Mechanisms of sex differences in atrial fibrillation: role of hormones and differences in electrophysiology, structure, function, and remodelling.

Atrial fibrillation (AF) is the clinically most prevalent rhythm disorder with large impact on quality of life and increased risk for hospitalizations and mortality in both men and women. In recent years, knowledge regarding epidemiology, risk factors, and patho-physiological mechanisms of AF has greatly increased. Sex differences have been identified in the prevalence, clinical presentation, associated comorbidities, and therapy outcomes of AF. Although it is known that age-related prevalence of AF is lower in women than in men, women have worse and often atypical symptoms and worse quality of life as well as a higher risk for adverse events such as stroke and death associated with AF. In this review, we evaluate what is known about sex differences in AF mechanisms-covering structural, electrophysiological, and hormonal factors-and underscore areas of knowledge gaps for future studies. Increasing our understanding of mechanisms accounting for these sex differences in AF is important both for prognostic purposes and the optimization of (targeted, mechanism-based, and sex-specific) therapeutic approaches.

Noninvasive epicardial and endocardial mapping of premature ventricular contractions.

AIMS: The aim of the present study was to estimate the accuracy of a novel non-invasive epicardial and endocardial electrophysiology system (NEEES) for mapping ectopic ventricular depolarizations. METHODS AND RESULTS: The study enrolled 20 patients with monomorphic premature ventricular contractions (PVCs) or ventricular tachycardia (VT). All patients underwent pre-procedural computed tomography or magnetic resonance imaging of the heart and torso. Radiographic data were semi-automatically processed by the NEEES to reconstruct a realistic 3D model of the heart and torso. In the electrophysiology laboratory, body-surface electrodes were connected to the NEEES followed by unipolar EKG recordings during episodes of PVC/VT. The body-surface EKG data were processed by the NEEES using its inverse-problem solution software in combination with anatomical data from the heart and torso. The earliest site of activation as denoted on the NEEES 3D heart model was compared with the PVC/VT origin using a 3D electroanatomical mapping system. The site of successful catheter ablation served as final confirmation. A total of 21 PVC/VT morphologies were analysed and ablated. The chamber of interest was correctly diagnosed non-invasively in 20 of 21 (95%) PVC/VT cases. In 18 of the 21 (86%) cases, the correct ventricular segment was diagnosed. Catheter ablation resulted in acute success in 19 of the 20 (95%) patients, whereas 1 patient underwent successful surgical ablation. During 6 months of follow-up, 19 of the 20 (95%) patients were free from recurrence off antiarrhythmic drugs. CONCLUSION: The NEEES accurately identified the site of PVC/VT origin. Knowledge of the potential site of the PVC/VT origin may aid the physician in planning a successful ablation strategy.

First insights into cryoballoon-based pulmonary vein isolation taking the individual time-to-isolation into account.

AIMS: Cryoballoon (CB)-based pulmonary vein isolation (PVI) is an established treatment for symptomatic atrial fibrillation (AF). In the present study, we sought to assess the efficacy and safety of CB-based PVI taking the individual time-to-isolation (TTI) into account. METHODS AND RESULTS: Sixty consecutive patients with drug-refractory paroxysmal atrial fibrillation [n = 49 (82%)] or short-standing persistent atrial fibrillation [n = 11 (18%)] underwent ablation with a 28-mm second-generation CB. The TTI was assessed by spiral mapping-catheter recordings and subsequently followed by an additional freeze-time of 120 s. No bonus freeze-cycle was applied. If the TTI could not be assessed, a fixed freeze-cycle duration of 240 s was applied and successful PVI confirmed thereafter. Clinical follow-up (FU) included 12-lead ECGs and 24 h Holter-ECGs at 3, 6, and 12 months. A blanking period of 3 months was defined. A total of 239 pulmonary veins (PVs) were identified and successfully isolated. The mean TTI assessed in 170/239 (71%) PVs was 52 ± 32 s. The mean number of CB applications was 1.2 ± 0.5; mean freeze-cycle duration was 192 ± 41 s. Mean procedure and fluoroscopy times were 80 ± 24 min and 16 ± 7 min, respectively. Transient phrenic nerve palsy occurred in one patient (2%). During a mean FU of 405 ± 67 days, 43 patients (72%) remained in stable sinus rhythm. CONCLUSIONS: Integrating an individual TTI protocol to CB-based PVI results in shorter freeze-cycle applications in a substantial portion of targeted PVs and an arrhythmia-free survival comparable to conventional ablation protocols. The complication rate is low.

