of entities.

Outcome after tailored catheter ablation of atrial tachycardia using ultra-high-density mapping.

INTRODUCTION: Tailored catheter ablation of atrial tachycardias (ATs) is increasingly recommended as a potentially easy treatment strategy in the era of high-density mapping (HDM). As follow-up data are sparse, we here report outcomes after HDM-guided ablation of ATs in patients with prior catheter ablation or cardiac surgery. METHODS AND RESULTS: In 250 consecutive patients (age 66.5 ± 0.7 years, 58% male) with ATs (98% prior catheter ablation, 13% prior cardiac surgery) an HDM-guided catheter ablation was performed with the support of a 64-electrode mini-basket catheter. A total of 354 ATs (1.4 ± 0.1 ATs per patient; mean cycle length 304 ± 4.3 ms; 64% macroreentry, 27% localized reentry, and 9% focal) with acute termination of 95% were targeted in the index procedure. A similar AT as in the index procedure recurred in five patients (2%) after a median follow-up time of 535 days (interquartile range (IQR) 25th-75th percentile: 217-841). Tailored ablation of reentry ATs with freedom from any arrhythmia was obtained in 53% after a single procedure and in 73% after 1.4 ± 0.4 ablation procedures (range: 1-4). A total of 228 patients (91%) were free from any arrhythmia recurrence after 210 days (IQR: 152-494) when including optimal usual care. CONCLUSIONS: Tailored catheter ablation of ATs guided by HDM has a high acute success rate. The recurrence rate of the index AT is low. In patients with extensive atrial scaring further ablation procedures need to be considered to achieve freedom from any arrhythmia.

Entrainment mapping: Theoretical considerations and practical implementation.

Entrainment mapping enables the diagnosis and characterization of reentrant arrhythmias from analysis of the specific interaction between pacing maneuvers and tachycardia. Described 40 years ago, the implementation and interpretation of pacing maneuvers to entrain tachycardias has evolved into an indispensible tool for diagnosis and mapping reentrant cardiac arrhythmias. For complex re-entry pathways entrainment mapping allows determination of the relation of pacing sites to the re-entry circuit and discrimination of relevant re-entry parts from bystander areas. Careful interpretation is needed to recognize misleading findings. The general physiology of re-entry, and the application, interpretation, limitations, and pitfalls of entrainment maneuvers used for cardiac mapping is reviewed.

Temporal trends in safety and complication rates of catheter ablation for atrial fibrillation.

INTRODUCTION: Atrial fibrillation (AF) ablation is increasingly common, but is associated with potential major complications. Technology, experience, and protocols have evolved significantly in recent times, and may have impacted procedural safety. We sought to compare AF ablation safety profiles, including complication rates and fluoroscopy times in a "modern" versus "historical" cohort. METHODS AND RESULTS: We evaluated consecutive patients undergoing AF ablation from a modern cohort (MC) from 2014 to 2015 and a historic cohort (HC) from 2009 to 2011 for complications. Major complications were categorized according to Heart Rhythm Society guidelines. We included 1,425 patients, 726 in the HC and 699 in the MC. The MC was older, had more OSA and less valvular AF. Fifty-two (3.5%) procedures suffered major complications across the cohorts, with significantly fewer in the MC (5.0% vs. 2.3%, P  =  0.007). The largest reductions were seen in vascular, hemorrhagic, ischemic stroke, and perforation/tamponade related complications. Periprocedural antiplatelets drugs (aHR 2.1 [95 CI 1.1-3.9], P  =  0.02) and force-sensing catheters (aHR 0.4 [95 CI 0.2-0.9], P  =  0.03) were independently related to major complication rates. Direct oral anticoagulants and uninterrupted anticoagulation were not associated with complications. There was a decrease in both fluoroscopy (-17.4 minutes [95 CI 19.2-15.6], P < 0.0001) and radiofrequency ablation times (-561 seconds [95CI -750 to -371], P < 0.0001). CONCLUSIONS: The safety profile of AF ablation has improved significantly in less than a decade.

