CLOSE-Guided Pulmonary Vein Isolation to Treat Persistent Atrial Fibrillation: 1-Year Outcome.

BACKGROUND: CLOSE-guided pulmonary vein isolation (PVI) is based on contiguous and optimized (Ablation Index-guided) radiofrequency lesions. The efficacy of CLOSE-guided PVI in persistent atrial fibrillation (AF) treatment has been poorly evaluated. METHODS: In two centers, 50 patients eligible for persistent AF ablation underwent CLOSE-guided PVI (Ablation Index ≥ 450 at the anterior wall, ≥300 at posterior wall, intertag distance ≤ 6 mm). If PVI failed to restore sinus rhythm (SR), electrical cardioversion (ECV) was performed. Atrial substrate modification (ASM) was performed only if PVI and ECV failed to restore SR. Recurrence was defined as any recorded episode of AF, atrial tachycardia (AT) or atrial flutter (AFL) > 30 s on Holter electrocardiographs at 3, 6 and 12 months. RESULTS: From the 50 patients (64 ± 10 years, 14% long-standing persistent AF), SR was restored by ECV in 34 patients (68%) 56 ± 38 days prior to ablation. On the day of ablation, 42 patients (84%) were on class I-III anti-arrhythmic drug therapy (ADT) and the rhythm was AF in 23/50 patients. PVI was achieved in all patients; after PVI, ECV was required in 21 patients and ASM in 1 patient. The mean procedure time, radiofrequency time and fluoroscopy time were 141 ± 33 min, 23 ± 7 min and 7 ± 6 min, respectively. At 12 months, single-procedure freedom from AF/AT/AFL was 80%, with 19 patients (38%) receiving class I-III ADT. CONCLUSIONS: In a population of patients with persistent AF monitored with intermittent cardiac rhythm recordings, CLOSE-guided PVI resulted in high single-procedure arrhythmia-free survival at 1 year. Future large-scale studies involving continuous cardiac monitoring are necessary.

Prevalence and Clinical Characteristics of Patients with Pause-Dependent Atrioventricular Block.

BACKGROUND: In patients with complete atrioventricular block (AVB), the prevalence and clinical characteristics of patients with pause-dependent AVB (PD-AVB) is not known. Our objective was to assess the prevalence of PD-AVB in a population of patients with complete (or high-grade) AVB. METHODS: Twelve-lead electrocardiogram (ECG) and/or telemonitoring from patients admitted (from September 2020 to November 2021) for complete (or high-degree) AVB were prospectively collected at the University Hospital of Nice. The ECG tracings were analyzed by an electrophysiologist to determine the underlying mechanism of PD-AVB. RESULTS: 100 patients were admitted for complete (or high-grade) AVB (men 55%; 82 ± 12 years). Arterial hypertension was present in 68% of the patients. Baseline QRS width was 117 ± 32 ms, and mean left ventricular ejection fraction was 56 ± 7%. Fourteen patients (14%) with PD-AVB were identified, and presented similar clinical characteristics in comparison with patients without PD-AVB, except for syncope (which was present in 86% versus 51% in the non-PD-AVB patients, p = 0.01). PD-AVB sequence was induced by: Premature atrial contraction (8/14), premature ventricular contraction (5/14), His extrasystole (1/14), conduction block in a branch (1/14), and atrial tachycardia termination (1/14). All patients with PD-AVB received a dual-chamber pacemaker during hospitalization. CONCLUSION: The prevalence of PD-AVB was 14%, and may be underestimated. PD-AVB episodes were more likely associated with syncope in comparison with patients without PD-AVB.

Slow pathway elimination using antegrade conduction improvement with fast atrial pacing during AVNRT radiofrequency ablation: a proof-of-concept study.

