Clinical utility of automated ablation lesion tagging based on catheter stability information (VisiTag Module of the CARTO 3 System) with contact force-time integral during pulmonary vein isolation for atrial fibrillation. J Interv Card Electrophysiol. 2016;47:245-252. [PMID: 27278517 DOI: 10.1007/s10840-016-0156-z]

Clinical insights into the role of bepridil in recurrence prevention after ablation of persistent atrial fibrillation

Background

The role of bepridil in preventing atrial fibrillation (AF) recurrence following ablation for persistent atrial fibrillation (PerAF) remains uncertain, particularly in patients with severe atrial substrates.

Methods

This retrospective study included 232 consecutive PerAF patients who underwent AF ablation between 2014 and 2019. Among them, 162 received bepridil for 3 months post-ablation (Bepridil group), while 70 received no antiarrhythmic drugs (No-AADs group). Baseline characteristics, procedural details, and outcomes were compared. Kaplan-Meier analysis and Cox regression models were used to evaluate AF/atrial tachycardia (AT) recurrence, with bepridil use treated as a time-dependent covariable.

Results

The Bepridil group had a higher body mass index (25.1 ± 3.7 vs. 23.8 ± 3.9), a higher prevalence of patients with a LAD >40 mm and a LAV >50 mL (67.9% vs. 47.1%, 64.2% vs. 48.5%, respectively), and lower left atrial appendage flow velocity (37.6 ± 15.0 vs. 42.7 ± 20.5 cm/min). They more frequently underwent intracardiac atrial cardioversion (61.7% vs. 40.0%) and additional extra-pulmonary vein ablation (35.2% vs. 15.7%), but were less likely to receive balloon-based ablation (39.5% vs. 62.9%) (p < 0.05 for all comparison). During a median follow-up of 23.3 months, AF/AT-free survival at 2 years was comparable between the Bepridil and No-AADs groups (80.4% vs. 81.7%; p = 0.61). This finding remained consistent after adjusting for baseline characteristics and considering bepridil as a time-dependent covariable. No bepridil-related adverse events occurred.

Conclusion

Bepridil may have a limited role in preventing AF/AT recurrence in PerAF patients, particularly those with severe atrial substrates. However, its overall impact appears to be small, warranting further investigation.

Validation of ablation site classification accuracy and trends in the prediction of potential reconnection sites for atrial fibrillation using the CARTONET® R12.1 model

Background

CARTONET® enables automatic ablation site classification and reconnection site prediction using machine learning. However, the accuracy of the site classification model and trends of the site prediction model for potential reconnection sites are uncertain.

Methods

We studied a total of 396 cases. About 313 patients underwent pulmonary vein isolation (PVI), including a cavotricuspid isthmus (CTI) ablation (PVI group) and 83 underwent PVI and additional ablation (i.e., box isolation) (PVI+ group). We investigated the sensitivity and positive predictive value (PPV) for automatic site classification in the total cohort and compared these metrics for PV lesions versus non-PV lesions. The distribution of potential reconnection sites and confidence level for each site was also investigated.

Results

A total of 29,422 points were analyzed (PV lesions [n = 22 418], non-PV lesions [n = 7004]). The sensitivity and PPV of the total cohort were 71.4% and 84.6%, respectively. The sensitivity and PPV of PV lesions were significantly higher than those of non-PV lesions (PV lesions vs. non-PV lesions, %; sensitivity, 75.3 vs. 67.5, p < .05; PPV, 91.2 vs. 67.9, p < .05). CTI and superior vena cava could not be recognized or analyzed. In the potential reconnection prediction model, the incidence of potential reconnections was highest in the posterior, while the confidence was the highest in the roof.

Conclusion

The automatic site classification of the CARTONET®R12.1 model demonstrates relatively high accuracy in pulmonary veins excluding the carina. The prediction of potential reconnection sites feature tends to anticipate areas with poor catheter stability as reconnection sites.

Trends over the recent 6 years in ablation modalities and strategies, post-ablation medication, and clinical outcomes of atrial fibrillation ablation

Background

Ablation strategies and modalities for atrial fibrillation (AF) have transitioned over the past decade, but their impact on post-ablation medication and clinical outcomes remains to be fully investigated.

Methods

We divided 682 patients who had undergone AF ablation in 2014-2019 (420 paroxysmal AFs [PAF], 262 persistent AFs [PerAF]) into three groups according to the period, that is, the 2014-2015 (n = 139), 2016-2017 (n = 244), and 2018-2019 groups (n = 299), respectively.

