Catheter ablation for atrial fibrillation

Catheter-Integrated Fractal Microelectronics for Low-Voltage Ablation and Minimally Invasive Sensing

Pulse field ablation (PFA) has become a popular technique for treating tens of millions of patients with atrial fibrillation, as it avoids many complications associated with traditional radiofrequency ablation. However, currently, limited studies have used millimeter-scale rigid electrodes modified from radiofrequency ablation to apply electrical pulses of thousands of volts without integrated sensing capabilities. Herein, we combine fractal microelectronics with biomedical catheters for low-voltage PFA, detection of electrode-tissue contact, and interventional electrocardiogram recording. The fractal configuration increases the ratio of the microelectrode insulating edge to area, which facilitates the transfer of current from the microelectrode to the tissue, increasing the ablation depth by 38.6% at 300 V (a 10-fold reduction compared to current technology). In vivo ablation experiments on living beagles successfully block electrical conduction, as demonstrated by voltage mapping and electrical pacing. More impressively, this study provides the first evidence that microelectrodes can selectively ablate cardiomyocytes without damaging nerves and blood vessels, greatly improving the safety of PFA. These results are essential for the clinical translation of PFA in the field of cardiac electrophysiology.

Simulation Optimization of Spatiotemporal Dynamics in 3D Geometries

Many engineering and healthcare systems are featured with spatiotemporal dynamic processes. The optimal control of such systems often involves sequential decision making. However, traditional sequential decision-making methods are not applicable to optimize dynamic systems that involves complex 3D geometries. Simulation modeling offers an unprecedented opportunity to evaluate alternative decision options and search for the optimal plan. In this paper, we develop a novel simulation optimization framework for sequential optimization of 3D dynamic systems. We first propose to measure the similarity between functional simulation outputs using coherence to assess the effectiveness of decision actions. Second, we develop a novel Gaussian Process (GP) model by constructing a valid kernel based on Hausdorff distance to estimate the coherence for different decision paths. Finally, we devise a new Monte Carlo Tree Search (MCTS) algorithm, i.e., Normal-Gamma GP MCTS (NG-GP-MCTS), to sequentially optimize the spatiotemporal dynamics. We implement the NG-GP-MCTS algorithm to design an optimal ablation path for restoring normal sinus rhythm (NSR) from atrial fibrillation (AF). We evaluate the performance of NG-GP-MCTS with spatiotemporal cardiac simulation in a 3D atrial geometry. Computer experiments show that our algorithm is highly promising for designing effective sequential procedures to optimize spatiotemporal dynamics in complex geometries.

DNA Framework-Enabled 3D Organization of Antiarrhythmic Drugs for Radiofrequency Catheter Ablation

Preorganizing molecular drugs within a microenvironment is crucial for the development of efficient and controllable therapeutic systems. Here, the use of tetrahedral DNA framework (TDF) is reported to preorganize antiarrhythmic drugs (herein doxorubicin, Dox) in 3D for catheter ablation, a minimally invasive treatment for fast heartbeats, aiming to address potential complications linked to collateral tissue damage and the post-ablation atrial fibrillation (AF) recurrence resulting from incomplete ablation. Dox preorganization within TDF transforms its random distribution into a confined, regular spatial arrangement governed by DNA. This, combined with the high affinity between Dox and DNA, significantly increases local Dox concentration. The exceptional capacity of TDF for cellular internalization leads to a 5.5-fold increase in intracellular Dox amount within cardiomyocytes, effectively promoting cellular apoptosis. In vivo investigations demonstrate that administering TDF-Dox reduces the recurrence rate of electrical conduction after radiofrequency catheter ablation (RFCA) to 37.5%, compared with the 77.8% recurrence rate in the free Dox-treated group. Notably, the employed Dox dosage exhibits negligible adverse effects in vivo. This study presents a promising treatment paradigm that strengthens the efficacy of catheter ablation and opens a new avenue for reconciling the paradox of ablation efficacy and collateral damage.

Electrophysiological mapping of the epicardium via 3D-printed flexible arrays

Cardiac electrophysiology mapping and ablation are widely used to treat heart rhythm disorders such as atrial fibrillation (AF) and ventricular tachycardia (VT). Here, we describe an approach for rapid production of three dimensional (3D)-printed mapping devices derived from magnetic resonance imaging. The mapping devices are equipped with flexible electronic arrays that are shaped to match the epicardial contours of the atria and ventricle and allow for epicardial electrical mapping procedures. We validate that these flexible arrays provide high-resolution mapping of epicardial signals in vivo using porcine models of AF and myocardial infarction. Specifically, global coverage of the epicardial surface allows for mapping and ablation of myocardial substrate and the capture of premature ventricular complexes with precise spatial-temporal resolution. We further show, as proof-of-concept, the localization of sites of VT by means of beat-to-beat whole-chamber ventricular mapping of ex vivo Langendorff-perfused human hearts.

Catheter Ablation With Morphologic Repetitiveness Mapping for Persistent Atrial Fibrillation

Importance

Catheter ablation for persistent atrial fibrillation (AF) has shown limited success.

Objective

To determine whether AF drivers could be accurately identified by periodicity and similarity (PRISM) mapping ablation results for persistent AF when added to pulmonary vein isolation (PVI).

Design, Setting, and Participants

This prospective randomized clinical trial was performed between June 1, 2019, and December 31, 2020, and included patients with persistent AF enrolled in 3 centers across Asia. Data were analyzed on October 1, 2022.

Intervention

Patients were assigned to the PRISM-guided approach (group 1) or the conventional approach (group 2) at a 1:1 ratio.

Main Outcomes and Measures

The primary outcome was freedom from AF or other atrial arrhythmia for longer than 30 seconds at 6 and 12 months.

Results

A total of 170 patients (mean [SD] age, 62.0 [12.3] years; 136 men [80.0%]) were enrolled (85 patients in group 1 and 85 patients in group 2). More group 1 patients achieved freedom from AF at 12 months compared with group 2 patients (60 [70.6%] vs 40 [47.1%]). Multivariate analysis indicated that the PRISM-guided approach was associated with freedom from the recurrence of atrial arrhythmia (hazard ratio, 0.53 [95% CI, 0.33-0.85]).

Conclusions and Relevance

The waveform similarity and recurrence pattern derived from high-density mapping might provide an improved guiding approach for ablation of persistent AF. Compared with the conventional procedure, this novel specific substrate ablation strategy reduced the frequency of recurrent AF and increased the likelihood of maintenance of sinus rhythm.

Trial Registration

ClinicalTrials.gov Identifier: NCT05333952.

Cost-effectiveness analysis of digital therapeutics for home-based cardiac rehabilitation for patients with atrial fibrillation after catheter ablation

Background

In recent years, numerous guidelines and expert consensuses have recommended that digital technologies and products, such as digital therapeutics (DTx), be incorporated into cardiac rehabilitation (CR).

Objective

The study aims to compare the cost-effectiveness of DTx for home-based CR (HBCR) with that of the conventional HBCR for patients with atrial fibrillation (AF) after catheter ablation in a real-world clinical setting.