BACKGROUND: Radiofrequency (RF) ablation of slow pathway (SP) is usually performed in sinus rhythm while monitoring the occurrence of a slow junctional rhythm (JR). JR although sensitive, is not specific for elimination of SP conduction. Our objective was to prospectively evaluate feasibility and safety of SP elimination using fast atrial rate pacing (FAP) during RF delivery. METHODS: Consecutive patients admitted for atrioventricular nodal re-rentrant tachycardia (AVNRT) ablation were included. The rate of proximal coronary sinus (CS) pacing was set to a value constantly yielding antegrade SP conduction, while carefully monitoring the AH interval. RF delivery (at the lower part of Koch's triangle) was considered successful if the AH shortened ≥ 14 ms or if transition from Wenckebach (WK) periods to a 1:1 conduction occurred. RESULTS: 24 patients were included (54 ± 20 y). Typical AVNRT was induced in all (cycle length 349 ± 83 ms). RF delivery during CS pacing (335 ± 73 ms) led to AH shortening by 51 ± 25 ms in 13 patients. In 10 patients, a transition from 3:2 or 4:3 WK periods to 1:1 conduction occurred during the successful pulse. In one patient, atrial fibrillation was systematically induced during FAP, requiring conventional ablation. Non-inducibility, and SP conduction disappearance was obtained in all patients. No patient developed AV block. After a follow-up of 12 ± 3 months, no recurrences were observed. CONCLUSION: SP ablation using FAP during RF delivery allows direct visualisation of its disappearance. In our cohort of patients, this technique was feasible without safety compromise.

Does Unidirectional Block Exist after a Radiofrequency Line Creation? Insights from Ultra-High-Density Mapping (The UNIBLOCK Study).

BACKGROUND: Whether unidirectional conduction block (UB) can be observed after creation of a radiofrequency (RF) line is still debated. Previous studies reported a prevalence of 9 to 33% of UB, but the assessment was performed using a point-by-point recording across the line. Ultra-high-density (UHD) system may bring some new insights on the exact prevalence of UB. PURPOSE: A prospective study was conducted to assess the prevalence of UB and bidirectional block (BB) using UHD system after RF line creation. METHODS: Patients referred for atrial RF ablation procedure were included in this multicenter prospective study. UHD maps were performed by pacing both sides of the created line. RESULTS: A total of 80 maps were created in 40 patients (67 ± 12 years, 70% male) by pacing (mean cycle length 600 ± 57 ms) from both sides of the cavotricuspid isthmus line. After a 47 ± 17 min waiting time after the last RF application, UHD maps (mean number of 4842 ± 5010 electrograms, acquired during 6 ± 5 min) showed that BB was unambiguously confirmed on all of them. UB was not observed in any map. After a mean follow-up of 12 ± 4 months, 6 (14%) patients experienced an arrhythmia recurrence. CONCLUSION: After creation of an RF line, no case of UB was observed using UHD mapping, suggesting that the presence of a conduction block along a RF line is always associated with a block in the opposite direction.

Quality of life and healthcare utilisation improvements after atrial fibrillation ablation.

OBJECTIVE: Pulmonary vein isolation (PVI) guided by a standardised CLOSE (contiguous optimised lesions) protocol has been shown to increase clinical success after catheter ablation for paroxysmal atrial fibrillation (PAF). This study analysed healthcare utilisation and quality of life (QOL) outcomes from a large multicentre prospective study, measured association between QOL and atrial fibrillation (AF) burden and identified factors associated with lack of QOL improvement. METHODS: CLOSE-guided ablation was performed in 329 consecutive patients (age 61.4 years, 60.8% male) with drug-refractory PAF in 17 European centres. QOL was measured at baseline and 12 months post-ablation via Atrial Fibrillation Effect on QualiTy of Life Survey (AFEQT) and EuroQoL EQ-5D-5L questionnaires. All-cause and cardiovascular hospitalisations and cardioversions over 12 months pre-ablation and post-ablation were recorded. Rhythm monitoring included weekly and symptom-driven trans-telephonic monitoring, plus ECG and Holter monitoring at 3, 6 and 12 months. AF burden was defined as the percentage of postblanking tracings with an atrial tachyarrhythmia ≥30 s. Continuous measures across multiple time points were analysed using paired t-tests, and associations between various continuous measures were analysed using independent sample t-tests. Each statistical test used two-sided p values with a significance level of 0.05. RESULTS: Both QOL instruments showed significant 12-month improvements across all domains: AFEQT score increased 25.1-37.5 points and 33.3%-50.8% fewer patients reporting any problem across EuroQoL EQ-5D-5L domains. Overall, AFEQT improvement was highly associated with AF burden (p=0.009 for <10% vs ≥10% burden, p<0.001 for <20% vs ≥20% burden). Cardiovascular hospitalisations were significantly decreased after ablation (42%, p=0.001). Patients without substantial improvement in AFEQT (55/301, 18.2%) had higher AFEQT and CHA2DS2-VASc scores at baseline, and higher AF burden following PVI. CONCLUSIONS: QOL improved and healthcare utilisation decreased significantly after ablation with a standardised CLOSE protocol. QOL improvement was significantly associated with impairment at baseline and AF burden after ablation. TRIAL REGISTRATION NUMBER: NCT03062046.

