Irrigated Radiofrequency Ablation Catheter Research Articles

Long-Term Differences in AutonomicAlterations After Cryoballoonvs Radiofrequency AtrialFibrillation Ablation.

The long-term natural history of autonomic alterations following catheter ablation of drug-refractory paroxysmal atrial fibrillation is poorly defined. The authors sought to define the long-term impact of thermal catheter ablation on the cardiac autonomic system. The study included 346 patients with drug-refractory paroxysmal atrial fibrillation undergoing pulmonary vein isolation using thermal ablation energy (radiofrequency or cryoballoon ablation). All patients underwent insertion of a Reveal LINQ implantable cardiac monitor prior to ablation. The implantable cardiac monitor continuously recorded physical activity, heart rate variability (HRV) (measured as the standard deviation of the average normal-to-normal), daytime heart rate, and nighttime heart rate (NHR). Longitudinal autonomic data in the 2-month period prior to the date of ablation were compared with the 3 years following ablation. Following ablation, there was a significant decrease in HRV (10-20ms; P< 0.0001) and significant increases in daytime heart rate and NHR (10 beats/min [P< 0.0001] and 7 beats/min [P< 0.0001], respectively). Changes in autonomic parameters were greatest in the first 3months following ablation but remained significantly different from baseline for 36months following ablation. Greater changes in NHR and HRV were associated with improved freedom from recurrent arrhythmia. The type of thermal ablation energy had no influence on the heart rate and autonomic parameters. Pulmonary vein isolation using thermal ablation energy results in significant sustained changes in the heart rate parameters related to autonomic function. These changes are independent of the ablation technology employed and are associated with procedural success. (Cryoballoon vs Irrigated Radiofrequency Catheter Ablation: Double Short vs Standard Exposure Duration [CIRCA-DOSE]; NCT01913522).

Characterizing lesion morphology of a novel diamond-tip temperature-controlled irrigated radiofrequency ablation catheter.

The DiamondTemp ablation (DTA) system is a novel temperature-controlled irrigated radiofrequency (RF) ablation system that accurately measures tip-tissue temperatures for real-time power modulation. Lesion morphologies from longer RF durations with the DTA system have not been previously described. We sought to evaluate lesion characteristics of the DTA system when varying the application durations. A bench model using porcine myocardium was used to deliver discrete lesions in a simulated clinical environment. The DTA system was power-limited at 50 W with temperature set-points of 50 °C and 60 °C (denoted Group_50 and Group_60). Application durations were randomized with a range of 5-120 s. In total, 280 applications were performed. Steam pops were observed in five applications: two applications at 90 s and three applications at 120 s. Lesion size (depth and maximum width) increased significantly with longer applications, until 60 s for both Group_50 and Group_60 (depth: 4.5 ± 1.2 mm and 5.6 ± 1.3 mm; maximum width: 9.3 ± 2.7mm and 11.2 ± 1.7mm, respectively). As lesions transition from resistive to conductive heating (longer than 10 s), the maximum width progressed in a sub-surface propagation. Using a "Time after Temperature 60 °C" (TaT60) analysis, depths of 2-3 mm occur in 0-5 s and depths plateau at 4.6 ± 0.8 mm between 20 and 30 s. The DTA system rapidly creates wide lesions with lesion depth increasing over time with application durations up to 60 s. Using a TaT60 approach is a promising ablation guidance that would benefit from further investigation.

PO-03-042 A COOL DRINK OF WATER: CONVECTIVE ESOPHAGEAL COOLING PREVENTS THERMAL INJURY FROM RADIOFREQUENCY HEATING IN AN EX VIVO SWINE ESOPHAGUS MODEL

Esophageal heating and subsequent thermal injury are concerning adverse effects of radiofrequency (RF) energy ablation on the posterior wall of the left atrium. Active intraluminal esophageal cooling may provide thermal protection, allowing for effective delivery of RF energy to overlying myocardium without collateral damage to the underlying esophagus. To evaluate the impact of esophageal luminal cooling with a closed loop continuous flow irrigation on esophageal heating and thermal injury using an ex vivo model. A flexible tube was placed through the lumen of a swine esophagus and connected to a closed loop circuit consisting of a pump and water bath (Figure 1, panel A). The esophagus was submerged in a saline bath with a temperature of 36 °C and an impedance of 140 ohms. Ten non-contiguous RF lesions were delivered at 50 watts for 8 seconds directly on the outer esophageal wall with 4 mm irrigated RF ablation catheter. This was performed without irrigation (control), irrigation at 1.5 L/min with room temperature water (20 °C), and irrigation at 1.5 L/min with ice water (0 °C). Esophageal tissue samples were obtained from immunohistochemistry and the esophagus was cross sectioned and lesions were measured with digital calipers. Closed loop continuous flow esophageal irrigation with ice water yielded esophageal lesions with the smallest surface area (Figure 1, panel A), depth, and volume (Figure 1, panel B). Continuous esophageal irrigation with room temperature water resulted in the second smallest lesions. RF lesions without esophageal irrigation resulted in the largest and deepest lesion, as well as evidence of luminal esophageal injury (Figure 1, panel C & D). Histology showed preserved smooth muscle, glands, basement membrane and epithelium with cooled esophagus and transmural lesions with non-irrigated esophagus (Figure 1, panel C & D). Continuous endoluminal esophageal cooling reduced lesion size with RF energy delivery. There was no luminal injury with room temperature and ice water esophageal irrigation. Thus, both may be useful in prevention of endoluminal esophageal injury during poster wall RF ablation.

