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.

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.

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.

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.

High-power, short-duration atrial fibrillation ablations using contact force sensing catheters: Outcomes and predictors of success including posterior wall isolation.

BACKGROUND: Little is known about the long-term outcomes and predictors of success of high-power, short-duration (HPSD) contact force (CF) atrial fibrillation (AF) ablations. OBJECTIVE: The purpose of this study was to determine long-term freedom from AF and predictors of freedom from AF for 50-W, 5- to 15-second CF ablation. METHODS: We examined 4-year outcomes and predictors of freedom from AF after AF ablation for 1250 consecutive patients undergoing HPSD CF ablations. RESULTS: Patient demographics were age 66.6 ± 10.5 years, female 30.9%, left atrial (LA) size 4.26 ± 0.66 cm, paroxysmal AF 35.7%, persistent AF 56.6%, and longstanding AF 7.7%. Initial ablation times were procedure 114.2 ± 45.9 minutes, fluoroscopy 15.5 ± 11.5 minutes, and total radiofrequency 20.6 ± 7.7 minutes. TactiCath was used in 47.7%, SmartTouch in 52.3%, and posterior wall isolation (PWI) was performed in 34%. Four-year freedom from AF after multiple ablations were paroxysmal AF 87.0%, persistent AF 71.9%, and longstanding AF 64.9%. Single procedure success was 74.9% for TactiCath, 64.7% for SmartTouch (P <.001), and 73.0% for no PWI vs 58.9% for PWI (P <.0001). PWI did not change outcomes for paroxysmal AF but had worse outcomes for nonparoxysmal AF. Multivariate analysis showed 6 independent predictors of worse outcome after initial ablation: older age (P = .014), female gender (P <.0001), persistent AF (P = .0001), larger LA size (P <.001), PWI (P = .049), and use of SmartTouch vs TactiCath catheter (P = .007). Redo ablations were performed in 13.8%, and the outcome was better when more veins had reconnected after the initial ablation and when AF was paroxysmal. CONCLUSION: Analysis revealed 6 independent predictors of outcome for HPSD CF. At redo ablations, the outcome was better if more veins had reconnected and could be re-isolated.

Catheter ablation for failed surgical maze: comparison of cut and sew vs. non-cut and sew maze.

PURPOSE: To compare findings in patients undergoing atrial fibrillation(AF) and/or atrial flutter(AFl) ablation after failed cut and sew (CS) vs. non-cut and sew (NCS) surgical maze. METHODS: We compared 10 patients with prior CS to 25 with prior NCS maze undergoing catheter ablation after failed maze. RESULTS: Patient demographics: Age 68.3 ± 8.7 CS vs. 68.2 ± 9.2 NCS(P = 0.977), male 70% CS vs. 72% NCS(P = 1.000), LA size 5.11 ± 0.60 cm CS vs. 4.54 ± 0.92 cm NCS(P = 0.096), sternotomy 100% CS vs. 64% of NCS(P = 0.036). Concomitant heart surgery in 100% CS and 68% NCS(P = 0.073). NCS used radiofrequency 84%, cryoablation 8%, microwave 4%, and ultrasound 4%. All maze operations targeted pulmonary vein (PV) isolation. The maze also targeted the mitral isthmus 100% CS vs. 36% NCS(P = 0.001) and the tricuspid isthmus 90% CS vs. 40% NCS (P = 0.018). Maze failure arrhythmia mechanism was AF 0% CS and 56% NCS (P = 0.0006). Nine CS pts failed for AFl and 1 for RA tachycardia. For NCS pts, 11 failed for AFl. CS isolated 94% of PVs and NCS isolated only 26% of PVs (P < 0.0005). At EPS, clinical and induced arrhythmias were ablated and non-isolated PVs were isolated. After final ablation, arrhythmia-free rates were 60% for CS and 52% for NCS (P = 0.723) after 2.99 ± 2.35 years. CONCLUSIONS: After failed surgical maze, CS isolated nearly all PVs and NCS never isolated all PVs and the clinical rhythm was more frequently AF for NCS and AFl for CS. CS remains the surgical gold standard for durable PV isolation.