Standardized pulmonary vein isolation workflow to enclose veins with contiguous lesions: the multicentre VISTAX trial.

AIMS: To evaluate the safety and effectiveness of pulmonary vein isolation in paroxysmal atrial fibrillation (PAF) using a standardized workflow aiming to enclose the veins with contiguous and optimized radiofrequency lesions. METHODS AND RESULTS: This multicentre, prospective, non-randomized study was conducted at 17 European sites. Pulmonary vein isolation was guided by VISITAG SURPOINT (VS target ≥550 on the anterior wall; ≥400 on the posterior wall) and intertag distance (≤6 mm). Atrial arrhythmia recurrence was stringently monitored with weekly and symptom-driven transtelephonic monitoring on top of standard-of-care monitoring (24-h Holter and 12-lead electrocardiogram at 3, 6, and 12 months follow-up). Three hundred and forty participants with drug refractory PAF were enrolled. Acute effectiveness (first-pass isolation proof to a 30-min wait period and adenosine challenge) was 82.4% [95% confidence interval (CI) 77.4-86.7%]. At 12-month follow-up, the rate of freedom from any documented atrial arrhythmia was 78.3% (95% CI 73.8-82.8%), while freedom from atrial arrhythmia by standard-of-care monitoring was 89.4% (95% CI 78.8-87.0%). Freedom fromrepeat ablations by the Kaplan-Meier analysis was 90.4% during 12 months of follow-up. Of the 34 patients with repeat ablations, 14 (41.2%) demonstrated full isolation of all pulmonary vein circles. Primary adverse event (PAE) rate was 3.6% (95% CI 1.9-6.3%). CONCLUSIONS: The VISTAX trial demonstrated that a standardized PAF ablation workflow aiming for contiguous lesions leads to low rates of PAEs, high acute first-pass isolation rates, and 12-month freedom from arrhythmias approaching 80%. Further research is needed to improve the reproducibility of the outcomes across a wider range of centres.Clinical trial registration: ClinicalTrials.gov, number NCT03062046, https://clinicaltrials.gov/ct2/show/NCT03062046.

QT Interval Prolongation Under Hydroxychloroquine/Azithromycin Association for Inpatients With SARS-CoV-2 Lower Respiratory Tract Infection.

Association between Hydroxychloroquine (HCQ) and Azithromycin (AZT) is under evaluation for patients with lower respiratory tract infection (LRTI) caused by the Severe Acute Respiratory Syndrome (SARS-CoV-2). Both drugs have a known torsadogenic potential, but sparse data are available concerning QT prolongation induced by this association. Our objective was to assess for COVID-19 LRTI variations of QT interval under HCQ/AZT in patients hospitalized, and to compare manual versus automated QT measurements. Before therapy initiation, a baseline 12 lead-ECG was electronically sent to our cardiology department for automated and manual QT analysis (Bazett and Fridericia's correction), repeated 2 days after initiation. According to our institutional protocol (Pasteur University Hospital), HCQ/AZT was initiated only if baseline QTc ≤ 480ms and potassium level> 4.0 mmol/L. From March 24th to April 20th 2020, 73 patients were included (mean age 62 ± 14 years, male 67%). Two patients out of 73 (2.7%) were not eligible for drug initiation (QTc ≥ 500 ms). Baseline average automated QTc was 415 ± 29 ms and lengthened to 438 ± 40 ms after 48 hours of combined therapy. The treatment had to be stopped because of significant QTc prolongation in two out of 71 patients (2.8%). No drug-induced life-threatening arrhythmia, nor death was observed. Automated QTc measurements revealed accurate in comparison with manual QTc measurements. In this specific population of inpatients with COVID-19 LRTI, HCQ/AZT could not be initiated or had to be interrupted in less than 6% of the cases.