Results

Persistent AF became more prevalent and the left atrial (LA) diameter larger over the 6 years. Extra-pulmonary vein (PV)-LA ablation was more frequently performed in the 2014-2015 group than in the 2016-2017 and 2018-2019 groups (41.1% vs. 9.1% and 8.1%; p < .001). The 2-year freedom rate from AF/atrial tachycardias for PAF was similar among the three groups (84.0% vs. 83.1% vs. 86.7%; p = .98) but lowest in the 2014-2015 group for PerAF (63.9% vs. 82.7% and 86.3%; p = .025) despite the highest post-ablation antiarrhythmic drug use. Cardiac tamponade was significantly decreased in the 2018-2019 group (3.6% vs. 2.0% vs. 0.33%; p = 0.021). There was no difference in the 2-year clinically relevant events among the three groups.

Conclusion

Although ablation was performed in a more diseased LA and extra-PV-LA ablation was less frequent in recent years, the complication rate decreased, and AF recurrences for PAF remained unchanged, but that for PerAF decreased. Clinically relevant events remained unchanged over the recent 6 years, suggesting that the impact of the recent ablation modalities and strategies on remote clinically relevant events may be small during this study period.

High-power, short-duration ablation for atrial fibrillation: Pros and cons

This article reviews and compares the rationale and evidence supporting high-power, short-duration radiofrequency (RF) ablation with those of conventional-power, conventional-duration RF ablation for atrial fibrillation (AF). The pros and cons of each approach, biophysics of ablation, pre-clinical studies informing clinical utilization, and the accumulated clinical evidence are presented. Both conventional-power, conventional-duration RF ablation and high-power, short-duration ablation are similarly safe, and effective approaches for AF ablation. Theoretical advantages of high-power, short-duration ablation, including greater procedure efficiency and limited conductive heating of collateral structures, must be weighed against the narrower safety margin related to rapid energy delivery during high power ablation.

Impact of the combined use of intracardiac ultrasound and a steerable sheath visualized by a 3D mapping system on pulmonary vein isolation

BACKGROUND

A novel steerable sheath visualized on a three-dimensional mapping system has become available in this era in which a durable pulmonary vein (PV) isolation (PVI) with reduced fluoroscopy is required.

METHODS

In 60 patients who underwent a PVI with a visualized sheath (n = 30) and non-visualized conventional sheath (n = 30), the fluoroscopic time and catheter stability during the PVI were analyzed.

RESULTS

The fluoroscopic time during the transseptal access (0 [0, 0.1] vs. 1.4 [0.8, 2.3] minutes, P < .001) and PVI (0 [0, 0.1] vs. 0.4 [0.2, 1.1] minutes, P < .001) were shorter in the visualized sheath group than conventional sheath group. The procedure time during the PVI (32.0 [26.8, 36.3] vs. 41.0 [31.8, 47.3] minutes, P = .01), particularly during the right PVI (15.0 [12.8, 18.0] vs. 23.0 [15.8, 26.3] minutes, P = .009), was shorter in the visualized sheath group than conventional sheath group, however, that during the other steps was equivalent. The standard deviation of the catheter contact force during each radiofrequency application was smaller in the visualized sheath group than conventional sheath group (4.5 ± 2.7 vs. 4.9 ± 3.1 g, P = .001). The impedance drop for each lesion was larger in the visualized sheath group than conventional sheath group (10.7 ± 6.5 vs. 9.8 ± 5.5 ohms, P < .001). The incidence of acute PV reconnections per patient (30% vs. 23%, P = .56) and per PV segment (2.5% vs. 2.3%, P = .83) were similar between the two groups. No major complications occurred in either sheath group.

CONCLUSIONS

The use of visualized sheaths may reduce the fluoroscopic time and improve the catheter stability during the PVI.

Clinical outcomes after pulmonary vein isolation using an automated tagging module in patients with paroxysmal atrial fibrillation

Background

An automated tagging module (VISITAG™; Biosense Webster, Irvine, CA) allows objective demonstration of energy delivery. However, the effect of VISITAG™ on clinical outcomes remains unclear. This study evaluated (1) clinical outcome after AF ablation using VISITAG™ and (2) the prevalence of gaps in the ablation line.