3D-electroanatomical mapping of the left atrium and catheter-based pulmonary vein isolation in pigs: A practical guide.

To propose a standardized workflow for 3D-electroanatomical mapping guided pulmonary vein isolation in pigs. Danish female landrace pigs were anaesthetized. Ultrasound-guided puncture of both femoral veins was performed and arterial access for blood pressure measurement established. Fluoroscopy- and intracardiac ultrasound-guided passage of the patent foramen ovale or transseptal puncture was performed. Then, 3D-electroanatomical mapping of the left atrium was conducted using a high-density mapping catheter. After mapping all pulmonary veins, an irrigated radiofrequency ablation catheter was used to perform ostial ablation to achieve electrical pulmonary vein isolation. Entrance- and exit-block were confirmed and re-assessed after a 20-min waiting period. Lastly, animals were sacrificed to perform left atrial anatomical gross examination. We present data from 11 consecutive pigs undergoing pulmonary vein isolation. Passage of the fossa ovalis or transseptal puncture was uneventful and successful in all animals. Within the inferior pulmonary trunk 2-4 individual veins as well as 1-2 additional left and right pulmonary veins could be cannulated. Electrical isolation by point-by-point ablation of all targeted veins was successful. However, pitfalls including phrenic nerve capture during ablation, ventricular arrhythmias during antral isolation close to the mitral valve annulus and difficulties in accessing right pulmonary veins were encountered. Fluoroscopy- and intracardiac ultrasound-guided transseptal puncture, high-density electroanatomical mapping of all pulmonary veins and complete electrical pulmonary vein isolation can be achieved reproducibly and safely in pigs when using current technologies and a step-by-step approach.

Zero-fluoroscopy ablation of the cavotricuspid isthmus guided by intracardiac echocardiography in patients with typical atrial flutter

Abstract Introduction In previous studies we have demonstrated the advantages of electrophysiology catheter navigation by intracardiac echocardiography (ICE). In this prospective study we investigated ICE-guided zero-fluoroscopy ablation of the cavotricuspid isthmus (CTI) involving a decapolar diagnostic and an irrigated radiofrequency (RF) ablation catheter in patients with typical atrial flutter (AFL). Methods and results Twenty-seven consecutive patients (mean age 73.4±11.6 years, 18 male) with ECG-recordings suggesting ongoing (n=19) or recent CTI-dependent AFL underwent an electrophysiological study (EPS) utilizing solely ICE for catheter navigation. All EPS could be successfully accomplished without the need for fluoroscopy. CTI-dependent AFL was confirmed by entrainment manoeuvre in all patients with ongoing AFL. Mean EPS duration was 44.0±20.3 minutes and mean ablation procedure duration was 22.3±16.4 minutes. RF ablation was applied for 6.3±3.1 minutes (50 Watts, irrigated RF-ablation in all patients). After the last RF application, bidirectional CTI-Block was confirmed by differential pacing in all patients. Echocardiographic parameters such as CTI-length, prominence of the eustachian ridge (ER), and depth of the CTI-pouch on the ablation plane (Figure 1) were assessed to analyse their correlation with EPS- or ablation procedure duration. CTI-pouch was shallower in patients with ablation procedure duration above median (4,9±1.09mm vs. 6.3±0.9mm, p=0.048), suggesting a more laterally ablation plane in these patients, where the CTI musculature is stronger. CTI-length or ER-prominence above the respective median did not correlated with longer EPS duration. However, in some cases with prominent ER inversion of the ablation catheter was needed to achieve contact of catheter-tip to the tissue. An asymptomatic intramural hematoma was diagnosed by ICE after successful ablation in one patient, no other major or minor complications were documented in this study. Conclusions Zero-fluoroscopy CTI ablation guided solely by intracardiac echocardiography in patients with CTI-dependent AFL is feasible and safe. ICE visualisation may help to localize the optimal ablation plane, to detect and correct poor tissue contact of the catheter tip and recognise early potential complications during the ablation procedure. Funding Acknowledgement Type of funding sources: None.