Low complication rates using high power (45-50 W) for short duration for atrial fibrillation ablations.

BACKGROUND: Many centers use radiofrequency (RF) energy at 25-35 W for 30-60 seconds. There is a safety concern about using higher power, especially on the posterior wall. OBJECTIVE: The purpose of this study was to examine complication rates for atrial fibrillation (AF) ablations performed with high-power, short-duration RF energy. METHODS: We examined the complication rates of 4 experienced centers performing AF ablations at RF powers from 45-50 W for 2-15 seconds per lesion. In total, 13,974 ablations were performed in 10,284 patients. On the posterior wall, 11,436 ablations used 45-50 W for 2-10 seconds, and 2538 ablations used power reduced to 35 W for 20 seconds. Esophageal temperature monitoring was used in 13,858 (99.2%). RESULTS: Demographics were age 64 ± 11 years, male 68%, left atrial size 4.4 ± 0.7 cm, paroxysmal AF 37%, persistent AF 42%, longstanding AF 20%, antiarrhythmic drugs failed 1.4 ± 0.7, hypertension 54%, diabetes 15%, previous cerebrovascular accident/transient ischemic attack 7%, and CHA2DS2-VASc score 2.1 ± 1.4. Procedural time was 116 ± 41 minutes. Complications were death in 2 (0.014%; 1 due to stroke and 1 due to atrioesophageal fistula), pericardial tamponade in 33 (0.24%; 26 tapped, 7 surgical), strokes <48 hours in 6 (0.043%), strokes 48 hours-30 days in 6 (0.043%), pulmonary vein stenosis requiring intervention in 2 (0.014%), phrenic nerve paralysis in 2 (0.014%; both resolved), steam pops 2 (0.014%) without complications, and catheter char 0 (0.00%). There was 1 atrioesophageal fistula in 11,436 ablations using power 45-50 W on the posterior wall and 3 in 2538 ablated with 35 W on the posterior wall (P = .021), although 2 of the 3 had no esophageal monitoring during a fluoroless procedure. CONCLUSION: AF ablations can be performed at 45-50 W for short durations with very low complication rates. High-power, short-duration ablations have the potential to shorten procedural and total RF times and create more localized and durable lesions.

Atrial fibrillation ablation using very short duration 50 W ablations and contact force sensing catheters.

PURPOSE: The optimal radiofrequency (RF) power and lesion duration using contact force (CF) sensing catheters for atrial fibrillation (AF) ablation are unknown. We evaluate 50 W RF power for very short durations using CF sensing catheters during AF ablation. METHODS: We evaluated 51 patients with paroxysmal (n = 20) or persistent (n = 31) AF undergoing initial RF ablation. RESULTS: A total of 3961 50 W RF lesions were given (average 77.6 ± 19.1/patient) for an average duration of only 11.2 ± 3.7 s. As CF increased from < 10 to > 40 g, the RF application duration decreased from 13.7 ± 4.4 to 8.6 ± 2.5 s (p < 0.0005). Impedance drops occurred in all ablations, and for patients in sinus rhythm, there was loss of pacing capture during RF delivery suggesting lesion creation. Only 3% of the ablation lesions were at < 5 g and 1% at > 40 g of force. As CF increased, the force time integral (FTI) increased from 47 ± 24 to 376 ± 102 gs (p < 0.0005) and the lesion index (LSI) increased from 4.10 ± 0.51 to 7.63 ± 0.50 (p < 0.0005). Both procedure time (101 ± 19.7 min) and total RF energy time (895 ± 258 s) were very short. For paroxysmal AF, the single procedure freedom from AF was 86% at 1 and 2 years. For persistent AF, it was 83% at 1 year and 72% at 2 years. There were no complications. CONCLUSIONS: Short duration 50 W ablations using CF sensing catheters are safe and result in excellent long-term freedom from AF for both paroxysmal and persistent AF with short procedure times and small amounts of total RF energy delivery.

Impact of obesity on atrial fibrillation ablation: Patient characteristics, long-term outcomes, and complications.

