Sven Knecht

Initial impedance decrease as an indicator of good catheter contact: Insights from radiofrequency ablation with force sensing catheters

BACKGROUND Good catheter-tissue contact force (CF) is critical for transmural and durable lesion formation during radiofrequency (RF) ablation but is difficult to assess in clinical practice. Tissue heating during RF application results in an impedance decrease at the catheter tip. OBJECTIVE The purpose of this study was to correlate achieved CF and initial impedance decreases during atrial fibrillation (AF) ablation. METHODS We correlated achieved CF and initial impedance decreases in patients undergoing ablation for AF with two novel open-irrigated CF-sensing RF catheters (Biosense Webster SmartTouch, n = 647 RF applications; and Endosense TactiCath, n = 637 RF applications). We then compared those impedance decreases to 691 RF applications with a standard open-irrigated RF catheter (Biosense Webster ThermoCool). RESULTS When RF applications with the CF-sensing catheters were analyzed according to an achieved average CF <5 g, 5-10 g, 10-20 g, and >20 g, the initial impedance decreases during ablation were larger with greater CF. Corresponding median values at 20 seconds were 5 Ω (interquartile range [IQR] 2-7), 8 Ω (4-11), 10 Ω (7-16), and 14 Ω (10-19) with the SmartTouch and n/a, 4 Ω (0-10), 8 Ω (5-12), and 13 Ω (8-18) with the TactiCath (P <.001 between categories for both catheters). When RF applications with the SmartTouch (CF-sensing catheter, median achieved CF 12 g) and ThermoCool (standard catheter) were compared, the initial impedance decrease was significantly greater in the CF-sensing group with median decreases of 10 Ω (6-14 Ω) vs 5 Ω (2-10 Ω) at 20 seconds (P <.001 between catheters). CONCLUSION The initial impedance decrease during RF applications in AF ablations is larger when greater catheter contact is achieved. Monitoring of the initial impedance decrease is a widely available indicator of catheter contact and may help to improve formation of durable ablation lesions.

Anatomical Predictors for Acute and Mid-Term Success of Cryoballoon Ablation of Atrial Fibrillation Using the 28 mm Balloon

Anatomical Predictors for Acute and Mid‐Term Success of Cryoballoon Ablation. Introduction: Cryoballoon (CB) pulmonary vein isolation (CB‐PVI) for the treatment of paroxysmal atrial fibrillation (AF) has been demonstrated to be safe and reliable. Preprocedural patient selection to address the high variability in pulmonary vein (PV) anatomy may improve the acute and chronic success of CB‐PVI. The purpose of this study was to identify anatomical predictors for CB‐PVI failure using the 28 mm balloon.

Validation of a novel spiral mapping catheter for real-time recordings from the pulmonary veins during cryoballoon ablation of atrial fibrillation

BACKGROUND The Achieve mapping catheter allows real-time recordings from the pulmonary veins (PVs) during cryoballoon (CB) ablation of atrial fibrillation (AF). OBJECTIVE To assess the clinical applicability of the Achieve mapping catheter and the value of real-time recordings from the PVs during CB. METHODS Patients with paroxysmal AF undergoing CB ablation were studied. Recordings from the PVs were analyzed during (real-time recordings) and after CB ablation and validated by using a variable circumferential mapping catheter (Achieve group; n = 20). A comparison was made by using a group of patients in whom CB ablation with a guidewire and a variable circumferential mapping catheter was performed (Guidewire group; n = 20). RESULTS Forty patients (age 58±11 years; ejection fraction 0.59±0.07; left atrial size 40±6 mm) with paroxysmal AF were included. In the Achieve group, real-time recordings from the PVs could be obtained in 40 of 80 (50%) PVs and could be seen more often at the left-sided PVs (25 of 39, 64%) than at the right-sided PVs (15 of 41, 37%; P = .02). Validation with a standard circumferential mapping catheter confirmed PV isolation in 75 of 80 (93%) PVs. After a single procedure and a follow-up of 14±4 months, 25 of 40 (63%) patients were in sinus rhythm with no significant difference between groups. CONCLUSIONS The Achieve catheter can be used as a substitute for a guidewire during CB ablation, but real-time recordings can be obtained only in half of the PVs and are not sufficient to accurately confirm isolation of all PVs.