Atrial fibrillation in partial anomalous pulmonary venous return: right atrial drainage from one vein and epicardial conduction from another vein.

A 72-year-old man with a history of patch closure of sinus venosus atrial septal defect (ASD) and uncorrected partial anomalous pulmonary venous return (PAPVR) of the right superior pulmonary vein (RSPV) draining to right superior vena cava (Figure 1A) presented for atrial fibrillation (AF) ablation. In addition to the PAPVR of the RSPV, computed tomography angiography showed four veins draining into the left atrium (LA): a right middle pulmonary vein (RMPV), a right inferior pulmonary vein, and two left-sided pulmonary veins. Mapping showed the RSPV was electrically silent but pulmonary vein potentials were present in all other pulmonary veins. An irrigated radiofrequency ablation catheter was used to perform wide antral circumferential ablation of the pulmonary veins in the LA. After completion of the line as well as a carinal line, an entrance block was seen in all pulmonary veins except the RMPV. Mapping while pacing the posterior LA showed earliest activation was deep within the RMPV 1 cm from the antrum. Pacing within the pulmonary vein at the low output (ensuring absence of direct RA capture) showed earliest activation in the posterior right atrium (RA) even prior to LA activation (Figure 1B). These findings were consistent with bidirectional conduction across an epicardial electrical connection between RMPV and RA. The site of earliest RA activation was directly adjacent to the phrenic nerve as delineated by high output pacing. As such, ablation was not undertaken to isolate this vein out of concern for phrenic nerve injury. Recurrence of AF has not been seen at a 6-month follow-up.

Influence of Monitoring Strategy on Assessment of Ablation Success and Postablation Atrial Fibrillation Burden Assessment: Implications for Practice and Clinical Trial Design.

Various noninvasive intermittent rhythm monitoring strategies have been used to assess arrhythmia recurrences in trials evaluating pharmacological and invasive therapeutic interventions for atrial fibrillation (AF). We determined whether a frequency and duration of noninvasive rhythm monitoring could be identified that accurately detects arrhythmia recurrences and approximates the AF burden derived from continuous monitoring using an implantable cardiac monitor (ICM). The rhythm history of 346 patients enrolled in the CIRCA-DOSE trial (Cryoballoon Versus Contact-Force Irrigated Radiofrequency Catheter Ablation) was reconstructed. Using computer simulations, we evaluated event-free survival, sensitivity, negative predictive value, and AF burden of a range of noninvasive monitoring strategies, including those used in contemporary AF ablation trials. A total of 126 290 monitoring days were included in the analysis. At 12 months, 164 patients experienced atrial arrhythmia recurrence as documented by the ICM (1-year event-free survival, 52.6%). Most noninvasive monitoring strategies used in AF ablation trials had poor sensitivity for detecting arrhythmia recurrence. Sensitivity increased with the intensity of monitoring, with serial (3) short-duration monitors (24-/48-hour ECG monitors) missing a substantial proportion of recurrences (sensitivity, 15.8% [95% CI, 8.9%-20.7%] and 24.5% [95% CI, 16.2%-30.6%], respectively). Serial (3) longer-term monitors (14-day ECG monitors) more closely approximated the gold standard ICM (sensitivity, 64.6% [95% CI, 53.6%-74.3%]). AF burden derived from short-duration monitors significantly overestimated the true AF burden in patients with recurrences. Increasing monitoring duration resulted in improved correlation and concordance between noninvasive estimates of the invasive AF burden (R2 = 0.85 and interclass correlation coefficient = 0.91 for serial [3] 14-day ECG monitors versus ICM). The observed rate of postablation atrial tachyarrhythmia recurrence is highly dependent on the arrhythmia monitoring strategy employed. Between-trial discrepancies in outcomes may reflect different monitoring protocols. On the basis of measures of agreement, serial long-term (7-14 day) intermittent monitors accumulating at least 28 days of annual monitoring provide estimates of AF burden comparable with ICM. However, ICMs outperform intermittent monitoring for arrhythmia detection, and should be considered the gold standard for clinical trials. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01913522.

Prevalence and outcome of early recurrence of atrial tachyarrhythmias in the Cryoballoon vs Irrigated Radiofrequency Catheter Ablation (CIRCA-DOSE) study.