Methods

This retrospective analysis included 157 consecutive patients (mean age, 56.7 years; 73.2% men) with paroxysmal atrial fibrillation who underwent successful PVI between 2013 and 2016. Outcomes after the index procedure were compared between those using the VISITAG™ module (VISITAG group, n = 62) and those not using it (control group, n = 95). The primary outcome was recurrence of AF or atrial tachycardia after a blanking period of 3 months.

Results

The VISITAG group showed significantly shorter overall procedure time (172.2 ± 37.6 min vs. 286.9 ± 66.7 min, P < 0.001), ablation time (49.8 ± 9.7 min vs. 82.8 ± 28.2 min, P < 0.001), and fluoroscopy time (11.8 ± 5.3 min vs. 34.2 ± 30.1 min, P < 0.001) compared with controls. The 1-year recurrence-free survival rate was not statistically different between the groups (70.8% in the VISITAG group vs. 79.2% in the control group, P = 0.189). Gaps in the VISITAG line were common in the both carina and left side pulmonary veins. Patients without gaps (≥ 5 mm) by the criteria emphasizing catheter stability (> 15 s, < 4 mm range, > 60% force over time, > 6 g contact force) showed higher recurrence-free survival rate compared with those with gaps (borderline statistical significance, 91.7% vs. 66.0%, P = 0.094).

Conclusion

Use of the VISITAG™ module significantly reduced procedure, ablation, and fluoroscopic times with a similar AF/AT recurrence rate compared with the conventional ablation. Clinical implications of minimizing gaps along the ablation line should be evaluated further in the future prospective studies.

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.

The modified ablation index: a novel determinant of acute pulmonary vein reconnections after pulmonary vein isolation

BACKGROUND

Although pulmonary vein isolation (PVI) guided by the ablation index (AI) has been well-developed, acute PV reconnections (PVRs) still occur. This study aimed to compare the prognostic performance of the modified AI and its optimal cut-off value for the prediction of acute PVRs to ensure durable PVI.

METHODS

Three-dimensional left atrium (LA) voltage maps created before an extensive encircling PVI in 64 patients with atrial fibrillation (AF) (45 men, 62 ± 10 years) were examined for an association between electrogram voltage amplitude recorded from the PV-LA junction and acute post-PVI PVRs (spontaneous PVRs and/or ATP-provoked dormant PV conduction).

RESULTS

Acute PVRs were observed in 22 patients (34%) and 33 (3%) of the 1012 PV segments. Acute PVRs were significantly associated with segments with higher bipolar voltage zones (3.23 ± 1.17 vs. 1.97 ± 1.20 mV, P < 0.0001), lower mean AI values (449 [428-450] vs. 460 [437-486], P = 0.05), and radiofrequency lesion gaps ≥ 6 mm (48 vs. 32%, P = 0.04), but not with contact force, force-time integral, or power. We created the modified AI calculated as AI/LA bipolar voltage, and found it to be significantly lower in areas with acute PVRs than in those without (152 [109-185] vs. 256 [176-413] AU/mV, P < 0.0001). Univariate analysis showed the prognostic performance of the modified AI, with an area under the curve of 0.801 (0.775-0.825), to be the highest of all the significant parameters.

CONCLUSIONS

Low values of the novel modified AI on the PV-encircling ablation line were strongly associated with acute PVRs.

Gains in Paroxysmal Atrial Fibrillation Ablation Using a Standardized Workflow to Optimize Contact Force Technologies

Background

Catheter ablation technology has evolved rapidly in recent years. There is a need to understand the impact of these advances on efficiency, safety, and effectiveness in real-world populations. The objective of this study was to evaluate a standardized workflow that integrates a contact force (CF) catheter and stability module in an attempt to optimize efficiency and clinical outcomes of paroxysmal atrial fibrillation (PAF) ablation, and to compare the outcomes of this workflow with existing ablation technologies at a high-volume center.

Methods

Consecutive ablations for PAF from July 2013 - June 2016 were included. Radiofrequency (RF) ablations were performed with the ThermocoolSF Catheter (SF) through April 2014, after which a change was made to the ThermocoolSmarttouchCatheter (ST)with a standardized workflow. Cryoballoon ablations (CA) were performed with theArctic FrontAdvancebetween July 2013 and March 2016. Systematic collection of 12-month effectiveness data began in July 2014. Prior to that time, only acute outcomes and reablations were captured.

