Contact Force Group Research Articles

Study on efficacy, recurrence rate and related risk factors between ablation index and contact force guided radiofrequency ablation of paroxysmal atrial fibrillation in elderly patients

Objective: To compare the efficacy, safety and recurrence rate between ablation index (AI) and contact force (CF) guided radiofrequency ablation of paroxysmal atrial fibrillation in elderly patients. Methods: Elderly patients (age ≥60 years) with paroxysmal atrial fibrillation who received radiofrequency ablation for the first time at Department of Cardiology, Beijing Friendship Hospital from April 2018 to April 2019 were enrolled. Patients were divided into 2 groups: AI-group (n=40) and CF group (n=37) depending on their ablation methods. Follow-up was performed until 1 year post the procedure, and efficacy related indexes like first-pass pulmonary vein isolation (PVI) rate, ablation duration, operation duration and major complications were compared between 2 groups. The recurrence rates between 2 groups and related risk factors after radiofrequency ablation were analyzed. Results: A total of 77 patients [mean age (68.5±6.4) years, 40 were male] were enrolled at last. In AI guided patients, frequency of first-pass PVI rate was higher [52.5%(21 cases) vs 29.7%(3 cases), P=0.011] with a shorter ablation duration [(24.5±1.7) min vs (33.7±2.2) min, P<0.001] and operation duration [(136.6±6.1) min vs (139.7±7.4) min, P=0.048] compared with CF guided group. At 1 year follow-up, AI group showed an amendatory recurrence rate in Kaplan-Meier analysis (22.5% vs 40.5%,log-rank P=0.048). Multivariate Cox regression analysis showed that CF guided ablation (HR=3.272,95%CI:1.319-8.114,P=0.011), enlarged anteroposterior diameter of the left atrium (HR=4.233,95%CI:1.511-11.862,P=0.006) and complicated with coronary heart disease (HR=4.829,95%CI:1.399-16.666,P=0.013) were independent risk factors for recurrence of atrial fibrillation in elderly patients. Conclusions: Compared with CF guided ablation, radiofrequency ablation of paroxysmal atrial fibrillation in elderly patients guided by AI showed a higher first-pass PVI rate, shorter procedure duration of both ablation time and total operation time, meanwhile a lower recurrence rate. Further analysis revealed that different ablation alternation (AI or CF), enlarged anteroposterior diameter of left atrium, and complicated with coronary heart disease are independent risk factors for recurrence after radiofrequency ablation of atrial fibrillation in elderly patients.

Contact force guided radiofrequency current application at developing myocardium

Catheter contact is akey determinantfor lesion size in radiofrequency catheter ablation (RFA). Monitoring of contact force (CF) during RFA has been shown to improve efficacy of RFA in experimental settings as well as in adult patients. Coronary artery narrowing after RFA has been described in experimental settings as well as in children and adults and may be dependent from catheter contact. The value of CF monitoring concerning these issues has not been systematically studied yet. Value of high versus low CF during RFA in piglets was studied to assess lesion size and potential coronary artery involvement mimicking RFA in small children. RFA with continuous CF monitoring was performed in 24 piglets (median weight 18.5 kg) using a 7 F TactiCath Quartzradiofrequency (RF) ablation catheter (Abbott). A total of 7 lesions were induced in each animal applying low (10-20 g) or high (40-60 g) CF. RF energy was delivered with a target temperature of 65°C at 30 W for 30 s. Coronary angiography was performed prior and immediately after RF application. Animals were assigned to repeat coronary angiography followed by heart removal after 48 h (n = 12) or 6 months (n = 12). Lesions with surrounding myocardium were excised, fixated, and stained. Lesion volumes were measured by microscopic planimetry. A total of 148 RF lesions were identified in the explanted hearts. Only in the subset of lesions at the AV annulus 6 month after ablation, lesion size and number of lesions exhibiting transmural extension were higher in the high CF group compared to low CF. In all other locations CF had no impact on lesion size and mural extension after 48 h as well as after 6 months. Additional parameters such as lesion size index and force time integral were also not related to lesion size. Coronary artery damage was present in two animals after 48 h and in one after 6 months and was not related to CF. In our experimental setting, lesion size in piglets was not related to catheter CF. Transmural extension of the RF lesions involving the layers of the coronary arteries was frequently noted irrespective of CF. Coronary artery narrowing was present in 3/24 animals and was not related to CF. In infants and toddlers, low CF (10-20 g) may be of adequate effect. Impact of CF monitoring during conventional RF ablation in children requires further investigation.

