Feasibility of double-blinded, placebo-controlled interventional study for assessing catheter ablation efficacy in persistent atrial fibrillation: Insights from the ORBITA AF feasibility study.

BACKGROUND: To date, there are no randomized, double-blinded clinical trials comparing catheter ablation to DC cardioversion (DCCV) with medical therapy in patients with persistent atrial fibrillation (PersAF). Conducting a large-scale trial to address this question presents considerable challenges, including recruitment, blinding, and implementation. We conducted a pilot study to evaluate the feasibility of conducting a definitive placebo-controlled trial. METHODS: This prospective trial was carried out at Barts Heart Centre, United Kingdom, employing a randomized, double-blinded, placebo-controlled design. Twenty patients with PersAF (duration <2 years) were recruited, representing 10% of the proposed larger trial as determined by a power calculation. The patients were randomized in a 1:1 ratio to receive either PVI ± DCCV (PVI group) or DCCV + Placebo (DCCV group). The primary endpoint of this feasibility study was to evaluate patient blinding. Patients remained unaware of their treatment allocation until end of study. RESULTS: During the study, 35% of patients experienced recurrence of PersAF prior to completion of 12 months follow-up. Blinding was successfully maintained amongst both patients and medical staff. The DCCV group had a trend to higher recurrence and repeat procedure rate compared to the PVI group (recurrence of PersAF 60% vs 30%; p = .07 and repeat procedure 70% vs 40%; p = .4). The quality of life experienced by individuals in the PVI group showed improvement, as evidenced by enhanced scores on the AF specific questionnaire (AF PROMS) (3 [±4] vs 21 [±8]) and SF-12 mental-component raw score (51.4 [±7] vs 43.24 [±15]) in patients who maintained sinus rhythm at 12 months. CONCLUSION: This feasibility study establishes the potential for conducting a blinded, placebo-controlled trial to evaluate the efficacy of PVI versus DCCV in patients with PersAF.

Catheter ablation of atrial fibrillation with a multi-electrode radiofrequency balloon; first and early two centre experience in Europe.

INTRODUCTION: The Heliostar™ ablation system is a novel RF balloon ablation technology with an integrated three-dimensional mapping system. Here, we describe our early experience and procedural outcomes using this technology for atrial fibrillation catheter ablation. METHODS: We sought to comprehensively assess the first 60 consecutive patients undergoing pulmonary vein isolation using the novel HELISOTAR™ RF balloon technology including procedural outcomes. A comparison of the workflow between two different anaesthetic modalities (conscious sedation [CS] vs. general anaesthesia [GA]) was made. Procedural data were collected prospectively from two high-volume centers (Barts Heart Centre, UK and University Hospital of Zurich, Zurich). A standardized approach for catheter ablation was employed. RESULTS: A total of 35 patients had the procedure under CS and the remaining under GA. Mean procedural and fluoroscopy times were 84 ± 33 min and 1.1 min. The median duration of RF energy application was 7 (5-9.8) mins per patient. All veins were successfully isolated, and the median isolation time was 10 (7-15) seconds. Our cohort's rate of procedural complications was low, with no mortality within 30 days postprocedure. CONCLUSION: Our early experience shows that catheter ablation using the Heliostar™ technology can be performed efficiently and safely; however, long-term data is yet to be established. Low fluoroscopy requirements, short learning curves and use of this technology with CS is possible, including the use of an oesophageal temperature probe.

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.

Ablation versus anti-arrhythmic therapy for reducing all hospital episodes from recurrent atrial fibrillation: a prospective, randomized, multi-centre, open label trial.

AIMS: There is rising healthcare utilization related to the increasing incidence and prevalence of atrial fibrillation (AF) worldwide. Simplifying therapy and reducing hospital episodes would be a valuable development. The efficacy of a streamlined AF ablation approach was compared to drug therapy and a conventional catheter ablation technique for symptom control in paroxysmal AF. METHODS AND RESULTS: We recruited 321 patients with symptomatic paroxysmal AF to a prospective randomized, multi-centre, open label trial at 13 UK hospitals. Patients were randomized 1:1:1 to cryo-balloon ablation without electrical mapping with patients discharged same day [Ablation Versus Anti-arrhythmic Therapy for Reducing All Hospital Episodes from Recurrent (AVATAR) protocol]; optimization of drug therapy; or cryo-balloon ablation with confirmation of pulmonary vein isolation and overnight hospitalization. The primary endpoint was time to any hospital episode related to treatment for atrial arrhythmia. Secondary endpoints included complications of treatment and quality-of-life measures. The hazard ratio (HR) for a primary endpoint event occurring when comparing AVATAR protocol arm to drug therapy was 0.156 (95% CI, 0.097-0.250; P < 0.0001 by Cox regression). Twenty-three patients (21%) recorded an endpoint event in the AVATAR arm compared to 76 patients (74%) within the drug therapy arm. Comparing AVATAR and conventional ablation arms resulted in a non-significant HR of 1.173 (95% CI, 0.639-2.154; P = 0.61 by Cox regression) with 23 patients (21%) and 19 patients (18%), respectively, recording primary endpoint events (P = 0.61 by log-rank test). CONCLUSION: The AVATAR protocol was superior to drug therapy for avoiding hospital episodes related to AF treatment, but conventional cryoablation was not superior to the AVATAR protocol. This could have wide-ranging implications on how demand for AF symptom control is met. TRIAL REGISTRATION: Clinical Trials Registration: NCT02459574.

