Atrial Lesions Research Articles

Preclinical evaluation of a novel single-shot pulsed field ablation system for pulmonary vein and atrial ablation.

Pulsed field ablation (PFA) is a nonthermal ablative strategy that achieves cell death via electroporation. Herein, we investigated the preclinical safety and efficacy of PFA using two novel 8-French, 16-electrode spiral PFA/mapping catheters (ElePulse; CRC EP, Inc.). Bipolar PFA (>1.8 kV) was performed using 30 s, single-shot, QRS-gated applications. Altogether, 94 atrial structures were ablated in 23 swine, one canine, and one ovine, including right and left atria and atrial appendages, pulmonary veins, and superior and inferior (IVC) vena cavae. We also examined the impact of PFA on the phrenic nerve (14 swine) and on a deviated esophagus after delivery of PFA from inside the IVC (five swine). All applications were single-shot without catheter repositioning. Minimal microbubbling was observed without significant skeletal muscle twitching/activation (mean acceleration: 0.05 m/s2 ). There was a marked reduction in post-PFA versus pre-PFA atrial electrogram amplitude (0.17 ± 0.21 vs. 1.18 ± 1.08 mV; p < .0001). Lesion durability was demonstrated up to 3 months in all targeted tissues. Histologically, lesions were contiguous and transmural, except in the atrial appendage, and without any thermal effects. Magnetic resonance, gross, and histologic examinations of the brain, rete mirabile, and kidneys revealed no thromboembolism. No acute/long-term phrenic nerve dysfunction was encountered. Although within 2 h of ablation, histologic examinations of the esophagus revealed acute PFA-related changes in the muscular layer, these completely resolved by 21 ± 5 days. A novel, single-shot, spiral PFA system is capable of safely creating large, durable atrial lesions without significant adverse effects on the phrenic nerve or the esophagus.

Optimal conditions for high-power, short-duration radiofrequency ablation using a novel, flexible-tipped, force-sensing catheter.

High-power, short-duration (HPSD) radiofrequency ablation (RFA) reduces procedure time; however, safety and efficacy thresholds vary with catheter design. The study sought to determine optimal HPSD ablation conditions with a novel flexible-tipped, contact force-sensing RFA catheter. RFA lesions were created in thigh muscle (16 swine) over a range of conditions (51-82 W, 2-40 g, 8-40 mL/min irrigation). An intracardiac study was performed (12 swine) to characterize steam pop thresholds. Lesions were created in a second intracardiac study (14 swine, n = 290 pulmonary vein isolation [PVI] lesions) with combinations of radiofrequency power, duration, and contact force. PVI was tested, animals were sacrificed, and lesions were measured. The likelihood of coagulation formation in the thigh model was <20% when power was ≤79 W, when contact force was ≤40 g, when duration was ≤11 seconds, and when irrigation rates were 8 to 40 mL/min. The impact of contact force on lesion safety and efficacy was more pronounced using HPSD (60 W/8 seconds) compared with conventional ablation (30 W/45 seconds) (P = .038). During PVI, focal atrial lesions ranged in width from 4.2 to 12.5 mm and were transmural 80.8% of the time. PVI was achieved in 13 of 14 veins. Logistic regression identified that the optimal parameters for radiofrequency application were 60 to 70 W with a duration <8 seconds and <15 g contact force. Optimal HPSD lesions with this this flexible-tipped, force-sensing RFA catheter were created at 60 to 70 W for <8 seconds with <15 g contact force. Chronic studies are ongoing to assess radiofrequency parameter refinements and long-term lesion durability using these conditions.

Additional left atrial lesions improve the effect of cryoballoon pulmonary vein isolation in paroxysmal atrial fibrillation patients

Aim. Cryoballoon ablation (CBA) is one of the methods for catheter pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (AF). Left atrial additional lesion (LAAL) to PVI were proposed to eliminate extrapulmonary AF triggers. Nonetheless whether the additional lesions improve CBA effectiveness is not clear.Methods. Primary CBA procedures performed for paroxysmal AF during 2017-2021 were analyzed. The study group (Algorithm group, n=82) was recruited prospectively in 2019-2021. As the first step CBA PVI were performed in all pts. In those who were on sinus rhythm (SR) after the PVI, AF induction attempts with burst atrial pacing were performed. Pts with induced AF and those who stayed on AF after PVI underwent LAAL at the left ganglionated plexus area. In case of stable SR (non-inducible AF) the procedure finished. If AF was inducible or did not terminate during CBA, the second LAAL set were performed - LA posterior wall lesions. If AF was still inducible or did not terminate, the SR was restored by electrical cardioversion. The control group (Control group, n=94) was formed retrospectively from patients with routinely performed only CBA PVI with achievement of isolation criteria in 2017-2019. If AF continued, sinus rhythm was restored by cardioversion. There were no attempts of induction AF during the procedure.Results. The Algorithm and Control groups were comparable in terms of clinical, demographic and electrophysiological characteristics. At 12 months postoperatively, the effectiveness was higher in the Algorithm group than in the Control group (78.0% vs. 62.8%, p = 0.044). No adverse effects were found.Conclusion. Thus, the stepwise approach with LAAL increases the effectiveness of CBA in the long-term period and does not affect the risk of complications.

