Atrial fibrillation cryoablation is an effective day case treatment: the UK PolarX vs. Arctic Front Advance experience.

AIMS: Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation for atrial fibrillation (AF). There are limited data on the PolarX Cryoballoon. The study aimed to establish the safety, efficacy, and feasibility of same day discharge for Cryoballoon PVI. METHODS AND RESULTS: Multi-centre study across 12 centres. Procedural metrics, safety profile, and procedural efficacy of the PolarX Cryoballoon with the Arctic Front Advance (AFA) Cryoballoon were compared in a cohort large enough to provide definitive comparative data. A total of 1688 patients underwent PVI with cryoablation (50% PolarX and 50% AFA). Successful PVI was achieved with 1677 (99.3%) patients with 97.2% (n = 1641) performed as day case procedures with a complication rate of <1%. Safety, procedural metrics, and efficacy of the PolarX Cryoballoon were comparable with the AFA cohort. The PolarX Cryoballoon demonstrated a nadir temperature of -54.6 ± 7.6°C, temperature at 30 s of -38.6 ± 7.2°C, time to -40°C of 34.1 ± 13.7 s, and time to isolation of 49.8 ± 33.2 s. Independent predictors for achieving PVI included time to reach -40°C [odds ratio (OR) 1.34; P < 0.001] and nadir temperature (OR 1.24; P < 0.001) with an optimal cut-off of ≤34 s [area under the curve (AUC) 0.73; P < 0.001] and nadir temperature of ≤-54.0°C (AUC 0.71; P < 0.001), respectively. CONCLUSIONS: This large-scale UK multi-centre study has shown that Cryoballoon PVI is a safe, effective day case procedure. PVI using the PolarX Cryoballoon was similarly safe and effective as the AFA Cryoballoon. The cryoablation metrics achieved with the PolarX Cryoballoon were different to that reported with the AFA Cryoballoon. Modified cryoablation targets are required when utilizing the PolarX Cryoballoon.

Coronary sinus electrogram characteristics predict termination of AF with ablation and long-term clinical outcome.

INTRODUCTION: Markers predicting atrial fibrillation (AF) termination and freedom from AF/atrial tachycardia (AT) has been proposed. This study aimed to evaluate the role of novel coronary sinus (CS) electrogram characteristics in predicting the acute ablation response and freedom from AF/AT during follow-up. METHODS: Patients undergoing ablation for persistent AF as part of the Stochastic Trajectory Analysis of Ranked signals mapping study were included. Novel CS electrogram characteristics including CS cycle length variability (CLV) and CS activation pattern stability (APS) and proportion of low voltage zones (LVZs) were reviewed as potential predictors for AF termination on ablation and freedom from AF/AT during follow-up. The relationship between localized driver characteristics and CS electrogram characteristics was also assessed. RESULTS: Sixty-five patients were included. AF termination was achieved in 51 patients and 80% of patients were free from AF/AT during a follow-up of 29.5 ± 3.7 months. CS CLV of <30 ms, CS APS of ≥30% and proportion of LVZ < 30% showed high diagnostic accuracy in predicting AF termination on ablation and freedom from AF/AT during follow-up (CS CLV odds ratio [OR] 25.6, area under the curve [AUC] 0.91; CS APS OR 15.9, AUC 0.94; proportion of LVZs OR 21.4, AUC 0.88). These markers were independent predictors of AF termination on ablation and AF/AT recurrence during follow-up. Ablation of a smaller number of drivers that demonstrate greater dominance strongly correlate with greater CS organization. CONCLUSION: Novel CS electrogram characteristics were independent predictors of AF termination and AF/AT recurrence during follow-up. These markers can potentially aid in predicting outcomes and guide ablation and follow-up strategies.

Ethanol ablation for ventricular arrhythmias: A systematic review and meta-analysis.