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).

Transseptal puncture for left atrial ablation: Risk factors for cardiac tamponade and a proposed causative classification system.

AIMS: Cardiac tamponade is a high morbidity complication of transseptal puncture (TSP). We examined the associations of TSP-related cardiac tamponade (TRCT) for all patients undergoing left atrial ablation at our center from 2016 to 2020. METHODS AND RESULTS: Patient and procedural variables were extracted retrospectively. Cases of cardiac tamponade were scrutinized to adjudicate TSP culpability. Adjusted multivariate analysis examined predictors of TRCT. A total of 3239 consecutive TSPs were performed; cardiac tamponade occurred in 51 patients (incidence: 1.6%) and was adjudicated as TSP-related in 35 (incidence: 1.1%; 68.6% of all tamponades). Patients of above-median age [odds ratio (OR): 2.4 (1.19-4.2), p = .006] and those undergoing re-do procedures [OR: 1.95 (1.29-3.43, p = .042] were at higher risk of TRCT. Of the operator-dependent variables, choice of transseptal needle (Endrys vs. Brockenbrough, p > .1) or puncture sheath (Swartz vs. Mullins vs. Agilis vs. Vizigo vs. Cryosheath, all p > .1) did not predict TRCT. Adjusting for operator, equipment and demographics, failure to cross the septum first pass increased TRCT risk [OR: 4.42 (2.45-8.2), p = .001], whilst top quartile operator experience [OR: 0.4 (0.17-0.85), p = .002], transoesophageal echocardiogram [TOE prevalence: 26%, OR: 0.51 (0.11-0.94), p = .023], and use of the SafeSept transseptal guidewire [OR: 0.22 (0.08-0.62), p = .001] reduced TRCT risk. An increase in transseptal guidewire use over time (2016: 15.6%, 2020: 60.2%) correlated with an annual reduction in TRCT (R2 = 0.72, p < .001) and was associated with a relative risk reduction of 70%. CONCLUSIONS: During left atrial ablation, the risk of TRCT was reduced by operator experience, TOE-guidance, and use of a transseptal guidewire, and was increased by patient age, re-do procedures, and failure to cross the septum first pass.

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.

Early pacemaker implantation for transcatheter aortic valve implantation is safe and effective.

BACKGROUND: Permanent pacemaker (PPM) implantation is a common complication of transcatheter aortic valve implantation (TAVI). The optimum timing of PPM implantation is still unclear as conduction abnormalities evolve and a balance needs to be struck between conservative delays in the hope of conduction recovery and overutilization of pacing. This study aimed to assess the safety and efficacy of early PPM implantation, without an observation period, among TAVI patients. METHODS: This is a retrospective, observational study of 1398 TAVI patients. Clinical and pacing data were collected at baseline, 30 days and at a median of 15 (4-21) months post-TAVI. Study endpoints included PPM-related complications, pacing utilization and hospital length of stay. RESULTS: One hundred five patients (8.2%) required a PPM, of which 13 were implanted pre and 92 post-TAVI. Seventy-six percent required pacing for either second- or third-degree heart block. Time to implantation for post-TAVI PPM was 1 (0-3) day. Six patients experienced a pacing-related complication- lead displacement (n = 3), hematoma (n = 2), and device infection (n = 1). Pacing utilization defined as pacing >10% of the time or a pacing requirement at the time of the pacing check was demonstrated in 83% of patients. Multivariate analysis revealed complete heart block (CHB) was the only independent predictor of pacing utilization. Hospital length of stay for the post-TAVI PPM group was longer than the group without PPM (4 [2-8] vs. 3 [2-4] days; p < .001). CONCLUSIONS: Early PPM implantation in TAVI patients is safe and majority of patients require pacing in the short and mid-term.

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.

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.

A multi-center experience of ablation index for evaluating lesion delivery in typical atrial flutter.

