Early ablation of newly diagnosed paroxysmal atrial fibrillation (NEWPaAF) versus newly diagnosed persistent atrial fibrillation (NEWPeAF): Comparison of patient populations and ablation outcomes.

INTRODUCTION: Little is known about very early atrial fibrillation (AF) ablation after first AF detection. METHODS: We evaluated patients with AF ablation <4 months from newly diagnosed paroxysmal AF (NEWPaAF) and newly diagnosed persistent AF (NEWPeAF). We compared the two patient populations and compared ablation outcomes to those undergoing later ablation. RESULTS: Ablation was done <4 months from AF diagnosis in 353 patients (135 = paroxysmal, 218 = persistent). Early ablation outcome was best for NEWPaAF versus NEWPeAF for initial (p = 0.030) but not final (p = 0.102) ablation. Despite recent AF diagnosis in both groups, they were clinically quite different. NEWPaAF patients were younger (64.3 ± 13.0 vs. 67.3 ± 10.9, p = 0.0020), failed fewer drugs (0.39 vs. 0.60, p = 0.007), had smaller LA size (4.12 ± 0.58 vs. 4.48 ± 0.59 cm, p < 0.0001), lower BMI (28.8 ± 5.0 vs. 30.3 ± 6.0, p = 0.016), and less CAD (3.7% vs. 11.5%, p = 0.007), cardiomyopathies (2.2% vs. 22.9%, p = 0.0001), hypertension (46.7% vs. 67.4%, p < 0.0001), diabetes (8.1% vs. 17.4%, p = 0.011) and sleep apnea (20.0% vs. 30.3%, p = 0.031). For NEWPaAF, early ablation AF-free outcome was no better than later ablation (p = 0.314). For NEWPeAF, AF-free outcomes were better for early ablation than later ablation (p < 0.0001). Delaying ablation allowed more strokes/TIAs in both AF types (paroxysmal p = 0.014, persistent p < 0.0001). CONCLUSIONS: Patients presenting for early ablation after newly diagnosed persistent AF have more pre-existing comorbidities and worse initial ablation outcomes than patients with NEWPaAF. For NEWPaAF, there was no advantage to early ablation, as long as the AF remained paroxysmal. For NEWPeAF, early ablation gave better outcomes than later ablation and they should undergo early ablation. For both AF types, waiting was associated with more neurologic events, suggesting all patients should consider earlier ablation.

HPSD ablation for AF high-power short-duration RF ablation for atrial fibrillation: A review.

This manuscript reviews the literature for all in silico, ex vivo, in vitro, in vivo and clinical studies of high-power short-duration (HPSD) radiofrequency (RF) ablations. It reviews the biophysics of RF energy delivery applicable to HPSD and the use of surrogate endpoints to guide the duration of HPSD ablations. In silico modeling shows that a variety of settings in power, contact force and RF duration can result in the same surrogate endpoint value of ablation index and several HPSD combinations produce lesion volumes similar to a low-power long-duration (LPLD) RF application. HPSD lesions are broader with more endocardial effect and are slightly shallower but still transmural. The first 10 s of RF application is most important for lesion formation with diminishing effect beyond 20 s. The ideal contact force is 10-20 g with only a small effect beyond 30 g. In vitro and in vivo models confirm that HPSD makes transmural lesions that are often broader and shallower, and with proper settings, result in fewer steam pops than LPLD. One randomized trial shows better outcomes with HPSD and validates lesion size index as a surrogate endpoint. Clinical studies of HPSD using comparator groups of LPLD ablations uniformly show shorter procedure times and shorter total RF energy delivery for HPSD. HPSD generally has a higher first pass vein isolation rate and a lower acute vein reconnection rate than LPLD. Although not dramatically different from LPLD, long-term freedom from atrial fibrillation and complication rates seem slightly better with HPSD.

Comparison of CHADS2 and CHA2DS2-VASC anticoagulation recommendations: evaluation in a cohort of atrial fibrillation ablation patients.