INTRODUCTION: Ethanol ablation (EA) is an alternative option for subjects with ventricular arrhythmias (VAs) refractory to conventional medical and ablative treatment. However, data on the efficacy and safety of EA remain sparse. METHODS: A systematic literature search was conducted. The primary outcomes were 1) freedom from the targeted VA and 2) freedom from any VAs post-EA. Additional safety outcomes were also analyzed. RESULTS: Ten studies were selected accounting for a population of 174 patients (62.3 ± 12.5 years, 94% male) undergoing 185 procedures. The overall acute success rate of EA was 72.4% (confidence interval [CI95% ]: 65.6-78.4). After a mean follow-up of 11.3 ± 5.5 months, the incidence of relapse of the targeted VA was 24.4% (CI95% : 17.1-32.8), while any VAs post-EA occurred in 41.3% (CI95% : 33.7-49.1). The overall incidence of procedural complications was 14.1% (CI95% : 9.8-19.8), with pericardial complications and complete atrioventricular block being the most frequent. An anterograde transarterial approach was associated with a higher rate of VA recurrences and complications compared to a retrograde transvenous route; however, differences in the baseline population characteristics and in the targeted ventricular areas should be accounted. CONCLUSION: EA is a valuable therapeutic option for VAs refractory to conventional treatment and can result in 1-year freedom from VA recurrence in 60%-75% of the patients. However, anatomical or technical challenges preclude acute success in almost 30% of the candidates and the rate of complication is not insignificant, highlighting the importance of well-informed patient selection. The certainty of the evidence is low, and further research is necessary.

ECG-I phenotyping of persistent AF based on driver burden and distribution to predict response to pulmonary vein isolation (PHENOTYPE-AF).

BACKGROUND: This prospective trial sought to phenotype persistent atrial fibrillation (AF) based on AF mechanisms using electrocardiographic imaging (ECGI) mapping to determine whether this would predict long-term freedom from arrhythmia after pulmonary vein isolation (PVI). METHODS: Patients with persistent AF of <2 years duration underwent cryoballoon PVI. ECGI mapping was performed before PVI to determine potential drivers (PDs) defined as rotational activations completing ≥1.5 revolutions or focal activations. The coprimary endpoint was the association between (1) PD burden (defined as the number of PD occurrences) and (2) PD distribution (defined as the number of segments on an 18-segment model of the atria harboring PDs) with freedom from arrhythmia at 1-year follow up. RESULTS: Of 100 patients, 97 completed follow up and 52 (53.6%) remained in sinus rhythm off antiarrhythmic drugs. Neither PD burden nor PD distribution predicted freedom from arrhythmia (hazard ratio [HR]: 1.01, 95% confidence interval [CI]: 0.99-1.03, p = .164; and HR: 1.04, 95% CI: 0.91-1.17, p = .591, respectively). Otherwise, the burden of rotational PDs, rotational stability, and the burden of PDs occurring at the pulmonary veins and posterior wall all failed to predict arrhythmia recurrence (all p > .10). CONCLUSIONS: AF mechanisms as determined using ECGI mapping do not predict outcomes after PVI for persistent AF. Further studies using different methodologies to characterize AF mechanisms are warranted (NCT03394404).

PolarX Cryoballoon metrics predicting successful pulmonary vein isolation: targets for ablation of atrial fibrillation.

AIM: Evaluate the novel PolarX Cryoballoon in atrial fibrillation (AF) catheter ablation through a propensity-matched comparison with the Arctic Front Advance (AFA). The aim was also to identify cryoablation metrics that are predictive of successful pulmonary vein isolation (PVI) with the PolarX Cryoballoon. METHODS AND RESULTS: This prospective multi-centre study included patients that underwent cryoablation for AF. All patients underwent PVI with reconnection assessed after a 30-min waiting period and adenosine. Safety, efficacy, and cryoablation metrics were compared between PolarX and a propensity-matched AFA cohort. Seventy patients were included with 278 veins treated. In total, 359 cryoablations were performed (1.3 ± 0.6 per vein) to achieve initial PVI with 205 (73.7%) veins isolating with a single cryoablation. Independent predictors for achieving initial PVI included temperature at 30 s [odds ratio (OR) 1.26; P = 0.003] and time to reach -40°C (OR 1.88; P < 0.001) with an optimal cut-off of ≤-38.5°C at 30 s [area under the curve (AUC) 0.79; P < 0.001] and ≤-40°C at ≤32.5 s (AUC 0.77; P < 0.001), respectively. Of the 278 veins, 46 (16.5%) veins showed acute reconnection. Temperature at 30 s (≤-39.5°C, OR 1.24; P = 0.002), nadir temperature (≤-53.5°C, OR 1.35; P = 0.003), and time to isolation (≤38.0 s, OR 1.18; P = 0.009) were independent predictors of sustained PVI. Combining two of these three targets was associated with reconnection in only 2-5% of PVs. Efficacy and safety of the PolarX Cryoballoon were comparable to AFA Cryoballoon, however, cryoablation metrics were significantly different. CONCLUSIONS: The PolarX Cryoballoon has a different cryoablation profile to AFA Cryoballoon. Prospective testing of these proposed targets in large outcomes studies is required.