Long-term comparison of contact force-guided versus conventional irrigated cool-tip circumferential pulmonary vein isolation of atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background In atrial fibrillation (AF) patients, pulmonary vein isolation by means of catheter ablation (CA) is the most effective therapeutic option in order to maintain sinus rhythm. To improve successful PV isolation and effective lesion creation, contact force (CF)-sensing catheters were developed and have become routinely available. Previous studies did not always show superior clinical efficacy in comparison with non-CF CA. Moreover, data about long term clinical outcome are still lacking, especially by patients with persistent atrial fibrillation. Purpose The aim of the present study was to compare the outcome of CF-controlled ablation versus non-CF guided radiofrequency (RF) ablation of AF with regard to ablation characteristics and AF recurrence. Methods Consecutive patients, who underwent a mean 1.7±0.9 point-by-point RF CA for AF at our hospital between January of 2014 and October of 2017, were enrolled in the study. 354 patients were ablated without CF. After routine availability of CF catheters in October of 2016, 165 consecutive patients were ablated using CF. In case of crossover between the groups, follow up was censored. The primary endpoint was any recurrence documented as symptomatic or asymptomatic atrial tachycardia or atrial fibrillation &amp;gt;30 s after the 3-month blanking period. Secondary endpoints were procedural characteristics and periprocedural complications. Results 62% of the enrolled patients had persistent AF. There were no significant differences in baseline characteristics (male gender 63% vs 62%, P=0.846; persistent AF 61% vs. 65%, P=0.496; BMI 29.0±5.2 vs 29.3±5.2 kg/m2, P=0.582; hypertension 76% vs 80%, P=0.369; coronary artery disease 14% vs 20%, P=0.076; left atrial diameter 43.3±7.0 vs 43.8±7.3 mm, P=0.386; diabetes 13% vs 10%, P=0.312; sleep apnoea 7% vs 10%, P=0.167) between the groups, except for older age in the CF group (62.8±10.0 vs 65.0±10.4 years, P=0.021). In the first 12 months arrythmia-free survival was significantly higher in the CF group (Figure 1, Log-Rank (Mantel-Cox) P=0.049). Over 2.8 ± 1.8 years of follow-up, 47% of the patients in the CF group remained free of AF recurrence compared to 36% in the non-CF group (Log-Rank (Mantel-Cox) P=0.236). In multivariable Cox regression analysis using backward elimination, non-CF ablation was an independent risk factor for AF recurrence (HR=1.31; P=0.027) besides age (HR=1.023; P=0.001), persistent AF (HR=1.481; P=0.001), and left atrial diameter (HR=1.023; P=0.004). All other clinical factors were non-significant (Figure 2). Total fluoroscopy time (27.6±16.0 vs. 14.4±7.9 min) and total procedure time (133.4±38.8 vs. 110.1±28.0 min) were significantly lower for CF guided CA (P&amp;lt;0.001). Complication rates did not differ between groups (P=0.123). Conclusions In our long-term single center study the AF recurrence rate was lower after CF PVI as compared to non-CF PVI.

CA-530-01 USE THE FORCE: ADEQUATE CATHETER CONTACT FORCE IS CRITICAL FOR HIGH QUALITY LESIONS GUIDED BY ABLATION INDEX

Ablation Index (AI) is a measure used to estimate lesion size based on power, contact force (CF), and lesion duration. Ideally, AI-guided titration of lesion duration corrects for variations in contact force. Impedance drop is a validated measure that correlates well with lesion formation. Therefore, analysis of the relationship between AI, CF, and impedance drop may offer insight into possible residual influences of CF on lesion formation. To investigate and characterize the impact of CF on impedance drop during AI-guided ablation. We retrospectively reviewed atrial fibrillation ablation cases (AFAs) performed at a single center. We examined the correlation between CF and Impedance drop within narrow ranges of AI (17 groups). In a secondary analysis, we matched lesion pairs with high and low CF (< 10 g and > 20 g) for stability, AI, lesion location, and power. Matched pairs were compared using a t-test. There were 13444 lesions with AI between 320 and 530 from 91 AFAs. For lesions that had a low AI (< 402.3), we observed mostly no residual correlation between contact force and impedance drop ( Fig 1). For lesions with high AI (> 402.3), we observed a consistent significant correlation between CF and impedance drop (Fig 1). In the matched sample, the high CF group had a greater impedance drop when compared to the low CF group: 8.5 ±5.3 vs 7.0 ±4.0 Ohms p < 0.01 (Figure 2), despite having similar AI. When examining the subset of matched pairs with AI < 400, we observed no significant difference in impedance drop between the high and low CF groups: 6.7 ±4.7 vs 6.5 ±4.1 Ohms (p = 0.6). When examining the matched pairs with AI > 400, we again observed a significant difference: 9.8 ±5.3 vs 7.3 ±3.9 Ohms p < 0.01 (Fig 2). Contact force had an important residual impact on impedance drop in high AI lesions ( > 400) but not in low AI lesions (< 400). This may be due to differences in conductive versus resistive heating requirements. Ablation Index using a fixed formula for duration, force, and power, may not accurately predict lesion formation throughout all value ranges and optimization of adequate contact force remains important for larger and deeper lesions.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Ablation Index Outcome in Redo Persistent Atrial Fibrillation Ablation: Results of a Short-Term Study.