Early recurrence of atrial tachyarrhythmia (ERAT) is common after pulmonary vein isolation (PVI) and has been associated with an increased risk of late atrial fibrillation (AF) recurrence. The purpose of this study was to determine the incidence and outcomes of patients experiencing ERAT after PVI using advanced-generation ablation technologies. This is a prespecified substudy of the CIRCA-DOSE (Cryoballoon vs Irrigated Radiofrequency Catheter Ablation: Double-Short vs Standard Exposure Duration) trial, a prospective, randomized, multicenter study comparing PVI with contact force-guided radiofrequency ablation to secondary-generation cryoballoon ablation for paroxysmal AF. All study patients received an implantable cardiac monitor to allow continuous rhythm monitoring. ERAT was defined as any recurrent atrial tachyarrhythmia within the first 90 days after AF ablation. ERAT occurred in 61% of the 346 patients at a median of 12 days (range 1-90 days) after ablation. ERAF was a significant predictor of late recurrence (60.1% with ER vs 25.9% without ER; P <.001) and symptomatic atrial tachyarrhythmia (31.6% with ERAF vs 6.7% without ERAF; P <.001). Receiver operating curve analyses revealed a strong correlation between ERAT timing and burden and late recurrence. Multivariate analysis identified ER timing (hazard ratio [HR] 2.90; 95% confidence interval [CI] 1.41-5.95; P = .004) and burden (HR 1.05 per 1% ER burden; 95% CI 1.04-1.07; P <.001) as strong independent predictors of late recurrence. Incidence rate, timing, burden, and prognostic significance of ER did not differ between the study groups. ERAT remains common after PVI despite use of advanced-generation ablation technologies. Early AF recurrence beyond 3 weeks after ablation is associated with increased risk of late recurrence.

Autonomic Alterations After Pulmonary Vein Isolation in the CIRCA-DOSE (Cryoballoon vs Irrigated Radiofrequency Catheter Ablation) Study.

BackgroundThe natural history of autonomic alterations following catheter ablation of drug‐refractory paroxysmal atrial fibrillation is poorly defined, largely because of the historical reliance on non‐invasive intermittent rhythm monitoring for outcome ascertainment.Methods and ResultsThe study included 346 patients with drug‐refractory paroxysmal atrial fibrillation undergoing pulmonary vein isolation using contemporary advanced‐generation ablation technologies. All patients underwent insertion of a Reveal LINQ (Medtronic) implantable cardiac monitor before ablation. The implantable cardiac monitor continuously recorded physical activity, heart rate variability (measured as the SD of the average normal‐to‐normal), daytime heart rate, and nighttime heart rate. Longitudinal autonomic data in the 2‐month period leading up to the date of ablation were compared with the period from 91 to 365 days following ablation. Following ablation there was a significant decrease in SD of the average normal‐to‐normal (mean difference versus baseline of 19.3 ms; range, 12.9–25.7; P<0.0001), and significant increases in daytime and nighttime heart rates (mean difference versus baseline of 9.6 bpm; range, 7.4–11.8; P<0.0001, and 7.4 bpm; range, 5.4–9.3; P<0.0001, respectively). Patients free of arrhythmia recurrence had significantly faster daytime (11±11 versus 8±12 bpm, P=0.001) and nighttime heart rates (8±9 versus 6±8 bpm, P=0.049), but no difference in SD of the average normal‐to‐normal (P=0.09) compared with those with atrial fibrillation recurrence. Ablation technology and cryoablation duration did not influence these autonomic nervous system effects.ConclusionsPulmonary vein isolation results in significant sustained changes in the heart rate parameters related to autonomic function. These changes are correlated with procedural outcome and are independent of the ablation technology used.RegistrationURL: https://www.clinicaltrials.gov; Unique identifier: NCT01913522.

Incidence of ablation-induced esophageal injury associated with high-power short duration temperature-controlled pulmonary vein isolation using a specialized open-irrigated ablation catheter: A retrospective single-center study.

To evaluate short-term efficacy and incidence of ablation-induced endoscopically detected esophageal injury in patients undergoing high-power, short-duration (HPSD) pulmonary vein isolation using a novel irrigated radiofrequency ablation catheter and ablation generator setup. Atrial fibrillation (AF) patients, who underwent AF ablation using an irrigated radiofrequency ablation catheter specifically designed for a HPSD ablation approach (50 W, with a target Ablation Index of 350 at posterior wall), received postablation esophageal endoscopy after ablation. In total 45 consecutive patients (67 ± 10 years; 58% male; 42% paroxysmal AF) undergoing AF ablation using a specialized ablation catheter (QDOT) were included in the study. Thirty-one of 45 patients (69%) underwent a first-time pulmonary vein isolation (Group 1, 67 ± 11 years; 55% male; 48% paroxysmal AF). Fourteen patients (31%) underwent a redo AF procedure (Group 2, 66 ± 8 years; 64% male; 29% paroxysmal AF). Patients undergoing first-time pulmonary vein isolation were included in the final analysis. In these patients an endoscopically detected esophageal lesion (EDEL) was detected in 5 of 31 (16%) patients (erosion n = 2, ulcer n = 3). Mean contact force at posterior wall ablation sites was significantly lower in patients with postprocedural EDEL compared with patients without EDEL (11.9 ± 0.8 g vs. 15.6 ± 4.7 g). PVI using a specialized high-power ablation catheter in conjunction with a HPSD ablation approach results in a 16% incidence of EDEL in first AF ablation candidates. Future studies evaluating high-power short duration ablation strategies should include esophageal endoscopy to estimate the risk of clinically relevant esophageal complications.

