Real-time local impedance monitoring to assess tissue lesion during pulmonary vein isolation: a new tool for AF ablation

POSTER PRESENTATIONS

Background The combination of highly localized impedance (LI) and contact force (CF) may improve tissue characterization and lesion prediction during radiofrequency (RF) pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF). Objective We report the outcomes of our acute and long-term clinical evaluation of CF-LI guided PVI in consecutive AF ablation cases from an international multicenter clinical setting. Methods Consecutive patients (pts) from 16 European centers undergoing de novo AF RF catheter ablation with the Stablepoint catheter endowed of CF and LI measurement capabilities were enrolled in the CHARISMA registry. Ablation was guided by the magnitude and time-course of LI drop during RF delivery. The maximum distance between each ablation spot (center-to-center) was suggested to be ≤6 mm. Procedural endpoint was the achievement of the PVI as assessed by entrance and exit block. Post-ablation, all patients were monitored with ambulatory event monitoring. Additional ECG monitoring was performed as indicated by patient symptoms. Data are reported as mean±SD. Results From a total of 212 consecutive pts, 151 were followed-up for at least 12 months after the procedure and were included in this 1-year outcome analysis (61.6% paroxysmal AF, 38.4% persistent AF, 78.8% de novo procedures, 21.2% redo procedures). Baseline LI was 161.2±19 Ω with LI drop of 21.9±9 Ω (LI drop rate=3.1±2 Ω/s). The first pass isolation rate per vein was 93.3%. LI drop was predicted by baseline LI (r=0.56, 95%CI:0.55 to 0.57, p<0.0001). Effective ablation spots showed both higher baseline LI and LI drop compared with PV gap spots (161.4Ω vs 153.0Ω, p<0.0001 for baseline LI; 22.1Ω vs 14.4Ω, p<0.0001 for LI drop). No steam pops or complications, including atrio-esophageal fistula or tamponade were reported during or after the procedures. At the end of the procedures all PVs were successfully isolated in all study patients. During a median follow-up of 377 [365 – 402] days, 11 (7.3%) patients experienced an early recurrence of AF during the 90-day blanking period. Overall, 21 pts (13.9%) suffered an AF recurrence after the 90-days blanking period (10.8% with paroxysmal AF vs 19% with persistent AF, p=0.226; 10.9% for de novo procedures vs 25.0% for redo procedures, p=0.079). De novo paroxysmal AF pts showed the lowest rate of recurrence (5 out 69 pts, 7.2%). The time to recurrence was comparable among AF type (HR=1.73; 0.73 to 4.05; p=0.210 for persistent vs paroxysmal AF) whereas was shorter in repeated AF ablation procedures (HR=2.49; 1.04 to 5.98; p=0.042 for redo vs de novo procedure). Early recurrence was not associated with late recurrence (HR=2.29; 0.68 to 7.76; p=0.182). Conclusions In our experience, the magnitude of LI drop is predictive of PV segment isolation. An ablation strategy for PVI guided by CF-LI technology was safe and effective, and resulted in a low recurrence rate of AF at 1-year follow-up irrespective of underlying AF type.

A new era of atrial fibrillation (AF) treatment began in 1997–1998 with the discovery that triggers within the pulmonary veins initiate AF and reports that elimination of these triggers is successful in treating AF in its paroxysmal form.1–3 However, in patients with persistent AF, the success rate of exclusive pulmonary vein isolation is substantially lower.4,5 To improve the outcome of persistent AF ablation, different ablation strategies have been explored, but to date the optimal strategy has not been defined. Although some groups argue that limited ablation, including pulmonary vein isolation and, if present, ablation of nonpulmonary vein triggers, is sufficient for persistent AF ablation, other groups, including ours, favor more extensive, substrate-based ablation in addition to pulmonary vein isolation. In this review, we will discuss the rationale for a substrate-based ablation strategy to treat persistent AF and show why elimination of triggers is not sufficient in most patients with persistent AF. Response by Roten et al on p 1232 In a simple model, an electric impulse in AF can form because of abnormalities in impulse generation (triggers) or can result from abnormal impulse propagation (reentry). By a strict definition, a trigger is a focal source of new impulse generation. The mechanism by which a new impulse can form is either abnormal automaticity or triggered activity. Trigger-ablation protocols target these sources of new impulse generation. Abnormal impulse propagation, on the other hand, depends on altered substrate properties causing nonuniform or slowed conduction. This in turn causes multiple forms of wave reentry thought to be responsible for AF perpetuation: random reentry (multiple wavelets), macro- and microreentry, or functional reentry (rotors). Substrate-based ablation strategies aim to abate abnormal impulse propagation and interrupt any form of atrial reentry. Triggers of paroxysmal AF are mainly located in the pulmonary …