Methods

Based on a single-center, prospective, blinded, randomized, parallel controlled trial of DTx-based HBCR for AF patients after catheter ablation, 100 AF patients undergoing catheter ablation were selected and randomized at a 1:1 ratio into a UC group (conventional HBCR) and DT group (DTx-based HBCR). The intervention lasted for 12 weeks. Medical cost data and clinical efficacy data (VO2max) were acquired from trial data. Effect data (QALYs, anxiety and depression status, health beliefs related to cardiovascular disease, and exercise self-efficacy) were obtained from a patient questionnaire. The cost-effectiveness analysis was conducted to assess the economic benefits of DTx-based HBCR versus conventional HBCR, and the robustness of the results was verified by sensitivity analysis.

Results

In the DT group (n = 49), the mean QALYs increased 0.119 ± 0.09, VO2max increased 9.3 ± 8.0 mL/(min*kg), anxiety, depression, health belief, and exercise self-efficacy had improved, and the total medical cost was 75,080.55 ± 19,746.62 CNY. In the UC group (n = 48), the mean QALYs increased 0.077 ± 0.06, VO2max increased 4.9 ± 6.6 mL/(min*kg), anxiety, depression, health belief, and exercise self-efficacy had improved, and the total medical cost was 73,972.66 ± 16,582.04 CNY. The difference in the medical cost was 1107.89 CNY, and the incremental cost-effectiveness ratio was 33,572.42 CNY/QALY, which was lower than the willingness-to-pay threshold of 85,698 CNY (China's per capita GDP in 2022).

Conclusion

DTx-based HBCR is more effective and cost-effective than conventional HBCR.

Late Gadolinium Enhancement Magnetic Resonance Imaging Evaluation of Post-Atrial Fibrillation Ablation Esophageal Thermal Injury Across the Spectrum of Severity

Background Esophageal thermal injury (ETI) is a byproduct of atrial fibrillation (AF) ablation using thermal sources. The most severe form of ETI is represented by atrioesophageal fistula, which has a high mortality rate. Late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) allows identification of ETI. Hence, we sought to evaluate the utility of LGE-MRI as a method to identify ETI across the entire spectrum of severity. Methods and Results All AF radiofrequency ablations performed at the University of Utah between January 2009 and December 2017 were reviewed. Patients with LGE-MRI within 24 hours following AF ablation as well as patients who had esophagogastroduodenoscopy in addition to LGE-MRI were identified. An additional patient with atrioesophageal fistula who had AF ablation at a different institution and had MRI and esophagogastroduodenoscopy at the University of Utah was identified. A total of 1269 AF radiofrequency ablations were identified. ETI severity was classified on the basis of esophageal LGE pattern (none, 60.9%; mild, 27.5%; moderate, 9.9%; severe, 1.7%). ETI resolved in most patients who underwent repeat LGE-MRI at 3 months. All patients with esophagogastroduodenoscopy-confirmed ETI had moderate-to-severe LGE 24 hours after ablation MRI. Moderate-to-severe LGE had 100% sensitivity and 58.1% specificity in detecting ETI, and a negative predictive value of 100%. Atrioesophageal fistula was visualized by both computed tomography and LGE-MRI in one patient. Conclusions LGE-MRI is useful in detecting and characterizing ETI across the entire severity spectrum. LGE-MRI exhibits an extremely high sensitivity and negative predictive value in screening for ETI after AF ablation.

Catheter-integrated soft multilayer electronic arrays for multiplexed sensing and actuation during cardiac surgery

The rigidity and relatively primitive modes of operation of catheters equipped with sensing or actuation elements impede their conformal contact with soft-tissue surfaces, limit the scope of their uses, lengthen surgical times and increase the need for advanced surgical skills. Here, we report materials, device designs and fabrication approaches for integrating advanced electronic functionality with catheters for minimally invasive forms of cardiac surgery. By using multiphysics modelling, plastic heart models and Langendorff animal and human hearts, we show that soft electronic arrays in multilayer configurations on endocardial balloon catheters can establish conformal contact with curved tissue surfaces, support high-density spatiotemporal mapping of temperature, pressure and electrophysiological parameters and allow for programmable electrical stimulation, radiofrequency ablation and irreversible electroporation. Integrating multimodal and multiplexing capabilities into minimally invasive surgical instruments may improve surgical performance and patient outcomes.

Opposite effect of ablation on early/late-phase thromboembolic incidence in patients with atrial fibrillation: A meta-analysis on more than 100 000 individuals

Background

Atrial fibrillation (AF) is an important risk factor for thromboembolic events, for which catheter ablation represents an effective therapy for rhythm control. Intuitively, ablation may reduce the incidence of thromboembolism, but data is quite limited.

Hypothesis

Catheter ablation was associated with the fewer risk of thromboembolism compared with nonablation in patients with AF.

Methods

A systematic search was performed in PubMed, EMBASE, the Web of Science, and the Cochrane Library from inception to September 2019. Random‐effects model was used to estimate the risk ratios (RR) for the thromboembolic events between the ablation and nonablation groups.

Results

Twenty‐five studies (12 randomized controlled trials and 13 observational studies) with 104 687 participants were included. Pooled analysis suggested that ablation was associated with a 35% lower risk of total thromboembolic events compared to nonablation group (RR = 0.65; 95% CI, 0.51‐0.82; P = .0003). When separated into early‐phase (<30 days) and late‐phase (>30 days) events, ablation was associated with an increased early‐phase thromboembolism (RR = 1.96; 95% CI, 1.35‐2.83; P = .0004) but a decreased late‐phase thromboembolism (RR = 0.75; 95% CI, 0.63‐0.90; P = .002). Subgroup analysis according to different study types found similar results were found in observation studies, but not in RCT studies because the sample size was too small to be conclusive.

Conclusions

In patients with AF, catheter ablation was associated with a fewer risk of overall and late‐phase thromboembolism in comparison with nonablation. However, over the early postoperative period, catheter ablation was associated with the double higher risk of thromboembolic events.

Use of Cardiac Computed Tomography and Magnetic Resonance Imaging in Case Management of Atrial Fibrillation with Catheter Ablation

Atrial fibrillation (AF) is the most common arrhythmia associated with the risk of morbidity and mortality in clinical patients. AF is considered as an arrhythmia type that develops and progresses through close connection with cardiac structural arrhythmogenic substrates. Since the introduction of catheter ablation-mediated electrical isolation of arrhythmogenic substrates, cardiac imaging indicates improved treatment outcome and prognosis with appropriate candidate selection, ablation catheter guidance, and post-ablation follow-up. Currently, cardiac computed tomography (CCT) and cardiovascular magnetic resonance (CMR) imaging are essential in the case management of AF at both pre-and post-procedural stages of catheter ablation. In this review, we discuss the roles and technical considerations of CCT and CMR imaging in the management of patients with AF undergoing catheter ablation.

Topographic characteristics of the left atrial medial isthmus

BACKGROUND

The purpose of this study was to provide detailed topography of the left atrial medial isthmus (situated between the right inferior pulmonary vein ostium and the medial part of the mitral annulus).

METHODS

Two hundred human hearts (Caucasian, 22.5% females, 48.7 ± 4.9 years old) were investigated.

