His bundle combined with deep septal left bundle branch area pacing for atrial fibrillation prior to atrioventricular node ablation.

Background: To mitigate the risk of dyssynchrony-induced cardiomyopathy, international guidelines advocate His bundle pacing (HBP) with a ventricular backup lead prior to atrioventricular node ablation in treatment-refractory atrial fibrillation and normal left ventricular ejection fraction. As a result of concerns with long-term pacing parameters associated with HBP, this case series reports an adopted strategy of HBP combined with deep septal left bundle branch area pacing (dsLBBAP) in this patient cohort, enabling intrapatient comparison of the two pacing methods. Methods and Results: Eight patients aged 72 ± 10 years (left ventricular ejection fraction 53 ± 4%) underwent successful combined HBP and dsLBBAP implant prior to AV node ablation. Intrinsic QRS duration was 118 ± 46 ms. When compared to dsLBBAP, HBP had lower sensed ventricular amplitude (2.4 ± 1.1 vs. 15 ± 5.3 V, p = .001) and lower lead impedance (522 ± 57 vs. 814 ± 171ohms, p = .02), but shorter paced QRS duration (101 ± 20 vs. 119 ± 17 ms, p = .02). HBP pacing threshold was 1.0 ± 0.6 V at 1 ms pulse width, and dsLBBAP pacing threshold was 0.5 ± 0.2 V at 0.4 ms pulse width. Five patients underwent cardiac CT showing adequate dsLBBAP ventricular septal penetration (8.6 ± 1.3 mm depth, 2.4 ± 0.5 mm distance from left ventricular septal wall). No complications occurred during a mean follow-up duration of 121 ± 92 days. Conclusions: Combined HBP and dsLBBAP pacing is a feasible approach as a pace and ablate strategy for atrial fibrillation refractory to medical therapy.

Remote Device Interrogation Kiosks (ReDInK) - Pharmacy Kiosk Remote Testing of Pacemakers and Implantable Cardioverter-Defibrillators for Rural Victorians. A Novel Strategy to Tackle COVID-19.

BACKGROUND: In the era of COVID-19, travel restrictions and social distancing measures have changed the landscape for device interrogations of pacemakers and defibrillators for rural Victorians. Previously, device checks were performed infrequently in large volume, face-to-face rural clinics by visiting cardiologists and technicians. Access to remote areas and social distancing restrictions have made these clinics unfeasible to operate. The Cardiac Society of Australia and New Zealand (CSANZ) and Heart Rhythm Society (HRS) COVID-19 consensus statements have suggested the utilisation of remote monitoring to minimise the potential spread of COVID-19 infections between clinicians and high-risk patients. A novel solution to this challenge was the implementation of a remote device interrogation (RI) service located in two kiosks at two rural pharmacies. This service was termed Remote Device Interrogation Kiosks (ReDInK). AIM: This cross-sectional observational study aimed to describe the set-up process, safety and efficacy of RI and customer satisfaction of the ReDInK program. METHODS: Two-hundred-and-ninety-two (292) rurally located patients with implantable cardiac devices were identified via the cardiology department database. Of these, 101 (44%) were enrolled into the ReDInK program across two rurally located pharmacies between April and July 2020. RI was performed and download outcomes were reviewed. A customer satisfaction survey assessed attitudes towards the program and explored options of ongoing service application. RESULTS: Of 101 patients enrolled into ReDInK, 96 (95%) resulted in satisfactory device checks. Four (4) individuals failed-to-attend and one individual experienced technical download issues. Of the 96 satisfactory device checks, three required in-person follow-up for reasons including battery replacement, lead repositioning and in-person programming. No adverse events were reported. A satisfaction telephone survey was conducted with 81 (83%) participants enrolled in ReDInK. Seventy-one (71) individuals (88%) of those surveyed expressed satisfaction and 73 (90%) labelled the process as efficiently conducted. Sixty-nine (69) (85%) participants felt reassured that this service was established during the pandemic. However 47 (58%) participants reported they would still feel comfortable to undergo in-person reviews despite social distancing recommendations. CONCLUSIONS: With the COVID-19 pandemic posing restrictions to social distancing and reducing unnecessary in-person interaction, the ReDInK program emerges as an efficacious and safe solution for patients in rural Victoria. The program's widely positive reception and successful conduction in rural Victoria invites further opportunity for a wider application of similar programs, expanding its role to metropolitan areas.