BackgroundAblation index (AI) is a novel catheter-based parameter that has improved the outcome and safety of radiofrequency (RF) ablation of pulmonary vein isolations (PVIs). This index incorporates contact force (CF) (g), time (s), and power (W) parameters. The role of AI in redo ablations for persistent atrial fibrillation (peAF) has not been fully investigated. Hence, the impact of AI on the success of the redo PVI during the short-term follow-up period is the aim of this study.MethodsA retrospective analysis of 39 consecutive patients who underwent redo PVI ablations for peAF was carried out between January 2016 and December 2018. Target values for AI were 500 - 550 for anterior and roof and 400 - 380 for posterior and inferior regions. We compared outcomes between AI-guided and catheter CF ablations (i.e., forced time integral (FTI) of more than 400 g/s) during a follow-up of 24 months.ResultsPulmonary vein reconnections at redo procedure were similar in both groups (P = 0.1). AF free burden period was non-significant (mean 15.53 ± 2.4 months in AI group vs. 15.22 ± 1.9 months in CF group, P = 0.79) at 24 months. The AI group demonstrated greater numbers of patients for whom anti-arrhythmic therapy could be de-escalated over 1 year (n = 11 (65%) in AI vs. n = 6 (27%) in CF, P = 0.02). Fewer patients underwent escalation of their anti-arrhythmic therapy (n = 2 (12%) in AI vs. n = 7 (32%) in CF, P = 0.15). The AI group trended towards a shorter procedure time (111.6 ± 27 min) compared to the CF group (133 ± 40 min) (P = 0.06). Other procedural details were comparable.ConclusionRedo PVI interventions using AI lead to a significant de-escalation in medication during follow-up. Procedure time and radiation dose using AI tends to be shorter. Both techniques are safe with minimal complications.

Smart Touch Radiofrequency Catheter Ablation versus Cryoballoon Ablation of Pulmonary Veins in Patients with Paroxysmal Atrial Fibrillation

AIM: Evaluation of the safety and efficacy of pulmonary veins isolation in patients with paroxysmal atrial fibrillation (AF) using two new different technologies, cryoballoon (CB) ablation and radiofrequency ablation with contact force (CF)-sensing catheters.&#x0D; METHODS: Prospective single-center evaluation, carried out from January 2016 to June 2018 in Critical Care Medicine Department – Cairo University, comparing CF radiofrequency (Thermocool® SmartTouch, Biosense Webster, Inc.) (CF group) with CB ablation (Arctic Front Advance 28 mm CB, Medtronic, Inc.) (CB group), in regards to procedural safety and efficacy, as well as recurrence at 12 months. Overall, 50 consecutive patients were enrolled (25 in each group).&#x0D; RESULTS: The characteristics of patients of both the groups were similar (46.9 ± 11.2 years, the proportion of women 36%, mean documented AF duration 3 ± 2.3 years, mean CHA2DS2-VASc score 1.4 ± 1.3, and mean HAS-BLED 1.4 ± 0.6). Duration of the procedure was significantly lower in the CB group (171.7 ± 15.24 vs. 199.3 ± 18.94 min, p = 0.002), with a longer duration of fluoroscopy and X-ray exposure in the CB group than the CF group but statistically non-significant difference (58.60 ± 11.57 vs. 48.7 ± 13.86 min and 6273 ± 4934 cGy cm² vs. 6853 ± 5069 cGy cm², p = 0.1 and p = 0.2, respectively). Overall complication rate was similar in both groups: 2 (8%) in each group. At 12 months, AF recurrence occurred in 7 patients (28%) in the CF group and in 9 patients (36%) in the CB group (log rank p = 0.682).&#x0D; CONCLUSION: Pulmonary vein isolation using CF-guided RF and second-generation CB leads to comparable single-procedure arrhythmia-free survival at up to 12 months with similar overall complication rate.

Re-definition of blanking period in radiofrequency catheter ablation of atrial fibrillation in the contact force era.