Results

Procedural data for 32 SF, 232 ST, and 59 CA procedures for PAF were available. Mean procedure times were similar across SF and CA, and moderately shorter with ST (p=0.0201). Fluoroscopy times were substantially reduced with ST (p<0.0001). Complication rates were low and similar across all cohorts (p=0.4744), whereas reablation rates were lowest in the ST cohort (p=0.0194).

Conclusions

PAF ablation using integrated CF and catheter stability technology with a systematic ablation workflow maylead to improvements in both procedural efficiency and reablation rates, without compromising patient safety.

Influence of balloon temperature and time to pulmonary vein isolation on acute pulmonary vein reconnection and clinical outcomes after cryoballoon ablation of atrial fibrillation

BACKGROUND

Limited data exist on indicators of durable pulmonary vein isolation (PVI) undergoing cryoballoon ablation (CBA) for atrial fibrillation (AF). We investigated whether balloon temperature and time to PVI can be used to predict early PV reconduction (EPVR), including residual PV conduction and adenosine triphosphate-induced dormant conduction and the relation between touch-up ablation of EPVR sites and mid-term recurrence of AF.

METHODS

We obtained procedural and outcome data from the records of 130 consecutive patients who underwent CBA and followed up for 13.4 months.

RESULTS

EPVR was identified in 86 (17%) PVs of 61 (47%) patients. Balloon temperatures during 30 seconds (-27 ± 5.7°C vs -31 ± 5.5°C), 60 seconds (-36 ± 5.6°C vs -41 ± 5.4°C), and at the nadir point (-41 ± 7.4°C vs -49 ± 7.0°C) were significantly higher, and the time to PVI was longer (90 ± 50 seconds vs 52 ± 29 seconds) in PVs with EPVR than in those without (P < 0.0001 for all). Among PVs without EPVR, the time to PVI was longer and balloon temperature was lower for the left superior pulmonary vein/ right inferior pulmonary vein (LSPV/RIPV) than for the right superior pulmonary vein/left inferior pulmonary vein (RSPV/LIPV) (time: 60 ± 25/73 ± 37 seconds vs 41 ± 31/45 ± 20 seconds, P < 0.0001) (temp: -39.2 ± 11.3/-39.4 ± 8.3°C vs -33.8 ± 10.6/-33.6 ± 6.8°C, P = 0.0023). AF recurrence rates were equivalent between patients with and without EPVR (13% [8/69] vs 15% [9/61], P = 0.845).

CONCLUSIONS

Cryoballoon temperature and time to PVI appear to be useful in predicting durable PVI, that is, prevention of EPVR, but the balloon temperature and time required for PVI differ between PVs. Although EPVR does not predict AF recurrence, high success rates can be expected when touch-up ablation of EPVR sites is performed.

Comparison of the efficacy between impedance-guided and contact force-guided atrial fibrillation ablation using an automated annotation system

BACKGROUND

This study compared the efficacy of catheter ablation of atrial fibrillation (AF) between impedance (IMP)-guided and contact force (CF)-guided annotation using the automated annotation system (VisiTag™).

METHODS

Fifty patients undergoing pulmonary vein isolation (PVI) for AF were randomized to the IMP-guided or CF-guided groups. The annotation criteria for VisiTag™ were a 10 second minimum ablation time and 2 mm maximum catheter movement range. A minimum CF of 10 g was added to the criteria in the CF-guided group. In the IMP-guided group, a minimum IMP drop of over 5 Ω was added to the criteria.

RESULTS

The rates of successful PVI after an initial ablation line were higher in the CF-guided group (80% vs 48%, P = .018). Although average CF was similar between two groups, the average force-time integral (FTI) was significantly higher in the CF-guided group (298.3 ± 65. 2 g·s vs 255.1 ± 38.3 g·s, P = .007). The atrial arrhythmia-free survival at 1 year demonstrated no difference between the two groups (84.0% in the IMP-guided group vs 80.0% in the CF-guided group, P = .737). If the use of any antiarrhythmic drug beyond the blanking period was considered as a failure, the clinical success rate at 1 year was 52.0% for the CF-guided group vs 56.0% for the IMP-guided group (P = .813).

CONCLUSIONS

Atrial fibrillation ablation using an automated annotation system guided by CF improved the success rate of PVI after the initial circumferential ablation. An IMP-guided annotation combined with catheter stability criteria showed similar clinical outcomes as compared to the CF-guided annotation.