Early lesion visualization after catheter ablation for atrial fibrillation: rationale and preliminary results of the CALAMARI study

Abstract Funding Acknowledgements Type of funding sources: None. Background Incomplete atrial lesion is related to high atrial fibrillation (AF) recurrence after Pulmonary vein antrum isolation (PVAI). Objectives The CALAMARI study is a single-center, prospective, observational study with a longitudinal design. The primary aim is to assess PVAI lesion and its development over time using cardiovascular magnetic resonance (CMR). The secondary objective is to identify possible predictors of AF recurrence. Methods 96 consecutive patients undergoing PVAI for paroxysmal AF will undergo four sequential CMR: 1) pre-PVAI CMR 2) post-PVAI CMR, immediately after the ablation 3) CMR one-day or one-week post-PVAI 4) CMR 3-months post-PVAI. Dark-blood short-inversion-time recovery (DB-STIR) will identify oedema. Pre- and post-contrast prepped inversion-recovery with long inversion time (IR-prep) and three-dimensional late gadolinium enhancement (3D-LGE) images will be used to visualize atrial lesion (AL). Qualitative and quantitative assessments of AL will be performed. Patients will be followed-up for 2 years to identify AF recurrence. Preliminary results Ten patients (63.1±5.7 years old, 80% male) completed a pre-PVAI CMR and a post-PVAI-CMR. The AL post-PVAI was visible in 9 patients (90%) using post-contrast IR-prep sequences and in 6 patients (60%) using pre-contrast IR-prep and 3D-LGE. Microvascular obstruction was identified in 7 (70%) patients using IR-prep-post-contrast. On DB-STIR, edema was visualized in all patients with a significant increase in the left atrium wall thickening in CMR post-PVAI vs. pre-PVAI CMR (6.4±2.9 vs. 3.4±1.5, p = 0.09). Conclusion Post-PVAI AL visualization with CMR is feasible in most patients. The CALAMARI study will better understand the AL modifications over time.

Lesion formation following pulsed field ablation for pulmonary vein and posterior wall isolation.

Pulsed field ablation (PFA) results in unique lesion formation, but there is lack of in-vivo validation in terms of scar formation following atrial fibrillation (AF) ablation. We aimed to access atrial lesion formation based on late gadolinium enhancement (LGE) cardiovascular magnetic resonance imaging (CMR) following PFA for pulmonary vein (PV) and posterior wall isolation (PWI). AF ablation was performed in 10 patients using a 31mm pentaspline PFA catheter. After pulmonary vein isolation (PVI; n=8 PFA-applications/ PV; n=4 in basket and n=4 in flower configuration), another eight applications in flower configuration were conducted for concomitant PWI. Patients underwent LGE CMR 3 months after ablation aiming for quantification of left atrial (LA) scar. Acute procedural success was achieved in all patients. Mean procedure duration was 62±7min. and mean LA dwell time of the PFA catheter was 13±2min. Mean post ablation total LA scar burden was 8.1±2.1% and mean scar width was 12.8±2.1mm. At the posterior LA, 22.6±2.2% of the anatomical segment resulted in chronic scar tissue, concentrated at the PW. Postablation CMR found no evidence for PV stenosis or collateral damage of adjacent structures. At 7 months of follow-up, 9/10 patients (90%) were free from arrhythmia recurrence. PFA for AF resulted in durable and transmural atrial scar tissue at the PVs and PW. LGE CMR found a very homogeneous and contiguous lesion pattern with no signs for collateral damage.