RESULTS

The mean length of the medial isthmus was 42.4 ± 8.6 mm. Additionally, the medial isthmus line was divided by the oval fossa into three sections with equal mean lengths (upper: 14.2 ± 7.2 vs middle: 14.1 ± 6.1 vs lower: 14.9 ± 4.6 mm; P > .05). The left upper section of the atrial wall was thinner than the lower section (2.5 ± 1.1 vs 3.4 ± 1.6 mm; P < .0001). This study noted three separate spatial arrangements of the isthmus line. Type I (54.5%) had an oval fossa located outside the isthmus line; type II (32.5%) had an oval fossa crossed by the isthmus line, and type III (13.0%) had an oval fossa rim located tangentially to the isthmus line. In 68.5% of the examined specimens, the isthmus area had a smooth surface. Conversely, the remaining 31.5% had additional structures within its borders such as diverticula, recesses, and tissue bridges.

CONCLUSION

This study is the first to describe the morphometric and topographical features of the left atrial medial isthmus. Interventions within the medial isthmus line should be performed cautiously, especially when they are transected by the oval fossa (32.5%). Careful navigation of the area is also recommended due to the possibility of existent additional structures. The latter could lead to catheter entrapment during ablation procedures.

Catheter Ablation of Long-standing Persistent Atrial Fibrillation: a Reckless Challenge or a Way to Real Cure?

Long-standing persistent atrial fibrillation (L-PeAF) is a category in which rhythm control is attempted while atrial fibrillation (AF) is maintained for more than 1 year. Because AF is a progressive disease and L-PeAF accompanies significant electrical and structural remodeling of atria, it is difficult to restore and maintain sinus rhythm in patients with L-PeAF. Nonetheless, the rhythm outcome is being increasingly improved by the development of sophisticated mapping devices, highly efficient catheters, and evidence-based ablation strategies, and the rational choice of patient selection criteria. This review discusses the evolution of the rhythm control outcome of L-PeAF and its future direction of development.

Long-term symptom improvement and patient satisfaction following catheter ablation of supraventricular tachycardia: insights from the German ablation registry

Aims

To analyse outcomes of supraventricular tachycardia (SVT) ablations performed within a prospective German Ablation Quality Registry.

Methods and results

Data from 12 566 patients who underwent catheter ablation of SVT between January 2007 and January 2010 to treat atrial fibrillation (AFIB, 37.2% of procedures), atrial flutter (AFL, 29.9%), atrioventricular nodal re-entrant tachycardia (AVNRT, 23.2%), atrioventricular re-entrant tachycardia (6.3%), and focal atrial tachycardia (AT, 3.4%) were prospectively collected. Patients were followed for at least 1 year. The periprocedural success rate was 96.3%, ranging from 84.3% (focal AT) to 98.9% (AVNRT). Kaplan-Meier mortality estimate at 1 year was 1.4% overall, and as high as 2.6% in the AFL group and 2.8% in the focal AT group. Recurrence of ablated or another symptomatic SVT was observed in 3783 (32.6%) of patients, ranging from 17.2% (AVNRT) to 45.6% (AFIB). Repeat ablation was performed in 12.0% of patients. After 1 year, 74.1% of survivors perceived ablation therapy as successful, 15.7% as partly successful, and 9.6% as unsuccessful. Even in those patients with arrhythmia recurrence, 76.0% perceived ablation as successful or partly successful and 89.6% would still undergo repeat ablation in the same institution.

Conclusion

Ablation therapy for SVT is a safe procedure bringing symptomatic improvement and satisfaction to three quarters of patients after 1 year. Even in patients with arrhythmia recurrence, a high satisfaction level and adherence to the ablating institution could be documented. Strikingly high mortality and stroke rates in follow-up were observed in AFL patients, who apparently need consistent long-term anticoagulation and more medical attention.

Comparison of the Efficancy and Complication Rates of the Hybrid Maze, Complete Cox-Maze and Catheter Ablation in the Treatment of Atrial Fibrillation

Introduction

Atrial fibrillation is the most common cardiac arrhythmia in the United States. It has been associated with a reduction in patient quality of life and more serious complications such as stroke and heart failure. The aim of this study was to compare the efficacy of commonly performed invasive procedures in keeping patients in normal sinus rhythm.

Methods and Results

A retrospective chart review was performed on all patients who underwent primary radiofrequency catheter ablation, the complete Cox-maze, or the hybrid maze at OSF Saint Anthony Medical Center between January 2010 and December 2013 (n=140). Immediately post-procedure, arrhythmia recurrence rates did not differ between the groups (p = 0.28). At all follow-up points thereafter, however, differences in procedural efficacy between surgical and catheter therapy remained highly significant (p < 0.001). At 2 years, 20.3% of the catheter ablation patients were in normal sinus rhythm, when compared to 57.9% of hybrid maze and 72.7% the complete Cox-maze groups. A difference in major complication rates was noted (p = 0.04), with the complete Cox-maze having a 17.4%, the hybrid having 22.7%, and the catheter ablation group having 5.6%.

Conclusions

This study was unable to detect differences in the efficacy rates of the surgical procedures, however they were both superior to catheter ablation. Although the hybrid approach is considered minimally invasive, complication rates were similar to those of the complete Cox-maze. Catheter ablation was the safest procedure, and since evidence of reduced mortality after the use of aggressive rhythm therapy is currently lacking, the results suggest that hybrid surgery for atrial fibrillation should be used after the failure of more conservative measures.

Chinese herbal medicine for patients with atrial fibrillation: protocol for a systematic review and meta-analysis

BACKGROUND

Atrial fibrillation (AF) is the most clinically common cardiac arrhythmia. Chinese herbal medicine (CHM) has been widely applied in the treatment of AF, However, to our knowledge, there has been no systematic review and meta-analysis of randomized controlled trails (RCTs) regarding the effectiveness of this treatment. Therefore, we provide a protocol to evaluate the effectiveness and safety of CHM for AF.

METHODS

The databases reviewed to collect RCTs related to CHM treatment for AF will be as follows: 3 English literature databases, which are PubMed, Embase, and Cochrane Library, and 3 Chinese literature databases, which are CBM, CNKI, and Wanfang. The data collection in the above-mentioned databases will be from the time when the respective databases were established to December 2017. The maintenance of sinus rhythm and p-wave dispersion will be accepted as the primary outcomes. Quality of life (QOL), such as QOL scale embolic events, bleeding events, and symptom improvement (such as chest distress, palpitations, etc) will be measured as secondary outcomes. Two reviewers will independently screen the titles, abstracts, or even full texts, and extract data. Methodological quality will be evaluated according to the Cochrane risk of bias. All analyses will be applied by RevMan (version 5.3).

RESULTS

The results of study will be disseminated via both international conference and peer-review journal.

CONCLUSION

The conclusion of our systematic review will provide evidence to judge whether CHM is an effective intervention for patient with AF.