Risk factors for developing pacing induced LV dysfunction: Experience from a tertiary center in the UK.

BACKGROUND: The risk factors for developing pacing induced left ventricular dysfunction (LVD) in patients with high burden of right ventricular pacing (RVP) is poorly understood. Therefore, in the present study, we aimed to assess the determinants of pacing induced LVD. METHODS: Our data were retrospectively collected from 146 patients with RVP > 40% who underwent generator change (GC) or cardiac resynchronization therapy (CRT) upgrade between 2016 and 2019 who had left ventricular ejection fraction (EF) ≥50% at initial implant. RESULTS: A total of 75 patients had CRT upgrade due to pacing induced LVD (EF < 50%) and 71 patients with preserved LV function (EF ≥ 50%) had a GC. Primary indication for pacing in both groups was complete heart block. Male predominance (p = .008), prior myocardial infarction (MI) (p = .001), atrial fibrillation (AF) (p = .009), chronic kidney disease (CKD) (p = .005), and borderline low systolic function (BLSF) (EF 50%-55%) (p = .04) were more prevalent in the CRT upgrade group. Presence of AF (odds ratio [OR] = 3.05, 95% confidence interval [CI] 1.42-6.58; p = .004), BLSF (OR = 3.8, 95% CI 1.22-11.8; p = .02), and male gender (OR = 2.41, 95% CI 1.14-5.08; p = .02) were independent predictors for RVP induced LVD. Age (OR = 1.08, 95% CI 1.02-1.14; p = .005) and BLSF (OR = 5.33, 95% CI 1.26-22.5; p = .023) were independent predictors of earlier development of LVD after implant. CONCLUSIONS: Our results suggested that AF, BLSF, and male gender are predictors for development of pacing induced LVD in patients with high RVP burden. LVD can occur at any time after pacemaker implant with BLSF and increasing age associated with earlier development of LVD.

Contemporary Practice and Optimising Referral Pathways for Implantable Cardiac Monitoring for Atrial Fibrillation after Cryptogenic Stroke.

OBJECTIVES: Diagnosing atrial fibrillation (AF) in patients following Cryptogenic stroke (CS) has therapeutic implications that can reduce the risk of further strokes. However, it's indolent and paroxysmal nature makes this challenging. Prolonged rhythm monitoring using implantable loop recorders (ILRs) can significantly increase the AF detection rate in the clinical trial paradigm. Whether this can be translated to real-world practice is unknown. An evaluation of referral pathways, workload and real-world efficacy may help select patients and inform service development. MATERIALS AND METHODS: Retrospective review of all patients with CS referred to a tertiary electrophysiology referral hospital for ILR implantation between February 2017 and October 2020 for AF detection was conducted. The electronic health record was used to determine demographic and mortality data. Remote monitoring was used to identify AF occurrence. RESULTS: 107 patients were included. The average time from stroke to ILR implantation was 10.5 (5.9-18.6) months. The average monitoring duration was 18.1 ± 11.2 months with 15 (14.0%) patients diagnosed with AF and commenced on anticoagulation. One diagnosis were made in the first 30 days whereas 11 (73%) were made within 12 months. Paroxysmal AF episodes ranged from 6 min to 13 h. Patients with CHA2DS2-VASc >3 were more likely to have AF (20.3% vs 4.7%, p = 0.02). Age was independently associated with AF detection after multi-variate regression. 352 ± 1171 unique events were recorded per patient, 75% of which were for suspected AF. External manufacturer-led triage of transmissions reduced transmission volume by 33%. CONCLUSIONS: ILR-based AF detection rate was high among referred CS patients, despite implantation occurring relatively late. Older patients may be less likely to be referred despite positive correlation between age and AF detection. Although recording algorithms and external triage reduced transmission volume, specialist analysis was required to manage the ILR event burden.

Ablation guided by STAR-mapping in addition to pulmonary vein isolation is superior to pulmonary vein isolation alone or in combination with CFAE/linear ablation for persistent AF.