Assessment of structural changes in the left atrium myocardium according to cardiac magnetic resonance with contrast before and after balloon cryoablation in patients with persistent atrial fibrillation

Aim. To study the structural changes of the left atrium myocardium according to magnetic resonance imaging with contrast in patients with persistent atrial fibrillation before and after balloon cryoablation and compare the results with the effectiveness of the intervention.Material and methods of research. The study included 28 patients with persistent form of atrial fibrillation. All patients before and after magnetic resonance imaging underwent cardiac magnetic resonance imaging with delayed contrast using a high-resolution MR pulse sequence (voxel size 1,25x1,25x1,25 mm) before and after cryoablation.The severity of atrial fibrous lesion was calculated automatically using a specialized LGE HEART Analyzer program using algorithms based on the myocardial contrast index with a threshold value of 1.38. The clinical efficacy of the intervention was evaluated after 12 months and the relationship was determined structural changes in the myocardium of the left atrium according to contrast magnetic resonance imaging data before and after the cryoablation.Results. The severity of fibrotic myocardial lesion of the left atrium before balloon cryoablation was 1,5 [0,16; 9,3]%. In Utah patients, stage 1 fibrosis was detected in 71,4% (n=20), stage 2 in 14,3% (n=4), stage 3 in 3,6% (n=1), stage 4 in 10,7% (n=3). 3 months after cryoablation, there was an increase in the severity of fibrosis of 2,7 [1,02; 18,8]% (p&lt;0,001). Overall efficiency of the intervention rate was 57,1%. The construction of Kaplan- Meyer curves demonstrated that the intervention was most effective in patients with minimal severity of fibrosis before ablation (Utah I) and least effective in more pronounced fibrotic lesion (stage Utah III and IV)Conclusion. Magnetic resonance imaging of the heart with contrast allows to assess fibrotic lesion of the myocardium of left atrial, which may be one of the factors of the effectiveness of interventional treatment of persistent AF.

ECG-patch assessment of atrial fibrillation during the very-early blanking predicts late blanking period recurrence: preliminary data from a prospective registry

Abstract Funding Acknowledgements Type of funding sources: None. Background Ablation of atrial fibrillation (AF) is a procedure that causes significant atrial tissue lesions, with transient, albeit significant tissue oedema and inflammation. These mechanisms may trigger early rhythm abnormalities that do not necessarily correlate with future arrhythmias, and, therefore, evaluation of AF recurrence is currently validated by routine ECG and ambulatory 24h Holter monitoring, only after a 3-month blanking period. However, recent data have shown that AF episodes occurring during the blanking period are common and may predict late AF recurrences. The E-Patch (Bio Tel Heart) is an innovative, thin single-use adhesive electrode with extended continuous ECG monitoring for up to 120h. Aim To assess if continuous extended monitoring in the very-early blanking period can be associated with event recorder data performed in the late blanking period after AF ablation. Methods Single-centre, prospective, longitudinal study, including consecutive patients (P) 24h after AF ablation, monitored with the E-patch. The effectiveness of the device in continuously recording within 5 days after ablation was analyzed, as well as the occurrence of AF episodes during an external 7- day loop-recorder, obtained in the 2nd-month post-ablation. Results A total of 30P were included (57% male, 63±8 years). AF ablation was performed with radiofrequency (RF) energy in 14P and with a balloon of cryoenergy in 16P. All P were in sinus rhythm at the beginning of the recording. The mean number of hours of recording was 113±16, with no discomfort complaints in the use of the device or interpretation artefacts. During the E-patch monitoring, a total of 10P (33%) presented AF (AF burden 6.8% of the recording, IQR 3.0-20%). All 30P underwent an external loop recorder for 7 days 2 months post-ablation, with 40% showing AF periods (&amp;gt; 30 seconds duration). All 10P that had AF detection in the very-early E-patch recording had also recurrence in the 2 nd month of extended 7-day continuous recording. Very- early AF detection had a sensitivity of 83.3% and a specificity of 100% to detect late blanking period AF (ROC 0.916±0.06; 95%CI 080-1.0). Conclusions The use of the E-patch very-early after AF ablation is effective for AF detection and is highly predictive of AF recurrence in the late blanking period. These findings require validation in larger studies to assess the potential of very-early assessment in the determination of a higher risk for AF recurrence.

Thoracoscopic Surgical Ablation of Lone Atrial Fibrillation: Long-term Outcomes at 7 Years