Incidence of intracardiac thrombus formation prior to electrical cardioversion in respect to the mode of oral anticoagulation.

AIMS: To evaluate the incidence of newly diagnosed intracardiac thrombi (ICT) in respect to the mode of OAC in patients undergoing cardioversion (CV). METHODS AND RESULTS: We prospectively assessed transesophageal echocardiography (TEE) and OAC therapy prior to CV in AF patients with ≥48-hour duration scheduled for CV. A total of 60 first-time ICT (4.7%) were diagnosed in 1,286 TEE, with highest rate in patients without OAC (9.6% vs. OAC 4.1%, P  =  0.009) and an apparently lower rate in nonvitamin K antagonist anticoagulants (NOAC) therapy compared to vitamin K antagonist (VKA) (2.5% vs. 5.3%, P  =  0.02). VKA therapy control 4 weeks prior to CV was overall average (time in therapeutic range 60%) and patients showed more frequently clinical characteristics and TEE parameters associated with risk for ICT. Even among patients with effective OAC therapy (uninterrupted NOAC and VKA therapy with international normalized ratio (INR) ≥2.0 for 3 weeks), ICT occurred in 2.7%, but with no difference between both groups (P  =  0.22). There was no difference between different types of NOAC. Independent predictors for ICT were history of embolism, hypertension, BMI, absence of OAC, renal function, reduced atrial appendage flow, and presence of spontaneous echo contrast. CONCLUSION: NOAC therapy seems favorable in the overall prevention of ICT, although this is likely to be caused by suboptimal VKA therapy control and differences in the overall health status between VKA and NOAC patients. ICT occurred even with effective OAC therapy suggesting individual TEE-guided cardioversion in patients at risk.

Influence of energy source on early atrial fibrillation recurrences: a comparison of cryoballoon vs. radiofrequency current energy ablation with the endpoint of unexcitability in pulmonary vein isolation.

Introduction: Comparative data of early recurrence rates of atrial fibrillation (ERAF) following second-generation cryoballoon (CB-G2) and radiofrequency current (RFC) ablation for pulmonary vein isolation (PVI) in paroxysmal AF (PAF) are rare. We randomized PAF patients into either PVI with CB-G2 (group 1) or PVI with a combined RFC-approach applying contact force (CF) with the endpoint of unexcitability (group 2) to investigate ERAF. Methods and results: In group 1 (n = 30), CB-G2-PVI was performed. After CF-PVI in group 2 (n = 30), bipolar pacing on the ablation line and additional ablation until unexcitability was conducted. Follow-up included 48 h of in-hospital monitoring followed by 5-day Holter ECGs 1, 2, 3, 6, 12 months postablation to evaluate ERAF. Acute PVI was reached in 100% of group 2 and in 99% of group 1. Shorter procedure durations (98.0 ± 21.9 vs. 114.3 ± 18.7 min, P < 0.05) but extended fluoroscopy times (15.4 ± 3.9 vs. 10.0 ± 4.3 min, P < 0.05) were found in the CB-G2 group. Ten non-severe complications occurred (6 vs. 4 in group 1 and 2, P = 0.73). In group 2, five patients suffered from ERAF vs. seven patients in group 1 (P = 0.67). The time until the occurrence of ERAF was shorter in group 2 (1 day (q1-q3: 1-4.5)) when compared with group 1 (22 (q1-q3: 6-54) days, P = 0.025). Conclusion: ERAF rates were equal among groups; however, they occurred earlier in the initial phase after RFC ablation when compared with CB-G2. PVI utilizing cryoablation is associated with shorter procedure durations but extended fluoroscopy time while being similarly secure.

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.

Characterization, Mapping, and Ablation of Complex Atrial Tachycardia: Initial Experience With a Novel Method of Ultra High-Density 3D Mapping.