Long-term comparison of cryoballoon and radiofrequency ablation of paroxysmal atrial fibrillation: A propensity score matched analysis

BACKGROUND Although radiofrequency (RF) and cryoballoon (CB) based technologies for pulmonary vein isolation (PVI) have both individually been demonstrated to be effective and safe for the treatment of paroxysmal AF, head-to-head comparisons are lacking. The purpose of this study was to compare the outcome of cryoballoon versus radiofrequency ablation in patients with paroxysmal atrial fibrillation undergoing pulmonary vein isolation. METHODS Out of a prospective registry of 327 patients undergoing PVI, 208 patients (age 58±11 years, ejection fraction 59±6%, left atrial size 39±6 mm) with paroxysmal AF were identified. The presented dataset was obtained by 1:1 propensity score matching and contained 142 patients undergoing CB-PVI or RF-PVI in conjunction with a 3D mapping system, respectively. We compared single procedure efficacy of the two methods using a Cox proportional hazards model. RESULTS After a mean follow-up of 28 months and a single procedure, AF recurred in 37 of 71 (52%) in the CB-PVI group and in 31 of 71 patients (44%) in the RF-PVI group (HR [95% CI]=1.19 [0.74, 1.92], p=0.48). Recurrence of AF for PVI using solely the CB was observed in 23 of 51 (45%) patients and in 23 of 51 (45%) patients in the corresponding RF-PVI group (HR [95% CI]=0.93 [0.52, 1.66], p=0.81). Complication rate was not different between the groups. CONCLUSION A propensity score matched comparison between CB-PVI and RF-PVI using a 3D-mapping system for AF ablation showed similar long-term success rates.

Pacemaker Implantation and Need for Ventricular Pacing during Follow-Up after Transcatheter Aortic Valve Implantation

To categorize indications of permanent pacemaker (PPM) implantation after transcatheter aortic valve implantation (TAVI), to determine predictors for conduction disturbances and to quantify the need for ventricular pacing during follow‐up.

Incidence of new-onset atrial fibrillation after cavotricuspid isthmus ablation for atrial flutter

Aims In patients with cavotricuspid isthmus (CTI) ablation for atrial flutter (AFL), the decision to hold oral anticoagulation (OAC) often becomes an issue. The purpose of this study was to describe the incidence of the development of atrial fibrillation (AF) after CTI ablation in patients with documented AFL with and without a previous history of AF and to identify risk predictors for the occurrence of AF after CTI. Methods and results We included 364 consecutive patients undergoing successful CTI ablation. Thereof, 230 patients (170 male; age 66 ± 11 years) had AFL only (AFL group) and 134 patients (94 male; age 65 ± 11 years) had AFL and previously documented AF (AFL and AF group). Over a mean follow-up of 22 ± 20 months, 163 (71%) patients in the AFL group and 67 (50%) patients in the AFL and AF groups had no documentation of a recurrent atrial arrhythmia (P < 0.001). AF developed in 51 patients (22%) in the AFL group and in 57 (43%) patients in the AFL and AF groups (P < 0.001). In patients without history of AF, left atrial diameter was the only predictor of development of AF (HR 1.058 [95%CI 1.011-1.108], P = 0.016). Multivariate analysis of the total population identified history of AF (HR 1.918 [95%CI 1.301-2.830], P = 0.001) and BMI as predictors for AF development (HR 1.052 [95%CI 1.012-1.093], P = 0.011). Conclusion Our results indicate that new-onset AF develops in a significant proportion of patients undergoing CTI for AFL. One should therefore be careful to withhold OAC. Furthermore, pulmonary vein isolation should be considered in conjunction with CTI, particularly in patients with previously documented AF.

Effective reduction of fluoroscopy duration by using an advanced electroanatomic-mapping system and a standardized procedural protocol for ablation of atrial fibrillation: 'the unleaded study'.

AIMS It is recommended to keep exposure to ionizing radiation as low as reasonably achievable. The aim of this study was to determine whether fluoroscopy-free mapping and ablation using a standardized procedural protocol is feasible in patients undergoing pulmonary vein isolation (PVI). METHODS AND RESULTS Sixty consecutive patients were analysed: Thirty consecutive patients undergoing PVI using Carto3 were treated using a standardized procedural fluoroscopy protocol with X-ray being disabled after transseptal puncture (Group 1) and compared with a set of previous 30 consecutive patients undergoing PVI without a specific recommendation regarding the use of fluoroscopy (Group 2). The main outcome measures were the feasibility of fluoroscopy-free mapping and ablation, total fluoroscopy time, total dose area product (DAP), and procedure time. Sixty patients (age 60 ± 10 years, 73% male, ejection fraction 0.55 ± 0.09, left atrium 42 ± 8 mm) were included. In Group 1, total fluoroscopy time was 4.2 (2.6-5.6) min and mapping and ablation during PVI without using fluoroscopy was feasible in 29 of 30 patients (97%). In Group 2, total fluoroscopy time was 9.3 (6.4-13.9) min (P < 0.001). Total DAP was 13.2 (6.2-22.2) Gy*cm(2) in Group 1 compared with 17.5 (11.7-29.7) Gy*cm(2) in Group 2 (P = 0.036). Total procedure time did not differ between Groups 1 (133 ± 37 min) and 2 (134 ± 37 min, P = 0.884). CONCLUSION Performing mapping and ablation guided by an electroanatomic-mapping system during PVI without using fluoroscopy after transseptal puncture using a standardized procedural protocol is feasible in almost all patients and is associated with markedly decreased total fluoroscopy duration and DAP.