How is Contact Force implemented in routine clinical practice? Results from a French National and Monaco Survey.

BACKGROUND: Combination of elementary parameters (force, time, power, impedance drop) has been proposed to optimize radiofrequency (RF) delivery. They have been partially validated in clinical studies. AIMS: The aim of this study was to assess contact-force (CF) implementation into clinical practice. METHODS: A 36-question electronic form was sent to 105 electrophysiologists (EP) including some general questions concerning the practice of catheter atrial fibrillation ablation and items concerning the parameters used for CF-guided ablation. RESULTS: Answers from 98 EP were collected (93% response rate). The CF-catheters used were Smart Touch, Biosense (52%), Tacticath, Saint-Jude Medical (12%), or both (27%) and no CF (9%). The power applied on the left atrial (LA) anterior (LAAW) and posterior (LAPW) wall was, respectively, 26-34 W (for 73% of the EP) and below 25 W (88% of the EP). Forty percent of the Visitag® users mostly used the nominal parameters. Seventy-five percent of the users did not use automatic display of the impedance drop. For the Tacticath users, 57% used a target value of 400 gs on the LAAW and 300 to 400 gs on the LAPW. Lesion Size Index was exceptionally used. CONCLUSIONS: The parameters used for CF-guided ablation are widely variable among the different operators. Further prospective studies are needed to validate the targets for automatic annotation of the RF applications.

Electrocardiographic modifications induced by breast implants.

BACKGROUND: Echocardiography realization can be challenging in the presence of breasts implants (BI). It is less known if electrocardiograms (ECG) may be modified in the presence of BI. METHODS: ECG from women with BI (and without any known cardiac structural disease) were sent and analyzed by two experienced electrophysiologists (EP1 and EP2) who were blinded and completely unaware of the context of the patients (Group 1). ECG from a control matched-group of female women without BI (Group 2) were also blindly sent for analysis. RESULTS: ECG were collected from 28 women with BI (42 ± 8 years) without any acute medical condition. A proportion of 42% of the ECG were considered abnormal by EP1 and 46% by EP2. The abnormalities were for EP1: negative T waves (5), ST depression in inferolateral leads (2), absence of R wave progression from V1 to V4 (4), left ventricular (LV) hypertrophy (1), long QT(1), early repolarization (1), short PR (1); For EP2: negative T waves (6), ST depression in inferolateral leads (2), absence of R wave progression from V1 to V4 (4), LV hypertrophy(3), long QT (1), early repolarization (1). ECG from group 2 were considered abnormal in only 1 patient (5%) for EP1, and normal in all for EP2 (P = 0.0002 between the groups). CONCLUSIONS: ECG from women with BI were considered abnormal in 42% to 46% of the cases by expert readers. ECG interpretation can thus be misleading in these women.

Evaluation of a Strategy Aiming to Enclose the Pulmonary Veins With Contiguous and Optimized Radiofrequency Lesions in Paroxysmal Atrial Fibrillation: A Pilot Study.