Incidence of Significant Delayed Esophageal Temperature Drop After Cryoballoon-Based Pulmonary Vein Isolation.

BACKGROUND: The second-generation cryoballoon (CB2) has demonstrated superior clinical outcome. Potential procedural complications include esophageal thermal lesions due to excessive esophageal temperature (ET). Safety cut-offs for the ET have previously been published. A safety margin was incorporated due to a delayed esophageal temperature decline even after termination of the CB2 freeze cycle. The extent of these delayed temperature drops requires further systematic evaluation. METHODS AND RESULTS: The study enrolled 29 patients with paroxysmal or shortstanding persistent AF who underwent CB2-based PVI. Freeze cycle duration was 240 seconds. No bonus freeze was applied after successful PVI. The intraluminal ET was continuously measured via a transorally inserted probe (SensiTherm, St. Jude Medical, Inc.). The CB2 temperature and ET were recorded throughout the procedure using a camera setup. The mean number of freeze cycles per patient was 4.3 ± 2. A total of 147 cryoenergy applications were analyzed. A delayed decline in ET of >0.5 °C was recorded following termination of 23.1% of freeze cycles. The maximum drop in delayed ET was 6.4 °C. Excessive esophageal cooling during the freeze cycle exceeding 8.5 °C/min may result in ET ≤10 °C. CONCLUSIONS: Following termination of cryoenergy delivery, the ET may decline an additional 6.4 °C. Proposed ET safety cut-offs during CB2-based PVI need to account for a significant ET drop that may occur even after termination of the individual freeze cycle.

One-year clinical outcome after pulmonary vein isolation in persistent atrial fibrillation using the second-generation 28 mm cryoballoon: a retrospective analysis.

AIMS: The purpose of this study was to determine efficacy of pulmonary vein isolation (PVI) using the 28 mm cryoballoon (CB) in patients with persistent atrial fibrillation (AF). Superior acute and 1-year outcome has been demonstrated following PVI, using the second-generation CB in patients with paroxysmal AF. Data on the outcome in patients with persistent AF are sparse. METHODS AND RESULTS: Forty-nine patients (20 female, mean age 63 ± 10 years, mean left atrial diameter 46 ± 5 mm) with persistent AF [median AF duration since first diagnosis: 48 (20:192) months] underwent second-generation 28 mm CB-based PVI. The freeze cycle duration was set at 240 s. After successful PVI, a bonus freeze cycle of 240 s was applied in the first 11/49 (22%) patients, and no bonus freeze cycle was used in the remaining 38/49 (78%) patients. Follow-up (FU) was based on outpatient clinic visits at 3, 6, and 12 months, which included Holter electrocardiograms and telephone interviews. Recurrence was defined as an episode of symptomatic and/or documented atrial tachyarrhythmia >30 s beyond the 3-month blanking period. A total of 193 pulmonary veins (PVs) were identified and 193/193 (100%) PVs were successfully isolated. No phrenic nerve paralysis occurred. Follow-up was obtained in 49/49 (100%) patients with a mean FU duration of 416 ± 178 days. After the 3-month blanking period, antiarrhythmic medication was discontinued in 33/49 (67%) patients. Thirty-four of 49 (69%) patients remained in stable sinus rhythm. CONCLUSIONS: In patients with persistent AF, use of the second-generation 28 mm CB was associated with a 69% 1-year clinical success rate.

Ablation of atrial fibrillation in patients ≥75 years: long-term clinical outcome and safety.