INTRODUCTION: The optimal ablation approach for persistent atrial fibrillation (AF) remains unclear. METHODS AND RESULTS: Objective was to compare the long-term rates of freedom from AF/AT in patients that underwent STAR mapping guided ablation against outcomes of patients undergoing conventional ablation procedures. Patients undergoing ablation for persistent AF as part of the Stochastic Trajectory Analysis of Ranked signals (STAR) mapping study were included. Outcomes following 'pulmonary vein isolation (PVI) plus STAR mapping guided ablation (STAR mapping cohort) were compared to patients undergoing PVI alone ablation during the same time period and also a propensity-matched cohort undergoing PVI plus the addition of complex fractionated electrogram (CFAE) and/or linear ablation ("conventional ablation"). Rates of procedural AF termination and freedom from AF/AT during follow-up were compared. Sixty-five patients were included in both the STAR cohort and propensity matched conventional ablation cohort. AF termination rates were significantly higher in the STAR cohort (51/65, 78.5%) than conventional ablation cohort (10/65, 15.4%) and PVI alone ablation cohort (13/50, 26.0%; STAR cohort vs. other 2 cohorts both p < .001). There was no significant difference in procedure time between the three cohorts. During ≥20 months follow-up a lower proportion of patients had AF/AT recurrence in the STAR cohort (20.0%) compared with the conventional ablation cohort (50.8%) or the PVI alone ablation cohort (50.0%; both p < .05 compared to STAR cohort). CONCLUSIONS: Outcomes of PVI plus STAR mapping guided ablation was superior to PVI alone or in combination with linear/CFAE ablation. A multicenter randomized controlled trial is planned to confirm these findings.

First experience of POLARx™ versus Arctic Front Advance™: An early technology comparison.

INTRODUCTION: Cryoballoon ablation is an established technique to achieve pulmonary vein isolation in patients with atrial fibrillation (AF). Recently, a new manufacturer of cryoballoon achieved regulatory CE marking (POLARx™; Boston Scientific). We describe our early experience of using this new market entrant of the technology and describe procedural aspects in comparison to the incumbent Medtronic Arctic Front Advance™. METHODS: We assessed the first 40 AF ablations performed with the POLARx catheter at the Barts Heart Centre. These patients were compared with a contemporaneous series of patients undergoing ablation by the same operators using the Arctic Front Advance. Procedural metrics were prospectively recorded. RESULTS: A total of four operators undertook 40 cases using the POLARx catheter, compared with 40 cases using the Arctic Front Advance. Procedure times (60.0 vs. 60.0 min) were similar between the two technologies, however left atrial dwell time (35.0 vs 39.0 min) and fluoroscopy times (3.3 vs. 5.2 min) were higher with the POLARx. Measured nadir and isolation balloon temperatures were significantly lower with POLARx. Almost all veins were isolated with a median freezing time of 16.0 (POLARx) versus 15.0 (Arctic Front Advance) min. The rate of procedural complications was low in both groups. CONCLUSION: The POLARx cryoballoon is effective for pulmonary vein isolation. Measured isolation and nadir temperatures are lower compared with the predicate Arctic Front Advance catheter. The technology appears similar in acute efficacy and has a short learning curve, but formal dosing studies may be required to prove equivalence of efficacy.

Catheter ablation of atrial fibrillation in patients with hypertrophic cardiomyopathy: a European observational multicentre study.

AIMS: Atrial fibrillation (AF) is common in hypertrophic cardiomyopathy (HCM). Data on the efficacy of catheter ablation of AF in HCM patients are sparse. METHODS AND RESULTS: Observational multicentre study in 137 HCM patients (mean age 55.0 ± 13.4, 29.1% female; 225 ablation procedures). We investigated (i) the efficacy of catheter ablation for AF beyond the initial 12 months; (ii) the available risk scores, stratification schemes and genotype as potential predictors of arrhythmia relapse, and (iii) the impact of cryoballoon vs. radiofrequency in procedural outcomes. Mean follow-up was 43.8 ± 37.0 months. Recurrences after the initial 12-month period post-ablation were frequent, and 24 months after the index procedure, nearly all patients with persistent AF had relapsed, and only 40% of those with paroxysmal AF remained free from arrhythmia recurrence. The APPLE score demonstrated a modest discriminative capacity for AF relapse post-ablation (c-statistic 0.63, 95% CI 0.52-0.75; P = 0.022), while the risk stratification schemes for sudden death did not. On multivariable analysis, left atrium diameter and LV apical aneurysm were independent predictors of recurrence. Fifty-eight patients were genotyped; arrhythmia-free survival was similar among subjects with different gene mutations. Rate of procedural complications was high (9.3%), although reducing over time. Outcome for cryoballoon and radiofrequency ablation was comparable. CONCLUSION: Very late AF relapses post-ablation is common in HCM patients, especially in those with persistent AF. Left atrium size, LV apical aneurysm, and the APPLE score might contribute to identify subjects at higher risk of arrhythmia recurrence. First-time cryoballoon is comparable with radiofrequency ablation.