Advanced fully integrated radiofrequency/optical-coherence-tomography irrigated catheter for atrial fibrillation ablation.

The inability of current catheter ablation procedures to accurately monitor lesion formation limits their safety and efficacy. An advanced fully integrated radiofrequency (RF)/optical coherence tomography (OCT) ablation catheter is developed, which enables real-time monitoring during ablation. An OCT fiber array is especially designed, developed and integrated into an off-the-shelf irrigated RF ablation catheter. In-vitro experimental studies performed on poultry and ovine hearts demonstrate the ability of the integrated RF/OCT system to provide information on the quality and orientation of catheter/wall contact. Experimental results show that adipose tissue can be accurately identified from normal myocardial tissue with 94% accuracy and lesion formation is monitored with an overall accuracy of 93%. The ability to predict pop events is also demonstrated, with an accuracy of 86%.

Quality of Life and Health Care Utilization in the CIRCA-DOSE Study.

This study evaluated the impact of contact force-guided radiofrequency ablation versus cryoballoon ablation on quality of life and health care utilization. Traditional outcome parameters, such as arrhythmia-free survival, are insufficient to evaluate the clinical impact of atrial fibrillation (AF), as it fails to the capture patient- and health system-level differences in treatment approaches. The CIRCA-DOSE (Cryoballoon Vs. Contact-Force Atrial Fibrillation Ablation) study randomly assigned 346 patients with drug-refractory paroxysmal AF to contact force-guided radiofrequency or cryoballoon ablation. Health-related quality-of-life (HRQOL) was assessed at baseline, and at 6 and 12months post-ablation using a disease-specific and generic HRQOL instruments. Health care utilization (hospitalization, emergency department visits, and cardioversion) and antiarrhythmic drug use for the 12months preceding ablation was compared with the 12months following ablation. Disease-specific and generic HRQOL was moderately to severely impaired at baseline and improved significantly at 6 and 12months of follow-up (median improvement in AFEQT [Atrial Fibrillation Effect on QualiTy of Life] score 32.4 [interquartile range: 17.7 to 48.9]). When compared with the 12months pre-ablation, the proportion and absolute number of cardioversions decreased significantly (41.1% vs. 10.1% of patients, 137 vs. 35 events; p<0.0001). Similar significant reductions in emergency department visits (66.7% vs. 25.1% of patients, 224 vs. 87 events; p<0.0001), and hospitalizations (25.5% vs. 14.5% of patients, 86 vs. 50 events; p<0.001) were observed. There were no significant differences between randomized groups. In this multicenter randomized trial, catheter ablation with advanced-generation technologies resulted in a significant improvement in HRQOL and a significant reduction in health care utilization in the year following AF ablation. (Cryoballoon vs. Irrigated Radiofrequency Catheter Ablation [CIRCA-DOSE]; NCT01913522).

Impact of Female Sex on Clinical Presentation and Ablation Outcomes in the CIRCA-DOSE Study.

This study sought to evaluate sex-specific differences in atrial fibrillation (AF) presentation and catheter ablation outcomes in the prospective, multicenter, randomized CIRCA-DOSE (Cryoballoon vs. Irrigated Radiofrequency Catheter Ablation: Double Short vs. Standard Exposure Duration) study. Similar to other cardiovascular conditions, significant sex-specific differences have been observed in the epidemiology, pathophysiology, presentation, and natural history of AF. Unfortunately, there are major gaps in our understanding of the pathophysiological basis for the observed sex-specific differences and their implications on therapy and prognosis. This study examined sex-specific differences in AF presentation, symptom severity and health-related quality of life, symptomatic and asymptomatic arrhythmia recurrence, AF burden, and health care utilization. Freedom from any atrial tachyarrhythmia and symptomatic atrial tachyarrhythmia were similar between male (hazard ratio: 1.18; 95% confidence interval: 0.85 to 1.64; p=0.39) and female patients (hazard ratio: 1.00; 95% confidence interval: 0.62 to 1.59; p=0.92). Post-ablation, the median AF burden (percentage time in AF) was 0.00% (interquartile range: 0.00% to 0.16%) in male patients and 0.00% (interquartile range: 0.00% to 0.17%) in female patients, with no difference observed between the sexes (p=0.30). Periprocedural complications occurred twice as frequently in female patients (3.5% vs. 7.0%; p=0.18). In comparison to male patients, female patients reported a significantly worse symptom score and quality of life at baseline and all follow-up intervals, but they derived similar magnitude of improvement post-ablation. There was no difference between male and female patients with respect to emergency department visits, hospitalization, cardioversion, or repeat ablation. When compared with male patients, female patients have significantly worse symptom scores and quality of life at baseline. Despite this, female patients with symptomatic paroxysmal AF derive similar benefit in freedom from recurrent arrhythmia and similar improvements in quality of life following AF ablation. (Cryoballoon vs. Irrigated Radiofrequency Catheter Ablation: Double Short vs. Standard Exposure Duration [CIRCA-DOSE]; NCT01913522).