AIMS: The prevalence of atrial fibrillation (AF) increases with age. Catheter ablation is an established treatment option for patients with symptomatic AF. We sought to determine the safety and long-term clinical efficacy of AF ablation in patients ≥75 years. METHODS AND RESULTS: Patients ≥75 years with symptomatic, drug-refractory AF were included in the study. Circumferential pulmonary vein isolation (PVI) was performed in all patients, extended to ablation of complex fractionated atrial electrograms, and/or linear lesions in PVI non-responders. Retrospective follow-up (FU) was based on routine outpatient clinic visits and regular telephone interviews. A total of 94 patients (54 male, age 78 ± 2 years, and left atrium diameter 46 ± 6 mm) with drug-refractory AF [55/94 (59%) paroxysmal AF (PAF), 29/94 (31%) persistent AF, and 10/94 (11%) long-standing persistent AF] underwent ablation. Follow-up was obtained in 93/94 (99%) patients. Following a single procedure, 35/93 (38%) patients were in stable sinus rhythm (SR; 46% PAF, 31% persistent AF, and 10% long-standing persistent AF) after a mean FU of 37 ± 20 months. After a mean of 1.5 ± 0.6 procedures, 55/93 (59%) patients were ultimately in stable SR (76% PAF, 41% persistent AF, and 20% long-standing persistent AF). In a total of 137 procedures, 8 major (5.8%) and 26 minor (19%) complications occurred. CONCLUSIONS: Catheter ablation in patients ≥75 years is associated with a favourable clinical long-term outcome in patients with PAF, while results are less promising in persistent or long-standing persistent patients. The safety profile of AF ablation in patients ≥75 years is comparable with patients of younger age.

One-year clinical success of a 'no-bonus' freeze protocol using the second-generation 28 mm cryoballoon for pulmonary vein isolation.

AIMS: Studies on the use of the second-generation 28 mm cryoballoon (CB) for the treatment of atrial fibrillation (AF) have reported superior 1-year clinical outcome. Customarily, a bonus freeze cycle is applied after pulmonary vein isolation (PVI). The purpose of the present study was to assess the 1-year clinical outcome following PVI foregoing a bonus freeze cycle. METHODS AND RESULTS: Patients with drug-refractory paroxysmal AF (PAF) or persistent AF underwent PVI using the second-generation 28 mm CB. The freeze cycle duration was set at 240 s. No bonus freeze cycle was applied. Clinical follow-up (FU) included 12-lead ECGs and 24h-Holter ECGs at 3, 6, and 12 months. A total of 45 patients (age 60 ± 11 years, mean LA diameter 42.1 ± 8.6 mm, n = 38 [84%] PAF) underwent CB-based PVI. Of 177 pulmonary veins (PVs) identified, 176/177 (99%) PVs were successfully isolated. The mean number of CB applications was 1.2 ± 0.4, 1.5 ± 0.8, 1.4 ± 0.7, 1.1 ± 0.3 and 1.7 ± 1.2 for the right superior PVs, right inferior PVs, left superior PVs, left inferior PVs, and left common PVs, respectively. Mean procedure and fluoroscopy times were 113 ± 32 and 19 ± 7 min, respectively. Phrenic nerve palsy occurred in 1/45 (2%) patients. One of 45 (2%) patients was lost to FU. After a mean FU period of 392 ± 58 (267-522) days including a 3-month blanking period, 36 of 44 (82%) patients remained in stable sinus rhythm. Five out of eight patients with arrhythmia recurrence underwent a second procedure. Only those PVs isolated with a single freeze cycle (5/11 PVs, 45%) demonstrated PV reconduction. In contrast, no PV reconnection was found in PVs initially treated with multiple freeze cycles. CONCLUSIONS: A 'no-bonus'-freeze protocol for PVI using the second-generation 28 mm CB resulted in an 82% 1-year clinical success rate. A bonus freeze cycle following successful PVI may not be essential to superior clinical outcome.

Validation of the mapping accuracy of a novel non-invasive epicardial and endocardial electrophysiology system.