OBJECTIVES: This study sought to evaluate the safety and the acute and 1 year outcomes of an ablation protocol aiming to enclose the PV with a contiguous and optimized RF circle by targeting region-specific criteria for lesion depth assessed by ablation index and interlesion distance. BACKGROUND: Reconnections after pulmonary vein (PV) isolation are explained by insufficient lesion depth and/or discontiguity of radiofrequency (RF) lesions. METHODS: A total of 130 consecutive patients with paroxysmal atrial fibrillation (AF) underwent PV encircling using a contact force-sensing catheter. RF was delivered targeting interlesion distance ≤6 mm and ablation index ≥400 at posterior wall and ≥550 at anterior wall. Recurrence was defined as any AF, atrial tachycardia (AT), or atrial flutter (AFL) (AF/AT/AFL >30 s) on Holter electrocardiographs at 3, 6, and 12 months. RESULTS: Procedure and RF time per circle were 155 ± 28 min and 17 ± 5 min, respectively. Incidence of first-pass and adenosine-proof isolation were 98% and 98%, respectively. One short-lived transient ischemic attack was observed. At 12 months, single-procedure freedom from AF/AT/AFL was 91.3% in those 104 patients off antiarrhythmic drug therapy and 96.2% in those 26 patients on antiarrhythmic drug therapy. Single-procedure freedom from both AF/AT/AFL and antiarrhythmic drug therapy was 73.1%. CONCLUSIONS: This study suggests that an ablation protocol respecting strict criteria for lesion depth and contiguity results in acute durable PV isolation followed by a high single-procedure arrhythmia-free survival at 1 year. A prospective, multicenter trial is ongoing.

Improving procedural and one-year outcome after contact force-guided pulmonary vein isolation: the role of interlesion distance, ablation index, and contact force variability in the 'CLOSE'-protocol.

Aims: We have recently shown that a contact force (CF)-guided ablation protocol respecting region-specific criteria of lesion contiguity and lesion depth ('CLOSE' protocol) is associated with high incidence of acute durable pulmonary vein (PV) isolation (PVI) and a high single-procedure arrhythmia-free survival at 1 year. In the present study, we compared efficiency, safety, and efficacy of 'CLOSE'-guided PVI to conventional CF-guided PVI (CONV-CF). Methods and results: Fifty consecutive paroxysmal atrial fibrillation (AF) patients underwent PV encircling using a CF-sensing catheter targeting an interlesion distance (ILD) ≤6 mm and ablation index (AI) ≥400 and ≥550 at posterior and anterior wall ('CLOSE' group). Results were compared to the last 50 patients undergoing 'CONV-CF'. All patients underwent adenosine testing after PVI. Arrhythmia recurrence was defined as any atrial tachyarrhythmia (ATA) >30 s on Holter at 3, 6, and 12 months. Clinical characteristics did not differ. Contact force variability was comparable in between both groups (proportion of applications with intermittent contact 2% in 'CLOSE' vs. 1% in CONV-CF, P = 0.67). In the 'CLOSE' group, procedure time and radiofrequency (RF) time per circle were shorter (respectively 149 ± 33 min vs. 192 ± 42 min, P < 0.0001 and 18 ± 4 min vs 28 ± 7.5 min, P < 0.0001) and incidence of adenosine-proof isolation was higher (97% vs. 82%, P < 0.001). No complications were observed in the 'CLOSE' group, one tamponade in the 'CONV-CF' group. At 12 months, single-procedure freedom from ATA was 94% in 'CLOSE' vs. 80% in 'CONV-CF' group (P < 0.05). In both groups, the majority of reconnections at repeat were associated with either ILD > 6 mm and/or AI < 400/550 (100% vs. 83%, P = 0.99). Conclusion: 'CLOSE'-guided PVI improves procedural and 1 year outcome in CF-guided PVI while shortening procedure time. Improvement cannot be explained by differences in CF variability and is most likely due to the strict application of criteria for contiguity and ablation index. A randomized controlled trial is needed to exclude the possible contribution of a learning curve.

Evaluation of left atrial linear ablation using contiguous and optimized radiofrequency lesions: the ALINE study.