BACKGROUND: There is an association between obesity and atrial fibrillation (AF). The impact of obesity on AF ablation procedures is unclear. OBJECTIVE: The purpose of this study was to evaluate the influence of body mass index (BMI) on patient characteristics, long-term ablation outcomes, and procedural complications. METHODS: We evaluated 2715 patients undergoing 3742 AF ablation procedures. BMI was ≥30 kg/m2 in 1058 (39%) and ≥40 kg/m2 in 129 (4.8%). Patients were grouped by BMI ranges (<25, 25-<30, 30-<35, 35-<40, and ≥40 kg/m2). RESULTS: As BMI increased from <25 to ≥40 kg/m2, age decreased from 65.3 ± 11.2 to 61.2 ± 9.2 years (P < .001), left atrial size increased from 3.91 ± 0.68 to 4.72 ± 0.62 cm (P < .005), and CHADS2 scores increased from 1.24 ± 1.10 to 1.62 ± 1.09 (P < .001). As BMI increased, paroxysmal AF decreased from 48.0% to 16.3% (P < .0001) and there was an increase in dilated cardiomyopathy (from 7.6% to 12.4%; P < .0001), hypertension (from 41.0% to 72.9%; P < .0001), diabetes (from 4.3% to 23.3%; P < .0001), and sleep apnea (from 7.0% to 46.9%; P < .0001). For the entire cohort, for BMI ≥35 kg/m2 the 5-year ablation freedom from AF decreased from 67%-72% to 57% (P = .036). For paroxysmal AF, when BMI was ≥40 kg/m2 ablation success decreased from 79%-82% to 60% (P = .064), and for persistent AF, when BMI was ≥35 kg/m2 ablation success decreased from 64%-70% to 52%-57% (P = .021). For long-standing AF, there was no impact of BMI on outcomes (P = .624). In multivariate analysis, BMI ≥35 kg/m2 predicted worse outcomes (P = .036). Higher BMI did not impact major complication rates (P = .336). However, when BMI was ≥40 kg/m2, minor (from 2.1% to 4.4%; P = .035) and total (from 3.5% to 6.7%; P = .023) complications increased. CONCLUSION: In patients undergoing AF ablation, increasing BMI is associated with more patient comorbidities and more persistent and long-standing AF. BMI ≥35 kg/m2 adversely impacts ablation outcomes, and BMI ≥40 kg/m2 increases minor complications.

Ablation of atypical atrial flutters using ultra high density-activation sequence mapping.

PURPOSE: The purpose of this study was to evaluate ultra high density-activation sequence mapping (UHD-ASM) for ablating atypical atrial flutters. METHODS: For 23 patients with 31 atypical atrial flutters (AAF), we created UHD-ASM. RESULTS: Demographics age = 65.3 ± 8.5 years, male = 78%, left atrial size = 4.66 ± 0.64 cm, redo ablation 20/23(87%). AAF were left atrial in 30 (97%). For each AAF, 1273 ± 697 points were used for UHD-ASM. Time to create and interpret the UHD-ASM was 20 ± 11 min. For every AAF, the entire circuit was identified. Thirty (97%) were macroreentry. AAF cycle length was 267 ± 49 ms, and the circuit length was 138 ± 38 mm (range 35-187). Macroreentry atrial flutters took varied pathways, but each had an area of slow conduction (ASC) averaging 16 ± 6 mm (range 6-29) in length. Entrainment was not utilized. We targeted the ASC and ablation terminated AAF directly in 19/31 (61.3%) and altered AAF activation in 7/31 (22.6%), all of which terminated directly with additional mapping/ablation. AAF degenerated to atrial fibrillation in 2/31 (6.5%) with RF and could not be reinduced after ASC ablation. Median time from initial ablation to AAF termination was 64 s. Thus, 28/31 (90.3%) terminated with RF energy and/or could not be reinduced after ASC ablation. At 1 year of follow-up, 77% were free of atrial tachycardia or atrial flutter and 61% were free of all atrial arrhythmias. CONCLUSIONS: Using rapidly acquired UHD-ASM, the entire AAF circuit as well as the target ASC could be identified. Most AAF were left atrial macroreentry. Ablation of the ASC or microreentry focuses directly terminated or eliminated AAF in 90.3% without the need for entrainment mapping.