AIMS: Use of a non-invasive electrocardiographic mapping system may aid in rapid diagnosis of atrial or ventricular arrhythmias or the detection of ventricular dyssynchrony. The aim of the present study was to validate the mapping accuracy of a novel non-invasive epi- and endocardial electrophysiology system (NEEES). METHODS AND RESULTS: Patients underwent pre-procedural computed tomography or magnetic resonance imaging of the heart and torso. Radiographic data were merged with the data obtained from the NEEES during pacing from implanted pacemaker leads or pacing from endocardial sites using an electroanatomical mapping system (CARTO 3, Biosense Webster). The earliest activation as denoted on the NEEES three-dimensional heart model was compared with the true anatomic location of the tip of the pacemaker lead or the annotated pacing site on the CARTO 3 map. Twenty-nine patients [mean age: 62 ± 11 years, 6/29 (11%) female, 21/29 (72%) with ischaemic cardiomyopathy] were enrolled into the pacemaker verification group. The mean distance from the non-invasively predicted pacing site to the anatomic reference site was 10.8 ± 5.4 mm for the right atrium, 7.7 ± 5.8 mm for the right ventricle, and 7.9 ± 5.7 mm for the left ventricle activated via the coronary sinus lead. Five patients [mean age 65 ± 4 years, 2 (33%) females] underwent CARTO 3 verification study. The mean distance between non-invasively reconstructed pacing site and the reference pacing site was 7.4 ± 2.7 mm for the right atrium, 6.9 ± 2.3 mm for the left atrium, 6.5 ± 2.1 mm for the right ventricle, and 6.4 ± 2.2 for the left ventricle, respectively. CONCLUSION: The novel NEEES was able to correctly identify the site of pacing from various endo- and epicardial sites with high accuracy.

Wide circumferential versus individual isolation of pulmonary veins using the endoscopic ablation system.

INTRODUCTION: The endoscopic ablation system (EAS) allows for effective pulmonary vein isolation (PVI). The feasibility of wide circumferential as compared to individual PVI using the EAS has not been formally assessed. METHODS: Patients with paroxysmal or short-persistent atrial fibrillation were assigned to individual PVI (group A) or wide circumferential PVI (group B). In group B, circumferential PVI was attempted only if the ipsilateral inferior PV was visualized while the ablation system targeted the superior PV and vice versa. Otherwise, individual PVI was performed. RESULTS: A total of 38 patients were enrolled (Group A: 20 patients, age 61 ± 7 years, LA-diameter 43 ± 5 mm; Group B: 18 patients, age 62 ± 10 years, LA-diameter 43 ± 4 mm). In group A, 20/20 (100%) right superior (RSPV) and inferior (RIPV) PVs, 18/19 (95%) left superior (LSPV) and inferior (LIPV) PVs, and 1/1 (100%) left common ostium (LCPV) were successfully isolated. First-pass success rate was 95%, 85%, 68%, and 95% for the RSPV, RIPV, LSPV, and LIPV, respectively. Touch-up radiofrequency ablation was required in 1/19 (5%) LSPV and LIPV. In group B, an attempt at circumferential PVI was feasible in 2/18 (11%) septal PVs and successful on first pass. Lateral circumferential PVI was attempted and successful on first-pass in 7/13 (54%) LSPVs and LIPVs and 1/5 (20%) LCPVs. CONCLUSIONS: Using the EAS in patients with AF, separate isolation of individual PVs rather than wide circumferential PVI should be the preferred ablation strategy.

The incidence of phrenic nerve injury during pulmonary vein isolation using the second-generation 28 mm cryoballoon.

INTRODUCTION: The second-generation cryoballoon (CB; Arctic Front Advance, Medtronic Inc., Minneapolis, MN, USA) has demonstrated greater procedural efficacy compared to the original CB. Whether increased efficacy translates into a higher incidence of phrenic nerve (PN) injury needs further evaluation. MATERIALS AND METHODS: In patients with drug-refractory paroxysmal atrial fibrillation (AF) or short-standing persistent AF, pulmonary vein isolation (PVI) was performed using the 28 mm second-generation CB. During cryoenergy delivery along the septal PVs, continuous PN pacing was performed. The freeze cycle was aborted in case of weakening or loss of diaphragmatic contraction. RESULTS: A total of 115 patients (42 female, mean age 61 ± 11 years, mean LA-diameter 43 ± 6 mm) with a history of paroxysmal AF (93/115 patients [81%]) or short-standing persistent AF (22/115 patients [19%]) underwent CB-based PVI. A total 445 of 448 (99%) PVs were isolated successfully. PN palsy (PNP) occurred in 4 of 115 (3.5%) patients, while applying cryoenergy to the right superior PV. Despite prompt interruption of the freezing cycle, PN function failed to recover during the periprocedural phase. PN recovery was observed as late as 10 months postablation. CONCLUSIONS: Using the second-generation 28 mm CB, PNP occurred in 4 of 115 (3.5%) patients. While 1 of 4 PNP recovered 10 months after ablation, long-term outcome in the remaining 3 patients is currently unknown due to the rather short follow-up period.