BACKGROUND: Anatomical studies demonstrate significant variation in cavotricuspid isthmus (CTI) architecture. METHODS: Thirty-eight patients underwent CTI ablation at two tertiary centers. Operators delivered 682 lesions with a target ablation index (AI) of 600 Wgs. Ablation parameters were recorded every 10-20 ms. Post hoc, Visitags were trisected according to CTI position: inferior vena cava (IVC), middle (Mid), or ventricular (V) lesions. RESULTS: There were no complications. 92.1% of patients (n = 35) remained in sinus rhythm after 14.6 ± 3.4 months. For the whole CTI, peak AI correlated with mean impedance drop (ID) (R2  = 0.89, p < .0001). However, analysis by anatomical site demonstrated a non-linear relationship Mid CTI (R2  = 0.15, p = .21). Accordingly, while mean AI was highest Mid CTI (IVC: 473.1 ± 122.1 Wgs, Mid: 539.6 ± 103.5 Wgs, V: 486.2 ± 111.8 Wgs, ANOVA p < .0001), mean ID was lower (IVC: 10.7 ± 7.5Ω, Mid: 9.0 ± 6.5Ω, V: 10.9 ± 7.3Ω, p = .011), and rate of ID was slower (IVC: 0.37 ± 0.05 Ω/s, Mid: 0.18 ± 0.08 Ω/s, V: 0.29 ± 0.06 Ω/s, p < .0001). Mean contact force was similar at all sites; however, temporal fluctuations in contact force (IVC: 19.3 ± 12.0 mg/s, Mid: 188.8 ± 92.1 mg/s, V: 102.8 ± 32.3 mg/s, p < .0001) and catheter angle (IVC: 0.42°/s, Mid: 3.4°/s, V: 0.28°/s, p < .0001) were greatest Mid CTI. Use of a long sheath attenuated these fluctuations and improved energy delivery. CONCLUSIONS: Ablation characteristics vary across the CTI. At the Mid CTI, higher AI values do not necessarily deliver more effective ablation; this may reflect localized fluctuations in catheter angle and contact force.

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.

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.

Automated detection of repetitive focal activations in persistent atrial fibrillation: Validation of a novel detection algorithm and application through panoramic and sequential mapping.

INTRODUCTION: Identifying drivers in persistent atrial fibrillation (AF) remains challenging. We sought to validate an automated system for detection of focal activation using basket and PentaRay catheters in AF. METHODS: Patients having ablation for atrial tachycardia (AT) and persistent AF were mapped. Thirty-second unipolar basket and PentaRay recordings were analyzed using CARTOFINDER. Focal activation or "region of interest" (ROI) was defined as more than or equal to 2 consecutive focal activations with one electrode leading relative to its neighbors with QS morphology on the unipolar electrogram. ROI was validated in AT. AF patients were mapped to (1) look for evidence of focal activations on wavefront maps, (2) evaluate whether these were detected as ROI on basket recordings, and (3) whether these sites could be identified on sequential PentaRay recordings. RESULTS: ROIs were identified in five focal ATs but none of 16 reentrant ATs. Twenty-eight AF patients had 35 focal drivers identified from basket wavefront maps with an ablation response in all (16 cycle length slowing and 19 AF termination). Thirty focal activations were detected on basket ROI maps (86%). Twenty-three of 28 patients had sequential PentaRay mapping and 22 of 30 focal drivers in these patients (73%) were identified as ROI. These drivers had greater temporal stability (3.6 ± 0.6 vs 2.7 ± 0.6; P < 0.001), higher recurrence rate (12.4 ± 2.7 vs 7.2 ± 0.9; P < 0.001), and more frequently were associated with AF termination ( P < 0.001) compared with those not identified as ROI. CONCLUSIONS: Focal activations can be detected in AF using sequential recordings. The ablation response at focal sources suggests they may be viable therapeutic targets.

A nurse-led implantable loop recorder service is safe and cost effective.

INTRODUCTION: Implantable loop recorders (ILR) are predominantly implanted by cardiologists in the catheter laboratory. We developed a nurse-delivered service for the implantation of LINQ (Medtronic; Minnesota) ILRs in the outpatient setting. This study compared the safety and cost-effectiveness of the introduction of this nurse-delivered ILR service with contemporaneous physician-led procedures. METHODS: Consecutive patients undergoing an ILR at our institution between 1st July 2016 and 4th June 2018 were included. Data were prospectively entered into a computerized database, which was retrospectively analyzed. RESULTS: A total of 475 patients underwent ILR implantation, 271 (57%) of these were implanted by physicians in the catheter laboratory and 204 (43%) by nurses in the outpatient setting. Six complications occurred in physician-implants and two in nurse-implants (P = .3). Procedural time for physician-implants (13.4 ± 8.0 minutes) and nurse-implants (14.2 ± 10.1 minutes) were comparable (P = .98). The procedural cost was estimated as £576.02 for physician-implants against £279.95 with nurse-implants, equating to a 57.3% cost reduction. In our center, the total cost of ILR implantation in the catheter laboratory by physicians was £10 513.13 p.a. vs £6661.55 p.a. with a nurse-delivered model. When overheads for running, cleaning, and maintaining were accounted for, we estimated a saving of £68 685.75 was performed by moving to a nurse-delivered model for ILR implants. Over 133 catheter laboratory and implanting physician hours were saved and utilized for other more complex procedures. CONCLUSION: ILR implantation in the outpatient setting by suitably trained nurses is safe and leads to significant financial savings.