Early recurrence (ER) of atrial fibrillation (AF) is defined as the recurrence of atrial tachyarrhythmias within 3 months after AF ablation, however, this definition is based on data from the era of radiofrequency catheter ablation (RFCA), without contact force (CF) technology. We investigated the significance of ER as a risk factor for late recurrence (LR) in paroxysmal AF (PAF) patients treated with CF and non-CF-guided ablation. We studied 395 patients with PAF who underwent RFCA. Of these, 97 patients underwent RFCA without-CF technology (non-CF group) and 298 underwent with CF technology (CF group). Over a 2-year postablation follow-up period, LR occurred in 54 (55.7%) patients in the non-CF group, and in 105 (35.2%) patients in the CF group. ER had a more significant relationship with LR in the CF group, and all patients in the CF group with ER in the third month developed LR. PAF patients with ER who have undergone CF-guided ablation have a greater risk of LR than those who have undergone non-CF-guided ablation. ER in the third month after CF-guided ablation may indicate an absolute risk of LR. Blanking period could be defined as 2 months in the CF era.

P1409Effectiveness of atrial fibrillation ablation using a contact force stability module with contact force or non-contact force catheter

Abstract Funding Acknowledgements This study was funded by Biosense Webster, Inc. Background Catheter ablation is a mainstream treatment option for atrial fibrillation (AF). Recently, contact force (CF) enabled ablation catheters and a stability module were developed to allow for real-time CF sensing and improvement of catheter-tissue stability, which is important for achieving an optimal clinical outcome. We assessed the relative effectiveness of these new technologies, as well as the optimal CF stability parameters, in a real-world setting. Purpose To compare the clinical effectiveness of AF ablations performed with a CF catheter using location stability settings of 2.5 mm maximum distance for 12 s minimum (2.5/12) vs. a non-CF catheter with settings of 3 mm for 7 s (3/7). Methods Within 1/14–4/18, 176 de novo AF ablations using either a CF catheter with stability settings of 2.5/12 (n = 92, 5/16–4/18) or a non-CF catheter with stability settings of 3/7 (n = 84, 1/14–3/14) were performed by a single operator at a Canadian medical center. Patients routinely wore 48 hour Holter monitors every three months through the first year. The primary measures of effectiveness were Kaplan-Meier (KM) survival estimates of freedom from AF/atrial tachycardia (AT)/atrial flutter (AFL) recurrence after a 3-month blanking period and reablation. Results The CF group was 62.9 ± 10.0 years old, 57.6% male, and 66.3% paroxysmal (PAF). The non-CF group was 61.6 ± 9.9 years old, 63.1% male, and 76.2% PAF. Procedural complications consisted of a single vascular access complication in the non-CF group. The 12-month estimate of freedom from AF/AT/AFL recurrence was 79.4% in the CF group vs. 64.8% in the non-CF group (p = 0.058 for difference in survival over time). 12-month freedom from reablation was 90.4% in the CF group vs. 70.5% in the non-CF group (p = 0.002). Conclusion CF ablation with more stringent stability settings of 2.5/12 was more effective than non-CF ablation with stability settings of 3/7, likely attributable to the CF catheter enabling visualization of catheter-tissue contact and the stability module facilitating maintenance of CF stability during ablation. Abstract Figure.

231Local impedance-guided ablation and ultra-high density mapping provide improved ablation metrics vs conventional or contact force-guided ablation for cavotricuspid isthmus dependent atrial flutter