Optimization of late gadolinium enhancement cardiovascular magnetic resonance imaging of post-ablation atrial scar: a cross-over study

BACKGROUND

Cardiovascular magnetic resonance (CMR) imaging may be used to visualize post-ablation atrial scar (PAAS), and three-dimensional late gadolinium enhancement (3D LGE) is the most widely employed technique for imaging of chronic scar. Detection of PAAS provides a unique non-invasive insight into the effects of the ablation and may help guide further ablation procedures. However, there is evidence that PAAS is often not detected by CMR, implying a significant sensitivity problem, and imaging parameters vary between leading centres. Therefore, there is a need to establish the optimal imaging parameters to detect PAAS.

METHODS

Forty subjects undergoing their first pulmonary vein isolation procedure for AF had detailed CMR assessment of atrial scar: one scan pre-ablation, and two scans post-ablation at 3 months (separated by 48 h). Each scan session included ECG- and respiratory-navigated 3D LGE acquisition at 10, 20 and 30 min post injection of a gadolinium-based contrast agent (GBCA). The first post-procedural scan was performed on a 1.5 T scanner with standard acquisition parameters, including double dose (0.2 mmol/kg) Gadovist and 4 mm slice thickness. Ten patients subsequently underwent identical scan as controls, and the other 30 underwent imaging with a reduced, single, dose GBCA (n = 10), half slice thickness (n = 10) or on a 3 T scanner (n = 10). Apparent signal-to-noise (aSNR), contrast-to-noise (aCNR) and imaging quality (Likert Scale, 3 independent observers) were assessed. PAAS location and area (%PAAS scar) were assessed following manual segmentation. Atrial shells with standardised %PAAS at each timepoint were then compared to ablation lesion locations to assess quality of scar delineation.

RESULTS

A total of 271 3D acquisitions (out of maximum 280, 96.7%) were acquired. Likert scale of imaging quality had high interobserver and intraobserver intraclass correlation coefficients (0.89 and 0.96 respectively), and showed lower overall imaging quality on 3 T and at half-slice thickness. aCNR, and quality of scar delineation increased significantly with time. aCNR was higher with reduced, single, dose of GBCA (p = 0.005).

CONCLUSION

3D LGE CMR atrial scar imaging, as assessed qualitatively and quantitatively, improves with time from GBCA administration, with some indices continuing to improve from 20 to 30 min. Imaging should be performed at least 20 min post-GBCA injection, and a single dose of contrast should be considered.

TRIAL REGISTRATION

Trial registry- United Kingdom National Research Ethics Service 08/H0802/68 - 30th September 2008.

Impact of left atrial size on isolation area in the acute phase of pulmonary vein isolation using 28 mm cryoballoon

BACKGROUND

The impact of left atrial (LA) size on isolation area (ISA) using a 28-mm second-generation cryoballoon (CB) in the acute phase after pulmonary vein isolation (PVI) and the differences of CB from contact force-guided radiofrequency (RF) ablation have not been fully investigated.

METHODS

We examined 85 consecutive patients (CB group, 35; RF group, 50) with drug-refractory paroxysmal atrial fibrillation who underwent their first PVI procedure at two institutions. We evaluated ISA after PVI using 3D-Merge computed tomography images (GE Healthcare, Little Chalfont, UK) and high-resolution electroanatomical mapping.

RESULTS

Total ISA was significantly smaller in the CB group (20.6 ± 6.0 cm² ) than in the RF group (29.0 ± 7.1 cm² ; P < 0.0001). In the CB group, ISA of the left pulmonary vein (LPV), right pulmonary vein (RPV), and total ISA were not correlated with the left atrial surface area (LASA). The ratios of ISA to LASA (%ISA) of LPV and total ISA negatively correlated with LASA in the CB group (LPV: r = -0.4001, P = 0.0173; total ISA: r = -0.4733, P = 0.0041). In contrast, in the RF group, ISA of LPV, RPV, and total ISA positively correlated with LASA; (LPV: r = 0.5155, P = 0.001; RPV: r = 0.6398, P < 0.0001; total ISA: r = 0.7299, P < 0.0001).

CONCLUSION

ISA created using CB was significantly smaller than that using RF and did not change regardless of LASA increment. Differences in ISA between the two groups became more prominent in the large atrium.

Contiguity Between Ablation Lesions and Strict Catheter Stability Settings Assessed by VISITAGTM Module Improve Clinical Outcomes of Paroxysmal Atrial Fibrillation Ablation - Results From the VISITALY Study

BACKGROUND

Our aim was to evaluate the clinical outcome of paroxysmal atrial fibrillation (AF) ablation with contact force technology, using an automated lesion tagging system (VISITAGTM module) with strict criteria of catheter stability.