AIMS: Atrial fibrillation (AF) is associated with a high incidence of strokes/thromboembolism. The CHADS2 score assigns points for several clinical variables to identify stroke risk. The CHA2DS2-VASC score uses the same variables but also incorporates age 65 to 74, female gender, and vascular disease in an effort to provide a more refined risk of stroke/thromboembolism. We aimed to examine oral anticoagulation (OAC) recommendations for a cohort of patients undergoing AF ablation depending upon whether thrombo-embolic risk was determined by the CHADS2 or CHA2DS2-VASC score. METHODS AND RESULTS: For 1411 patients we compared OAC recommendations for each of these risk stratification schemes to one of the three OAC strategies: (i) NO-OAC, (ii) CONSIDER-OAC, and (iii) DEFINITE-OAC. Compared with the CHADS2 score, the CHA2DS2-VASC score reduced NO-OAC from 40.3 to 21.8% and CONSIDER-OAC from 36.6 to 27.9% while increasing DEFINITE-OAC from 23.0 to 50.2% of patients. Age 65 to 74 and female gender accounted for 95.2% and vascular disease for only 4.8% of recommendations for more aggressive OAC using CHA2DS2-VASC. Most vascular disease occurred in patients with higher CHADS2 scores already recommended for DEFINITE-OAC (P < 0.0001). Reclassifying 30 females of age <65 with a CHA2DS2-VASC score of 1 to the NO-OAC group had minimal effect on the overall recommendations. CONCLUSION: Compared with the CHADS2 score, in our AF ablation population, the CHA2DS2-VASC score markedly increases the number of AF patients for whom OAC is recommended. It will be important to determine by randomized trials if this major paradigm shift to greater use of OAC using the CHA2DS2-VASC scoring improves patient outcomes.

Peri-procedural interrupted oral anticoagulation for atrial fibrillation ablation: comparison of aspirin, warfarin, dabigatran, and rivaroxaban.

AIMS: Atrial fibrillation ablation requires peri-procedural oral anticoagulation (OAC) to prevent thromboembolic events. There are several options for OAC. We evaluate peri-procedural AF ablation complications using a variety of peri-procedural OACs. METHODS AND RESULTS: We examined peri-procedural OAC and groin, bleeding, and thromboembolic complications for 2334 consecutive AF ablations using open irrigated-tip radiofrequency (RF) catheters. Pre-ablation OAC was warfarin in 1113 (47.7%), dabigatran 426 (18.3%), rivaroxaban 187 (8.0%), aspirin 472 (20.2%), and none 136 (5.8%). Oral anticoagulation was always interrupted and intraprocedural anticoagulation was unfractionated heparin (activated clotting time, ACT = 237 ± 26 s). Pre- and post-OAC drugs were the same for 1591 (68.2%) and were different for 743 (31.8%). Following ablation, 693 (29.7%) were treated with dabigatran and 291 (12.5%) were treated with rivaroxaban. There were no problems changing from one OAC pre-ablation to another post-ablation. Complications included 12 (0.51%) pericardial tamponades [no differences for dabigatran (P = 0.457) or rivaroxaban (P = 0.163) compared with warfarin], 12 (0.51%) groin complications [no differences for rivaroxaban (P = 0.709) and fewer for dabigatran (P = 0.041) compared with warfarin]. Only 5 of 2334 (0.21%) required blood transfusions. There were two strokes (0.086%) and no transient ischaemic attacks (TIAs) in the first 48 h post-ablation. Three additional strokes (0.13%), and two TIAs (0.086%) occurred from 48 h to 30 days. Only one stroke had a residual deficit. Compared with warfarin, the neurologic event rate was not different for dabigatran (P = 0.684) or rivaroxaban (P = 0.612). CONCLUSION: Using interrupted OAC, low target intraprocedural ACT, and irrigated-tip RF, the rate of peri-procedural groin, haemorrhagic, and thromboembolic complications was extremely low. There were only minimal differences between OACs. Low-risk patients may remain on aspirin/no OAC pre-ablation. There are no problems changing from one OAC pre-ablation to another post-ablation.