Electrical isolation of a substrate after myocardial infarction: a novel ablation strategy for unmappable ventricular tachycardias--feasibility and clinical outcome.

AIMS: Catheter ablation can abolish clinical ventricular tachycardia (VT) in patients after myocardial infarction (MI). However, VT frequently recurs after ablation. The best ablation strategy is still unknown, particularly in patients with unmappable VTs. We hypothesized that isolation of the arrhythmogenic substrate would be a feasible and effective ablation strategy for the treatment of ischaemic VT. METHODS AND RESULTS: Twelve patients (54 ± 8 years, left ventricular ejection fraction, LVEF 32 ± 13%) underwent catheter ablation for sustained VT (anterior MI = 10, inferior MI = 2). All patients had recurrent defibrillator shocks, including electrical storms in seven patients, despite anti-arrhythmic drugs. During electrophysiological study, 3 ± 2 VTs were induced. Three-dimensional mapping of the left ventricle revealed a low-voltage (<1.5 mV) area with fractionated electrograms and late potentials, with a mean area of 62 ± 20 cm(2). Isolation of the entire low-voltage area was attempted with a circumferential line along the low-voltage area border-zone. Substrate isolation was successfully achieved in 6 of 12 (50%) patients. Focal discharge within the isolated area was demonstrated in three of six (50%) patients. During a median follow-up of 479 [297; 781] days, 8 of 12 patients (66.7%) remained free of VT recurrence after a single procedure. In five of the six patients (83.3%) with successful substrate isolation, there were no VT recurrences when compared with three of the six patients (50%) with no substrate isolation. CONCLUSION: Electrical isolation of the entire substrate is feasible and appears to be an effective treatment in patients with late VT after MI.

In vivo left-ventricular contact force analysis: comparison of antegrade transseptal with retrograde transaortic mapping strategies and correlation of impedance and electrical amplitude with contact force.

AIMS: Clinical outcomes following radiofrequency ablation of ventricular tachycardias (VTs) depend on catheter tip-to-tissue contact force (CF). Left-ventricular (LV) mapping is performed via antegrade-transseptal or retrograde-transaortic approaches, and the applied CF may depend on the approach used. This study evaluated (i) the impact of antegrade-transseptal vs. retrograde-transaortic LV-mapping approaches on CF and catheter stability and (ii) the clinical value of the commonly used surrogate markers of catheter-myocardial contact-impedance, unipolar, and bipolar electrogram amplitudes. METHODS AND RESULTS: An antegrade-transseptal and a retrograde-transaortic LV-mapping approach was performed in 10 patients undergoing VT ablation by using CF-sensing catheters. Operators were blinded to CF data and data were analysed according to 11 predefined LV segments. Three thousand three hundred and twenty-four mapping points (1577 antegrade, 1747 retrograde) were analysed, including 80 (2.4%) points with maximum CF > 100 g. Median antegrade and retrograde CF were 16.0 g (q1-q3; 8.4-26.2) and 15.3 g (9.8-23.4), respectively. Contact force was significantly higher antegradely in mid-anteroseptum, mid-lateral, and apical segments, and significantly higher retrogradely in basal-anteroseptum, basal-inferoseptum, basal-inferior, and basal-lateral segments. Contact force did correlate with impedance, unipolar, and bipolar electrogram amplitudes; however, there were large overlaps. CONCLUSIONS: Antegrade vs. retrograde LV-mapping approaches result in different CF. A combined approach to the LV mapping may improve the overall LV mapping, potentially resulting in better clinical outcomes for the left VT catheter ablation. The previous surrogate markers used to assess CF do correlate with in vivo CF; however, due to a larger overlap, their clinical value is limited.

Incidence and anatomical locations of catheter instability during circumferential pulmonary vein isolation using contact force.