METHODS AND RESULTS

We enrolled 200 consecutive patients who underwent pulmonary vein isolation (PVI) in 11 centers and were followed up for 12 months. The stability setting was within 3 mm for ≥10 s and for ≥15 s in 47% and 53% of patients, respectively. A mean of 67.2±21.9 VISITAGs was acquired. Freedom from atrial tachyarrhythmias at follow-up was 77.5% (155/200), and the contiguity between lesions was associated with a higher chronic success rate (96% vs. 77.1%; log-rank P=0.036). Radiofrequency (RF), fluoroscopy times, and recurrence rates at the 12-month follow-up were significantly lower than in a comparison group of 80 patients without VISITAGTM module (42.7±14.5 vs. 50.9±23.6 min; P=0.032; 11.6±7.8 vs. 18.4±12.8 min; P=0.003 and 22.5% vs. 41.2%; P=0.02). Two major complications (1 cardiac tamponade and 1 minor stroke) were observed only in the control group.

CONCLUSIONS

Paroxysmal AF ablation with contact force technology and strict criteria of stability using the VISITAG module was a safe procedure, associated with an improvement in efficiency and a reduction of atrial tachyarrhythmia recurrence at the 12-month follow-up compared with manual annotation. Contiguity between lesions seemed to enhance effectiveness outcomes.

Contact force facilitates the achievement of an unexcitable ablation line during pulmonary vein isolation

AIMS

Contact force (CF) catheters provide catheter-tissue contact information to improve outcome of pulmonary vein isolation (PVI) in paroxysmal atrial fibrillation (PAF). We evaluated different target-CF values for achievement of the additional endpoint of an unexcitable ablation line.

METHODS

A total of 106 patients undergoing PVI were randomized into three groups (G) (G1: target-CF 15 g, G2: target-CF 10 g, G3: CF concealed from operator). The PVI encircling line was divided into predefined sections. Excitable tissue along the PVI-line identified by high output pacing (10 V, 2 ms) was targeted for further ablation.

RESULTS

Mean average CF was 17.4 ± 4.7 g (G1) vs. 12.3 ± 6.0 g (G2) vs. 11.1 ± 6.5 g (G 3) (p < 0.001). Primary unexcitable ablation lines were found in 38.6, 19.4 and 5.7% (G1, G2, G3 respectively; G1 vs. G2 p < 0.05, G1 vs. G3 p < 0.001, G2 vs. G3 ns). Additional radiofrequency (RF)-energy to achieve unexcitability was lowest in G1 (3.6 ± 3.1 kJ vs. 8.6 ± 7.2 kJ (G2) and 10.4 ± 6.7 (G3), p ≤ 0.001, G2 vs. G3 ns) with accordingly lowest additional RF applications in G1 (3.0 ± 2.6 vs. 7.0 ± 5.4 in G2 and 8.4 ± 4.0 in G3; G1 vs. G2 and G3, p < 0.001, G 2 vs. G 3 ns). Sections along ablation lines with low initial CF were most likely to reveal excitability. Single procedure success was 81.9 vs. 73.5 vs. 71.4% (G 1, 2 and 3, p = 0.6) during 437 ± 254 day follow-up.

CONCLUSION

Higher tip-to-tissue CF during PVI facilitates the achievement of an unexcitable ablation line, requiring less additional RF-energy.

Contact force technology integrated with 3D navigation system for atrial fibrillation ablation: improving results?

INTRODUCTION

Pulmonary veins isolation (PVI) by radiofrequency (RF) ablation is currently an established treatment for symptomatic, drug-resistant paroxysmal atrial fibrillation. Although the effectiveness of the therapy has been clearly demonstrated, success rate after a single procedure is still sub-optimal. The main reason for recurrences after PVI is electrical pulmonary vein-atrium reconnection. In order to increase the likelihood of permanent PVI, the creation of a transmural, durable lesion is mandatory. The main determinants of lesion size and transmurality are power, stability, duration and contact-force during RF application. In recent times, catheters with contact-force sensors have been developed and released for clinical use. Areas covered: The present review summarizes rational and clinical evidences for efficacy and safety of contact force (CF) technology integrated into 3D navigation systems for AF ablation. Expert commentary Although CF technology has a strong rational, clinical data on the superior safety and efficacy of CF technology over traditional non-CF catheters are still conflicting. The reason for that is very likely to rely on the lack of definite data on how to optimize CF parameters and how to integrate CF data with power, duration of RF applications and information on catheter stability.