BackgroundAntiarrhythmic drugs and transcatheter ablation in atrial fibrillation (AF) provide suboptimal rhythm control with a not negligible rate of failure in paroxysmal AF (PAF) and nonparoxysmal AF (n-PAF) at midterm and long-term follow-up. This study evaluated the safety profile and long-term efficacy of thoracoscopic ablation in patients with lone AF. MethodsA consecutive 153 patients with lone AF were prospectively enrolled and underwent thoracoscopic surgical ablation. Inclusion criteria were symptomatic AF refractory to pharmacologic therapy (Vaughan-Williams class I-III), age >18 years, and absence of left atrial thrombosis. Exclusion criteria were long-standing AF >5 years, left atrial diameter >55 mm, and contraindication to oral anticoagulation. The “box lesion set” (encircling of pulmonary veins) was always used. Exclusion of the left atrial appendage was performed only in selected cases. The primary study end point was freedom from AF. Secondary end points were overall survival and cumulative incidence function of cardiac event–related death, cerebrovascular accidents, and pacemaker implantation. ResultsThere was no in-hospital mortality. Early postoperative complications were pacemaker implantation (4/153 [2.6%]), cerebrovascular accident (2/153 [1.3%]) with full recovery of both, and bleeding requiring surgical revision (2/153 [1.3%]). Overall freedom from AF at 7 years was 86% ± 4% (76.9% in n-PAF, 96.1% in PAF). Survival freedom from AF in patients without antiarrhythmic drugs in PAF and n-PAF groups was 79.1% and 52.2%, respectively. ConclusionsThoracoscopic surgical ablation of lone AF by means of an isolated left atrial box lesion provided an excellent long-term rhythm outcome, even in long-standing persistent AF. The isolated left atrial ablation showed an excellent safety profile with low incidence of pacemaker implantation and postoperative complications.

PO-03-034 OUTCOMES OF A 3-MONTH MAPPING STUDY FOLLOWING PULMONARY VEIN ISOLATION USING A NOVEL SINGLE-SHOT PULSED FIELD ABLATION SYSTEM IN A PORCINE MODEL

Pulsed field ablation (PFA) is a non-thermal ablative strategy that achieves cell death via electroporation. We investigated the durability of PFA lesions using 2 novel PFA/mapping catheters (CRC EP Inc, San Jose, CA) at repeat EP studies performed 3 months post-ablation. In total, 16 pulsed field applications were delivered using the PFA catheters in 3 swine under general anesthesia in the absence of paralytic agents, including: 1 application to the left atrial appendage, 9 applications to the right pulmonary veins (PVs), 3 applications to the inferior common PV and 3 applications to the right ventricle (RV). The design of the PFA catheters consists of an 8-Fr, 16-electrode, bidirectional, 25-mm or 30-mm spiral, the latter bearing 2 distal pairs of mapping electrodes active even during PFA delivery. The catheters were inserted through a commercially available 8.5-Fr steerable introducer (Agilis, Abbott, Chicago, IL). Bipolar PFA (>2 kV) was performed using single-shot, QRS-gated applications under 3D mapping and intracardiac echocardiographic guidance. Skeletal muscle activation intensity was quantified using an accelerometer (Phyphox, Aachen, Germany). Lesions were assessed by pre- versus post-EGM analysis, pacing threshold, 3D voltage mapping (EnSite, Abbott), necropsy, and histology. All applications were single-shot (34 ± 12 s) without repositioning the catheter. Minimal microbubbling was observed with mild to no skeletal muscle stimulation (acceleration <4 m/s2). No tachyarrhythmias were induced during PFA. Immediately post-ablation, bilateral PV isolation was confirmed with partial ablation of posterior wall and the coronary sinus (CS). Repeat 3D mapping at 3 months validated complete lesion durability at the PFA locations, once again illustrating bilateral PV isolation. However, there was conduction recovery at the adjacent, non-ablated/non-targeted sites (e.g., the posterior wall and CS). Accordingly, there was significant reduction in 3-month post- versus pre-PFA EGMs at the atrial PFA sites (1.38 ± 0.70 mV vs. 0.04 ± 0.03 mV, P<0.0001) and at the RV ablation sites (1.6 ± 1.3 mV vs. 0.2 ± 0.1 mV, P<0.05) with marked increase in the pacing thresholds (>20 mA vs. <10 mA, P<0.001). Lesions were contiguous measuring 26 ± 8 x 18 ± 6 mm and transmural in the atria and 38 ± 14 mm x 28 ± 9 mm and 5 ± 2 mm deep in the RV. A novel PFA catheter system can create large, single-shot atrial and ventricular lesions in vivo that are completely durable at 3 months.

PO-01-105 PRECLINICAL EVALUATION OF ACUTE AND CHRONIC CIRCUMFERENTIAL, LINEAR AND FOCAL PULSED FIELD ABLATION LESION SETS CREATED USING A “MAP & ABLATE” SPHERICAL MULTIELECTRODE ARRAY CATHETER