Very long term outcomes of atrial fibrillation ablation.

BACKGROUND: Little is known about the very long term durability of atrial fibrillation (AF) ablation. OBJECTIVE: The purpose of this study was to evaluate very long term AF ablation outcomes. METHODS: We followed 5200 patients undergoing 7145 ablation procedures. We evaluated outcomes after single and multiple ablation procedures for paroxysmal (PAF; 33.6%), persistent (PeAF; 56.4%), and long-standing (LsAF; 9.9%) AF. We compared 3 ablation eras by initial ablation catheter: early (101 patients) using solid big tip (SBT) catheters (October 2003 to December 2005), intermediate (2143 patients) using open irrigated tip (OIT) catheters (December 2005 to August 2016), and contemporary (2956 patients) using contact force (CF) catheters (March 2014 to December 2021). RESULTS: AF freedom at 5, 10, and 15 years was as follows: initial ablation: PAF 67.8%, 56.3%, 47.6%; PeAF 46.6%, 35.6%, 26.5%; and LsAF 30.4%, 18.0%, 3.4%; final ablation: PAF 80.3%, 72.6%, 62.5%; PeAF 60.1%, 50.2%, 42.5%; and LsAF 43.4%, 32.0%, 20.6%. For PAF and PeAF, CF ablation procedures were better than OIT ablation procedures (P < .0001) and both were better than SBT ablation procedures (P < .001). LsAF had no outcome improvement over the eras. The 8-year success rate after final ablation for CF, OIT, and SBT catheter eras was as follows: PAF 79.1%, 71.8%, 60.0%; PeAF 55.9%, 50.7%, 38.0%; and LsAF 42.7%, 36.2%, 31.8%. Highest AF recurrence was in the first 2 years, with a 2- to 15-year recurrence of 2%/yr. Success predictors after initial and final ablation procedures were younger age, smaller left atrium, shorter AF duration, male sex, less persistent AF, lower CHA2DS2-VASc score, fewer drugs failed, and more recent catheter era. CONCLUSION: After year 2, there is 2%/yr recurrence rate for all AF types. Ablation success is best in the CF catheter era, intermediate in the OIT era, and worst in the SBT era. Over the ablation eras, outcomes improved for PAF and PeAF but not for LsAF. We should follow patients indefinitely after ablation. We need an understanding of how to better ablate more persistent AF.

The use of dabigatran immediately after atrial fibrillation ablation.

INTRODUCTION: Atrial fibrillation (AF) ablation requires postprocedural anticoagulation to prevent thromboembolic events because of the ablation procedure itself or due to recurrent AF postprocedure. Dabigatran is a new anticoagulant and may be useful after AF ablation to prevent thromboembolic events. METHODS AND RESULTS: We evaluated 123 consecutive patients who were started on dabigatran after AF ablation. Patients were given enoxaparin 0.5 mg/kg at the end of the procedure, which was repeated 12 hours later and then discontinued. Dabigatran was started 22 hours postablation with drug dose based on renal function. Primary outcomes were thromboembolic events, bleeding complications, and side effects over a 30-day follow-up period. The preablation anticoagulant was warfarin in 56 (45.5%) patients, dabigatran in 34 (27.6%), and aspirin in 26 (21.1%). Seven (5.7%) patients were on no anticoagulant before ablation. The patients on dabigatran before ablation with normal renal function had the drug stopped 36 hours preablation. There were no preprocedural or intraprocedural thromboembolic episodes or bleeding. Three patients received dabigatran 75 mg bid and the rest 150 mg bid. There were no postablation strokes, transient ischemic attacks, or systemic thromboemboli in any patient. Three patients discontinued dabigatran and were changed to warfarin, 2 because of gastrointestinal side effects and 1 because of a diffuse rash. CONCLUSIONS: Dabigatran is safe and well tolerated after AF ablation. It did not cause bleeding complications and there were no thromboembolic events. Dabigatran appears to be an alternative to warfarin after AF ablation.