Fluoroscopy-Free Pulmonary Vein Isolation in Patients with Atrial Fibrillation and a Patent Foramen Ovale Using Solely an Electroanatomic Mapping System

Introduction The advent of electroanatomical mapping (EAM) systems for pulmonary vein isolation (PVI) has dramatically decreased radiation exposure. However, the need for some fluoroscopy remains for obtaining left atrial (LA) access. The aim was to test the feasibility of fluoroscopy-free PVI in patients with atrial fibrillation (AF) and a patent foramen ovale (PFO) guided solely by an EAM system. Methods Consecutive patients with AF undergoing PVI and documented PFO were studied. An EAM-guided approach without fluoroscopy and ultrasound was used. After completing the map of the right atrium, the superior vena cava and the coronary sinus, a catheter pull-down to the PFO was performed allowing LA access. The map of the LA and subsequent PVI was also performed without fluoroscopy. Results 30 patients [age 61±12 years, 73% male, ejection fraction 0.64 (0.53–0.65), LA size in parasternal long axis 38±7 mm] undergoing PVI were included. The time required for right atrial mapping including transseptal crossing was 9±4 minutes. Total procedure time was 127±37 minutes. Fluoroscopy-free PVI was feasible in 26/30 (87%) patients. In four patients, fluoroscopy was needed to access (n = 3) or to re-access (n = 1) the LA. In these four patients, total fluoroscopy time was 5±3 min and the DAP was 14.9±13.4 Gy*cm2. Single-procedure success rate was 80% (24/30) after a median follow-up of 12 months. Conclusion In patients with a documented PFO, completely fluoroscopy-free PVI is feasible in the vast majority of cases.

Reliability of luminal oesophageal temperature monitoring during radiofrequency ablation of atrial fibrillation: insights from probe visualization and oesophageal reconstruction using magnetic resonance imaging

Aims A current concept to prevent atrio-oesophageal fistula during radiofrequency (RF) catheter ablation of atrial fibrillation is to monitor luminal oesophageal temperature (LET). The objective of this study was to describe the temporal course of LET and to assess the reliability of monitoring the maximal LET during pulmonary vein isolation (PVI) using irrigated multi-electrode (IMEA, nMARQTM) and focal ablation catheters. Methods and results We studied 40 patients with LET monitoring during PVI (20 patients using the IMEA and 20 patients using the focal catheter). A linear probe was used and visualized in the 3D mapping system. Left atrial and oesophageal reconstructions from delayed enhanced magnetic resonance imaging were integrated. Analysing 745 temperature profiles, LET >38°C was observed in 48 of 296 (17%) and 44 of 449 (10%) ablations for the IMEA and the focal catheter, respectively (P = 0.012). Temporal latency after interruption of RF energy delivery was observed for both catheters. Time until LET baseline temperature was restored after an increase of >1°C was 100 and 86 s for the IMEA and the focal catheter, respectively (P = 0.183). Imprecise representation of the maximal LET was observed in 24 (60%) and 28 patients (70%) for the left and right PVs, respectively. Conclusion Due to the unknown exact lateral position of the LET probe within the oesophagus, the measured temperature does not necessarily reflect the maximal LET. The absence of LET increase does not rule out significant temperature increase within the oesophagus. Consequently, the temperature information of the linear multipolar probe should be used with caution.

One-year follow-up after irrigated multi-electrode radiofrequency ablation of persistent atrial fibrillation

AIMS Irrigated multi-electrode ablation (IMEA) is a novel tool to perform pulmonary vein isolation (PVI). The aim was to compare IMEA with point-by-point radiofrequency (RF) ablation in patients with persistent atrial fibrillation (AF) undergoing PVI. METHODS AND RESULTS Forty-nine patients (age 60 ± 9 years, 82% male) were studied. In 24 patients, the IMEA catheter was used in conjunction with an electroanatomic mapping system. Twenty-five patients undergoing RF point-by-point ablation (RF-PVI) served as a control group. Validation of PVI based on the IMEA catheter was performed using a standard circular mapping catheter. Ninety-two of 94 pulmonary veins (PVs) (98%) were isolated using IMEA alone. Procedure time was 125 ± 23 min in the IMEA group and 127 ± 31 min in the RF-PVI group (P = 0.79). Fluoroscopy time was 12.2 (11-16.1) min with IMEA compared with 5.2 (4.1-9.3) min in the RF-PVI group (P < 0.001). Net ablation time was 11.8 (10.2-15.4) min in the IMEA group compared with 33.6 (30.3-40.1) min in the RF-PVI group (P < 0.001). Of 94 PVs presumed to be isolated after IMEA ablation, validation using a standard circular mapping catheter showed persistent PV potentials in 33 PVs (35%), requiring additional IMEA ablation. At 12 months, 16 of 24 patients (67%) in the IMEA group compared with 17 of 25 patients (68%) in RF-PVI group were free from AF (P > 0.99). CONCLUSION With similar total procedure duration, IMEA-PVI was associated with shorter net ablation time and longer fluoroscopy time. Irrigated multi-electrode ablation recordings were not sufficient to confirm isolation in 35% of PVs. Single-procedure efficacy after 12 months was similar between the two groups.