Post-operative cardiac implantable electronic devices in patients undergoing cardiac surgery: a contemporary experience.

AIMS: Optimum timing of pacemaker implantation following cardiac surgery is a clinical challenge. European and American guidelines recommend observation, to assess recovery of atrioventricular block (AVB) (up to 7 days) and sinus node (5 days to weeks) after cardiac surgery. This study aims to determine rates of cardiac implantable electronic devices (CIEDs) implants post-surgery at a high-volume tertiary centre over 3 years. Implant timing, patient characteristics and outcomes at 6 months including pacemaker utilization were assessed. METHODS AND RESULTS: All cardiac operations (n = 5950) were screened for CIED implantation following surgery, during the same admission, from 2015 to 2018. Data collection included patient, operative, and device characteristics; pacing utilization and complications at 6 months. A total of 250 (4.2%) implants occurred; 232 (3.9%) for bradycardia. Advanced age, infective endocarditis, left ventricle systolic impairment, and valve surgery were independent predictors for CIED implants (P < 0.0001). Relative risk (RR) of CIED implants and proportion of AVB increased with valve numbers operated (single-triple) vs. non-valve surgery: RR 5.4 (95% CI 3.9-7.6)-21.0 (11.4-38.9) CIEDs. Follow-up pacing utilization data were available in 91%. Significant utilization occurred in 82% and underutilization (<1% A and V paced) in 18%. There were no significant differences comparing utilization rates in early (≤day 5 post-operatively) vs. late implants (P = 0.55). CONCLUSION: Multi-valve surgery has a particularly high incidence of CIED implants (14.9% double, 25.6% triple valve). Age, left ventricle systolic impairment, endocarditis, and valve surgery were independent predictors of CIED implants. Device underutilization was infrequent and uninfluenced by implant timing. Early implantation (≤5 days) should be considered in AVB post-multi-valve surgery.

Drivers in AF colocate to sites of electrogram organization and rapidity: Potential synergy between spectral analysis and STAR mapping approaches in prioritizing drivers for ablation.

INTRODUCTION: Stochastic trajectory analysis of ranked signals (STAR) mapping has recently been used to ablate persistent atrial fibrillation (AF) with high rates of AF termination and long-term freedom from AF in small, single-arm studies. We hypothesized that rapidity and organization markers would correlate with early sites of activation (ESA). METHODS: Patients undergoing persistent AF ablation as part of the STAR mapping study were included. Five-minute unipolar basket recordings used to create STAR maps were used to determine the minimum-cycle length (Min-CL) and CL variability (CLV) at each electrode to identify the site of the fastest Min-CL and lowest CLV across the left atrium (LA). The location of ESA targeted with ablation was compared with these sites. Dominant frequency was assessed at ESA and compared with that of neighboring electrodes to assess for regional gradients. RESULTS: Thirty-two patients were included with 83 ESA ablated, with an ablation response at 73 sites (24 AF termination and 49 CL slowing ≥30 ms). Out of these, 54 (74.0%) and 56 (76.7%) colocated to sites of fastest Min-CL and lowest CLV, respectively. Regional CL and frequency gradients were demonstrable at majority of ESA. ESA colocating to sites of fastest Min-CL and lowest CLV were more likely to terminate AF with ablation (odds ratio, 34 and 29, respectively, P = .02). These showed a moderate sensitivity (74.0% Min-CL and 75.3% CLV) and specificity (66.7% Min-CL and 76.9% CLV) in predicting ESA with an ablation response. CONCLUSIONS: ESA correlate with rapidity and organization markers. Further work is needed to clarify any role for spectral analysis in prioritizing driver ablation.

Same-day discharge following catheter ablation of atrial fibrillation: A safe and cost-effective approach.