INTRODUCTION: Conventional mapping of complex atrial tachycardias (ATs) can be challenging. Thus, we evaluated feasibility and utility of a novel, ultra high-density 3D mapping approach to characterize and map AT in these cases. METHODS AND RESULTS: Overall, 21 patients (67.4 ± 7.6 years; male: 52.4%, 1.9 ± 1.4 previous ablation procedures) with documented AT referred to our center underwent catheter ablation including ultra high-density mapping using a novel 64-electrode mini-basket catheter and an adjunctive 3D mapping system. A total of 24 AT (20 left atrial, 4 right atrial AT) were analyzed in 19 cases. In 2 patients, map acquisition failed due to scarce local electrograms and unstable AT cycle length, respectively. Underlying mechanisms were focal (n = 3), as well as local (n = 8) and macro (n = 13) reentry tachycardias with a mean cycle length of 311.8 ± 67.7 milliseconds. The analysis of propagation waves, activation and voltage revealed complex activation patterns and allowed for the identification of critical sites of AT initiation or maintenance without the need for further mapping techniques. In all cases critical sites could be verified by successful consecutive ablation. Mean mapping time was 19.4 ± 7.6 minutes, mean number of mapping points was 19,217 ± 10,270. Radiofrequency application until first effect was 165.1 ± 374.2 seconds; total procedure time was 157.6 ± 51.4 minutes, fluoroscopy time 21.7 ± 13.8 minutes, and total radiofrequency duration 1,016 ± 951.9 seconds, respectively. No severe complications occurred. CONCLUSION: Ultra high-density mapping of complex AT is safe and feasible. Further, it enables detailed insight into AT mechanisms. Critical AT sites can be identified precisely in order to guide successful catheter ablation.

Loss of Pace Capture on the Ablation Line During Pulmonary Vein Isolation versus "Dormant Conduction": Is Adenosine Expendable?

INTRODUCTION: Permanent pulmonary vein isolation (PVI) remains an essential goal of ablation therapy in patients with atrial fibrillation. Aim of this study was the intraindividual comparison of unexcitability to pacing along the ablation line versus dormant conduction (DC) as additional procedural endpoints. METHODS: A total of 58 patients with paroxysmal atrial fibrillation (PAF) underwent PVI by circumferential ablation of ipsilateral pulmonary veins (PVs), followed by testing for DC by adenosine administration. Irrespective of the presence of DC, pacing along the ablation line for left atrium capture was performed and additional radio frequency energy applied if necessary. PVs with initial DC were retested after achieving unexcitability. RESULTS: PVI was achieved in 224 of 224 PVs. In 33 of 224 PVs (15%) DC was revealed. At 92 of 112 ablation lines (82%) sites of excitability were found. Three (9%) of the initial 33 PVs with DC showed further DC after achieving unexcitability at repeated testing. Thirty-two of 33 assumed areas of unmasked PV-LA reconduction as revealed by DC-testing showed a corresponding site of excitability on the ablation line. After a follow-up of 11.6 ± 3.4 months 79% of patients were free of arrhythmia. CONCLUSIONS: Pacing for unexcitability can safely identify potential sites of DC and even sites that would have not been detected by testing for DC. Unexcitability, therefore, serves as a suitable and safe procedural endpoint not only for patients with contraindications to adenosine administration. Our data suggest that adenosine may be expendable when achieving unexcitability along the ablation line.

Intramural Needle Ablation for Refractory Premature Ventricular Contractions.