Can catheter ablation reduce the incidence of thromboembolic events in patients with atrial fibrillation?: Protocol for a systematic review and meta-analysis

Atrial fibrillation (AF), the most common cardiac arrhythmia, is a major risk factor for thromboembolic events, especially ischemic stroke. Catheter ablation is an effective method to maintain sinus rhythm in patients with AF. Although some observational studies have shown a relatively lower stroke rate after catheter ablation, whether catheter ablation can reduce the thromboembolic risk in patients with AF remains unclear. We aim to perform a systematic review to determine whether catheter ablation can prevent thromboembolism in patients with AF.PubMed, Embase, the Web of Science, and the Cochrane Library will be searched from January 2000 to the present for randomized controlled trials (RCTs) and non-randomized studies on catheter ablation in patients with AF. Other relevant sources, such as the references and conference proceedings, will also be manually retrieved. All studies will be limited to publication in English. The primary outcome will be thromboembolic events, including stroke, transient ischemic attack, and systemic embolic events. Study screening, data collection, and study quality assessment will be independently performed by 2 researchers. Disagreements will be resolved through team discussion or consultation with a third arbitrator. The risk of bias will be appraised using the Cochrane Collaboration tool and the Newcastle-Ottawa scale according to the different study designs, and a meta-analysis will be performed using RevMan V.5.3 software. The results will be presented as risk ratios and 95% confidence intervals for dichotomous data and continuous outcomes.Catheter ablation is an effective method to cure atrial fibrillation and maintain sinus rhythm. Although it is intuitive that if AF is eliminated, the thromboembolism in the heart would be abolished, and sequently the incidence of thromboembolic events would be decreased, this in fact has not yet been clarified. This systematic review and meta-analysis will be performed with the aim of comprehensively identifying studies that have reported the impact of AF ablation on thromboembolic events in patients with non-valvular AF by comparing an ablation group and non-ablation group. These outcomes will not only produce useful evidence-based data regarding the influence of catheter ablation on thromboembolic events in patients with AF but will also provide some guidance regarding anticoagulation regimens in patients who have undergone catheter ablation.

Atriobronchial Fistula Complicated by Septic Cerebral Air Emboli After Pulmonary Vein Ablation

OBJECTIVE

To describe a case of an infected atriobronchial fistula as a late complication after pulmonary vein ablation, leading to septic air emboli and requiring urgent cardiac surgery.

DATA SOURCES

Clinical observation.

STUDY SELECTION

Case report.

DATA EXTRACTION

Relevant clinical information. PubMed was searched for relevant literature.

DATA SYNTHESIS

Given its high success and low complication rate, pulmonary vein isolation is expected to be increasingly performed worldwide. Despite its success, some of its rare complications are potentially devastating and are difficult to diagnose early. In this report, we present the case of a 32-year-old woman, who was readmitted to hospital 2 months after pulmonary vein ablation. The clinical picture resembled meningococcemia with spreading petechiae on legs and arms raising concern for Waterhouse-Friderichsen syndrome. Further echocardiographic investigation led to the discovery of massive amounts of intracardiac air which demanded urgent lung isolation and sternotomy. Intraoperatively a small infected left atrial perforation was oversewn and a fistula to the right main bronchus was closed by means of an autologous pericardial patch. One month later, still revalidating, she could be discharged home with only minor neurologic sequelae.

CONCLUSIONS

Clinicians should be aware of the dramatic complications of invasive antiarrhythmic procedures and their atypical and late presentations. Better preprocedural appreciation of cardiac wall thickness, early echocardiographic diagnosis, and swift referral for cardiac surgery might impact outcome dramatically.

A review of rate control in atrial fibrillation, and the rationale and protocol for the RATE-AF trial

BACKGROUND AND OBJECTIVE

Atrial fibrillation (AF) is common and causes impaired quality of life, an increased risk of stroke and death as well as frequent hospital admissions. The majority of patients with AF require control of heart rate. In this article , we summarise the limited evidence from clinical trials that guides prescription, and present the rationale and protocol for a new randomised trial. As rate control has not yet been shown to reduce mortality, there is a clear need to compare the impact of therapy on quality of life, cardiac function and exercise capacity. Such a trial should concentrate on the long-term effects of treatment in the largest proportion of patients with AF, those with symptomatic permanent AF, with the aim of improving patient well-being.

DESIGN AND INTERVENTION

The RAte control Therapy Evaluation in permanent Atrial Fibrillation (RATE-AF) trial will enrol 160 participants with a prospective, randomised, open-label, blinded end point design comparing initial rate control with digoxin or bisoprolol. This will be the first head-to-head randomised trial of digoxin and beta-blockers in AF.

PARTICIPANTS

Recruited patients will be aged ≥60 years with permanent AF and symptoms of breathlessness (equivalent to New York Heart Association class II or above), with few exclusion criteria to maximise generalisability to routine clinical practice.

OUTCOME MEASURES

The primary outcome is patient-reported quality of life, with secondary outcomes including echocardiographic ventricular function, exercise capacity and biomarkers of cellular and clinical response. Follow-up will occur at 6 and 12 months, with feasibility components to inform the design of a future trial powered to detect a difference in hospital admission. The RATE-AF trial will underpin an integrated approach to management including biomarkers, functions and symptoms that will guide future research into optimal, personalised rate control in patients with AF.

ETHICS AND DISSEMINATION

East Midlands-Derby Research Ethics Committee (16/EM/0178); peer-reviewed publications.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT02391337; ISRCTN: 95259705. Pre-results.

Complex fractionated atrial electrograms, high dominant frequency regions, and left atrial voltages during sinus rhythm and atrial fibrillation

BACKGROUND

Ablation targeting complex fractionated atrial electrograms (CFAEs) or high dominant frequency (DF) sites is generally effective for persistent atrial fibrillation (AF). CFAEs and/or high DF sites may exist in low-voltage regions, which theoretically represent abnormal substrates. However, whether CFAEs or high DF sites reflect low voltage substrates during sinus rhythm (SR) is unknown.

METHODS

Sixteen patients with AF (8 with paroxysmal AF; 8, persistent AF) underwent high-density mapping of the left atrium (LA) with a 3-dimensional electroanatomic mapping system before ablation. The LA was divided into 7 segments and the mean bipolar voltage recorded during AF and SR, CFAEs (cycle lengths of 50-120 ms), and DF sites were assessed in each segment with either a duo-decapolar ring catheter (n=10) or a 64-pole basket catheter (n=6). Low-voltage areas were defined as those of <0.5 mV during AF and <1.0 mV during SR.

RESULTS

Regional mean voltage recorded from the basket catheter showed good correlation between AF and SR (r=0.60, p<0.01); however, the % low-voltage area in the LA recorded from the ring catheter showed weak correlation (r=0.34, p=0.05). Mean voltage was lower during AF than during SR (1.0 mV [IQR, 0.5-1.4] vs. 2.6 mV [IQR, 1.8-3.6], p<0.01). The regional and overall % low-voltage area of the LA was greater during AF than during SR (20% vs. 11%, p=0.05). CFAEs and high DF sites (>8 Hz) did not correlate with % low-voltage sites during SR; however, CFAEs sites were located in high-voltage regions during AF and high DF sites were located in low voltage regions during AF.

CONCLUSIONS

CFAEs and high DF areas during AF do not reflect damaged atrial myocardium as shown by the SR voltage. However, CFAEs and high DF sites may demonstrate different electrophysiologic properties because of different voltage amplitude during AF.