INTRODUCTION: The frequency of catheter ablation for atrial fibrillation (AF) has increased dramatically, stretching resources. Discharge on the same day as treatment may increase the efficiency and throughput. There are limited data regarding the safety of this strategy. METHODS: We performed a retrospective analysis of consecutive patients undergoing AF ablation in a tertiary center and in a district general hospital, and identified those discharged on the same day of treatment. The safety endpoint was any complication and/or presentation to hospital in the 48-h and at 30 days postdischarge. We performed an economic analysis to calculate potential cost saving. RESULTS: Among a total population of 2628 patients, we identified 727 subjects (61.1 ± 12.5 years, 69.6% male) undergoing day-case AF ablation. Cryoballoon technique was used in 79.2% of the day-cases, and 91.6% of the procedures were performed under conscious sedation. 1.8% (13) of the participants met the safety composite endpoint at 48-h, however only 0.7% (5) required at least 1 day of hospitalization. Bleeding or hematoma at the femoral access site (0.5%) and pericarditic chest pain (0.5%) were the main reasons for readmission. None experienced cardiac tamponade or other life-threatening complications in the 48-h postdischarge. Overall rate of complication and/or presentation to hospital at 30 days was 3.7%. Our day-case policy resulted in an annual cost-saving of approximately of £83 927 for our hospital. CONCLUSION: In this large multicentre cohort, same-day discharge in selected patients following AF ablation appears to be safe and cost-effective, with a very low rate of early readmission or post-discharge complication.

Non-vitamin K oral anticoagulants in hypertrophic cardiomyopathy patients undergoing catheter ablation of atrial fibrillation.

INTRODUCTION: Patients with hypertrophic cardiomyopathy (HCM) and atrial fibrillation (AF) require chronic anticoagulation due to high thromboembolic risk. Evidence supporting the use of non-vitamin K oral anticoagulants (NOACs) in patients with HCM remains sparse, and there are no data regarding the use of NOACs in patients with HCM undergoing catheter ablation of AF. METHODS: Observational nonrandomized study in four European centers. We aimed to investigate the safety and efficacy of NOACs compared with vitamin K antagonists (VKAs) in patients with HCM undergoing catheter ablation for AF. RESULTS: A total of 137 patients with HCM (mean age: 55.0 ± 13.4, 29.1% female) underwent 230 catheter ablations for AF (1.7 ± 1.0 per patient). A total of 55 patients (39.4%) underwent 70 procedures (30.4%) on NOAC, while the remaining were on VKA. Warfarin (97.6%) and rivaroxaban (56.4%) were the most frequently used agents in the respective groups. No procedure-related deaths were reported. We observed no significant difference in the rate of thromboembolism (VKA: 0.6%; NOAC: 0%; p = 1.0) or minor bleeding (VKA: 0.6%; NOAC: 1.4%; p = .54). There was a nonsignificant trend towards a lower incidence of major bleeding (VKA: 6.9%; NOAC: 1.4%; p = .09). CONCLUSION: These preliminary data suggest that NOACs are at least as safe and effective as VKAs in patients with HCM undergoing catheter ablation for AF.

Use of a multi-electrode radiofrequency balloon catheter to achieve pulmonary vein isolation in patients with paroxysmal atrial fibrillation: 12-Month outcomes of the RADIANCE study.

BACKGROUND: The RADIANCE first-in-man study evaluated acute (3-month) safety and design concept in terms of utility of a new multi-electrode radiofrequency (RF) balloon catheter (HELIOSTAR, Biosense Webster) to achieve pulmonary vein isolation (PVI). After study conclusion, a subset of patients was followed up to 12 months. METHODS: Patients with drug refractory paroxysmal atrial fibrillation were enrolled. Neurological assessment, cardiac and cerebral magnetic resonance imagings were performed pre and post procedure. Ablation was delivered at 15 Watts to each PV for 60 seconds (electrodes adjacent to the posterior wall limited to 20 seconds). Adenosine or isoproterenol was administered to confirm PVI. Esophageal endoscopy was performed 48 hours post procedure. Patients were clinically followed up for 12 months. RESULTS: Thirty-nine patients underwent catheter ablation from four centers. Mean age was 60.7 ± 10.0 years with 23 (57.5%) being male. Confirmation of PVI was performed in all PVs treated (152/152). Confirmation of isolation after one delivery was performed solely on 137 of 152 PVs of which 79.6% (109/137) achieved isolation with a single delivery of RF energy. Acute PV reconnection was seen in 4.6% (7/150) of PVs. Freedom from documented atrial arrhythmia at 12 months in those followed up was 86.4% (32/37). A total of 75.7% (28/37) of patients were free from atrial arrhythmia and off antiarrhythmic medications. CONCLUSION: The HELIOSTAR RF balloon catheter allows for rapid and safe PVI with majority of PVs only requiring one application.