Position Statement on the Management of Cardiac Electrophysiology and Cardiac Implantable Electronic Devices in Australia During the COVID-19 Pandemic: A Living Document.

The COVID-19 pandemic poses a significant stress on health resources in Australia. The Heart Rhythm Council of the Cardiac Society of Australia and New Zealand aims to provide a framework for efficient resource utilisation balanced with competing risks when appropriately treating patients with cardiac arrhythmias. This document provides practical recommendations for the electrophysiology (EP) and cardiac implantable electronic devices (CIED) services in Australia. The document will be updated regularly as new evidence and knowledge is gained with time.

Learning Curve and Initial Experience With Implementation of a His-Bundle Pacing Program in an Australian Setting.

BACKGROUND: His-bundle pacing (HBP) has emerged as a promising technique to avoid pacing complications associated with dyssynchrony from right ventricular pacing, but data are limited to experienced operators and centres. We aimed to evaluate the implementation and outcomes of an HBP program in an Australian setting. METHODS: Data were retrospectively collected on 140 consecutive HBP procedures attempted at three centres from March 2018 to September 2019. The cohort was divided into three groups (early: procedures 1-47, middle: 48-94, late: 95-140) to determine changes in procedural success in relation to operator experience. RESULTS: Median age was 76 years (IQR 68-80 yrs); 69% were male. Atrial fibrillation was present in 59%, left ventricular ejection fraction (LVEF) ≤40% in 25%, and left and right bundle branch blocks present in 23% and 16% respectively, and atrioventricular (AV) block was present in 26%. Overall procedural success was 87%, median implant threshold 0.8V@1 ms, and QRS duration improved in 64% of procedures. Procedural success (early 83%, middle 89%, late 89%, p=0.58) was not different, while median procedural time (early 98 mins, middle 83 mins, late 70 mins, p<0.001) improved across operator experience groups. Lower success rates were identified for patients with AV block (73% vs. 92%, p<0.01), a previous device (69% vs. 89%, p=0.02), moderate-severe TR (69% vs. 88%, p=0.04), and when right-sided access was required (25% vs. 89%, p<0.01). CONCLUSIONS: His-bundle pacing is a feasible procedure with continued improvement in procedural measures of success after an early learning period. The presence of AV block, a previous device, significant tricuspid regurgitation, or right-sided access may affect procedural success.

Atrial Tachycardia Arising From the Crista Terminalis, Detailed Electrophysiological Features and Long-Term Ablation Outcomes.

OBJECTIVES: The goal of this study was to characterize, in detail, focal atrial tachycardia (AT) arising from the crista terminalis to investigate associations with other atrial arrhythmia and to define long-term ablation outcomes. BACKGROUND: The crista terminalis is known to be the most common site of origin for focal AT, but it is not well characterized. METHODS: This study retrospectively identified a total of 548 ablation procedures for AT performed at a single center over a 16-year period, of which 171 were arising from the crista terminalis. RESULTS: Compared with patients with other AT sites of origin, crista terminalis AT patients were older (57.3 vs. 47.3 years), more commonly female (72.9% vs. 59.1%), were more commonly associated with coexistent atrioventricular nodal re-entry tachycardia (17.1% vs. 9.7%), and were more likely to be inducible with programmed stimulation (81.5% vs. 58.9%). There was preferential conduction in the superior-inferior axis along the crista terminalis. Acute ablation success rate was high (92.2%) and improved significantly when three-dimensional mapping was used (98.5%). Recurrence in the first 12 months after a successful ablation was 9.7%. Only 2 patients developed atrial fibrillation over the long-term follow-up of >7 years. CONCLUSIONS: This large series characterized the clinical and electrophysiological features and immediate and long-term ablation outcomes for AT originating from the crista terminalis. Features of the tachycardia suggest that age-related localized remodeling of the crista terminalis causes a superficial endocardial zone of conduction slowing leading to re-entry. Ablation outcomes were good, with long-term freedom from atrial arrhythmia.

Demonstration of pulmonary vein exit block following pulmonary vein isolation: A novel use for adenosine.