Mechanistic Insights Into Durable Pulmonary Vein Isolation Achieved by Second-Generation Cryoballoon Ablation

Background

The mechanism explaining the efficacy of cryoballoon ablation (CBA) for atrial fibrillation has not been clarified.

Methods and Results

We compared lesion characteristics between patients in whom pulmonary vein isolation (PVI) was performed by CBA (n=56) and those by contact force (CF)-based RF ablation (n=56). We evaluated the 3-dimensional PV morphology before and after cryoballoon inflation. After PVI, a 3D left atrial voltage map was created. Pacing (10 mA and 2 ms) was performed within the low voltage area from the ablation line, and electrically unexcitable ablated tissue was identified. ATP-provoked dormant conduction after PVI occurred in 9 of the 224 (4%) PVs in the CBA group and in 13 of the 224 (6%) PVs in the CF group (P=0.3935). The inflated balloon stretched the PV from the original PV ostial surface by 7.1±3.5 mm, but at sites with (vs, sites without) residual PV potential/dormant conduction, the extent of the PV distension was reduced (4.0±4.0 mm vs. 7.2±3.4 mm, P<0.0001). The unexcitable ablated tissue around the PVs was significantly wider in CB patients than in CF patients (16.7±5.1 mm vs. 5.3±2.3 mm, P<0.0001).

Conclusions

Use of the cryoballoon significantly distends the PV. Without this extensive distention, PVI may not be successful. CBA seems to yield wide unexcitable ablation zones. These factors seem to explain the durability of CBA lesions.

High-voltage zones within the pulmonary vein antra: Major determinants of acute pulmonary vein reconnections after atrial fibrillation ablation

PURPOSE

Recurrence of atrial fibrillation (AF) after pulmonary vein isolation (PVI) is mainly due to PV reconnections. Patient-specific tissue characteristics that may contribute remain unidentified. This study aimed to assess the relationship between the bipolar electrogram voltage amplitudes recorded from the PV-left atrial (LA) junction and acute PV reconnection sites.

METHODS

Three-dimensional LA voltage maps created before an extensive encircling PVI in 47 AF patients (31 men; mean age 62 ± 11 years) were examined for an association between the EGM voltage amplitude recorded from the PV-LA junction and acute post-PVI PV reconnections (spontaneous PV reconnections and/or ATP-provoked dormant PV conduction).

RESULTS

Acute PV reconnections were observed in 17 patients (36%) and in 24 (3%) of the 748 PV segments (16 segments per patient) and were associated with relatively high bipolar voltage amplitudes (3.26 ± 0.85 vs. 1.79 ± 1.15 mV, p < 0.0001) and a relatively low mean force-time integral (FTI) (428 ± 56 vs. 473 ± 76 gs, p = 0.0039) as well as FTI/PV-LA bipolar voltage (137 [106, 166] vs. 295 [193, 498] gs/mV, p < 0.0001). An analysis of the receiver operating characteristic curves revealed a high prognostic performance of the LA bipolar voltage and FTI/PV-LA bipolar voltage for acute PV reconnections (areas under the curve: 0.86 and 0.89, respectively); the best cutoff values were >2.12 mV and ≤183 gs/mV, respectively.

CONCLUSIONS

The PV-LA voltage on the PV-encircling ablation line and FTI/PV-LA voltage were related to the acute post-PVI PV reconnections. A more durable ablation strategy is warranted for high-voltage zones.

Paroxysmal atrial fibrillation ablation: Achieving permanent pulmonary vein isolation by point-by-point radiofrequency lesions

Pulmonary vein isolation by point-by-point radiofrequency catheter ablation constitutes the cornerstone of catheter ablation strategies for the treatment of atrial fibrillation. However, despite advances in pulmonary vein isolation ablation strategies, long-term success rates after ablation remain suboptimal, which highlights the need to develop techniques to achieve more durable lesions. Strategies proposed to improve the durability of pulmonary vein isolation can be divided into two groups: Those addressed to improving the quality of the lesion and those that optimize the detection of acute PV reconnection during the ablation procedure. This manuscript reviews the role and potential benefits of these techniques according to current clinical evidence.