A multielectrode spherical array catheter (Globe PF System, Kardium Inc., Canada) capable of both cardiac mapping and ablation with either pulsed field (PF) or radiofrequency (RF) energy has been developed. To assess efficacy and safety of creating flexible PFA lesion sets. Healthy canines (n=12) underwent transeptal access under general anesthesia. Electroanatomic maps with ostial tags, contact maps based on blood flow detection, and animated voltage maps were created. PFA was delivered at two strengths (1.7 & 1.8kV)and two pulse train designs (6 x 1.5-2 sec pulse-time or 3 x 3-4 sec pulse-time) to isolate a minimum of 2 pulmonary veins (PVs) (∼1 application) and to create linear/focal lesions. Animals survived in acute (n=6; 3±1 days survival) and chronic (n=12; 30±3 days survival) cohorts. In the chronic cohort, a repeat electrophysiological study was performed followed by detailed necropsy. In 12 animals, all targeted PVs (25/25, 100%) were acutely and durably isolated (13/13,100%). Discrete ablation on the roof and on the posterior wall was also successful in all 12 animals. Phrenic activation was only seen at one ablation site in one animal in each cohort. All 12 animals completed their survival period and gross pathological analysis revealed contiguous pink to dark-red lesions and pale-homogenous lesions in the acute and chronic cohorts, respectively. No thrombus or char was observed on the catheter. Histology revealed mean transmurality rates of 95.7% and 91% for the 74 and 75 sections analyzed in the acute and chronic cohorts, respectively. The lesion mean depths were 3.0±1.8 and 1.6±0.9 mm in the acute and chronic cohorts, respectively. There were variable amounts of hemorrhage and a minimal to moderate acute inflammatory response in the acute cohort. In the 2/6 canines that underwent necropsy on day 4 (the other 4 underwent necropsy on day 2 or 3), fibroblast proliferation was noted in addition to the above findings. In the chronic group, the entire lesion was replaced with fibrous connective tissue. No ablation damage to extracardiac structures was found. There were no signs of thromboembolism in any downstream organs, including no brain infarcts. This multielectrode spherical array catheter can deliver pulsed field ablation to both isolate PVs and deliver extra-PV left atrial lesions. These data provide the basis for ongoing and future clinical trials.

AB-452663-2 LEFT ATRIAL BOX ISOLATION GUIDED BY FORCE-POWER-TIME FORMULA (ABLATION INDEX): HIGH PREVALENCE OF EPICARDIAL CONDUCTION VIA SEPTOPULMONARY BUNDLE IN ATRIAL FIBRILLATION PATIENTS

Circumferential, continuous, transmural atrial lesions are desired to facilitate pulmonary vein (PV) isolation. However, atrial wall thickness around the PV is variable (5-6 mm in the superior/anterior segments and 2-4 mm in the inferior/posterior segments). Previous experimental studies have shown that radiofrequency (RF) lesion depth and diameter can be predicted by a logarithmic formula using contact force (CF), RF power and application time (Force-Power-Time Formula, Ablation Index, AI). The purpose of this study was to test the ability of AI guided ablation to achieve left atrial (LA) box isolation by a single RF encirclement and examine the location of residual conduction (gap) within the box in patients with atrial fibrillation (AF). In 42 patients with AF, LA box isolation was performed using a 7.5Fr CF catheter (ThermoCool SmartTouch SF, Biosense Webster) and CARTO system. Using RF power (35-40Watts) and CF (5-45g), a target AI value of 380-400 was used for posterior/inferior segments with an inter-lesion distance (ILD) of 4mm and a target AI value of 550-600 for anterior/superior/septal segments with an ILD of 6mm along the box circumference (Figure). RF was delivered until AI reached target values or terminated prematurely when esophageal temperature reached <38.5°C. After the first encirclement along the box line, activation mapping was performed to confirm box isolation and identify gap locations. Total RF time for box isolation was 27.2±4.6 min and box circumference length was 21.2±2.5 cm. Complete box isolation was obtained by the first encirclement in 17/42 (40%) pts. In the remaining 25/42 (60%) pts, activation mapping within the box lesion set identified earliest atrial activation along the ablation line in only 4/42 (10%) pts (indicating endocardial gaps), whereas activation mapping within the box identified earliest atrial activation at a site distant from the ablation line in 21/42 (50%) pts, suggesting epicardial conduction through a septopulmonary bundle (Figure). Focal ablation at endocardial gaps along the ablation line or at the epicardial focal breakouts within the box resulted in compete box isolation in all 25 pts. LA box isolation guided by AI effectively prevented endocardial gaps along the ablation line. However, epicardial conduction via a septopulmonary bundle was often observed (50%).

A rare case of left atrial inflammatory granuloma associated with pulmonary tuberculosis.