INTRODUCTION: Demonstration of exit block after pulmonary vein isolation (PVI) is the cornerstone of ablation for atrial fibrillation (AF). It requires the demonstration of local pulmonary vein (PV) capture and absence of conduction to the atrium but is often challenging due to the inability to see local paced PV-evoked potentials. We retrospectively examined the ability of adenosine to augment this technique during CARTO-based radiofrequency ablation procedures. METHODS: Retrospective analysis of evoked PV potentials during adenosine administration while testing for PV exit block at a single UK center. RESULTS: One hundred and twenty-nine PVs in 33 patients were isolated using radiofrequency energy to demonstrate entry block. Of those, the pacing of 24 veins under baseline conditions did not clearly demonstrate local PV-evoked potentials sufficient to be sure that the local vein was truly captured and dissociated from the atrium. Adenosine was administered in 19 of these, with 10 of 19 (52.6%) veins then demonstrating clear local PV-evoked potentials transiently during adenosine administration, sufficient to allow assessment of definite exit block. CONCLUSION: Adenosine administered during PV pacing allows transient visualization of local PV-evoked potentials after PVI facilitating the clearer demonstration of PV exit block in over 50% veins.

Characterising the difference in electrophysiological substrate and outcomes between heart failure and non-heart failure patients with persistent atrial fibrillation.

Aims: Characterizing the differences in substrate and clinical outcome between heart failure (HF) and non-heart failure (non-HF) patients undergoing persistent atrial fibrillation (AF) ablation. Methods and results: Using complex fractionated electrograms (CFE) as a surrogate marker of substrate complexity, we compared the bi-atrial substrate in patients with persistent AF with and without HF, at baseline and after ablation, to determine its impact on clinical outcome. In this retrospective analysis of two prospective studies, 60 patients underwent de-novo step-wise left atrial (LA) ablation, 30 with normal left ventricular ejection fraction (LVEF) ≥ 50% (non-HF group) and 30 with LVEF ≤ 35% (HF group). Multiple high-density bi-atrial CFE maps were acquired along with AF cycle length (AFCL) at each procedural stage. Change in bi-atrial CFE areas, AFCL and outcome data were then compared. In the non-HF group, higher CFE-areas were found at baseline and at each step of the procedure in the LA. In both LA and the right atrium (RA), baseline and final CFE area were also higher in the non-HF group. Single procedure, arrhythmia-free survival at 1 year was higher in the HF group compared with the non-HF group (72% vs. 43%, log rank P = 0.04). Final total bi-atrial CFE area was an independent predictor of arrhythmia recurrence. Conclusions: CFE represents an important surrogate marker of atrial substrate complexity. The atrial substrate in persistent AF differs between HF and non-HF with the latter representing a more complex 'primary' bi-atrial myopathy. LA focussed ablation results in more extensive substrate modification in HF and better clinical outcomes as compared with non-HF.

Pulmonary Vein Re-Isolation as a Routine Strategy Regardless of Symptoms: The PRESSURE Randomized Controlled Trial.

OBJECTIVES: The goal of this study was to determine whether a strategy of early re-isolation of pulmonary vein (PV) reconnection in all patients, regardless of symptoms, would reduce the recurrence of atrial fibrillation (AF) and improve quality of life. BACKGROUND: Lasting pulmonary vein isolation (PVI) remains elusive. PV reconnection is strongly linked to the recurrence of arrhythmia. METHODS: A total of 80 patients with paroxysmal AF were randomized 1:1 after contact force-guided PVI to receive either standard care or undergo a repeat electrophysiology study after 2 months regardless of symptoms (repeat study). At the initial procedure, PVI was demonstrated by entrance/exit block and adenosine administration after a minimum 20-min wait. At the repeat study, all sites of PV reconnection were re-ablated. Patients recorded electrocardiograms daily and whenever symptomatic for 12 months using a handheld monitor. Recurrence was defined as ≥30 s of atrial tachyarrhythmia (AT) after a 3-month blanking period. The Atrial Fibrillation Effect on Quality-of-Life Questionnaire was completed at baseline and at 6 and 12 months. RESULTS: All 40 patients randomized to repeat study attended for this after 62 ± 6 days, of whom 25 (62.5%) had reconnection of 41 (26%) PVs. There were no complications related to these procedures. Subjects recorded a total of 32,203 electrocardiograms (380 [335 to 447] per patient) during 12.6 (12.2 to 13.2) months of follow-up. AT recurrence was significantly lower for the repeat study group (17.5% vs. 42.5%; p = 0.03), as was AT burden (p = 0.03). Scores on the Atrial Fibrillation Effect on Quality-of-Life Questionnaire were higher in the repeat study group at 6 months (p < 0.001) and 12 months (p = 0.02). CONCLUSIONS: A strategy of routine repeat assessment with re-isolation of PV reconnection improved freedom from AT recurrence, AT burden, and quality of life compared with current standard care. (The Effect of Early Repeat Atrial Fibrillation [AF] on AF Recurrence [PRESSURE]; NCT01942408).