Emergency Covered Stent Implantation For Rupture Of A Pulmonary Vein After Balloon Angioplasty For Postinterventional Pulmonary Vein Stenosis

Pulmonary vein (PV) stenosis is a known complication of PV isolation procedures for atrial fibrillation. We describe in this report a case of emergency covered stent implantation for rupture of a PV after balloon angioplasty for postinterventional PV stenosis occlusion. Focus is on stent implantation and on a novel aspect of magnetic resonance imaging for postprocedural outcome evaluation. A focused review of the current literature regarding ongoing limitations of PV stenosis treatment is provided.

Persistent Atrial Fibrillation Ablation With or Without Contact Force Sensing

INTRODUCTION

Arrhythmia recurrences remain common after ablation of persistent atrial fibrillation (PersAF). Contact force (CF)-sensing catheters have been introduced for objective assessment of contact during radiofrequency application and have been suggested to improve outcomes in ablation of paroxysmal AF, but little is known about their role in PersAF ablation. We aimed to compare the procedural profiles and outcomes of (PersAF) ablation with or without using CF-sensing catheters.

METHODS

All consecutive patients undergoing first time ablation for PersAF between April 2014 and January 2015 at the Cleveland Clinic were included. Substrate modification was performed in addition to isolation of the pulmonary veins. Success rates were determined off antiarrhythmics over 1 year of follow-up.

RESULTS

The study included 174 patients (77 CF and 97 non-CF). Ablation with CF-sensing catheters resulted in shorter procedures (median 204 vs. 216 minutes, P = 0.04) and shorter fluoroscopy time (36 vs. 48 minutes, P = 0.0005), without statistical difference in radiation dose (225 vs. 270 milligrays, P = 0.1). Arrhythmia recurrences were less likely to be observed in the CF-sensing group (27.6% vs. 46.4%, P = 0.01, log-rank P = 0.004). In multivariable Cox analyses, the use of CF-sensing catheters was associated with a lower risk of arrhythmia recurrence (hazard ratio 0.49, 95% confidence interval 0.27-0.85, P = 0.01).

CONCLUSIONS

Compared to non-CF sensing, the use of CF-sensing catheters for PersAF ablation is associated with shorter procedures, shorter fluoroscopy time, and reduction in arrhythmia recurrences.

The Impact of First Procedure Success Rate on the Economics of Atrial Fibrillation Ablation

OBJECTIVES

The purpose of this study was to compare health care costs associated with repeat ablation of atrial fibrillation (AF) with health care costs associated with a successful first procedure.

BACKGROUND

Catheter ablation has become established as a rhythm control strategy for symptomatic paroxysmal and persistent AF. The economic impact of ablation is not completely understood, and it may be affected by repeat procedures performed for recurrent AF.

METHODS

The source of data was the MarketScan (Truven Health, Ann Arbor, Michigan) administrative claims dataset from April 2008 to March 2013, including U.S. patients with private and Medicare supplemental insurance. Patients who underwent an outpatient atrial ablation procedure and a diagnosis of AF were identified. Total health care cost was calculated for 1 year before and after the ablation. Patients were categorized as having undergone a repeat ablation if an additional ablation was performed in the following year.

RESULTS

Of 12,027 patients included in the study, repeat ablation was performed in 2,066 (17.2%) within 1 year. Patients with repeat ablation had higher rates of emergency department visits (43.4% vs. 32.2%; < 0.001) and subsequent hospitalization (35.6% vs. 21.5%; p < 0.001), after excluding hospitalizations for the repeat procedure. Total medical cost was higher for patients with repeat ablation ($52,821 vs. $13,412; p < 0.001), and it remained 46% higher even after excluding the cost associated with additional ablations ($19,621 vs. $13,412; p < 0.001).

CONCLUSIONS

Health care costs are significantly higher for patients with a repeat ablation for AF than for patients with only a single ablation procedure, even though both groups have similar baseline characteristics. The increased costs persist even after excluding the cost of the repeat ablation itself. These results emphasize the economic benefit of procedural success in AF ablation.

Clinical Significance of Additional Ablation of Atrial Premature Beats after Catheter Ablation for Atrial Fibrillation

PURPOSE

The clinical significance of post-procedural atrial premature beats immediately after catheter ablation for atrial fibrillation (AF) has not been clearly determined. We hypothesized that the provocation of immediate recurrence of atrial premature beats (IRAPB) and additional ablation improves the clinical outcome of AF ablation.

MATERIALS AND METHODS

We enrolled 200 patients with AF (76.5% males; 57.4±11.1 years old; 64.3% paroxysmal AF) who underwent catheter ablation. Post-procedure IRAPB was defined as frequent atrial premature beats (≥6/min) under isoproterenol infusion (5 μg/min), monitored for 10 min after internal cardioversion, and we ablated mappable IRAPBs. Post-procedural IRAPB provocations were conducted in 100 patients. We compared the patients who showed IRAPB with those who did not. We also compared the IRAPB provocation group with 100 age-, sex-, and AF-type-matched patients who completed ablation without provocation (No-Test group).

RESULTS

1) Among the post-procedural IRAPB provocation group, 33% showed IRAPB and required additional ablation with a longer procedure time (p=0.001) than those without IRAPB, without increasing the complication rate. 2) During 18.0±6.6 months of follow-up, the patients who showed IRAPB had a worse clinical recurrence rate than those who did not (27.3% vs. 9.0%; p=0.016), in spite of additional IRAPB ablation. 3) However, the clinical recurrence rate was significantly lower in the IRAPB provocation group (15.0%) than in the No-Test group (28.0%; p=0.025) without lengthening of the procedure time or raising complication rate.

CONCLUSION

The presence of post-procedural IRAPB was associated with a higher recurrence rate after AF ablation. However, IRAPB provocation and additional ablation might facilitate a better clinical outcome. A further prospective randomized study is warranted.

Heart Failure and Atrial Fibrillation

Atrial fibrillation is commonly experienced by patients with heart failure, and as the heart failure progresses and worsens, the more likely the patient is to develop atrial fibrillation. Several factors play into this, including common risk factors, such as advanced age, hypertension, and ischemic or valvular heart disease. Treatment is aimed at anticoagulation, to prevent thromboembolic stroke, and rate control to prevent further hemodynamic compromise. Rhythm control may be beneficial for many patients and this can be accomplished through the use of antiarrhythmic medications, cardioversion, and/or ablation.

The Effect of Catheter Ablation on Left Atrial Size and Function for Patients with Atrial Fibrillation: An Updated Meta-Analysis

BACKGROUND

Catheter ablation (CA) for atrial fibrillation (AF) is now an important therapeutic modality for patients with AF. However, data regarding changes in left atrial (LA) function after CA have indicated conflicting results depending on the AF types, follow-up period, and the analytical imaging tools. The objective of this review was to analyze the effect of CA on the LA size and function for patients with AF.