A 65-year-old female was accidentally found left atrial space-occupying lesion 2 days ago. The patient had a previous history of pulmonary tuberculosis for several years. Physical examination and laboratory tests were unremarkable. An electrocardiogram suggested a sinus heart rate with a left-sided electrical axis and a slightly depressed T wave in lead I and augmented vector foot. Transthoracic echocardiography showed that a solitary 18 mm × 15 mm mass was attached to the annulus root of the anterior mitral valve and protruded to the left atrium, causing mild mitral leaflet insufficiency (Panel A). Cardiac computed tomographic angiography showed a round mass located in the left atrium adjacent to the anterior mitral valve (Panel B). The patient underwent resection of the left atrial mass under extracorporeal circulation. During the procedure, a round-like mass measuring approximately 2.2 cm × 1.8 cm × 1.5 cm was found attached to the anterior mitral valve. The patient had an uneventful recovery and was discharged 5 days later. Post-operative pathology confirmed as an inflammatory granuloma (Panels C and D).

Multimodal imaging approach for the assessment of a complex, large left atrial lesion.

Multimodal imaging approach for the assessment of a complex, large left atrial lesion.

Quantitative late gadolinium enhancement cardiac magnetic resonance analysis of the relationship between ablation parameter and left atrial tissue lesion following pulmonary vein isolation.

The impact of ablation parameters on acute tissue lesion formation after pulmonary vein isolation (PVI) has not been sufficiently evaluated in patients with atrial fibrillation. Radiofrequency ablation lesion can be visualized by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR). We sought to quantitatively analyze the relationship between ablation parameter and tissue lesion following PVI at different segments of pulmonary vein (PV) using LGE-CMR. Twenty-one patients with atrial fibrillation who underwent PVI procedure were retrospectively enrolled. All patients underwent LGE-CMR examination within 3 days after radiofrequency ablation. Ablation parameters during PVI were documented, including lesion size index (LSI), force-time integral (FTI), power, contact force, temperature, and time of duration. The ablation point was projected onto 3-dimensional (3D) left atrial shell constructed base on LGE-CMR and corresponding image intensity ratio (IIR) was calculated on the same shell. A tissue lesion point was defined when the LGE-CMR IIR was > 1.2. In total, 1,759 ablation points were analyzed. The ablation parameters and IIRs for each PV segment were significantly different (P < 0.0001). IIRs corresponding to ablation points at posterior of PV tended to be higher than those at non-posterior of PV when similar ablation parameters were applied during ablation. LSI was a better predictor of tissue lesion existence following PVI than FTI, contact force, power, temperature, and duration time at non-posterior wall of PV. The IIR showed positive correlation with LSI at non-posterior wall of PV (non-posterior of right PV, r = 0.13, P = 0.001, non-posterior of left PV, r = 0.26, P < 0.0001). When similar ablation parameters were applied during PVI, the posterior wall of PV had more severe tissue lesion than non-posterior wall of PV. Therefore, it was reasonable to decrease ablation energy at posterior wall of PV. Moreover, LSI was a better index to reflect tissue lesion quality following PVI at non-posterior of PV.

Response to correspondence regarding 5-year follow up of the Amaze Randomized Controlled trial of ablation treatment for arrhythmia as an adjunct to cardiac surgery.

We thank Dr Garcia-Villarreal [1] for his comment on our article in which he questions the rate of return to stable sinus rhythm in the Amaze trial [2]. We should like to point out that the Amaze trial [3] was not an evaluation of the complete Cox-maze procedure, but an evaluation of concomitant atrial fibrillation surgery as it is done in the real world. Amongst our findings, we discovered that a large variety of lesion sets were being used and that many surgeons did not complete the full biatrial lesion set in their practice. We also found that there appears to be an ablation ‘dose–response’ in achieving return to sinus rhythm, with the greatest step-up achieved when the left atrial lesion set includes the mitral isthmus lesion. We therefore agree with Dr Garcia-Villarreal that concomitant atrial fibrillation surgery should ideally be as complete as possible, and there may be an argument for concentrating such surgery in the hands of interested and experienced surgeons. Despite this, over 5 years later, we have anecdotal evidence that less complete choices of lesion sets continue to be made. We agree that the experience of surgeons devoted to atrial fibrillation should help in maximizing return to sinus rhythm and may also aid in achieving better atrial function after surgery, which is at least as important for clinical patient outcomes as electrical sinus rhythm restoration (study registration ISRCTN82731440) [4].

Findings from repeat ablation using high-density mapping after pulmonary vein isolation with pulsed field ablation.