Impact of Left Common Pulmonary Veins in the Contact-Force vs. Cryoballoon Atrial Fibrillation Ablation (CIRCA-DOSE) Study.

Concerns remain regarding the effectiveness of PVI using the fixed diameter non-compliant cryoballoon in the presence of a left common pulmonary vein (LCPV). We sought to evaluate the effectiveness of PVI performed by contact-force guided radiofrequency (CF-RF) versus second-generation cryoballoon-based ablation in patients with LCPV. We enrolled 346 patients with paroxysmal AF and randomized them to CF-RF or cryoballoon ablation. PV anatomy was not assessed prior to enrolment, and there were no exclusions based on PV anatomy. All patients received an implantable cardiac monitor. LCPV was observed in 13.6% of patients (47/346). Left atrial time and fluoroscopy time did not differ between those with and without LCPV (P=0.58 and P=0.06, respectively). Freedom from any atrial tachyarrhythmia at one year was observed in 46.8% with LCPV and 54.5% without LCPV (P=0.06). In those with LCPV the freedom from any atrial tachyarrhythmia did not differ between those randomized to CF-RF or cryoballoon ablation (HR for recurrence 1.19, 95% CI 0.53-2.65, P=0.69). In those with LCPV the AF burden was reduced to a similar extent with CF-RF and cryoballoon ablation (99.7% vs. 99.5%, respectively; P=0.97). In this randomized clinical trial, the presence of a LCPV was associated with a trend towards higher rates of arrhythmia recurrence following PVI. No significant difference in arrhythmia recurrence was observed between patients with LCPV randomized to cryoballoon ablation or contact-force guided RF ablation, suggesting that either ablation modality is suitable in this population. (Cryoballoon vs. Irrigated Radiofrequency Catheter Ablation [CIRCA-DOSE], NCT01913522) This article is protected by copyright. All rights reserved.

Association of Atrial Fibrillation Episode Duration With Arrhythmia Recurrence Following Ablation

Contemporary guidelines recommend that atrial fibrillation (AF) be classified based on episode duration, with these categories forming the basis of therapeutic recommendations. While pragmatic, these classifications are not based on pathophysiologic processes and may not reflect clinical outcomes. To evaluate the association of baseline AF episode duration with post-AF ablation arrhythmia outcomes. The current study is a secondary analysis of a prospective, parallel-group, multicenter, single-masked randomized clinical trial (the Cryoballoon vs Irrigated Radiofrequency Catheter Ablation: Double Short vs Standard Exposure Duration [CIRCA-DOSE] study), which took place at 8 Canadian centers. Between September 2014 and July 2017, 346 patients older than 18 years with symptomatic AF referred for first catheter ablation were enrolled. All patients received an implantable cardiac monitor at least 30 days before ablation. Data analysis was performed in September 2019. Before ablation, patients were classified based on their longest AF episode. Ablation consisted of circumferential pulmonary vein isolation using standard techniques. Time to first recurrence of symptomatic or asymptomatic atrial tachyarrhythmia (AF, atrial flutter, or atrial tachycardia) following ablation and AF burden (percentage of time in AF) on preablation and postablation continuous rhythm monitoring. The study included 346 patients (mean [SD] age, 59 [10] years; 231 [67.7%] men). Overall, 263 patients (76.0%) had AF episode duration of less than 24 hours; 25 (7.2%), 24 to 48 hours; 40 (11.7%), 2 to 7 days; and 18 (5.2%), more than 7 days. Documented recurrence of any atrial tachyarrhythmia following ablation was significantly lower in patients with baseline AF episode duration of less than 24 continuous hours compared with those with longer AF episodes (24 hours vs 24-48 hours: hazard ratio [HR], 0.41; 95% CI, 0.21-0.80; P = .009; 24 hours vs 2-7 days: HR, 0.25; 95% CI, 0.14-0.45; P < .001; 24 hours vs >7 days: HR, 0.23; 95% CI, 0.09-0.55; P < .001). Patients with preablation AF episodes limited to less than 24 continuous hours had a significantly lower median (interquartile range) postablation AF burden (0% [0%-0.1%]) compared with those with AF preablation episodes lasting 2-7 days (0.1% [0%-1.0%]; P = .003) and those with AF preablation episodes lasting more than 7 days (1.0% [0%-5.4%]; P = .008). There was no significant difference in arrhythmia recurrence or AF burden between the 3 groups with a baseline AF episode duration of longer than 24 hours. In this study, patients with AF episodes limited to less than 24 continuous hours had a significantly lower incidence of arrhythmia recurrence following AF ablation. This suggests that current guidelines for classification of AF may not reflect clinical outcomes. ClinicalTrials.gov Identifier: NCT01913522.