METHODS

We searched for studies regarding LA size and function pre- and post-ablation in PubMed, Embase, the Cochrane Library, and Web of Knowledge through May 2014. LA function was measured by LA ejective fraction (LAEF), LA active ejective fraction (LAAEF), or both. Total and subgroup analyses were implemented using Cochrane Review Manager Version 5.2. Weighted mean differences with 95% confidence intervals were used to express the results of continuous outcomes using fixed or random effect models. I2 was used to calculate heterogeneity. To assess publication bias, Egger's test and Begg's funnel plot were performed using Stata 12.0.

RESULTS

Twenty-five studies (2040 enrolled patients) were selected for this meta-analysis. The LA diameter (LAD), maximum LA volume, and minimal LA volume were significantly decreased post-ablation, as compared with those at a pre-ablation visit. Compared with the pre-ablation outcomes, we found no significant differences in LAEF/LAAEF at a post-ablation follow-up. Decreases in LA volume and LAEF remained significant post-ablation for paroxysmal AF (PAF); however, the LAEF was insignificant changes in persistent AF (PeAF). Heterogeneity was significant in spite which individual study was excluded. A publication bias was not found. In a meta-regression analysis, we did not find any factor that contributed to the heterogeneity.

CONCLUSION

With CA, LA volumes and LAD were decreased significantly in patients with AF; LAEF was not significant changes in patients with PeAF but decreased in those with PAF.

Japanese Patients' and Physicians' Preferences for Anticoagulant Use in Atrial Fibrillation: Results from a Discrete-choice Experiment

Background: Anticoagulants are recommended for stroke prevention in patients with atrial fibrillation (AF), but are associated with an increased risk of bleeding; therefore, physicians face benefit-risk tradeoffs when prescribing anticoagulants to AF patients. Although the unmet medical need for safer anticoagulants has been well-documented, there is limited information about the importance that patients and physicians place on cardiovascular events. Objectives: The aim of this study was to quantify patients' and physicians' willingness to accept tradeoffs between the benefits and risks of anticoagulants in order to 1) document the potential differences between patients' and physicians' perceptions of benefits and risks and 2) support physicians' clinical decision making. Methods: Preferences from Japanese AF patients and board-eligible or board-certified physicians were elicited using a discrete-choice experiment. Random-parameters logit models were used to estimate importance weights for treatment-related changes in the annual risk of stroke, myocardial infarction, embolism, and bleeding. Results: Japanese patients (N=152) and physicians (N=164) showed different preferences. In particular, among non-fatal outcomes, patients considered disabling stroke to be 16 times more important than non-major clinically relevant bleeding and 2.6 times more important than extra-cranial major bleeding. In contrast, physicians considered the same stroke risk to be 2.7 times more important than non-major clinically relevant bleeding and equally important as major bleeding. Conclusions: Results suggest that Japanese patients are willing to tolerate a greater risk of bleeding in exchange for stroke prevention than are Japanese physicians. The findings demonstrate the importance of physician-patient communication in treatment decisions involving stroke preventative therapies.

Cardiological aspects of stroke prevention

Many cardiac disorders and their treatment are associated with an increased risk for ischemic or hemorrhagic stroke, so it is important for cardiologists to be aware of recent advances in the field of stroke prevention. Atrial fibrillation (AF) is the most common cardiac disorder associated with a substantial risk for ischemic stroke (IS). The availability of implantable cardiac monitoring devices has substantially increased the detection rate of occult AF after IS. The 4 new oral anticoagulants have advantages when compared with warfarin, the standard therapy in AF to prevent IS, demonstrating a reduced risk for IS or intracerebral hemorrhage. Patients with cardiomyopathy, cardiac valve replacement, recent myocardial infarction, larger aortic arch atheroma and patent foramen ovale all have some level of increased risk for IS. The best approach for IS prevention in these disorders remains unsettled and varying approaches are recommended.

Elimination Of Triggers Without An Additional Substrate Modification Is Not Sufficient In Patients With Persistent Atrial Fibrillation

Atrial fibrillation (AF) is a multifactorial disease with complex pathophysiology. Although restoring sinus rhythm delays the progression of atrial remodeling, non-pharmacologic intervention, such as radiofrequency catheter ablation (RFCA), should be done based on the background pathophysiology of the disease. While circumferential pulmonary vein isolation (CPVI) has been known to be the cornerstone of AF catheter ablation, a clinical recurrence rate after CPVI is high in patients with persistent AF (PeAF). Step-wise linear ablation, complex fractionate atrial electrogram (CFAE)-guided ablation, rotor ablation, ganglionate plexus ablation, and left atrial appendage isolation may improve the ablation success rate after CPVI. But, there are still substantial AF recurrences after such liberal atrial substrate ablation, and current ablation techniques regarding substrate modification still have limitations. Therefore, more understanding about AF pathophysiology and early precise intervention may improve clinical outcome of AF management. Keeping in mind "more touch, more scar," operators should generate most efficient substrate modification to achieve better long-term clinical outcome.

Feasibility, efficacy, and safety of radiofrequency ablation of atrial fibrillation guided by monitoring of the initial impedance decrease as a surrogate of catheter contact

BACKGROUND

The initial impedance decrease during radiofrequency (RF) ablation is an indirect marker of catheter contact and lesion formation. We aimed to assess feasibility, efficacy, and safety of an ablation approach guided by initial impedance decrease.

METHODS

A total of 25 patients with paroxysmal AF had point-by-point, wide antral pulmonary vein (PV) isolation. RF applications were aborted if a decrease of at least 5 Ω did not occur in the first 10 seconds; otherwise, ablation was continued for at least 20 seconds. Power was 30 Watts and reduced to 15-25 Watts on the posterior wall.

RESULTS

A total of 28% of RF applications were terminated because of inadequate impedance decrease. The remaining lesions showed a median decrease of 7.6 Ω (IQR 5.0-10.7) at 10 seconds and median duration of RF lesions was 38 seconds. Note that, 100 PVs were isolated with 49 rings. PVI occurred before anatomic completion of the ablation ring of adequate lesions in 39/49 (80%) and concurrent with ring completion in 7/49 (14%). Additional lesions were required in 3/49 (6%) rings. After PVI, additional lesions were required to eliminate dormant conduction in 2/47 (4%) and pace-capture on the ablation line in 24/49 vein pairs (49%). During short-term follow-up, 3 nonfatal esophageal injuries and 2 late pericardial effusions occurred. During a mean follow-up of 431 ± 87 days, 21/25 patients (84%) remained free of recurrent symptomatic atrial arrhythmias.

CONCLUSIONS

PVI guided by initial impedance decrease is feasible and results in PVI concurrent with or before completion of the ablation ring in 94% of patients. Single procedure efficacy after one year of follow-up was 84%. Near-term complications suggest that deeper lesions are created, indicating that further reduction of RF-power and duration is warranted.