Impact of pulmonary vein isolation on mechanisms sustaining persistent atrial fibrillation: Predicting the acute response.

BACKGROUND: Noninvasive mapping identifies potential drivers (PDs) in atrial fibrillation (AF). We analyzed the impact of pulmonary vein isolation (PVI) on PDs and whether baseline PD pattern predicted termination of AF. METHODS: Patients with persistent AF less than 2 years underwent electrocardiographic imaging mapping before and after cryoballoon PVI. We recorded the number of PD occurrences, characteristics (rotational wavefronts ≥ 1.5 revolutions or focal activations), and distribution using an 18-segment atrial model. RESULTS: Of 100 patients recruited, PVI terminated AF in 15 patients; 21.3% ± 9.1% (8.7 ± 4.8) of PDs occurred at the pulmonary veins (PVs) and posterior wall. PVI had no impact on PD occurrences outside the PVs and posterior wall (33.2 ± 12.9 vs 31.6 ± 12.5; P = .164), distribution over the remaining 13 segments (9 [8-11] vs 9 [8-10]; P = .634), the proportion of PDs that was rotational (82.9% ± 9.7% vs 83.6% ± 10.1%; P = .496), or temporal stability (2.4 ± 0.4 vs 2.4 ± 0.5 rotations; P = .541). Fewer focal PDs (area under the curve, 0.683; 95% CI, 0.528-0.839; P = .024) but not rotational PDs (P = .626) predicted AF termination with PVI. CONCLUSIONS: PVI did not have a global impact on PDs outside the PVs and posterior wall. Although fewer focal PDs predicted termination of AF with PVI, the burden of rotational PDs did not. It is accepted though not all PDs are necessarily real or important. Outcome data are needed to confirm whether noninvasive mapping can predict patients likely to respond to PVI.

Efficacy and safety of ablation index-guided catheter ablation for atrial fibrillation: an updated meta-analysis.

AIMS: Despite recent advances in catheter ablation for atrial fibrillation (AF), pulmonary vein reconnection (PVR), and AF recurrence remain significantly high. Ablation index (AI) is a new method incorporating contact force, time, and power that should optimize procedural outcomes. We aimed to evaluate the efficacy and safety of AI-guided catheter ablation compared to a non-AI-guided approach. METHODS AND RESULTS: A systematic search was performed on MEDLINE (via PubMED), EMBASE, COCHRANE, and European Society of Cardiology (ESC) databases (from inception to 1 July 2019). We included only studies that compared AI-guided with non-AI-guided catheter ablation of AF. Eleven studies reporting on 2306 patients were identified. Median follow-up period was 12 months. Ablation index-guided ablation had a significant shorter procedural time (141.0 vs. 152.8 min, P = 0.01; I2 = 90%), ablation time (21.8 vs. 32.0 min, P < 0.00001; I2 = 0%), achieved first-pass isolation more frequently [odds ratio (OR) = 0.09, 95%CI 0.04-0.21; 93.4% vs. 62.9%, P < 0.001; I2 = 58%] and was less frequently associated with acute PVR (OR = 0.37, 95%CI 0.18-0.75; 18.0% vs 35.0%; P = 0.006; I2 = 0%). Importantly, atrial arrhythmia relapse post-blanking was significantly lower in AI compared to non-AI catheter ablation (OR = 0.41, 95%CI 0.25-0.66; 11.8% vs. 24.9%, P = 0.0003; I2 = 35%). Finally, there was no difference in complication rate between AI and non-AI ablation, with the number of cardiac tamponade events in the AI group less being numerically lower (OR = 0.69, 95%CI 0.30-1.60, 1.6% vs. 2.5%, P = 0.39; I2 = 0%). CONCLUSIONS: These data suggest that AI-guided catheter ablation is associated with increased efficacy of AF ablation, while preserving a comparable safety profile to non-AI catheter ablation.

Cryoablation for persistent and longstanding persistent atrial fibrillation: results from a multicentre European registry.