In addition to contact force (CF), catheter stability is considered to be an important factor in creating radiofrequency lesions.To evaluate the catheter stability during pulmonary vein isolation (PVI) using CF-sensing catheter.PVI was performed in 32 patients using a CF-sensing catheter. Operators were blinded to CF. The application was arbitrarily defined as a "visually unstable" point if the catheter moved ≥ 4 mm. Data were analyzed according to 6 predefined segments for the ipsilateral PVs. As a parameter of catheter stability, the standard deviation (SD) of CF and relative standard deviation (RSD = 100 × SD of CF /average CF) were introduced.A total of 932 RF applications with 426 visually unstable points (UP; 45.7%) and 506 stable points (SP; 54.3%) were analyzed. SD was significantly higher at UP (8.0 g versus 5.7 g, P < 0.001), and RSD was significantly higher at UP (43.7% versus 26.5%, P < 0.001). Higher RSD was associated with visual instability in all the segments of both PVs, however, higher SD of CF was not in all segments. At the antero-superior segment of the LPV, and the roof and posteroinferior segments of the RPV, the RSD values were over 50%, suggesting catheter instability.Catheter instability occurred in 45% of ablations during PVI and was predominantly located in the antero-superior segment of the LPV and postero-inferior segment of the RPV, which may result in incomplete lesion formation. RSD had significant correlation with visual catheter stability.

Significant reduction in procedure duration in remote magnetic-guided catheter ablation of atrial fibrillation using the third-generation magnetic navigation system.

PURPOSE: The magnetic navigation system (MNS) has shown to be safe and effective for catheter ablation of atrial fibrillation (AF). However, longer procedure duration as compared to manual catheter ablation may limit its widespread use. This study aimed to assess the impact of the newest generation MNS using an optimized mapping and ablation protocol on the efficacy and safety of remote magnetic catheter (RMC)-guided pulmonary vein isolation (PVI). METHODS: This observational study included 52 patients with symptomatic AF who underwent RMC-guided PVI using the second-generation MNS Niobe II (initial 28 patients, group I) or the third-generation MNS Niobe ES in combination with an optimized mapping and ablation protocol (24 patients, group II). RESULTS: Acute PVI was achieved in 26/28 (93%) patients in group I and 24/24 patients (100%) in group II. Mean procedure time was 263.9 ± 81.9 min in group I and significantly lower in group II (139.7 ± 22.6 min, p < 0.01). Mean fluoroscopy time was 18.8 ± 8.7 min in group I and decreased to 7.9 ± 2.6 in group II (p < 0.01). After a median follow-up of 640.5 days (Q1 460.75; Q3 766.5), 16/24 (67%) patients undergoing RMC-guided PVI in group II remained in stable SR. No periprocedural complications were noted for either group. CONCLUSIONS: Use of the third-generation MNS for RMC-guided PVI is safe, effective, and drastically reduced procedure times.

Two-year outcome after pulmonary vein isolation using the second-generation 28-mm cryoballoon: lessons from the bonus freeze protocol.

BACKGROUND: Pulmonary vein isolation (PVI) using the second-generation cryoballoon (CB2) in patients with paroxysmal and persistent atrial fibrillation (AF) has demonstrated encouraging acute and mid-term results. Follow-up data on outcome beyond 1-year is lacking. The purpose of this analysis was to investigate the 2-year clinical outcome after CB2-based PVI. METHODS: Sixty patients (age 62 ± 11 years) with paroxysmal [45/60 (75%) patients] or short-standing persistent AF [15/60 (25%) patients] underwent 28-mm CB2-based PVI. Freeze-cycle duration was 240 s. After successful PVI, a bonus freeze-cycle of the same duration was applied. Follow-up was based on outpatient clinic visits at 3, 6, 12, 18, and 24 months including 24 h Holter-ECGs and telephone interviews. Recurrence was defined as any symptomatic and/or documented atrial tachyarrhythmia (ATA) episode >30 s following a 3-month blanking period. RESULTS: A total of 231 pulmonary veins (PV) were identified and 230/231 (99.6%) PVs were successfully isolated. Phrenic nerve palsy occurred in 2/60 (3.3%) patients. No other periprocedural complications occurred. Follow-up was available for 59/60 (98%) patients with a mean duration of 838 ± 67 days. A total of 43/59 (73%) patients remained in stable sinus rhythm. In 10/16 (63%) patients with ATA recurrence, a repeat procedure was performed using radiofrequency energy. The overall success rate after a maximum of two ablation procedures and a follow-up period of 838 ± 67 days was 88% (52/59) patients. CONCLUSIONS: Patients with paroxysmal or short-persistent AF undergoing PVI using the 28-mm CB2 demonstrated a 73% 2-year single-procedure clinical success rate.