Fourier, hyperbolic and relativistic heat transfer equations: a comparative analytical study

Parabolic heat equation based on Fourier's theory (FHE), and hyperbolic heat equation (HHE), has been used to mathematically model the temperature distributions of biological tissue during thermal ablation. However, both equations have certain theoretical limitations. The FHE assumes an infinite thermal energy propagation speed, whereas the HHE might possibly be in breach of the second law of thermodynamics. The relativistic heat equation (RHE) is a hyperbolic-like equation, whose theoretical model is based on the theory of relativity and which was designed to overcome these theoretical impediments. In this study, the three heat equations for modelling of thermal ablation of biological tissues (FHE, HHE and RHE) were solved analytically and the temperature distributions compared. We found that RHE temperature values were always lower than those of the FHE, while the HHE values were higher than the FHE, except for the early stages of heating and at points away from the electrode. Although both HHE and RHE are mathematically hyperbolic, peaks were only found in the HHE temperature profiles. The three solutions converged for infinite time or infinite distance from the electrode. The percentage differences between the FHE and the other equations were larger for higher values of thermal relaxation time in HHE.

Efficacy of Catheter Ablation for Persistent Atrial Fibrillation

Background—

Catheter ablation (CA) is commonly performed for persistent atrial fibrillation, but few high-quality randomized controlled trials (RCTs) exist, leading to funding restrictions being proposed in several countries. We performed a random-effects meta-analysis of RCTs and non-RCTs to assess the efficacy of CA for persistent atrial fibrillation.

Methods and Results—

We systematically searched PubMed, EMBASE, CENTRAL, OpenGrey, and clinicaltrials.gov for RCTs and non-RCTs reporting clinical outcomes after CA for persistent atrial fibrillation. Forty-six eligible studies were identified containing 3819 patients. After a single procedure, CA significantly reduced the risk of recurrent atrial fibrillation compared with medical therapy (odds ratio [OR], 0.32; 95% confidence interval [CI], 0.20–0.53; P <0.001). Outcomes were better if the pulmonary veins were encircled (OR, 0.26; 95% CI, 0.09–0.74; P =0.01), and electrical isolation reduced AF recurrence compared with purely anatomic encirclement (OR, 0.33; 95% CI, 0.13–0.86; P =0.02). Linear ablation within the left atrium (OR, 0.22; 95% CI, 0.10–0.49; P <0.001), but not complex fractionated atrial electrogram ablation (OR, 0.64; 95% CI, 0.35–1.18; P =0.15), significantly reduced AF recurrence. Results were not improved by performing more extensive linear lesion sets (OR, 0.77; 95% CI, 0.41–1.43; P =0.40) or from biatrial ablation (OR, 0.62; 95% CI, 0.31–1.24; P =0.17). Where data were available, the relative benefits seen held true both after a single or multiple procedure(s). Sensitivity analyses showed that inclusion of non-RCTs increased statistical power without biasing the calculated effect sizes.

Conclusions—

For patients with persistent atrial fibrillation, CA achieves significantly greater freedom from recurrent atrial fibrillation compared with medical therapy. The most efficacious strategy is likely to combine isolation of the pulmonary veins with limited linear ablation within the left atrium.

Spatial and temporal variability of the complex fractionated atrial electrogram activity and dominant frequency in human atrial fibrillation

BACKGROUND

The presence of complex fractionated atrial electrograms (CFAEs) and high dominant frequencies (DFs) during atrial fibrillation (AF) have been demonstrated to be related to AF maintenance. Therefore, sequential mapping of CFAEs and DFs have been used for target sites of AF ablation. However, such mapping strategies are valid only if the CFAEs and DFs are spatiotemporally stable during the mapping procedure. We obtained spatially stable multi-electrode recordings to assess the spatiotemporal stability of CFAEs and DFs.

METHODS

We recorded electrical activity during AF for 10 min with a 64-electrode basket catheter (48 bipole electrode pairs) placed in the left atrium in 36 patients with AF (paroxysmal AF [PAF], n=16; persistent AF [PerAF], n=20). The spatial and temporal distribution of the CFAEs (fractionation interval <120 ms) and high DFs (>8 Hz) at 1-min intervals for 10 min were compared for each of the 48 bipoles.

RESULTS

The baseline CFAEs were located at 68.5±14.0% (32.9±6.7) of the 48 bipoles; however, the high DF sites were fewer (9.6±8.6% [4.6±4.1 bipoles]). The CFAEs sites did not change significantly during the 10-min recording period (kappa statistic: 0.71±0.24); however, the high DF sites changed significantly (kappa statistic: 0.07±0.19). These spatiotemporal changes in the CFAEs and high DFs did not differ between patients with PAF and PerAF.

CONCLUSIONS

Regardless of the AF type, CFAEs sites, but not high DF sites, showed a high degree of spatial and temporal stability.

Clinical update on the management of atrial fibrillation

Atrial fibrillation (AF) is a cardiac arrhythmia associated with significant morbidity and mortality, affecting more than 3 million people in the United States and 1-2% of the population worldwide. Its estimated prevalence is expected to double within the next 50 years. During the past decade, there have been significant advances in the treatment of AF. Studies have demonstrated that a rate control strategy, with a target resting heart rate between 80 and 100 beats/minute, is recommended over rhythm control in the vast majority of patients. The CHA2 DS2 ≥ (congestive heart failure, hypertension, age ≥ 65 yrs, diabetes mellitus, stroke or transient ischemic attack, vascular disease, female gender) scoring system is a potentially useful stroke risk stratification tool that incorporates additional risk factors to the commonly used CHADS2 (congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, stroke transient ischemic attack) scoring tool. Similarly, a convenient scheme, termed HAS-BLED (hypertension, abnormal renal/liver function, stroke, bleeding history or predisposition, labile international normalized ratio, elderly, drugs/alcohol concomitantly), to assess bleeding risk has emerged that may be useful in select patients. Furthermore, new antithrombotic strategies have been developed as potential alternatives to warfarin, including dual-antiplatelet therapy with clopidogrel plus aspirin and the development of new oral anticoagulants such as dabigatran, rivaroxaban, and apixaban. Vernakalant has emerged as another potential option for pharmacologic conversion of AF, whereas recent trials have better defined the role of dronedarone in the maintenance of sinus rhythm. Finally, catheter ablation represents another alternative to manage AF, whereas upstream therapy with inhibitors of the renin-angiotensin-aldosterone system, statins, and polyunsaturated fatty acids could potentially prevent the occurrence of AF. Despite substantial progress in the management of AF, significant uncertainty surrounds the optimal treatment of this condition.

Management of atrial fibrillation in critically ill patients

Atrial fibrillation (AF) is common in ICU patients and is associated with a two- to fivefold increase in mortality. This paper provides a reappraisal of the management of AF with a special focus on critically ill patients with haemodynamic instability. AF can cause hypotension and heart failure with subsequent organ dysfunction. The underlying mechanisms are the loss of atrial contraction and the high ventricular rate. In unstable patients, sinus rhythm must be rapidly restored by synchronised electrical cardioversion (ECV). If pharmacological treatment is indicated, clinicians can choose between the rate control and the rhythm control strategy. The optimal substance should be selected depending on its potential adverse effects. A beta-1 antagonist with a very short half-life (e.g., esmolol) is an advantage for ICU patients because the effect of beta-blockade on cardiovascular stability is unpredictable in those patients. Amiodarone is commonly used in the ICU setting but has potentially severe cardiac and noncardiac side effects. Digoxin controls the ventricular response at rest, but its benefit decreases in the presence of adrenergic stress. Vernakalant converts new-onset AF to sinus rhythm in approximately 50% of patients, but data on its efficacy and safety in critically ill patients are lacking.