▪ Abstract Atrial fibrillation is frequently disabling and resistant to antiarrhythmic drugs. Curative treatment by catheter-based ablation has been shown to be feasible either by achieving long linear lesions, mainly in the left atrium, or by targeting the initiating focus, most frequently in the pulmonary veins. This paper reviews the different ablation approaches, their results, potential complications, and relative merits.

ORAL PRESENTATION

Wide-area antral pulmonary vein and posterior wall isolation by way of segmental nonocclusive applications using a novel radiofrequency ablation balloon

<i>Circulation: Arrhythmia and Electrophysiology</i> Editors’ Picks

Comparison of Transesophageal Echocardiography Versus Computed Tomography for Detection of Left Atrial Appendage Filling Defect (Thrombus)

Catheter ablation for persistent atrial fibrillation in an elderly patient with cor triatriatum sinister

Background: The precise mechanisms of random wave propagation perpetuated after pulmonary vein isolation (PVI) in atrial fibrillation (AF) has not been well clarified. Objectives: The purpose of this study was to define the mechanism of random wave propagation perpetuated after PVI in AF. We further clarified the difference in this perpetuating mechanism between paroxysmal and persistent AF. Methods: Endocardial mapping of the left atrium was performed before and after PVI in 7 paroxysmal and 7 persistent AF patients using a three-dimensional non-contact mapping system (EnSite 3000). We analyzed the difference in the left atrial activation sequence between paroxysmal and persistent AF, especially in relation to the complex fractionated electrograms (CFAE) region. Results: Random wave propagation after PVI was maintained by the combination of focal discharge, the activation around the isolated PV and mitral annulus, wave break and pivoting activation anchored around the functional conduction block region. The frequency of pivoting activation, wave break and wave fusion were significantly higher in the persistent AF than in the paroxysmal AF (8.4±10.4 vs. 2.0±3.5 times/sec; p&lt;0.001, 1.9±3.2 vs. 0±0 times/sec; p&lt;0.05, and 12.1±3.3 vs. 6.3±13.4 times/sec; p&lt;0.005). However, the frequency of focal discharge derived from non-PV region in persistent AF was lower than in paroxysmal AF (0.3±0.6 vs. 3.2±8.8 times/sec; p&lt;0.03). The area of CFAE was significantly reduced following PVI both in paroxysmal and persistent AF (18.0±16.9 to 2.2±4.9 cm 2 ; p&lt;0.0001, 26.8±22.3 to 6.6±2.9 cm 2 ; p&lt;0.0001). However, the area of CFAE in persistent AF was significantly larger than that in paroxysmal AF both before (p=0.003) and after PVI (p&lt;0.002). Pivoting activation and wave break were observed on the residual CFAE region which was still observed after PVI. Conclusions: Activation sequence of the wave during ongoing AF perpetuated after PVI was more disorganized in persistent AF than in paroxysmal AF. Disorganized activation after PVI in persistent AF was caused by the pivoting activation and wave break associated with the residual CFAE region.