Balloon-based pulmonary vein isolation for the treatment of paroxysmal atrial fibrillation (cryoballoon and laserballoon).

Electrical isolation of the pulmonary veins still remains one of the major objectives during catheter ablation of atrial fibrillation. In patients with paroxysmal atrial fibrillation, balloon-based technologies hold great promise to simplify the approach to successful pulmonary vein isolation. While the cryoballoon represents the only true 'single-shot' technology, the laserballoon allows real-time endoscopic visualization of the pulmonary vein antrum during energy delivery. Either technology aims at complete electrical isolation, requiring continuous transmural lesion sets encircling the pulmonary veins. Strategies to confirm and to improve upon the efficacy of pulmonary vein isolation are the key to acute and long-term clinical success and will be reviewed in this article.

Electrophysiological and electrocardiographic predictors of ventricular arrhythmias originating from the left ventricular outflow tract within and below the coronary sinus cusps.

AIMS: Ventricular arrhythmias (VAs) from the left ventricular outflow tract (LVOT) can originate from within or below the aortic sinus of valsalva (ASV). Mapping and ablation below the ASV is challenging and there are limited data predicting VA origins using electrocardiographic and electrophysiological features. METHODS: Thirty-four patients (56.7 ± 15.2 years; 19 males) with symptomatic VAs were analyzed. VA origins were determined by successful ablation. Patients were classified into 2 groups (group 1, VAs within the ASV; group 2, VAs below the ASV). Local activation and QRS morphology were compared between these 2 groups. RESULTS: Twelve patients were classified as group 1 and 22 as group 2. Presystolic potentials (PPs) during VAs were present in 11 patients (91 %) in group 1 and 3 (13 %) in group 2. S-wave amplitude and duration in lead I were lower and shorter in group 1 vs. group 2, respectively. Q-wave aVL/aVR ratio (Q-aVL/aVR) was smaller in group 1 vs. group 2. No group 1 patients had Q-aVL/aVR >1.45. PPs in the ASV was the strongest independent predictor for VAs originating within the ASV (OR: 30.003, P = 0.006). CONCLUSION: Deeper and longer S-waves in lead I and Q-aVL/aVR >1.45 suggest VAs originating below the ASV. Local PPs strongly suggest an origin within the ASV. ECG characteristics combined with local PPs can be a practical guide for ablating LVOT-VAs.

Comparison of contact force-guided procedure with non-contact force-guided procedure during left atrial mapping and pulmonary vein isolation: impact of contact force on recurrence of atrial fibrillation.

BACKGROUND: The aim of this study was to evaluate the impact of contact force (CF) visualization on the incidence of low and high CF during left atrial (LA) mapping and pulmonary vein isolation (PVI). METHODS: CF was assessed in 70 patients who underwent PVI. Three highly experienced operators performed all procedures. The operators were blinded to CF in group A (35 patients), and CF was displayed in group B (35 patients). In group B, optimal CF was defined as mean CF between 10 and 39g, and operators attempted to acquire points and ablate within this range. RESULTS: A total of 8401 mapping points were analyzed during LA mapping (group A: 4104, group B: 4297). Low CF <10g and high CF ≥40g were noted in a significantly larger number of points in group A (37.7 vs. 12.0 %, P < 0.001; 11.5 vs. 1.5 %, P < 0.001). At the mitral isthmus and ridge areas, CF was significantly lower (7.7 vs. 12.2g, P < 0.001; 5.3 vs. 11.7g, P < 0.001) in group A than in group B. PVI was successfully achieved in all patients. There were significant site-dependent CF differences between the two groups. Optimal CF was achieved in significantly more applications in group B (P < 0.001). There was no significant difference in atrial fibrillation (AF) recurrence rates after a minimum follow-up of 1 year between the two groups in this cohort (P = 0.24). No significant peri-procedural complications occurred in either group. CONCLUSIONS: CF visualization can assist in avoiding both low and high CF, which may have the potential to improve lesion formation and patient safety profile. In this study, CF-guided ablation did not affect AF recurrence.