Aims: Achieving block across linear lesions is challenging. We prospectively evaluated radiofrequency (RF) linear ablation at the roof and mitral isthmus (MI) using point-by-point contiguous and optimized RF lesions. Methods and results: Forty-one consecutive patients with symptomatic persistent AF underwent stepwise contact force (CF)-guided catheter ablation during ongoing AF. A single linear set of RF lesions was delivered at the roof and posterior MI according to the 'Atrial LINEar' (ALINE) criteria, i.e. point-by-point RF delivery (up to 35 W) respecting strict criteria of contiguity (inter-lesion distance ≤ 6 mm) and indirect lesion depth assessment (ablation index ≥550). We assessed the incidence of bidirectional block across both lines only after restoration of sinus rhythm. After a median RF time of 7 min [interquartile range (IQR) 5-9], first-pass block across roof lines was observed in 38 of 41 (93%) patients. Final bidirectional roof block was achieved in 40 of 41 (98%) patients. First-pass block was observed in 8 of 35 (23%) MI lines, after a median RF time of 8 min (IQR 7-12). Additional endo- and epicardial (54% of patients) RF applications resulted in final bidirectional MI block in 28 of 35 (80%) patients. During a median follow-up of 396 (IQR 310-442) days, 12 patients underwent repeat procedures, with conduction recovery in 4 of 12 and 5 of 10 previously blocked roof lines and MI lines, respectively. No complications occurred. Conclusion: Anatomical linear ablation using contiguous and optimized RF lesions results in a high rate of first-pass block at the roof but not at the MI. Due to its complex 3D architecture, the MI frequently requires additional endo- and epicardial RF lesions to be blocked.

PulmOnary vein isolation With vs. without continued antiarrhythmic Drug trEatment in subjects with Recurrent Atrial Fibrillation (POWDER AF): results from a multicentre randomized trial.

Aims: Catheter ablation is indicated in patients with symptomatic paroxysmal atrial fibrillation (AF) resistant to antiarrhythmic drug therapy (ADT). We investigated whether continued use of previously ineffective ADT beyond the post-ablation blanking period reduces recurrence of atrial tachyarrhythmia within the 1st year after ablation. Methods and results: This was a multicentre, randomized controlled study in patients undergoing contact force-guided pulmonary vein isolation (PVI) for paroxysmal AF in whom previously ineffective ADT was continued during a blanking period of 3 months. If free of AF at the end of the blanking period, patients were randomly assigned in the ratio of 1:1 to continue ADT (ADT ON group, n = 77) or discontinue ADT (ADT OFF group, n = 76). Patients were followed up until 1 year after PVI, with clinical visits, Holter monitoring, and quality-of-life (QOL) questionnaires at 6 and 12 months post-procedure. Analysis of the primary endpoint (any documented atrial tachyarrhythmia lasting >30 s) was performed according to the modified intention-to-treat principle. Secondary endpoints included repeat ablation, unscheduled visits, and QOL score. Baseline clinical characteristics and initial ablation procedure characteristics were comparable between both groups. Three patients were lost to follow-up in each arm. The primary endpoint was observed in 2 of 74 (2.7%) patients in the ADT ON group vs. 16 of 73 (21.9%) patients in the ADT OFF group (P < 0.001). The ADT ON group had a lower rate of repeat ablation [1.4% vs. 19.2%, hazard ratio (HR) = 0.053; 95% confidence interval (CI) 0.007-0.399; P < 0.01) and less unscheduled arrhythmia-related health care visits (2.7% vs. 20.5%, HR = 0.055, 95% CI 0.007-0.410; P < 0.01). Quality-of-life scores were similar in both groups. Conclusion: In patients free of AF at the end of 3 months of post-ablation blanking period, continued use of previously ineffective ADT significantly reduces the recurrence of atrial tachyarrhythmia in the 1st year after PVI.

Screening for atrial fibrillation in hospitalised geriatric patients.

OBJECTIVES: To assess whether daily short-term rhythm strip recordings on top of routine clinical care could increase the atrial fibrillation (AF) detection rate in the hospitalised elderly. METHODS: A hand-held device storing a bipolar ECG during 1 min was used for daily rhythm recording in hospitalised elderly patients. RESULTS: During 2 months, all patients admitted to the Department of Geriatric Medicine were screened (n=327). Five patients refused to participate in the study and 70 patients were unable to hold the device due to severe mental (n=46) or motor impairment (n=24). In the remaining 252 patients, 1582 recordings were successfully obtained after 1624 attempts with a median acquisition time of 1 min (min 1, max 9, IQR 1-2 min). The rhythm strips were not reliable interpretable due to artefacts in three patients or an implantable cardiac pulse generator in another 28 patients. Detailed clinical information was available in 214/221 patients. Mean age was 84±6 years. On top of 71 (33%) patients with AF identified by routine clinical care (history, n=64 or de novo detected during current hospitalisation, n=7), review of all rhythm strips identified another 28 patients (13%) with AF. All these patients had a CHA2DS2VASc score ≥2. A contraindication for anticoagulation was present in only 8/28 (25%) of identified patients. CONCLUSIONS: On top of routine clinical care, daily short-term rhythm strip recordings identified another 13% of elderly hospitalised patients with AF, leading to an overall prevalence of 46% in hospitalised patients. This can have significant therapeutic implications with respect to initiation of anticoagulation.