The Cryoballoon vs Irrigated Radiofrequency Catheter Ablation (CIRCA-DOSE) Study Results in Context.

The Cryoballoon vs Irrigated Radiofrequency Catheter Ablation: Double Short vs Standard Exposure Duration (CIRCA-DOSE) study was a multicentre, randomised, single-blinded trial that compared contact-force radiofrequency ablation and two different regimens of cryoballoon ablation. All patients received an implantable cardiac monitor for the purpose of continuous rhythm monitoring, with all arrhythmia events undergoing independent adjudication by a committee blinded to treatment allocation. The study demonstrated there were no significant differences between contact-force radiofrequency ablation and cryoballoon ablation with respect to recurrence of any atrial tachyarrhythmia, symptomatic atrial tachyarrhythmia, asymptomatic AF, symptomatic AF or AF burden. While the results of the CIRCA-DOSE study are reviewed here, this article focuses on considerations around the design of the study and places the observed outcomes in context.

Correlation of magnetic resonance imaging and post-ablation endoscopy to detect oesophageal thermal injury in patients after atrial fibrillation ablation: MRI-EDEL-study.

To correlate oesophageal magnetic resonance imaging (MRI) abnormalities with ablation-induced oesophageal injury detected in endoscopy. Ablation-naïve patients with atrial fibrillation (AF), who underwent ablation using a contact force sensing irrigated radiofrequency ablation catheter, received a cardiac MRI on the day of ablation, and post-ablation oesophageal endoscopy (OE) 1 day after ablation. Two MRI expert readers recorded presence of abnormal oesophageal tissue signal intensities, defined as increased oesophageal signal in T2-fat-saturated (T2fs), short-tau inversion-recovery (STIR), or late gadolinium enhancement (LGE) sequences. Oesophageal endoscopy was performed by experienced operators. Finally, we correlated the presence of any affection with endoscopically detected oesophageal thermal lesions (EDEL). Among 50 consecutive patients (age 67 ± 7 years, 60% male), who received post-ablation MRI and OE, complete MRI data were available in 44 of 50 (88%) patients. In OE, 7 of 50 (14%) presented with EDEL (Category 1 lesion: erosion n = 3, Category 2 lesion: ulcer n = 4). Among those with EDEL, 6 of 7 (86%) patients presented with increased signal intensities in all three MRI sequences, while only 2 of 37 (5%) showed hyperintensities in all three MRI sequences and negative endoscopy. Correspondingly, sensitivity, specificity, positive predictive value, and negative predictive value (NPV) for MRI (increased signal in T2fs, STIR, and LGE) were 86%, 95%, 75%, and 97%, respectively. Increased signal intensity in T2fs, STIR, and LGE represents independent markers of EDEL. In particular, the combination of all three has the highest diagnostic value. Hence, MRI may represent an accurate, non-invasive method to exclude acute oesophageal injury after AF ablation (NPV: 97%).

Prevalence and clinical impact of spontaneous and adenosine-induced pulmonary vein reconduction in the Contact-Force vs. Cryoballoon Atrial Fibrillation Ablation (CIRCA-DOSE) study