BACKGROUND: Frequent premature ventricular contractions (PVCs) are often amenable to catheter ablation. However, a deep intramural focus may lead to failure due to inability of standard ablation techniques to penetrate the focus. We sought to assess the efficacy and safety of infusion needle ablation (INA) for PVCs that are refractory to standard radiofrequency ablation. METHODS: Under 2 Food and Drug Administration approved protocols, INA was evaluated in patients with frequent PVCs that were refractory to standard ablation. Initial targets for ablation were selected by standard mapping techniques. INA was performed with a deflectable catheter equipped with an extendable/retractable needle at the tip that can be extended up to 12 mm into the myocardium and is capable of pacing and recording. After contrast injection for location assessment, radiofrequency ablation was performed with the needle tip using a temperature-controlled mode (maximum temperature 60 °C) with saline infusion from the needle. The primary end point was a decrease in PVC burden to <5000/24 hours at 6 months. The primary safety end point was incidence of procedure- or device-related serious adverse events. RESULTS: At 4 centers, 35 patients (age 55.3±16.9 years, 74.2% male) underwent INA. The baseline median PVC burden was 25.4% (interquartile range, 18.4%-33.9%) and mean left ventricular ejection fraction was 37.7±12.3%. Delivering 10.3±8.0 INA lesions/patient (91% had adjunctive standard radiofrequency ablation also) resulted in acute PVC elimination in 71.4%. After a mean follow-up of 156±109 days, the primary efficacy end point was met in 73.3%. The median PVC burden decreased to 0.8% (interquartile range, 0.1%-6.0%; P<0.001). The primary safety end point occurred in 14.3% consisting of 1 (2.9%) heart block, 1 (2.9%) femoral artery dissection, and 3 (8.6%) pericardial effusions (all treated percutaneously). CONCLUSIONS: INA is effective for the elimination of frequent PVCs that are refractory to conventional ablation and is associated with an acceptable safety profile. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT01791543 and NCT03204981.

Frequency Content of Unipolar Electrograms May Predict Deep Intramural Excitable Substrate: Insights From Intramural Needle Catheter Ablation of Ventricular Tachycardia.

OBJECTIVES: This study sought to identify midmyocardial arrhythmogenic substrates by examining the frequency content of unipolar endocardial surface electrograms, comparing sites with transmural scar versus sites with intramural excitable substrate (IES) as identified during needle catheter ablation for ventricular tachycardia (VT). BACKGROUND: Midmyocardial arrhythmogenic substrates are a common reason catheter ablation for VT may fail. METHODS: A total of 659 intramural needle sites were studied in 26 patients (age 61 ± 9 years, 85% male, 69% nonischemic cardiomyopathy) who underwent intramural needle catheter ablation for VT. Among 136 sites where endocardial pacing did not capture (threshold >10 mA), needle pacing captured at 29 indicating IES, and did not capture at 107 indicating transmural scar. Intramural needle ablation was performed at 21 of 29 IES sites. Analysis of voltage amplitude, duration, and power spectra of endocardial and intramural needle electrograms was performed. RESULTS: IES sites compared with transmural scar had higher endocardial unipolar electrogram voltage, 0.99 (interquartile range [IQR]: 0.69 to 1.62) mV versus 0.78 (IQR: 0.61 to 1.09) mV; p = 0.038; higher unipolar intramural needle electrogram voltage, 1.16 (0.80 to 1.69) mV versus 0.76 (0.6 to 1.12) mV; p = 0.003; higher endocardial unipolar frequency power particularly in the 5- to 20-Hz band, 1.97 (IQR: 0.93 to 3.89) mV2/s versus 1.03 (IQR: 0.63 to 2.22) mV2/s; p = 0.002; and higher unipolar intramural electrogram frequency particularly in the 0 to 10 Hz range, 3.02 (IQR: 0.98 to 6.95) mV2/s versus 1.33 (IQR: 0.70 to 3.13) mV2/s; p = 0.018. Endocardial unipolar frequency in the 5- to 20-Hz band identified sites with IES, area under the curve of 0.676; p = 0.002; power frequency integral of >0.77 mV2/s provided a 90% sensitivity and 41% specificity. CONCLUSIONS: The frequency content of unipolar electrograms may complement voltage in the detection of deep intramural substrates to facilitate VT catheter ablation. (Intramural Needle Ablation for Ablation of Recurrent Ventricular Tachycardia; NCT01791543).