Prior antiarrhythmic drug use and the outcome of atrial fibrillation ablation.

AIMS: Atrial fibrillation (AF) ablation is generally performed after patients fail antiarrhythmic drug (AAD) therapy. Some patients have drug contraindications or choose to avoid a lifetime of drug therapy. Little is known about the impact of previous drug therapy on ablation outcomes. We evaluated AAD use before AF ablation and its impact on ablation outcomes. METHODS AND RESULTS: We evaluated freedom from AF after ablation and patients' clinical characteristics by number of AADs failed in 1125 patients undergoing 1504 ablations. We also evaluated reasons why some patients did not receive prior drug therapy. Cox multivariate analysis examined factors predicting ablation failure. Patients failing more drugs before ablation were older (P = 0.001), had a longer duration of AF (P = 0.0001), were more likely female (P = 0.037), had more repeat ablations (P = 0.045), and less paroxysmal AF (P = 0.003). For patients with either paroxysmal or persistent AF, the number of drugs failed predicted AF recurrence (P = 0.0001). Other factors predicting AF recurrence following final ablation included age (P = 0.004), left atrial size (P = 0.002), female gender (P = 0.0001), and persistent AF (P = 0.0001). The reason for not receiving prior drug therapy was medical in 21.5% and patient choice in 78.5%. Number of drugs failed did not influence ablation outcome for patients with long-standing persistent AF (P = 0.352). CONCLUSIONS: For paroxysmal and persistent AF patients undergoing ablation, those failing fewer AADs have different clinical characteristics than those who fail more drugs. Our study also suggests that the more drugs failed pre-ablation, the lower the freedom from AF post-procedure, possibly due to AF progression during drug trials.

Correlation between sinus rhythm deceleration zones and critical sites for localized reentrant atrial flutter: A retrospective multicenter analysis.

Background: Atypical left atrial flutter (AFL) may be macroreentrant or spatially localized. The relationship between the critical isthmus (CI) for localized reentry with sinus rhythm (SR) conduction slowing has not been systematically examined. Objective: To examine the correlation between CI sites for localized AFL (L-AFL) and deceleration zones (DZ) identified by isochronal late activation mapping (ILAM) during baseline rhythm. Methods: Patients with localized AFL who underwent high-density activation mapping of both SR and AFL were retrospectively analyzed. L-AFL was defined as reentry restricted to 2 wall segments of the left atrium. CI was defined by activation mapping and sites of successful termination during ablation. DZ, defined as >3 isochrones within 1 cm radius during baseline rhythm, were correlated to the locations of the CI. Results: Thirty-one consecutive patients that underwent detailed sinus rhythm and AFL high-density activation maps were analyzed at 3 centers. A mean 4060 ± 3275 and 6209 ± 8656 points were collected in ILAM and AFL activation maps, respectively. At least 1 DZ (1.7 ± 0.77) was identified in all patients. ILAM showed 3.27 ± 0.52 isochrones per DZ (168 ± 32 ms), and co-localized to CI sites at a distance of 6.7 ± 3 mm. A total of 34% ± 14% of the AFL cycle length was contained within 0.5 cm of the DZ. Conclusions: In patients with L-AFL, CI co-localized with DZ during baseline rhythm, suggesting that DZ mapping during SR may yield candidate targets for ablation as an adjunct to pulmonary vein isolation to prevent a subtype of AFL.

Long-term results of atrial fibrillation ablation: the importance of all initial ablation failures undergoing a repeat ablation.