Pulsed-field ablation (PFA) can offer a novel perspective for atrial fibrillation (AF) ablation. We aimed to characterize the incidence of pulmonary vein (PV) reconnection, types of recurrent atrial tachyarrhythmia (ATa) and lesion quality after PFA-guided PV isolation (PVI). Patients undergoing second ablation for recurrent ATa following the initial PVI using the pentaspline PFA catheter were investigated. The rate of PV reconnection, the features of recurrent ATa, and the amount of isolated posterior wall (PW) surface area (ISAPW%) (ratio of the isolated- to total surface area on PW) were analyzed. Among 360 patients treated with PFA, 25 patients (paroxysmal AF, n = 19) with 99 PVs underwent a second procedure 6.1 ± 4.0 months after the initial procedure. The rate of PV reconnection was 9.1% (9 PVs). Patients presented with atrial tachycardia (AT) (n = 16), AF (n = 8) and typical atrial flutter (n = 1). The mechanism of all but one AT was macro-reentry. The critical isthmus was found to be linked to the initial lesion set at the left atrial (LA) PW in eight patients and linked to pre-existing substrate at the LA anterior wall in four patients. One AT had a focal origin at the septum. In three patients, AT were unmappable. Mean ISAPW% was 72.7 ± 19.0%. We revealed a remarkable low reconnection rate with a large antral lesion at the PW after pentaspline PFA catheter-guided PVI. However, macro-reentrant AT with a critical isthmus at the LAPW linked to the PVI lesion set was commonly observed.

Complete Left-Atrial Lesion Set versus Pulmonary Vein Isolation Only in Patients with Paroxysmal AF Undergoing CABG or AVR.

Background and Objectives: In patients with paroxysmal atrial fibrillation (AF) undergoing CABG or aortic valve surgery, many surgeons are not willing to open the left atrium to perform a complete left-sided Cox-Maze lesion set. Pulmonary vein isolation (PVI) is often favored in those patients. We investigated the outcome of patients with isolated pulmonary vein isolation compared to those receiving an extended left atrial (LA) lesion set. Materials and Methods: Between 2003 and 2016, 817 patients received concomitant surgical AF ablation in our institution. A total of 268 patients with paroxysmal AF were treated by surgical ablation concomitant to AVR or CABG. Of those, 86 patients underwent a complete left-sided lesion set, while 182 patients were treated with an isolated pulmonary vein isolation. The primary endpoint was freedom from atrial fibrillation at 12 months' follow-up. Results: There were no statistically significant differences regarding baseline characteristics. No major ablation-related complications were observed in any of the groups. In the PVI group, three patients (1.6%) had an intraoperative stroke, while two (2.3%) patients experienced a stroke in the LA ablation group (p = 0.98). In-hospital mortality was 3.4% in the PVI group, and 2.8% in the extended LA group (p = 0.33). Freedom from AF at 12 months' follow-up was 76% in the extended LA ablation group and 70% in the PVI group, showing no statistically significant difference (p = 0.32). Conclusion: Surgical AF ablation concomitant to CABG or AVR in patients with paroxysmal AF is safe and effective. There was no statistically significant difference between the compared lesion sets in terms of freedom from AF, survival or stroke rate after 12 months.

Paroxysmal atrial fibrillation ablation with a novel flexible tip radiofrequency catheter incorporating contact force sensing: acute results of the TactiFlex AF IDE trial

Abstract Background Catheter ablation is an established therapy for paroxysmal atrial fibrillation (PAF). The TactiFlex™ Ablation Catheter, Sensor-Enabled™ (TactiFlex SE) is a next-generation radiofrequency ablation catheter incorporating highly accurate fiber optics-based contact force sensing technology with a flexible, laser-cut tip. Purpose To demonstrate that ablation with TactiFlex SE is safe and effective for the treatment of drug refractory, symptomatic PAF. Methods The TactiFlex AF IDE is a prospective, non-randomized, multi-center clinical study which enrolled 355 subjects worldwide. Enrollment in the main study began on June 26, 2020 and completed on June 18, 2021. Subjects underwent de novo Pulmonary Vein Isolation (PVI) and, if indicated, a Cavotricuspid Isthmus ablation (CTI line) for CTI-dependent atrial flutter. Results Subjects were divided into two as treated subgroups: High Standard Power (HSP, n=189), defined as subjects with 100% of left atrial lesions ablated at ≥40 W, and Low Standard Power (LSP, n=119), defined as subjects with at least one left atrial lesion ablated at &amp;lt;40W. First pass success, defined as isolation of all pulmonary veins (PVs) confirmed after a minimum 20 min waiting period was achieved in 93.5% (175/186) and 84.5% (98/116) of HSP and LSP subjects, respectively (p=0.0104). Significant decreases in the HSP versus LSP procedures were also seen in total procedure time (112.0 min [89.0, 139.5] and 149.0 [115.0, 182.0], respectively [p&amp;lt;0.001]), total RF time for PV ablation (14.0 min [11.0, 19.0] and 29.0 [19.0, 41.0], respectively [p&amp;lt;0.0001]), total fluoroscopy time (4.0 min [0.0, 11.0] and 8.0 [3.0, 17.0], respectively [p&amp;lt;0.0001]) and irrigation fluid volume (378.0 mL [310.0, 466.0] and 636.0 [476.0, 829.0], respectively [p&amp;lt;0.0001]) (values given as Median [Q1, Q3]), see Figure 1. Both HSP and LSP subjects had a low rate of repeat procedures (1.6% [3/182] and 4.3% [5/115], respectively [p=0.2684]) and primary safety endpoint events (4.8% [9/189] and 4.2% [5/119], respectively [p=0.8182]) through 90 days post-index procedure. Conclusion The acute data on the TactiFlex SE catheter demonstrates safe and effective treatment of PAF using either a HSP or LSP ablation strategy. Ablation procedures performed using a HSP strategy were shorter and required less irrigation fluid and fluoroscopy. It is anticipated these results will be reflected in the 12-month safety and effectiveness primary endpoints. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Abbott