Feasibility and clinical efficacy of left atrial ablation for the treatment of atrial tachyarrhythmias in patients with left atrial appendage closure devices.

BACKGROUND: Left atrial appendage (LAA) closure devices have been introduced recently as an alternative for oral anticoagulation (OAC) in patients with nonvalvular atrial fibrillation (AF). Because of potential overlap of ablation target areas and the previously implanted LAA closure device, as well as potential complications such as mechanical damage to the device, left atrial (LA) ablation remains a subject of debate in these patients. OBJECTIVE: We report on the feasibility and clinical efficacy of LA ablation after implantation of LAA closure devices. METHODS: Eight patients (6 men; age 69 ± 8 years) with symptomatic paroxysmal AF (n = 5) or persistent AF (mean CHA2DS2-VASc score 3.6 ± 0.7, mean HAS-BLED score 3.6 ± 1.5) and previously implanted WATCHMAN (7 patients) or AMPLATZER Cardiac Plug (1 patient) LAA closure devices received radiofrequency-based LA ablation (4 via circumferential pulmonary vein isolation [CPVI], 4 via CPVI and additional LA linear lesions or complex fractionated atrial electrograms) after a mean of 201 days (range 41-756 days) after LAA closure. RESULTS: Successful LA ablation was achieved without device interference or periprocedural complications. After a mean of 503 days (range 113-1006 days), transesophageal echocardiography (TEE) was performed in all patients to assess for device-related complications. No device dislocation or leakage was observed. In 1 patient (12.5%), a device-related thrombus was found despite therapeutic OAC with dabigatran. Five patients (63%) remained in stable sinus rhythm, and no bleeding events or stroke occurred during a follow-up of 554 days (range 218-1006 days). CONCLUSION: LA ablation after LAA closure appears to be feasible. Device-related thrombus formation in 1 patient suggests the need for further TEE examinations after LA ablation after LAA closure device implantation.

Once Isolated, Always Isolated? Incidence and Characteristics of Pulmonary Vein Reconduction After Second-Generation Cryoballoon-Based Pulmonary Vein Isolation.

BACKGROUND: The second-generation cryoballoon delivers effective pulmonary vein isolation (PVI) associated with superior 1-year clinical outcome. However, data on reconduction of previously isolated PV are sparse. METHODS AND RESULTS: A total of 421 patients underwent second-generation 28-mm cryoballoon-based PVI in 2 centers (St. George's hospital and Harburg hospital, Hamburg, Germany) between June 2012 and May 2015. Sixty-six of 421 (16%) patients (39/66, 59% women; mean age, 63±10 years, mean left atrium diameter, 45±6 mm) with a history of paroxysmal (40/66, 61%) or persistent atrial fibrillation and atrial tachyarrhythmia recurrences despite previous successful second-generation 28-mm cryoballoon-based PVI were included in this analysis. During the index PVI, the standard freeze cycle duration was 240 s. After successful PVI, a bonus freeze cycle of 240 s was applied in the first 15 of 66 (23%) patients, whereas no bonus freeze cycle was applied in the remaining patients. Repeat procedures were performed after a median of 205 (131-357) days following the index ablation. Electric reconduction was assessed for all PVs, and reablation was performed using radiofrequency energy. Persistent electric isolation was noted in 178 of 258 (69%) PVs. In 17 of 66 (26%) patients, all previously targeted PVs remained isolated. A significant difference toward highest reconduction rate for the posteroinferior segment of the right inferior PV was found (P=0.0002). CONCLUSIONS: The second-generation cryoballoon ablation is associated with a high rate of persistent PVI. The posteroinferior segment of the right inferior PV showed the highest reconduction rate and seems to be a predilection site for PV reconduction.