BACKGROUND: Ablation is more successful for patients with paroxysmal atrial fibrillation (AF1) than for those with persistent (AF2) or longstanding persistent AF (AF3). Many patients fail initial ablation and undergo repeat ablations. Little is known about repeat ablation procedure times, complications, and outcomes. METHODS: We evaluated Kaplan-Meier freedom from AF by AF type and sex for initial and repeat ablations and for final status of 843 patients undergoing 1122 ablations. We examined complications, procedure times and reasons why patients do not undergo repeat ablations. Cox multivariate analysis evaluated factors predicting ablation failure. RESULTS: Initial ablations were more successful in AF1 than AF2 or AF3 (P < .0001) patients. For each AF type, repeat ablations were more successful than initial ablations (P = .01 to <.001). Procedure times (139.1 ± 49.1 vs 135.3 ± 45.6 minutes, P = .248) and major complications (1.66% vs 2.87%, P = .216) were similar. Women had different clinical characteristics than men, similar initial and repeat ablation success rates but lower overall success because of fewer repeat ablations (57.8% vs 68.2%, P = .047) due to patient choice (P = .028). Patients with either successful initial ablations or undergoing repeat ablations had late AF recurrence rates of 0% to 1.5% a year. Age (P = .012), larger left atria (P = .002), female sex (P = .001), AF2 (P < .0001), AF3 (P = .003), and coronary disease (P = .003) predicted failure. CONCLUSIONS: Repeat ablations are more successful than initial ablations, have similar procedure times and complication rates, help determine final success rates, and may explain sex difference in success rates. For the best outcomes, patients should assume that a repeat ablation may be required to eliminate AF.

Atrial fibrillation ablation: "perpetual motion" of open irrigated tip catheters at 50 W is safe and improves outcomes.

BACKGROUND: Point-by-point use of open irrigated tip catheters (OITCs) at 50 W increases atrial fibrillation (AF) ablation cure rates but also increases complications. We determined if constantly moving the OITC (perpetual motion) when using 50 W increases ablation cure rates without increasing complications. METHODS: We evaluated procedural data, complications, and individual procedure cure rates (IPCRs) for AF ablation using closed tip catheters (CTC) versus OITC at 40, 45, and 50 W in 1,122 ablations. We used "perpetual motion" to move the OITC at 50 W every 3-10 seconds. RESULTS: The OITC showed higher IPCR than CTC at 45 W (P = 0.012) and 50 W (P < 0.0005). For the OITC, IPCR increased from 44.6% to 60.7% as power increased from 40 to 50 W (P = 0.008). The OITC appeared superior to the CTC for all types of AF. For paroxysmal AF, increasing OITC power from 40 to 50 W provided no increase in IPCR (70.6% vs 71.2%, P = 0.827). For persistent AF, increasing power from 40 to 50 W increased IPCR from 34.5% to 59.5% (P = 0.001). Complications were similar for the CTC and the OITC at any power. The OITC at 50 W had shorter procedure, left atrial, and fluoroscopy times (P < 0.0005). CONCLUSIONS: Increasing OITC power from 40 to 50 W increases IPCR with no increase in complications as long as the 50 W setting is done using "perpetual motion." The OITC 50 W power setting results in shorter procedure and fluoroscopy times and should be considered for AF ablations.

Open-window mapping of accessory pathways utilizing high-density mapping.

PURPOSE: Accessory pathway (AP) mapping is currently based on point-by-point mapping and identifying if a local electrogram's origin is atrial, pathway, or ventricular, which is time-consuming and prone to insufficient mapping. We sought to determine the feasibility of automated and high-density mapping to define AP location using open-window mapping (OWM), which does not rely on defining the electrogram's origin but simply detects the sharpest local signal at each point. METHODS: We enrolled 23 consecutive patients undergoing catheter ablation for atrioventricular reentrant tachycardia. High-density mapping was performed using OWM and ablation was performed. The successful site of ablation was determined by the loss of pathway function. RESULTS: OWM was 100% effective at identifying the successful site of ablation (average mapping time 7.3 ± 4.3 min.) Permanent AP elimination was achieved using a mean radiofrequency energy time of 18.5 ± 24.5 s/patient. Transiently successful ablations were 4.0 ± 1.8 mm from permanently successful sites and had lower contact force (5.1 ± 2.5 g vs. 11.7 ± 9.0 g; P = 0.041). Unsuccessful sites had similar contact force to permanently successful sites (12.2 ± 9.2 g vs. 11.7 ± 9.0 g; P = 0.856) but were 6.4 ± 2.0 mm away from successful sites. CONCLUSION: A novel technique of high-density, automated, and open-window mapping (OWM) effectively localizes APs without the need to differentiate the signal's site of origin. These findings suggest that OWM can be used to rapidly and successfully map and ablate APs. Both distances from the pathway and contact force were shown to be important for pathway ablation.