How to leverage local impedance to guide effective ablation strategy: A case series

Pulmonary vein isolation (PVI) using cryoballoon ablation (CBA) is mainly reserved for patients with drug-refractory or drug-intolerant symptomatic atrial fibrillation. We evaluated a large cohort of patients treated in a real-world setting and examined the safety and efficacy profile of CBA when applied as a first-line treatment for atrial fibrillation. In total, 249 patients (23% women; 56 ± 13 years; mean left atrial diameter 41 ± 7 mm; 73.5% paroxysmal atrial fibrillation; and 26.5% persistent atrial fibrillation) underwent an index PVI by CBA. Data were collected prospectively in the framework of the 1STOP ClinicalService project, involving 26 Italian cardiology centers. Median procedure and fluoroscopy times were 90.0 and 21.0 min, respectively. Acute procedural success was 99.8%. Acute/periprocedural complications were observed in seven patients (2.8%), including: four transient diaphragmatic paralyses, one pericardial effusion (not requiring any intervention), one transient ischemic attack, and one minor vascular complication. The Kaplan--Meier freedom from atrial fibrillation recurrence was 86.3% at 12 months and 76% at 24 months. Seventeen patients (6.8%) had a repeat catheter ablation procedure during the follow-up period. At last follow-up, 10% of patients were on an anticoagulation therapy, whereas 6.8% were on an antiarrhythmic drug. In our multicenter real-world experience, PVI by CBA in a first-line atrial fibrillation patient population was well tolerated, effective, and promising. CBA with a PVI strategy can be used to treat patients with paroxysmal and persistent atrial fibrillation with good acute procedural success, short procedure times, and acceptable safety. clinicaltrials.gov (NCT01007474).

Background Pulmonary vein isolation (PVI) performed with radio-frequency catheter ablation (CA) is an effective therapy for atrial fibrillation (AF). However previous data have suggested that PVI is less effective in persistent (PER) vs. paroxysmal (PAR) AF. Atrial fibrosis and scar, indeed, are an important substrate involved in persistent AF, and some author correlate them to an increased rate of recurrences after CA. For this reason several adjunctive ablation strategies have been suggested for invasive treatment in PER AF pts. However, there is a lack of evidence on their effectivness in current literature. Objective the aim of our study was to assess the rate of AF recurrences in PAR and PER AF patients after a first pulmonary vein isolation (IVP) procedure, and their relationship with low voltage areas of the left atrium assessed by means of high density mapping performed before CA. Methods we analyzed 214 patients of the SMOP-AF study (Substrate Mapping as Outcome Predictor in Atrial Fibrillation Ablation), a prospective multi-centric registry enrolling patients with both PAR and PER AF undergoing a first radio-frequency CA procedure aimed to obtain permanent PVI . High-density mapping was performed in sinus rhythm using the CARTO system before PVI. Areas with less than 0,5 mV on mapping were defined as low voltage zone (LVZ); LVZ was indexed on the atrial area. Comparisons were made by cross-tables and Chi-square test or Student T test. Results Patients with PER AF (n = 44, 21%) were older (63 ± 9 vs 58 ± 10 yrs, p = 0.01), but notably with no difference in LVEF and atrial dimensions as compared to pts with PAR AF. In addition no statistical difference was observed in procedural variables, except for a greater LVZ area on atrial mapping (8 ± 18 % vs. 5 ± 15 %, p = 0.04) and a longer p wave duration (115 ± 21 msec vs. 103 ± 18 msec, p = 0.01) in pts with PER AF. The incidence of recurrence in the overall population was 15.3% at 3 months and 13.7% from 3 to 12 months: there was no statistical difference in success-rate between PER and PAR pts (respectively 79,5% vs 86% p value = 0.315 in blanking period and 85,3% vs 86,5% p value = 0.8 at 3-12 months follow-up). No statistical difference was observed for ablation variables (number of lesion, contact force, force time integral) in pts with vs. without recurrences. Conclusion Our study showed that pulmonary vein isolation alone seems to be as effective in paroxismal and persistent AF patients with low degree of left atrial fibrosis. Our data call into question the idea that PVI alone is not effective in PER AF. High density mapping of the LA could help to identify a subset of PER AF patients with a limited extension of low voltage areas (i.e around 10% of the overall LA surface) that could benefit from PVI without adjunctive ablation strategies. Our data needs to be confirmed in a longer follow-up.

IntroductionAblation Index (AI) is a novel catheter-based parameter developed to improve and increase efficacy and safety of Pulmonary Vein Isolations (PVI) in the treatment of Atrial Fibrillation (AF). This method...

Subxiphoid Minimally Invasive Epicardial Ablation (Convergent Procedure) With Left Thoracoscopic Closure of the Left Atrial Appendage