Respiratory sinus arrhythmia is reduced after pulmonary vein isolation in patients with paroxysmal atrial fibrillation.

INTRODUCTION: Respiratory sinus arrhythmia (RSA) describes heart rate (HR) changes in synchrony with respiration. It is relevant for exercise capacity and mechanistically linked with the cardiac autonomic nervous system. After pulmonary vein isolation (PVI), the current therapy of choice for patients with paroxysmal atrial fibrillation (AF), the cardiac vagal tone is often diminished. We hypothesized that RSA is modulated by PVI in patients with paroxysmal AF. MATERIAL AND METHODS: Respiratory sinus arrhythmia, measured by using a deep breathing test and heart rate variability parameters, was studied in 10 patients (64 ±3 years) with paroxysmal AF presenting in stable sinus rhythm for their first catheter-based PVI. Additionally, heart rate dynamics before and after PVI were studied during sympathetic/parasympathetic coactivation by using a cold-face test. All tests were performed within 24 h before and 48 h after PVI. RESULTS: After PVI RSA (E/I difference: 7.9 ±1.0 vs. 3.5 ±0.6 bpm, p = 0.006; E/I ratio: 1.14 ±0.02 vs. 1.05 ±0.01, p = 0.003), heart rate variability (SDNN: 31 ±3 vs. 14 ±3 ms, p = 0.006; RMSSD: 17 ±2 vs. 8 ±2 ms, p = 0.002) and the HR response to sympathetic/parasympathetic coactivation (10.2 ±0.7% vs. 5.7 ±1.1%, p = 0.014) were diminished. The PVI-related changes in RSA correlated with the heart rate change during sympathetic/parasympathetic coactivation before vs. after PVI (E/I difference: r = 0.849, p = 0.002; E/I ratio: r = 0.786, p = 0.007). One patient with vagal driven arrhythmia experienced AF recurrence during follow-up (mean: 6.5 ±0.6 months). CONCLUSIONS: Respiratory sinus arrhythmia is reduced after PVI in patients with paroxysmal AF. Our findings suggest that this is related to a decrease in cardiac vagal tone. Whether and how this affects the clinical outcome including exercise capacity need to be determined.

Characteristics of myocardial tissue staining and lesion creation with an infusion-needle ablation catheter for the treatment of ventricular tachycardia in humans.

BACKGROUND: Intramural substrate causing ventricular tachycardia can be targeted by radiofrequency (RF) infusion-needle catheter ablation. OBJECTIVE: The purpose of the study was to assess fluid distribution within the myocardium after needle-ablation catheter infusion and its evidence to RF lesion creation. METHODS: In 25 patients (21 (84%) male; 67 ± 9 years; 8 (32%) with ischemic cardiomyopathy) intramural ablation of ventricular tachycardia was performed with a needle catheter. Fluoroscopic images of myocardial staining patterns produced by pre-RF saline/contrast infusion were analyzed. Lesion creation was defined as tissue inexcitability to high-output needle pacing. RESULTS: Data from 155 sites were eligible for analysis. Tissue staining was evident in 111 (72%) and absent in 44 (28%). The stain shapes were variable, with average dimensions of 20 ± 10 × 8 ± 4 mm with an area of 68 ± 58 mm2. Round/oval-shaped stains were most common (62 [56%]), while multisegmented (36 [32%]) and long flat (13 [12%]) configurations were less frequent. Evidence of staining was associated with evidence of lesion creation (92/111 (83%) vs 17/44 (39%); P ≤ .0001). Contrast staining around the needle was present in 50%, usually had blurred margins, and was associated with lesion creation. When staining extended well beyond the needle, the margins were often sharp, suggesting dissection through tissue planes, and lesion creation tended to be less effective. CONCLUSION: With infusion-needle ablation, preablation injection of contrast can help confirm an intramural position and predict lesion creation. Tissue diffusion patterns vary markedly, and studies to assess its relation to tissue architecture and ablation lesion geometry warrants further investigation. The findings also have implications for the injection of therapeutic agents into the regions of scar.