Abstract INTRODUCTION. Radiofrequency ablation (RFA) of cavotricuspid isthmus dependent atrial flutter (CTI-AFL) can be performed with fluoroscopy (Fluo) or 3-dimensional (3D) electroanatomic mapping and contact force (CF) catheters. Local impedance (LI) is an alternative but no comparisons have yet been made. METHODS. An observational study comparing Fluo, CF- and LI-guided RFA for CTI-AFL. In the LI group, if CTI block was not obtained after initial ablation, ultra-high density mapping (UHDm) was used to identify breakthrough sites. Contact was determined using patient specific LI; RF delivered until 20 ohm LI drop seen, or LI drop plateaued &amp;gt;2 secs. In the CF group 10-40g force was used. Power was limited to 40-50W in all groups. Total RFA time, time from RFA start to CTI block, no. of lesions required to achieve block, acute success, complications and re-ablation during follow-up were analysed using ANOVA. RESULTS. Data presented for 24 patients (7 Fluo, 7 CF, 10 LI). Mean RFA time: 6.6, 5.9, 3.2 min respectively (p = 0.0478). Statistically significant differences also seen with LI vs Fluo (p = 0.0451) and LI vs CF (p = 0.0313). Time from first RFA to block: 25.5, 19.8, 14.2 min (p = 0.5688); number of lesions to achieve block: 8.5, 10.3, 8 (p = 0.3909). 100% success and no complications in all groups. 0% need for re-ablation (16.3 ± 7, 12.6 ± 8, 6.5 ± 4.4 months follow-up). DISCUSSION. This data illustrates that UHDm and LI-guidance significantly reduces the amount of CTI RFA, by 52% and 47% vs Fluo and CF respectively (p = sig, fig. 1). A reduction from first RFA to block is also seen (43% and 37%; p = ns, fig. 2). Given no difference in the no. of lesions, LI-guided RFA during lesion formation shortens the duration of each lesion. Many patients require further RFA (+/- mapping) if they do not achieve block following the initial ablation line, resulting in longer procedures. Several patients without block in the LI group underwent repeat UHDm, which quickly identified CTI or epicardial-endocardial breakthrough (fig. 3 &amp; 4), allowing rapid targeting for re-ablation. In the fluo group, these procedures would often be significantly prolonged, meaning extensive RFA and radiation exposure. Fig. 1 shows smaller error bars with LI compared to the others, resulting in more predictable total ablation times; this could potentially benefit procedure scheduling (more procedures per unit time). We could not directly compare overall procedure time as many in the CF group had CTI RFA combined with left atrial RFA. Multiple LI cases were performed fluo-free with only magnetic tracking. This may allow case scheduling without a radiographer, with potential cost savings. CONCLUSION. LI-guided CTI-AFL RFA is safe and effective and has shown favourable ablation metrics compared to Fluo or CF-RFA. LI-RFA with UHDm more quickly and accurately identifies breakthrough and with fluoro-free technique could possibly reduce procedure time and cost. A larger study is planned to provide more insight. Abstract Figures

One-year outcomes after pulmonary vein isolation plus posterior wall isolation and additional non-pulmonary vein trigger ablation for persistent atrial fibrillation with or without contact force sensing: a propensity score-matched comparison.

Whether or not pulmonary vein isolation (PVI) plus left atrial posterior wall isolation (PWI) using contact force (CF) sensing improves the ablation outcome for persistent atrial fibrillation (AF) is unclear. This study compared the outcome of PVI plus PWI and additional non-PV trigger ablation for persistent AF with/without CF sensing. This retrospective cohort study analyzed 148 propensity score-matched persistent AF patients (median duration of persistent AF, 8months (interquartile range, 3-24months); left atrial diameter, 43 ± 7mm) undergoing PVI plus PWI and ablation of non-PV triggers provoked by high-dose isoproterenol, including 74 with CF-sensing catheters (CF group) and 74 with conventional catheters (non-CF group). PVI plus PWI with no additional ablation but cavotricuspid isthmus ablation was performed without non-PV triggers in 48 CF patients (65%) and 54 non-CF patients (73%) (P = 0.38). In all other patients, we performed additional ablation of provoked non-PV triggers. The Kaplan-Meier estimate of the rate of freedom from atrial tachyarrhythmia recurrence off antiarrhythmic drugs at 12months after the single procedure was higher in the CF group than in the non-CF group (85 vs. 70%, log-rank P = 0.030). A multivariable analysis revealed that using CF sensing and non-inducibility of AF from a non-PV trigger after PVI and PWI were significantly associated with a reduced rate of atrial tachyarrhythmia recurrence. Compared with non-CF sensing, PVI plus PWI and additional non-PV trigger ablation using CF-sensing catheters for persistent AF can reduce the rate of atrial tachyarrhythmia recurrence.

Cavotricuspid isthmus ablation using ablation index in typical right atrial flutter

Ablation index (AI) has been evaluated as guidance quality marker for pulmonary vein isolation, but not for linear ablation of the cavotricuspid isthmus (CTI) for typical right atrial flutter (AFL). We thus studied the feasibility and effectiveness of AI-guided CTI for AFL. Procedural and 6-month outcomes of ablation for AFL were retrospectively compared between consecutive patients undergoing either AI-guided ablation of CTI (n = 43; AI target of 500 for anterior 2/3 segments and 400 for posterior 1/3 segments) or contact force (CF)-guided ablation (n = 42) at a single center. Each Visitag dataset from all patients in each group was analyzed. AI guidance vs CF guidance was associated with: higher first-pass conduction block of CTI (93.0% vs 76.2%, P = .03) with similar ablation time; similar acute spontaneous CTI reconnection 2.3% vs 9.5%, P = .343); fewer radiofrequency (RF) applications (10.1 ± 2.8 vs 11.5 ± 3.0, P = .031) needed to achieve CTI directional block; significantly higher mean ablation time, impedance drop, force time integral and AI and similar mean CF and power of each VisiTag point. One inguinal hematoma and one pseudoaneurysm developed in the AI and CF groups, respectively. Recurrent AFL was recorded in two (4.7%) AI-group patients and four (9.5%) CF-group patients (P = .650). AI-guided ablation of CTI line for AFL appears feasible and effective with similar ablation time, fewer RF applications, a higher rate of first-pass conduction block, and no additional complications.