Determinants of Acute and Late Pulmonary Vein Reconnection in Contact Force-Guided Pulmonary Vein Isolation: Identifying the Weakest Link in the Ablation Chain.

BACKGROUND: Pulmonary vein reconnection (PVR) still determines recurrences of atrial fibrillation after contact force (CF)-guided pulmonary vein isolation. We studied whether acute PVR (adenosine and waiting time) and late PVR (at repeat) are explained by incomplete transmurality and contiguity within the deployed radiofrequency circle. METHODS AND RESULTS: We analyzed 42 CF-guided ipsilateral pulmonary vein isolation procedures. For each radiofrequency tag within the circle, we collected data reflecting lesion depth (time of application, power, impedance drop [Δ-Imp], CF, force-time integral [FTI], and ablation index [AI]) and contiguity (automated interlesion distance [ILD]). Ablation line contiguity index (ALCI) was developed as a novel automated algorithm combining depth and contiguity into one single criterion. Each circle was subdivided into 10 segments. For each segment, we determined its weakest link by annotating timemin, powermin, Δ-Impmin, CFmin, FTImin, AImin, ILDmax, and ALCImin. Compared with segments without PVR (n=758), PVR segments (n=44) were characterized by lower Δ-Impmin (4.8 versus 7.4 Ω), CFmin (8.5 versus 11.8 g), FTImin (351 versus 473 gs), AImin (367 versus 408 arbitrary unit [au]), and higher ILDmax (6.8 versus 5.5 mm). ALCImin was significantly lower in segments with PVR (74% versus 104%; P<0.001) and was associated with the highest accuracy to predict durable segments (area under the curve=0.73). CONCLUSIONS: In CF-guided pulmonary vein isolation, PVR is explained by lack of both lesion depth and contiguity within the deployed radiofrequency circle. ALCI, a novel measure combing contiguity and depth, is the most accurate predictor for durable segments. By avoiding weak links in the ablation chain, ALCI-guided ablation is expected to improve success rate of point-by-point radiofrequency ablation.

Is Mapping of Complex Fractionated Electrograms Obsolete?

Atrial fibrillation is the most common clinically encountered arrhythmia and catheter ablation has emerged as a viable treatment option in drug-refractory cases. Pulmonary vein isolation is widely regarded as the cornerstone for successful outcomes in paroxysmal AF given that the pulmonary veins are a frequent source of AF triggering. Ablation strategies for persistent AF are less well defined. Mapping and ablation of complex fractionated electrograms (CFAEs) is one strategy that has been proposed as a means of modifying the atrial substrate thought to be critical to the perpetuation of AF. Results of clinical studies have proved conflicting and there are now strong data to suggest that pulmonary vein isolation alone is associated with outcomes comparable to those of pulmonary vein isolation plus CFAE ablation. Several studies have demonstrated that the majority of CFAEs are passive phenomena and therefore not critical to the perpetuation of AF. Conventional mapping technologies (using a bipolar or circular mapping catheter) lack the spatiotemporal resolution to identify mechanisms of AF persistence. The development of wide-field mapping techniques allows simultaneous acquisition of activation data over large areas. This strategy has the potential to better identify regions critical to AF perpetuation, and preliminary data suggest that ablation outcomes are improved when guided by these techniques. While mapping and ablation of all CFAEs is almost certainly obsolete, better identification of regions responsible for AF persistence has the potential to improve outcomes in ablation of persistent AF.