Use of intraprocedural observation and pharmacologic challenges have been proposed as means to differentiate permanent pulmonary vein (PV)-left atrial conduction block from inadequate ablation lesions. The purpose of this study was to determine the prevalence and clinical impact of spontaneous and adenosine-provoked reconnection using contemporary atrial fibrillation (AF) ablation technologies. The CIRCA-DOSE (Cryoballoon vs. Irrigated Radiofrequency Catheter Ablation: Double Short vs. Standard Exposure Duration) study enrolled 346 patients with paroxysmal AF and randomized them to contact force-guided radiofrequency ablation (CF-RF) or cryoballoon ablation. Patients underwent provocative testing with adenosine after a 20-minute observation period. All patients received an implantable cardiac monitor for arrhythmia monitoring. Spontaneous reconnection was observed in 5.4% of PVs (71/1318) during the 20-minute postprocedure observation period, and dormant conduction was elicited in 5.7% of PVs (75/1318). Both spontaneous reconnection and dormant conduction were more common after CF-RF compared to cryoballoon ablation (P=.03 and P <.0001, respectively). Acute PV reconnection (spontaneous or adenosine-provoked) was associated with a significantly higher incidence of recurrent atrial tachyarrhythmia in the cryoballoon group (hazard ratio [HR] 2.39; 95% confidence interval [CI] 1.44-3.96; P = .0007) but not in the CF-RF group (HR 1.47; 95% CI 0.84-2.58; P = .16). In the absence of acute reconnection, the freedom from recurrent arrhythmia did not differ between groups (HR 0.95; 95% CI 0.6057-1.495; P = .83). Patients without spontaneous or adenosine-provoked reconnection had better outcomes compared to those with acute PV reconnection, suggesting that efforts should be directed toward ensuring an ideal ablation lesion at the first attempt in order to achieve durable PV isolation.

Catheter ablation of cardiac arrhythmias : Forms of energy and biophysical principles

Catheter ablation of cardiac arrhythmias has evolved over the years and has become acornerstone in the modern treatment of various supraventricular and ventricular arrhythmias. The goal of ablation is to permanently damage myocardium that is critically involved in the individual arrhythmia mechanism. Different catheters and forms of energy are available. Radiofrequency (RF) ablation is most common. Application of an alternating current at the catheter tip induces heating of tissue and, thus, leads to ablation of atargeted arrhythmogenic substrate. High temperatures (>70 °C at the catheter tip and >95 °C within the tissue) bear the risk of coagulum formation and steam pops and should be avoided, which limits power application. The evolution of irrigated RF ablation catheters enables the transfer of more power to the tissue and thereby increases the dimensions of the lesions. Cryoablation represents avaluable alternative. Cooling of tissue to -80 °C causes the intra- and extracellular formation of ice crystals, finally resulting in adense circumscribed scar. The cryomapping procedure grants improved surveillance of the safety of ablation. Cryoenergy is very popular for pulmonary vein isolation (PVI) using the cryoballoon. In addition to the laser balloon that is established for PVI, ultrasound, microwaves, and stereotactic irradiation complete the arsenal.

P2842Sequential application of horizontal and vertical orientation on radiofrequency ablation lesions produced by thermocool smarttouch SF catheter

Abstract Background Ablation lesions represent a complex interaction between the ablation catheter configuration and tissue anatomy. An understanding of each variable can assist in determination of the optimal lesion set. One such variable is the catheter orientation. With an irrigated radiofrequency ablation catheter with 6 pores (6P) near the distal tip, lesion surface area and volumes are smaller in the horizontal catheter orientation compared to the vertical catheter orientation. This finding is explained by the 6P irrigation catheter design, where irrigation fluid is discharged from six ports around the circumference of the electrode. Introduced in 2015, the ThermoCool SmartTouch® SF catheter has a 56-pore (56P) distribution to provide high density low volume irrigation settings. Irrigation catheters create smaller lesions in horizontal orientation compared to vertical orientation, however this has not been studied for the 56P irrigated catheter. Purpose Evaluate the impact of catheter orientation with sequential application of 56P catheter. Methods Ablation lesions were created on additive-free chicken model in a saline bath heated to 37°C using the 56P catheter under standard flow rate (8cc/min) conditions. Ablation energy of 20W and 30W was delivered twice for 30 seconds with 3 minutes interval between applications. Contact force (CF) of 5, 10, 15, and 20g was applied with the following conditions: horizontal catheter orientation followed by horizontal (HH), vertical by vertical (VV), horizontal by vertical (HV), and vertical by horizontal catheter orientation (VH). Measurements were obtained by lesion dissection through the midpoint by 3 independent operators. Kruskal-Wallis test was used for comparison of lesion depth, surface area and volume. Results Ninety-six lesions were analyzed. No coagulum or steam pops were included in the analysis. The minimum and maximum lesion depth, surface area and volume were 1.5 &amp; 6.0 mm, 14.1 &amp; 117.7mm2, 47.1 &amp; 471.0 mm3 respectively. There was no significant difference in the lesion depth, surface area or volume in HH, VV, HV or VH orientation at different CF with 20W and 30W. (Fig 1) Figure 1 Conclusion Unlike other irrigated catheters, catheter orientation with sequential application with different CF and power did not impact lesion depth, surface area and volume with 56P catheter. This finding could be considered useful in situations where the catheter orientation could be challenging owing to tissue anatomy to achieve adequate lesion size. Acknowledgement/Funding UVA Health System