High-Density Mapping and Ablation of Primary Nonfocal Left Atrial Tachycardia: Characterizing a Distinct Arrhythmogenic Substrate.

OBJECTIVES: This study sought to characterize primary left atrial tachycardia (LAT) mechanisms, electrical properties and substrate using high-density mapping. BACKGROUND: Nonfocal LAT can be found in patients without prior substrate modifying interventions. METHODS: Of 223 catheter ablation procedures for LAT 15 patients (60% male, age 74 ± 6 years) had nonfocal AT and no history of LA ablation or cardiac surgery. RESULTS: AT (mean cycle length 244 ± 32 ms) were identified as macro-re-entry (12 of 15) or localized re-entry (3 of 15). High-density electroanatomical mapping (EAM, performed in 13 patients) revealed a high proportion of low voltage areas (LVA, <0.45 mV, 41 ± 22%). Anterior LVA regions were predominantly related to the macro-re-entry and directly perpetuating the re-entrant circuit in 8 patients by formation of a conductive channel (width: 14 ± 7 mm, length: 11 ± 3 mm) between the inferior pole of the scar and the mitral valve (MV) annulus with electrophysiological features of diseased tissue. A tailored anterior ablation line successfully terminated AT in 9 patients (6 dominant circuit MV dependent, 3 dominant circuit scar dependent AT), while a lateral isthmus line was performed in 2 patients. Localized re-entries were successfully targeted by local ablation. Acute successful ablation could be achieved in 14 of 15 patients leading to a freedom from any arrhythmias in 9 of 15 patients (60%) after follow-up of 343 ± 203 days. CONCLUSIONS: Patients with nonfocal left atrial tachycardia without previous iatrogenic interventions show evidence for advanced atrial myopathy. High-density mapping revealed involvement of the anterior LA and allows for an individualized ablation approach beyond strategies usually applied in consecutive AT.

Catheter ablation of polymorphic ventricular tachycardia/fibrillation in patients with and without structural heart disease.

BACKGROUND: Catheter ablation for polymorphic ventricular tachycardia and ventricular fibrillation (PMVT/VF) may target triggering premature ventricular contractions (PVCs). Targeting ventricular scar has also been suggested, but data are limited. OBJECTIVE: The purpose of this study was to characterize the electrophysiological findings and ablation outcomes for patients with PMVT/VF and structural heart disease (SHD) compared to those with idiopathic VF. METHODS: Data from 32 consecutive patients (13 idiopathic VF, 19 SHD) with recurrent PMVT/VF who underwent catheter ablation were reviewed. RESULTS: A low-voltage area of myocardial scar was present in 15 of 19 patients with SHD. Sustained monomorphic ventricular tachycardia (SMVT) associated with scar was inducible and targeted in 8, 3 of whom had previous SMVT episodes separate from PMVT/VF episodes and 5 had no history of SMVT. Triggering PVCs were identified in 11 patients and arose from an area of endocardial scar in 6. Only scar ablation was performed in 8 patients who did not have triggering PVCs. All idiopathic VF patients underwent PVC ablation only. During a median of 540 days, 74% of SHD patients and 77% of idiopathic VF patients were free of recurrence, including 75% of those with only PVC ablation, 86% of those with scar plus PVC ablation, and 63% of those with only scar ablation. CONCLUSION: Patients with recurrent PMVT/VF and SHD often have a low-voltage scar associated with PVCs or inducible SMVT, which may also be the substrate for PMVT/VF. When present, substrate ablation targeting scar is a reasonable option for treatment of PMVT/VF even if PVCs are absent.