An ablation index operator-independent approach to improve efficacy in atrial fibrillation ablation at 24-month follow-up: a single center experience.

Since the introduction of catheter ablation as a mainstream treatment for atrial fibrillation (AF), several technical improvements have been put forward. In this contest, Ablation Index (AI) is an accurate ablation quality marker by incorporating power, delivery time, contact force (CF), and catheter stability in a weighted formula. The aim of our study is to evaluate the efficacy of AI-guided AF ablation over 24month follow-up. We evaluated 72 consecutive patients with drug-refractory paroxysmal (66.7%) and early-persistent AF (33.3%) undergoing AI-guided ablation, compared to 72 propensity-matched control patients who underwent CF-guided procedure. All procedures were performed by three skilled operators. Data concerning procedural characteristics and long-term freedom from AF recurrence were analyzed. At 24-month follow-up, Kaplan-Meier curves of AF recurrence were significantly lower in AI group than in CF group (15.5% vs. 30.6%; p 0.042). These findings were confirmed in a sub analysis regardless of the continued use of antiarrhythmic drugs in the follow-up (42.2% in AI-guided group and 66.7% in CF-guided group, p 0.004). At 24-month follow-up, a positive trend in the decrease of arrhythmia recurrences was observed in AI-guided ablation for all operators. AI-guided ablation results more effective than CF-guided ablation as demonstrated by a lower incidence of AF recurrences regardless of the use of antiarrhythmic drugs in the follow-up. Each operator seems to improve the long-term success using an AI-guided ablation, thus showing both the efficacy and the reproducibility of this approach.

Association between the use of contact force-sensing catheters and cardiac tamponade in atrial fibrillation ablation

IntroductionCardiac tamponade is a rare but life-threatening complication during atrial fibrillation (AF) catheter ablation. Contact force (CF)–sensing catheters improve ablation effectiveness. However, the impact of the application of CF-sensing catheters on the occurrence of cardiac tamponade remains unclear. The aim of this study is to evaluate the “real-world” impact of CF-sensing catheters on cardiac tamponade during AF ablation in an experienced medical center.Methods and resultsThis was a retrospective study of consecutive de novo AF ablation procedures at Beijing Anzhen Hospital between 2013 and 2016. The ablation procedure was divided into a CF group and a non-CF group. Logistic regression analysis was used to evaluate the association between the use of CF-sensing catheters and the risk of cardiac tamponade. A total of 5313 patients with AF were involved in this study. The incidence of cardiac tamponade in the CF group was significantly higher than that in the non-CF group (1.07% vs. 0.44%, P = 0.009). Of the cardiac tamponade cases in the non-CF group, 45.45% were delayed compared with 10% in the CF group (P = 0.011). Multivariate logistic regression analysis showed that CF-sensing catheters increased the risk of cardiac tamponade (OR = 2.34, 95% CI = 1.17–4.26, P = 0.015). Stratified analysis revealed patients with a smaller left atrium dimension, lower ejection fraction, longer procedure duration, or longer ablation duration had a greater risk of cardiac tamponade during ablation with CF-sensing catheters.ConclusionsCF-sensing catheters increase the risk of cardiac tamponade during AF ablation.

Three-year outcomes and reconnection patterns after initial contact force guided pulmonary vein isolation for paroxysmal atrial fibrillation.