Ablation index, a novel marker of ablation lesion quality: prediction of pulmonary vein reconnection at repeat electrophysiology study and regional differences in target values.

AIMS: Force-Time Integral (FTI) is commonly used as a marker of ablation lesion quality during pulmonary vein isolation (PVI), but does not incorporate power. Ablation Index (AI) is a novel lesion quality marker that utilizes contact force, time, and power in a weighted formula. Furthermore, only a single FTI target value has been suggested despite regional variation in left atrial wall thickness. We aimed to study AI's and FTI's relationships with PV reconnection at repeat electrophysiology study, and regional threshold values that predicted no reconnection. METHODS AND RESULTS: Forty paroxysmal atrial fibrillation patients underwent contact force-guided PVI, and the minimum and mean AI and FTI values for each segment were identified according to a 12-segment model. All patients underwent repeat electrophysiology study at 2 months, regardless of symptoms, to identify sites of PV reconnection. Late PV reconnection was seen in 53 (11%) segments in 25 (62%) patients. Reconnected segments had significantly lower minimum AI [308 (252-336) vs. 373 (323-423), P < 0.0001] and FTI [137 (92-182) vs. 228 (157-334), P < 0.0001] compared with non-reconnected segments. Minimum AI and FTI were both independently predictive, but AI had a smaller P value. Higher minimum AI and FTI values were required to avoid reconnection in anterior/roof segments than for posterior/inferior segments (P < 0.0001). No reconnection was seen where the minimum AI value was ≥370 for posterior/inferior segments and ≥480 for anterior/roof segments. CONCLUSION: The minimum AI value in a PVI segment is independently predictive of reconnection of that segment at repeat electrophysiology study. Higher AI and FTI values are required for anterior/roof segments than for posterior/inferior segments to prevent reconnection.

Long-term outcomes after ablation of persistent atrial fibrillation: an observational study over 6†years.

OBJECTIVES: To address the limited long-term outcome data for catheter ablation (CA) of persistent atrial fibrillation (PeAF), we analysed consecutive ablations performed at our centre from 1 January 2008 to 31 December 2010 and followed patients prospectively until January 2014. METHODS: Both arrhythmia recurrence and symptom relief were assessed. Follow-up data were collected from hospital records, supplemented by data from general practitioners and referring hospitals. At the end of the follow-up period, all patients were contacted by phone to determine their up-to-date clinical condition. RESULTS: 188 consecutive patients with PeAF (157 male, mean age 57.3±9.7 years, 20% with long-standing PeAF) underwent a mean of 1.75 procedures (range 1-4). Telephone follow-up was achieved for 77% of surviving patients. Over a mean follow-up of 46±16 months (range 4-72), 139 (75%) patients experienced arrhythmia recurrence after a single procedure and 90 (48%) after their final procedure. Median time to first recurrence was 210 days (range 91-1850). 71% of recurrences were within the first year following ablation and 91% within 2 years. At final follow-up, 82% of patients reported symptomatic improvement. 7 (2.3%) major complications occurred, and there was no procedure-related death or stroke. CONCLUSIONS: CA for PeAF is safe with a low rate of complications. Over a follow-up period of up to 6 years, a large majority of patients experience significant symptomatic improvement but recurrence after the initial procedure is the norm rather than the exception. 2 years' follow-up is sufficient to observe 90% of AF recurrences, but recurrence can occur even after 5 years' remission.

Reablated Sites of Acute Reconnection After Pulmonary Vein Isolation Do Not Predict Sites of Late Reconnection at Repeat Electrophysiology Study.

INTRODUCTION: Acute reconnection of pulmonary veins (PVs) is frequently seen in the waiting period following pulmonary vein isolation (PVI). There are concerns that reablation at these sites may not be durably effective due to tissue edema caused by the initial ablation. We aimed to prospectively study the relationship between acute and late reconnection. METHODS AND RESULTS: Wide-area circumferential PVI was performed in 40 paroxysmal AF patients. Spontaneous reconnection was assessed after a minimum 20-minute waiting period, with adenosine administered to unmask dormant reconnection. All sites of acute reconnection were ablated to reisolate the PV. All 40 patients then underwent repeat electrophysiology study after 2 months, regardless of symptoms, to identify late reconnection. Sites of acute and late reconnection were compared according to a 12-segment PVI model. Acute reconnection was seen in 28 (6%) PVI segments in 20 (50%) patients, affecting 24/160 (15%) PVs. All were successfully reisolated. At repeat electrophysiology study, 51 (11%) PVI segments were reconnected in 25 (62%) patients, affecting 41 (25%) PVs. The proportion of PVI segments with and without acute reconnection exhibiting late reconnection at repeat study was no different (14% vs. 10%, P = 0.524). There was also no difference in late reconnection between PVI circles or patients with and without acute reconnection. CONCLUSION: Most PVI segments that undergo further ablation for acute reconnection show persistent isolation at repeat electrophysiology study, and the rate of late reconnection for these segments is no different to that for segments that did not acutely reconnect. This implies that effective reablation is delivered at these sites.