Curative ablation of atrial fibrillation: comparison between deep sedation and general anesthesia

OBJECTIVE

To compare deep sedation with general anesthesia for curative ablation of atrial fibrillation.

METHODS

We conducted a prospective, randomized study with 32 patients, aged between 18 and 65 years, ASA 2 and 3, BMI d" 30 kg/m2, divided into two groups: deep sedation (G1) and general anesthesia (G2). All patients received intravenous midazolam (0.5 mg / kg). G1 received propofol (1mg/kg) and O2 by facemask, followed by continuous infusion of propofol (25-50mg/kg/min) and remifentanil (0.01-0.05 mg / kg / min). G2 received propofol (2mg/kg) and laryngeal mask with built-in drain tube, followed by continuous infusion of propofol (60-100mg/kg/min) and remifentanil (0.06 to 0.1g/kg/min). We compared heart rate, invasive blood pressure, arterial blood gases, complications and recurrence (outcome) in three months.

RESULTS

G1 patients had arterial blood gas with higher PaCO2 levels and lower pH (p = 0.001) and higher incidence of cough. There was a decrease in Mean Arterial Pressure (MAP) and Heart Rate (HR) in G2. Except cough, complications and recurrence were similar in both groups.

CONCLUSION

Both techniques can be used for the curative ablation of atrial fibrillation. General anesthesia provided smaller respiratory changes and greater immobility of the patient.

Pulmonary vein isolation in patients with paroxysmal atrial fibrillation is associated with regional cardiac sympathetic denervation

BACKGROUND

Circumferential pulmonary vein isolation (PVI) is the cornerstone of the current state-of-the-art management of atrial fibrillation (AF). However, the precise mechanisms behind AF relapses post PVI are still unknown. Since the activity of the autonomous nervous system is crucial in triggering paroxysmal AF, we hypothesized that PVI is associated with changes of cardiac sympathetic activity.

METHODS

Sixteen patients with paroxysmal AF underwent cardiac iodine-123-meta-iodobenzylguanidine (123I-mIBG) planar cardiac imaging and single-photon emission computed tomography with low-dose computed tomography (SPECT/CT) for attenuation correction before and 4 weeks after PVI. The heart-to-mediastinum ratio (H/M ratio), washout rate (WR), regional myocardial uptake, and regional washout were analyzed.

RESULTS

The late H/M ratio was unchanged by PVI (pre, 2.9 ± 0.5 vs. post, 2.7 ± 0.6, p = 0.53). Four of the 16 patients (25%) displayed regional deficits before PVI. After PVI, regional deficits were present in ten patients (62.5%) with newly emerging deficits localized in the inferolateral wall. In a 6-month follow-up, four out of the ten patients (40%) with regional 123I-mIBG defects suffered from a recurrence of AF, while only one of the six patients (16.7%) without a regional 123I-mIBG defect experienced a recurrence.

CONCLUSION

A significant number of patients with paroxysmal AF show regional cardiac sympathetic innervation deficits at baseline. In addition, PVI is associated with newly emerging defects. The presence of regional sympathetic denervation after PVI may correlate with the risk of AF relapses.

Immediate and medium-term outcomes of cryoballoon-based pulmonary vein isolation in patients with paroxysmal and persistent atrial fibrillation: single-centre experience

BACKGROUND

Pulmonary vein (PV) isolation with cryoballoon is a recently developed technique for the treatment of atrial fibrillation (AF) with acceptable mid-term results in terms of the success and safety. The purpose of our study is to identify the periprocedural complications, mid-term success rates and predictors of recurrence after AF ablation with cryoballoon.

METHOD

A total of 236 patients (54% male, mean age 54.6 ± 10.45 years and 79.6% paroxysmal AF) with symptomatic AF underwent PV isolation with cryoballoon due to failure with ≥1 antiarrhythmic drug previously. Procedural success, complications and follow-up data were defined according to recent guidelines.

RESULTS

Acute procedural success rate was 99.5%. Mean procedural and fluoroscopy times were 72.5 ± 5.3 and 14 ± 3.5 min. At a median of 18 (6-27) months follow-up, 80.8% of paroxysmal AF patients and 50.0% of persistent AF patients were free from AF recurrence. In multivariate regression analysis, body mass index (BMI) (hazard ratio (HR), 1.35; 95% confidence interval (CI), 1.18-2.93, p = 0.001), smoking (HR, 2.12; 95% CI, 1.36-6.67, p < 0.001), non-paroxysmal AF (HR, 1.26; 95% CI, 1.12-2.56, p = 0.024), duration of AF (HR, 1.42; 95% CI, 1.18-2.61, p = 0.015), left atrium (LA) diameter (HR, 2.42; 95% CI, 1.64-5.88, p < 0.001) and early AF recurrence (HR, 4.88; 95% CI, 2.86-35.6, p < 0.001) were independent predictors of AF recurrence following cryoablation.

CONCLUSION

Our results showed that AF ablation with cryoballoon is effective and safe. Non-paroxysmal AF, duration of AF, smoking, BMI, LA diameter and early recurrence were found to be the most powerful predictors and could be helpful to select patients for appropriate therapeutic strategy.

Initial impedance decrease as an indicator of good catheter contact: insights from radiofrequency ablation with force sensing catheters

BACKGROUND

Good catheter-tissue contact force (CF) is critical for transmural and durable lesion formation during radiofrequency (RF) ablation but is difficult to assess in clinical practice. Tissue heating during RF application results in an impedance decrease at the catheter tip.

OBJECTIVE

The purpose of this study was to correlate achieved CF and initial impedance decreases during atrial fibrillation (AF) ablation.

METHODS

We correlated achieved CF and initial impedance decreases in patients undergoing ablation for AF with two novel open-irrigated CF-sensing RF catheters (Biosense Webster SmartTouch, n = 647 RF applications; and Endosense TactiCath, n = 637 RF applications). We then compared those impedance decreases to 691 RF applications with a standard open-irrigated RF catheter (Biosense Webster ThermoCool).

RESULTS

When RF applications with the CF-sensing catheters were analyzed according to an achieved average CF <5 g, 5-10 g, 10-20 g, and >20 g, the initial impedance decreases during ablation were larger with greater CF. Corresponding median values at 20 seconds were 5 Ω (interquartile range [IQR] 2-7), 8 Ω (4-11), 10 Ω (7-16), and 14 Ω (10-19) with the SmartTouch and n/a, 4 Ω (0-10), 8 Ω (5-12), and 13 Ω (8-18) with the TactiCath (P <.001 between categories for both catheters). When RF applications with the SmartTouch (CF-sensing catheter, median achieved CF 12 g) and ThermoCool (standard catheter) were compared, the initial impedance decrease was significantly greater in the CF-sensing group with median decreases of 10 Ω (6-14 Ω) vs 5 Ω (2-10 Ω) at 20 seconds (P <.001 between catheters).

CONCLUSION

The initial impedance decrease during RF applications in AF ablations is larger when greater catheter contact is achieved. Monitoring of the initial impedance decrease is a widely available indicator of catheter contact and may help to improve formation of durable ablation lesions.