AIMS: Although cryoballoon pulmonary vein isolation is a well-established treatment for paroxysmal atrial fibrillation (AF), it's role in persistent AF is unclear. We examined procedural success and long-term outcomes of cryoablation in persistent and longstanding persistent AF. METHODS AND RESULTS: International multicentre registry from three UK and eight European centres. Consecutive patients undergoing cryoablation for persistent AF included. Procedural data, complications, and follow-up were prospectively recorded. Patients were followed-up at 3, 6, and 12 months with an electrocardiogram with open access to arrhythmia nurses thereafter. Ambulatory monitoring was dictated by symptoms. Success was defined as freedom from AF or atrial tachycardia lasting >30 s off antiarrhythmic drugs (AADs). Six hundred and nine consecutive cryoablation procedures. Mean procedure and fluoroscopy times were 95 ± 65 and 13 ± 10 min. Single procedure success rates were 368/602 (61%) off AADs over a median of 2.4 (1.0-4.0) years. Arrhythmia-free survival off AADs was 64% and 57% for persistent and longstanding persistent AF at 24 months of follow-up (P = 0.02). Rate of repeat ablations was 20% in persistent and 32% in longstanding persistent AF (P = 0.006). Cox regression analyses showed a significant association between duration of AF and left atrial diameter and arrhythmia recurrence [hazard ratio (HR) 1.05, P-value 0.01 and HR 1.02, P-value 0.004]. CONCLUSION: Cryoablation for persistent AF is safe, fast and has good outcomes at long-term follow-up. Cryoablation is reasonable as a first line option for these patients. Short procedure times may help increase capacity of cardiac units to meet the rising demand for AF ablation. Randomised control trials are needed to compare outcomes with different techniques.

Differentially expressed genes for atrial fibrillation identified by RNA sequencing from paired human left and right atrial appendages.

Atrial fibrillation is a significant worldwide contributor to cardiovascular morbidity and mortality. Few studies have investigated the differences in gene expression between the left and right atrial appendages, leaving their characterization largely unexplored. In this study, differential gene expression was investigated in atrial fibrillation and sinus rhythm using left and right atrial appendages from the same patients. RNA sequencing was performed on the left and right atrial appendages from five sinus rhythm (SR) control patients and five permanent AF case patients. Differential gene expression in both the left and right atrial appendages was analyzed using the Bioconductor package edgeR. A selection of differentially expressed genes, with relevance to atrial fibrillation, were further validated using quantitative RT-PCR. The distribution of the samples assessed through principal component analysis showed distinct grouping between left and right atrial appendages and between SR controls and AF cases. Overall 157 differentially expressed genes were identified to be downregulated and 90 genes upregulated in AF. Pathway enrichment analysis indicated a greater involvement of left atrial genes in the Wnt signaling pathway whereas right atrial genes were involved in clathrin-coated vesicle and collagen formation. The differing expression of genes in both left and right atrial appendages indicate that there are different mechanisms for development, support and remodeling of AF within the left and right atria.

STAR mapping method to identify driving sites in persistent atrial fibrillation: Application through sequential mapping.

INTRODUCTION: The optimal way to map localized drivers in persistent atrial fibrillation (AF) remains unclear. The objective of the study was to apply a novel vector mapping approach called Stochastic Trajectory Analysis of Ranked signals (STAR) in AF. METHODS AND RESULTS: Patients having persistent AF ablation were included. Early sites of activation (ESA) identified on global STAR maps created with basket catheters were used to guide AF ablation post-pulmonary vein isolation (PVI). All patients also had sequential STAR maps created with ≥10 PentaRay recordings of 30 seconds. These were validated offline in their ability to identify the ESA targeted with a study-defined ablation response (AF termination or cycle length [CL] slowing of ≥30 ms). Thirty-two patients were included in whom 92 ESA were identified on the global STAR maps, with 73 of 83 targeted sites demonstrating an ablation response (24 AF termination and 49 CL slowing). Sixty-one out of 73 (83.6%) ESA were also identified on the sequential STAR maps. These showed greater consistency (P < .001), were seen pre- and post-PVI (P < .001) and were more likely to be associated with AF termination on ablation (P = .007). The sensitivity and specificity of sequential mapping for the detection of ESA with an ablation response was 84.9% (95% confidence interval [CI] = 74.6-92.2) and 90.0% (95% CI = 55.5-99.8), respectively. During a follow-up of 19.4 ± 3.7 months, 28 (80%) patients were free from AF/atrial tachycardia. CONCLUSIONS: STAR mapping consistently identified ESA in all patients and the ablation response was compatible with ESA being driver sites. Mechanistically important ESA were successfully identified using sequential recordings.