Biatrial linear ablation in sustained nonpermanent AF: Results of the substrate modification with ablation and antiarrhythmic drugs in nonpermanent atrial fibrillation (SMAN-PAF) trial.

BACKGROUND: More advanced atrial fibrillation (AF) is associated with lower success rates after pulmonary vein isolation (PVI), and the optimal ablation strategy is uncertain. OBJECTIVES: To assess the impact of additional linear ablation (lines) compared to PVI alone. METHODS: In this multicenter randomized controlled trial, 122 patients (mean age 61.9 ± 10.5 years; left atrial diameter 43 ± 6 mm) with persistent AF (PeAF) or sustained (>12 hours) paroxysmal AF (SusPAF) with risk factors for atrial substrate were included and followed up for 12 months. Patients were randomized to PVI-only or PVI + lines (left atrial roof line, mitral isthmus line, and tricuspid isthmus line) group. Holter monitoring was performed at 3, 6, and 12 months and according to symptoms. The primary outcome was atrial tachyarrhythmia recurrence lasting ≥30 seconds. RESULTS: Baseline characteristics were comparable between groups; 61% had PeAF and 39% SusPAF. Successful PVI was achieved for 98% of pulmonary veins, and bidirectional block was obtained in 90% of lines. The primary end point occurred in 38% of the PVI + lines group and 32% of the PVI-only group (P = .50), which was consistent in both PeAF (36% vs 28%; P = .45) and SusPAF (42% vs 39%; P = .86). Compared with the PVI-only group, the PVI + lines group had higher procedure duration (209 ± 52 minutes vs 172 ± 44 minutes; P < .001), ablation time (4352 ± 1084 seconds vs 2503 ± 1061 seconds; P < .001), and radiation exposure (Dose-area product 3992 ± 6496 Gy·cm(2) vs 2106 ± 1679 Gy·cm(2); P = .03). Quality of life (disease-specific Atrial Fibrillation Effect on Quality of Life questionnaire and mental component scale of the Short Form 36 Health Survey) improved significantly during the study but did not differ between groups. CONCLUSION: Adding lines to wide antral PVI in substrate-based AF requires significantly more ablation, increases procedure duration and radiation dose, but provides no additional clinical benefit.

Primary Care Atrial Fibrillation Service: outcomes from consultant-led anticoagulation assessment clinics in the primary care setting in the UK.

OBJECTIVE: Stroke-risk in atrial fibrillation (AF) can be significantly reduced by appropriate thromboembolic prophylaxis. However, National Institute for Health and Care Excellence estimates suggest that up to half of eligible patients with AF are not anticoagulated, with severe consequences for stroke prevention. We aimed to determine the outcome of an innovative Primary Care AF (PCAF) service on anticoagulation uptake in a cohort of high-risk patients with AF in the UK. METHODS: The PCAF service is a novel cooperative pathway providing specialist resources within general practitioner (GP) practices. It utilises a four-phase protocol to identify high-risk patients with AF (CHA2DS2-VASc ≥ 1) who are suboptimally anticoagulated, and delivers Consultant-led anticoagulation assessment within the local GP practice. We assessed rates of anticoagulation in high-risk patients before and after PCAF service intervention, and determined compliance with newly-initiated anticoagulation at follow-up. RESULTS: The PCAF service was delivered in 56 GP practices (population 386,624; AF prevalence 2.1%) between June 2012 and June 2014. 1579 high-risk patients with AF with suboptimal anticoagulation (either not taking any anticoagulation or taking warfarin but with a low time-in-therapeutic-range) were invited for review, with 86% attending. Of 1063 eligible patients on no anticoagulation, 1020 (96%) agreed to start warfarin (459 (43%)) or a non-vitamin K antagonist oral anticoagulant (NOAC, 561 (53%)). The overall proportion of eligible patients receiving anticoagulation improved from 77% to 95% (p<0.0001). Additionally, 111/121 (92%) patients suboptimally treated with warfarin agreed to switch to a NOAC. Audit of eight practices after 195 (185-606) days showed that 90% of patients started on a new anticoagulant therapy had continued treatment. Based on data extrapolated from previous studies, around 30-35 strokes per year may have been prevented in these previously under-treated high-risk patients. CONCLUSIONS: Systematic identification of patients with AF with high stroke-risk and consultation in PCAF consultant-led clinics effectively delivers oral anticoagulation to high-risk patients with AF in the community.