Contact force (CF) sensing is a novel technology used for catheter ablation of atrial fibrillation (AF). We compared the single procedure success of CF-guided pulmonary vein isolation (PVI) with that of non-CF guided PVI during a 3-year (1,095 days) follow up period and analyzed the pattern of pulmonary vein (PV) reconnection. A cohort of 167 subjects (68 CF vs. 99 non-CF) with paroxysmal AF were included in the study. Atrial arrhythmia (AA) recurrence was defined as documented AF, atrial flutter, or atrial tachycardia lasting >30 seconds and occurring after 90 days. Subjects in the CF group showed a statistically nonsignificant improvement in AA free survival compared to those in the non-CF group (66.2% vs. 51.5%; P value: 0.06). A greater propensity for reconnection was noted around the right-sided PVs compared to left-sided PVs related in both catheter ablation groups. For example, in the CF group 36% of right-sided segments reconnected compared to 16% of left-sided segments (P value <0.01). A greater propensity for reconnection was noted around the right sided PV segments in both the CF and non-CF groups. The explanation for this finding was related to greater catheter instability around the right sided veins. Further research is needed to explore the utility of a "real-time" composite indicator that includes RF energy, CF and catheter stability in predicting transmural lesion formation during catheter ablation.

Lesion Size Index in Maximum Voltage-Guided Cavotricuspid Ablation for Atrial Flutter.

The application of optimum contact force (CF) can be used to improve ablation procedure success and safety. The lesion size index (LSI) is a novel dimensionless contact force parameter that allows for an accurate estimation of lesion volume in real time by integrating contact force (grams), duration (seconds) and power (watts). The aim was to correlate LSI values with current contact force parameters to achieve successful and safe bidirectional block of the cavotricuspid isthmus (CTI) using a maximum voltage-guided (MVG) ablation strategy. Fifteen consecutive patients (age 69 ± 7.9 years, nine males) with symptomatic atrial flutter (AFL) were evaluated and compared with 23 control (age 66.3 ± 10.4 years, 16 males) non-contact force-guided ablation cases. Irrigated-tip force-sensing ablation catheters (TactiCath Quartz™, St. Jude Medical, St. Paul, MN, USA) were used in the CF group to achieve the primary endpoint of complete bidirectional block of the isthmus. In the CF group, a total of 233 radiofrequency (RF) applications were examined. A mean LSI of 6.4 ±1.0 correlated with a force-time integral (FTI) of 581.2 ±230.9 g/s and an average CF of 13.9 ±4.9 g concurrently. Intraprocedural, fluoroscopy time and RF time demonstrated lower trends in the CF group, but no significance with respect to these trends was observed. The secondary endpoint of no reconnection within 20 min after the procedure was equally attained in both groups, and, likewise, the level of safety was comparable. An LSI value of >5 represents a new effective parameter in MVG ablation for the cavotricuspid region that demonstrates a safe profile. Guidance of CTI ablation using LSI and other contact force parameters of CF 13.9 ±4.9 g and FTI 581.2 ±230.9 g/s demonstrated highly effective and safe outcomes.

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

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

216-12: The Efficacy of Contact Force Catheter for Ablation of Atrial Fibrillation: Reduction of Dormant Conduction, Procedure Time and Fluoroscopy Time

Purpose of the study: Catheter ablation is being increasingly employed for the treatment of atrial fibrillation (AF). Catheter contact is an important determinant of lesion size. Contact force (CF) catheter technology may improve the ablation quality. The purpose of this study is to evaluate the procedural benefit of CF catheter. Method used: Sixty-eight consecutive patients, who underwent initial AF ablation including pulmonary vein isolation, were enrolled. We divided them to CF group (n = 52) and non-CF group (n = 16) according to the ablation catheter type. Dormant conduction was investigated by a bolus administration of 30mg of adenosine triphosphate during a continuous isoproterenol infusion (1.0-2.0 µg/min). Incidence of dormant conduction, procedure time and fluoroscopy time were compared between two groups. Summary of results: Dormant conduction, procedure time and fluoroscopy time were significantly reduced in CF group compared with non-CF group (Table1). Using multivariate analysis, dormant conduction was significantly associated with contact force catheter use (p = 0.018, 95% CI 0.020-0.708), not associated with atrial fibrillation type (persistent/paroxysmal: p = 0.675, 95% CI 0.165-11.108, long-standing/paroxysmal: p = 0.724, 95% CI 0.200-8.750) or left atrial diameter (p = 0.393, 95% CI 0.926-1.228)(Table2). Conclusion: Contact force catheter is effective to reduce dormant conduction, procedure time and fluoroscopy time during AF ablation. Table1 Table1

Use of the new contact force sensing ablation catheter dramatically reduces fluoroscopy time during atrial fibrillation ablation procedures