Evaluation of Isolation Area, Myocardial Injury and Left Atrial Function Following High-Power Short-Duration Radiofrequency or Second-Generation Cryoballoon Ablation for Atrial Fibrillation.

This randomized study aims to compare the left atrial (LA) lesion size, function, and tissue damage following pulmonary vein isolation (PVI) by high-power short-duration (HPSD) radiofrequency (RF) and second-generation cryoballoon (CB2) ablation. We enrolled 40 patients with paroxysmal atrial fibrillation who underwent PVI by HPSD RF (n = 21) or CB2 (n = 19). Every patient underwent LA CT angiography and transthoracic echocardiography (TTE) to assess the LA anatomy and function. Biomarker levels (hs-cTnT, hs-CRP, LDH) were compared pre- and post-procedurally. Pre- and post-ablation high-density mapping (HDM) was performed. The isolation area was defined under 0.2 mV bipolar voltage (low voltage area, LVA). We calculated the post-PVI LVA/LA surface ratio using LA CT-HDM merge images. At 3-month follow-up, TTE was performed to assess the changes in LA function. Post-ablation hs-cTnT level was significantly higher in the RF group (RF: 1249 ± 469 ng/L, CB2: 995 ± 280 ng/L, p = 0.024). Post-PVI hs-CRP (RF: 9.53 ± 10.30 mg/L, CB2: 12.36 ± 5.76 mg/L, p = 0.034) and LDH levels (RF: 349.9 ± 65.6 U/L, CB2: 451.6 ± 91.3 U/L, p < 0.001) were significantly higher following CB2 ablation. Post-PVI LVA/LA surface ratios were 8.37 ± 6.42% in the RF group and 13.58 ± 8.92% in the CB2 group (p = 0.022). LA function did not change significantly after the PVI procedure. Our data indicate that second-generation cryoballoon ablation produces a significantly larger LA lesion size compared to “point-by-point” HPSD radiofrequency. Both techniques preserve LA function. The myocardial component of tissue loss appears to be higher using HPSD radiofrequency ablation, with less collateral damage.

One hundred percent utilization of a modified CryoMaze III procedure for atrial fibrillation with mitral surgery

ObjectivesConcomitant atrial fibrillation often goes untreated because of surgeon concerns regarding lesion set complexity and pump times. We describe a new cryoablation procedure to address this. MethodsFrom June 2013 to March 2021, a modified CryoMaze III procedure was used using 3 left atrial ± 3 right atrial cryo-applications creating the key lesions of the Cox Maze III procedure. Since 2018, 3-minute cryo-lesions were used for the left atrial box lesion for total cryoablation times of 8 minutes for the left atrium ± 6 minutes for the right atrium. By using propensity matching, patients undergoing mitral valve surgery with no atrial fibrillation history were compared with CryoMaze III–treated patients. ResultsA total of 100% of the 277 patients with atrial fibrillation requiring mitral valve surgery ± other procedures received the modified CryoMaze III procedure. After propensity score matching (n = 161 each group), the modified CryoMaze III group had mean crossclamp and bypass times 10.5 and 13.4 minutes longer than the control group, respectively. There were no significant differences in 30-day mortality, morbidity, pacemaker use, renal dysfunction, or late survival between groups, but there were less postoperative strokes in the CryoMaze III group. Freedom from atrial fibrillation off antiarrhythmics was 77% (mean follow-up of 3.0 ± 2.1 years). At 12 months, freedom from atrial fibrillation off antiarrhythmics was 90% for the 3-minute ablation group. Late survival was similar to age- and sex-matched Centers for Disease Control and Prevention controls. ConclusionsThe modified CryoMaze III technique is efficient, safe, and effective. Education of the surgical community regarding the late benefits of ablation and the simplicity of this new technique should improve adoption of the Class I Guidelines to treat concomitant atrial fibrillation.