Recurrence of atrial tachyarrhythmia during the second month of the blanking period is associated with more extensive pulmonary vein reconnection at repeat electrophysiology study.

BACKGROUND: Current guidelines recommend a 3-month blanking period after pulmonary vein isolation (PVI) as early recurrence of atrial tachyarrhythmia (ERAT) may be due to transient proarrhythmic factors. However, studies have suggested that these factors resolve by 1 month. PV reconnection (PVrc) is strongly associated with postblanking AT recurrence in paroxysmal atrial fibrillation. We hypothesized that ERAT occurring beyond 4 weeks after PVI is associated with PVrc at repeat electrophysiology study. METHODS AND RESULTS: Forty patients with paroxysmal atrial fibrillation underwent mandatory repeat electrophysiology study 2 months after PVI, regardless of symptoms, to document the number of reconnected PVs. Antiarrhythmic drugs, including ß-blockers, were discontinued 4 weeks after PVI. Patients were instructed to record a 30-second ECG everyday between the 2 procedures using a portable monitor, with additional recordings for symptoms. ERAT was defined as ≥30 seconds of AT. Patients recorded a total of 3293 ECGs. Four (10%) patients had ERAT in the first 4 weeks (M1) only, 2 (5%) in month 2 (M2) only, and 11 (28%) in both. PVrc of 1 PV was identified in 12 (30%) patients and of >1 PV in 13 (32%) patients. ERAT in M2 was associated with PVrc, whereas M1 was not (11/13 [85%] versus 0/4 [0%]; P=0.006). M2 ERAT was strongly associated with PVrc of >1 PV (10/13 [77%] versus 3/27 [11%] without M2 ERAT; P<0.0001). CONCLUSIONS: ERAT occurring beyond 4 weeks after PVI is associated with PVrc and particularly of PVrc of >1 PV. ERAT confined to M1 is unrelated to underlying PVrc. The relationship between ERAT beyond 4 weeks after PVI and postblanking AT recurrence merits further investigation.

A novel marker to predict early recurrence after atrial fibrillation ablation: the ablation effectiveness quotient.

INTRODUCTION: Inability to predict clinical outcome despite acutely successful pulmonary vein isolation (PVI) remains the Achilles' heel of atrial fibrillation ablation (AFA). Arrhythmia recurrence is frequently due to recovery of radiofrequency (RF) ablation lesions believed to be complete at the original procedure. OBJECTIVES: We hypothesized that a high ratio between post-AFA levels of serum high sensitivity cardiac troponin T (HScTnT), a highly specific marker of acute myocardial injury, and duration of RF application (the ablation effectiveness quotient, AEQ) would indicate effective ablation and correlate with early clinical success. METHODS: We prospectively measured HScTnT levels in 60 patients (42 [70%] male, 22 [37%] with paroxysmal AF [PAF], mean age 62.5 ± 10.6 years) 12-18 hours after AFA and calculated the AEQ for each. Patients were followed-up with ECGs and Holter monitors for recurrence of atrial tachyarrhythmia (AT). RESULTS: Early recurrence of AT within 6 months occurred in 22 (37%). AT recurrence was not significantly related to left atrial size or comorbidities, nor to RF time or HScTnT level. Mean AEQ was significantly lower in those with recurrence than those without (0.35 ± 0.14 ng/L/s vs. 0.45 ± 0.18 ng/L/s), P = 0.02. Subgroup analysis showed this finding was due to patients with PAF in whom early significance was maintained to one year, with an AEQ >0.4 ng/L/s having 75% sensitivity and 90% specificity in predicting freedom from AT. CONCLUSION: A high AEQ correlates well with freedom from AT in patients with PAF in both the short and medium term. If confirmed in further studies, AEQ may become a useful marker of risk of AT post-AFA.