Internationally validated score to predict the outcome of non-paroxysmal atrial fibrillation ablation: the 'FLAME score'.

BACKGROUND: The clinical effectiveness of ablating non-paroxysmal atrial fibrillation (non-PAF) relies on proper patient selection. We developed and validated a scoring system to predict non-PAF ablation outcomes. METHODS: Data on 416 non-PAF ablations were analysed using binary logistic regression at a London centre. Identified preprocedural variables, which independently predicted freedom from atrial tachyarrhythmia. Twenty-one possible predictive variables and a model with c-statistic 0.751-explained outcome variation in London at mean follow-up 12±3 months. An additive point score (range 0-9) was developed-the FLAME score: female=1; long-lasting persistent atrial fibrillation=1; left atrial diameter in mm: 40 to <45 = 1, 45 to <50 = 2, 50 to <55=3, ≥55 =4; mitral regurgitation (MR) mild to moderate=1; extreme comorbidity=2. Extreme comorbidities include severe MR, moderate mitral stenosis, mitral replacement, hypertrophic cardiomyopathy or congenital heart disease. RESULTS: The FLAME score was applied to data (882 non-PAF ablations) at a Californian centre, and predicted the outcome of both single (p<0.0001) and multiple (p<0.0001) procedures. For first ablation (follow-up 2.1 years (median, IQR 1.0-4.1)), FLAME score: 0-1 predicts 62% success, 2-4 44% and ≥5 29% (Ptrend <0.0001). After the final ablation (mean procedures: 1.4±0.6, follow-up 1.8 years (median, IQR 0.8-3.6)), FLAME score: 0-1 predicts 81% success, 2-4 65% and ≥5 44% (Ptrend <0.0001). CONCLUSIONS: FLAME score is easily calculated, derived in London, and predicted single and multiple procedural outcomes for non-PAF ablations in California. In patients with a high score, even multiple procedures are usually ineffective.

Novel Low-Voltage MultiPulse Therapy to Terminate Atrial Fibrillation.

OBJECTIVES: This first-in-human feasibility study was undertaken to translate the novel low-voltage MultiPulse Therapy (MPT) (Cardialen, Inc., Minneapolis, Minnesota), which was previously been shown to be effective in preclinical studies in terminating atrial fibrillation (AF), into clinical use. BACKGROUND: Current treatment options for AF, the most common arrhythmia in clinical practice, have limited success. Previous attempts at treating AF by using implantable devices have been limited by the painful nature of high-voltage shocks. METHODS: Forty-two patients undergoing AF ablation were recruited at 6 investigational centers worldwide. Before ablation, electrode catheters were placed in the coronary sinus, right and/or left atrium, for recording and stimulation. After the induction of AF, MPT, which consists of up to a 3-stage sequence of far- and near-field stimulation pulses of varied amplitude, duration, and interpulse timing, was delivered via temporary intracardiac leads. MPT parameters and delivery methods were iteratively optimized. RESULTS: In the 14 patients from the efficacy phase, MPT terminated 37 of 52 (71%) of AF episodes, with the lowest median energy of 0.36 J (interquartile range [IQR]: 0.14 to 1.21 J) and voltage of 42.5 V (IQR: 25 to 75 V). Overall, 38% of AF terminations occurred within 2 seconds of MPT delivery (p < 0.0001). Shorter time between AF induction and MPT predicted success of MPT in terminating AF (p < 0.001). CONCLUSIONS: MPT effectively terminated AF at voltages and energies known to be well tolerated or painless in some patients. Our results support further studies of the concept of implanted devices for early AF conversion to reduce AF burden, symptoms, and progression.