Infusion Needle Radiofrequency Ablation for Treatment of Refractory Ventricular Arrhythmias.

BACKGROUND: Catheter ablation is effective for eliminating most drug-refractory ventricular arrhythmias (VA). However, a major reason for procedural failure is arrhythmia originating deep within the myocardium where it is inaccessible to conventional endocardial or epicardial approaches. Affected patients have limited therapeutic options. OBJECTIVES: The objective of this study was to assess the safety and outcome of a novel radiofrequency ablation catheter that used an extendable/retractable 27-g needle capable of targeting deep arrhythmia (intramural) substrate. METHODS: Patients who failed at least one prior catheter ablation procedure for sustained ventricular tachycardia (VT) or nonsustained VA with associated left ventricular dysfunction were enrolled at 3 centers. The target was sustained monomorphic VT in 26 patients, including 8 with recent VT storm or VT requiring intravenous medication, and 5 with incessant VA associated with ventricular dysfunction. RESULTS: Needle ablation was performed in 31 patients (median of 2 failed prior ablation procedures; 71% nonischemic heart disease). After a median of 15 needle lesions/patient, ablation abolished at least 1 inducible VT in 19 of 26 VT patients (73%), and suppressed ambient arrhythmia in 4 of 5 nonsustained arrhythmia patients. At the 6-month follow-up, 48% of patients were free of recurrent arrhythmia and another 19% were improved. Procedure-related complications included a single pericardial effusion treated with percutaneous drainage and a left ventricular pacing lead dislodgement with no deaths. CONCLUSIONS: In patients with recurrent ventricular arrhythmias refractory to medications and conventional catheter ablation, intramural needle radiofrequency ablation offers significant arrhythmia control with an acceptable procedural risk.

Left Ventricular Entropy Is a Novel Predictor of Arrhythmic Events in Patients With Dilated Cardiomyopathy Receiving Defibrillators for Primary Prevention.

OBJECTIVES: The aim of this study was to assess the utility of left ventricular (LV) entropy, a novel measure of myocardial heterogeneity, for predicting cardiovascular events in patients with dilated cardiomyopathy (DCM). BACKGROUND: Current risk stratification for ventricular arrhythmia in patients with DCM is imprecise. LV entropy is a measure of myocardial heterogeneity derived from cardiac magnetic resonance imaging that assesses the probability distribution of pixel signal intensities in the LV myocardium. METHODS: A registry-based cohort of primary prevention implantable cardioverter-defibrillator patients with DCM had their LV entropy, late gadolinium enhancement (LGE) presence, and LGE mass measured on cardiac magnetic resonance imaging. Patients were followed from implantable cardioverter-defibrillator placement for arrhythmic events (appropriate implantable cardioverter-defibrillator therapy, ventricular arrhythmia, or sudden cardiac death), end-stage heart failure events (cardiac death, transplantation, or ventricular assist device placement), and all-cause mortality. RESULTS: One hundred thirty patients (mean age 55 years, 83% men, LV ejection fraction 29%, mean LV entropy 5.58 ± 0.72, LGE present in 57%) were followed for a median of 3.2 years. Eighteen (14.0%) experienced arrhythmic events, 17 (13.1%) experienced end-stage heart failure events, and 7 (5.4%) died. LV entropy provided substantial improvement of predictive ability when added to a model containing clinical variables and LGE mass (hazard ratio: 3.5; 95% confidence interval: 1.42 to 8.82; p = 0.007; net reclassification index = 0.345, p = 0.04). For end-stage heart failure events, LV entropy did not improve the model containing clinical variables and LGE mass (hazard ratio: 2.03; 95% confidence interval: 0.78 to 5.28; p = 0.14). Automated LV entropy measurement has excellent intraobserver (mean difference 0.04) and interobserver (mean difference 0.03) agreement. CONCLUSIONS: Automated LV entropy measurement is a novel marker for risk stratification toward ventricular arrhythmia in patients with DCM.