ObjectivesTo study the impact of contact force (CF) sensing on fluoroscopy, procedure, left atrial (LA) and ablation times and number of ablations during atrial fibrillation (AF) ablation. BackgroundCatheter ablation is an effective treatment for symptomatic AF. Recently a new ablation catheter providing real-time CF has been approved for use. MethodsA nested case-control study was performed comparing radiofrequency ablation of AF using the irrigated CF-sensing ThermoCool SmartTouch catheter versus open-irrigated ThermoCool SF catheter (Biosense Webster, Inc., Diamond Bar, California). Demographic and procedure data were obtained and student t-test was used to compare data between groups. ResultsThirty consecutive adult patients were included with 15 patients in each group. Mean fluoroscopy time was significantly lower in CF group (19.4 ± 8 vs 40.7 ± 8 min, p < 0.0001). LA time was significantly lower in CF group (151.7 ± 44 vs 185.7 ± 35 min, p = 0.01). There were no significant differences in procedure time between CF and SF groups (204 ± 37 vs 207 ± 36 min) and ablation time (121 ± 32 vs 122 ± 37 min). When patients who only underwent pulmonary vein isolation (PVI) were compared, fluoroscopy time was significantly lower in CF group (18 ± 9 vs 37.8 ± 5 min, p < 0.0001) as was LA time (141.4 ± 39 vs 171.8 ± 30 min, p = 0.04). Fluoroscopy time was also significantly lower in CF subgroup with additional ablation (20.9 ± 7 vs 44.9 ± 10 min, p < 0.001). ConclusionUse of CF-sensing catheter significantly reduced fluoroscopy and LA times during AF ablation with similar acute efficacy.

Contact force-guided catheter ablation for the treatment of atrial fibrillation: a meta-analysis of randomized, controlled trials.

Contact force (CF) sensing technology allows real-time monitoring during catheter ablation for atrial fibrillation (AF). However, the effect of CF sensing technology on procedural parameters and clinical outcomes still needs clarification. Because of the inconsistent results thus far in this area, we performed a meta-analysis to determine whether CF sensing technology can improve procedural parameters and clinical outcomes for the treatment of AF. Studies examining the benefits of CF sensing technology were identified in English-language articles by searching the MEDLINE, Web of Science, and Cochrane Library databases (inception to May 2015). Ten randomized, controlled trials involving 1834 patients (1263 males, 571 females) were included in the meta-analysis (681 in the CF group, 1153 in the control group). Overall, the ablation time was significantly decreased by 7.34 min (95%CI=-12.21 to -2.46; P=0.003, Z test) in the CF group compared with the control group. CF sensing technology was associated with significantly improved freedom from AF after 12 months (OR=1.55, 95%CI=1.20 to 1.99; P=0.0007) and complications were significantly lower in the CF group than in the control group (OR=0.50, 95%CI=0.29 to 0.87; P=0.01). However, fluoroscopy time analysis showed no significantly decreased trend associated with CF-guided catheter ablation (weighted mean difference: -2.59; 95%CI=-9.06 to 3.88; P=0.43). The present meta-analysis shows improvement in ablation time and freedom from AF after 12 months in AF patients treated with CF-guided catheter ablation. However, CF-guided catheter ablation does not decrease fluoroscopy time.

Clinical impact of contact force and its regional variability on efficiency and effectiveness of pulmonary vein isolation for atrial fibrillation

BackgroundThe purpose of this study is to analyze the impact of average contact force (CF) and its regional variability during pulmonary vein isolation (PVI) for atrial fibrillation (AF) on periprocedural parameters and midterm outcome. MethodsThis retrospective cohort study enrolled 57 drug-refractory AF patients who underwent initial PVI for AF using an open-irrigated CF catheter (SmartTouch Thermocool, Biosense Webster, Diamond Bar, CA, USA). Thirty patients were assigned to a lower CF (LCF) group (average CF≤10g) and 27 patients to a higher CF (HCF) group (average CF>10g). The relationship between CF and clinical outcome was analyzed. ResultsPatients were followed-up for 317±57 days after PVI. The CF was 8.1±1.3g in the LCF group and 12.4±1.5g in the HCF group. Higher average CF was associated with shorter ablation time (28±6min vs. 36±9min, p=0.0002) and lower radiofrequency energy delivery (79±18 vs. 99±26, p=0.0016) for PVI. The rate of acute PV reconnection (APVR) was similar in both groups (LCF group 60% vs. HCF group 44%, p=0.36). Four patients (13%) in the LCF group and nine patients (33%) in the HCF group experienced AF-recurrence. Average CF did not impact on AF-recurrence during midterm clinical outcome (p=0.09 by log-rank test). In the non-recurrence group (n=44), average CF was higher at left posterosuperior PV and right anteroinferior PV than that in the recurrence group (n=13) (p=0.012 and p=0.004, respectively). ConclusionsHigher average CF decreased ablation time and radiofrequency energy delivery for PVI, but did not decrease APVR rate or improve midterm clinical outcome.