Comparison of antiarrhythmic drug therapy and radiofrequency catheter ablation in patients with paroxysmal atrial fibrillation: a randomized controlled trial

Results from a multicentre comparison of cryoballoon vs. radiofrequency ablation for paroxysmal atrial fibrillation: is cryoablation more reproducible?

AIM

Cryoballoon ablation (Cryoballoon) has emerged as a new alternative for the treatment of symptomatic drug-refractory atrial fibrillation (AF). Whether the results of Cryoballoon are more reproducible than those of radiofrequency (RF) ablation remains to be proved.

METHODS AND RESULTS

A total of 860 consecutive patients undergoing a first ablation procedure for paroxysmal AF (467 treated with RF and 393 treated with Cryoballoon) were selected from a prospective multicentre survey of AF ablation (FrenchAF). Radiofrequency and Cryoballoon were compared regarding mid-term efficacy and safety. During a median follow-up of 14 months (interquartile range 8-23), patients treated with Cryoballoon displayed similar rates of freedom from atrial arrhythmia relapse in centres performing this technique (68-80% at 18 months). However, in centres performing RF, a greater heterogeneity in procedural results was observed (46-79% were free from atrial arrhythmia relapse at 18 months). On multivariate analysis, Cryoballoon (HR = 0.47, 95% CI 0.35-0.65, P < 0.001) and annual AF ablation caseload (HR = 0.87 per every 100 AF ablation procedures per year; 95% CI 0.80-0.96, P = 0.003) were independent predictors of procedural success. However, on sensitivity analysis, according to the ablation method, annual AF ablation caseload predicted only sinus rhythm maintenance in the subgroup of patients treated with RF. Analysis of interoperator results with Cryoballoon and RF confirmed lower reproducibility of RF, but suggested that besides caseload, other operator-related factors may play a role.

CONCLUSION

Cryoballoon seems to be less operator-dependent and more reproducible than RF in the setting of paroxysmal AF ablation.

The role of catheter ablation in the management of atrial fibrillation

Atrial fibrillation is driven by spontaneous electrical activation emerging from the pulmonary veins. Catheter ablation using either radiofrequency or cryothermal energy electrically isolates these veins from the left atrium, both reducing the burden of atrial fibrillation episodes and improving the patient's symptoms. Catheter ablation is superior to antiarryhthmic drugs when patients are carefully selected. Underlying medical problems - including obesity, hypertension and obstructive sleep apnoea - should be optimally treated before considering ablation. Although this treatment has the potential to cure patients of their symptoms, they should be aware of the important associated procedural complications.

Catheter Ablation of Paroxysmal Atrial Fibrillation: Have We Achieved Cure with Pulmonary Vein Isolation?

Pulmonary vein isolation (PVI) is the cornerstone of current ablation techniques to eliminate atrial fibrillation (AF), with the greatest efficacy as a stand-alone procedure in patients with paroxysmal AF. Over the years, techniques for PVI have undergone a profound evolution, and current guidelines recommend PVI with confirmation of electrical isolation. Despite significant efforts, PV reconnection is still the rule in patients experiencing post-ablation arrhythmia recurrence. In recent years, use of general anesthesia with or without jet ventilation, open-irrigated ablation catheters, and steerable sheaths have been demonstrated to increase the safety and efficacy of PVI, reducing the rate of PV reconnection over follow-up. The widespread clinical availability of ablation catheters with real-time contact force information will likely further improve the effectiveness and safety of PVI. In a small but definite subset of patients, post-ablation recurrent arrhythmia is due to non-PV triggers, which should be eliminated in order to improve success. Typically, non-PV triggers cluster in specific regions such as the coronary sinus, the inferior mitral annulus, the interatrial septum, the left atrial appendage, the Eustachian ridge, the crista terminalis region, the superior vena cava, and the ligament of Marshall. Focal ablation targeting the origin of the trigger is recommended in most cases. Empirical non-PV ablation targeting the putative substrate responsible for AF maintenance with ablation lines and/or elimination of complex fractionated electrograms has not been shown to improve success compared to PVI alone. Similarly, the role of novel substrate-based ablation approaches targeting putative localized sources of AF (e.g., rotors) identified by computational mapping techniques is unclear, as they have never been compared to PVI and non-PV trigger ablation in an adequately designed randomized trial. This review highlights PVI techniques and outcomes in treating recurrent drug-refractory AF and discusses the potential role of additional non-PV ablation.

Stiff Left Atrial Syndrome: A Complication Undergoing Radiofrequency Catheter Ablation for Atrial Fibrillation

Radiofrequency catheter ablation for atrial fibrillation is an effective approach for treating atrial fibrillation. Its complications have attracted much attention, of which the stiff left atrial syndrome is a recently discovered complication that has not been completely understood. This study aims to investigate the concept, pathologic basis, clinical characteristics, predictors, and treatment protocols of the stiff left atrial syndrome after radiofrequency ablation for atrial fibrillation.

Novel Radiofrequency Ablation Strategies for Terminating Atrial Fibrillation in the Left Atrium: A Simulation Study

Pulmonary vein isolation (PVI) with radiofrequency ablation (RFA) is the cornerstone of atrial fibrillation (AF) therapy, but few strategies exist for when it fails. To guide RFA, phase singularity (PS) mapping locates reentrant electrical waves (rotors) that perpetuate AF. The goal of this study was to test existing and develop new RFA strategies for terminating rotors identified with PS mapping. It is unsafe to test experimental RFA strategies in patients, so they were evaluated in silico using a bilayer computer model of the human atria with persistent AF (pAF) electrical (ionic) and structural (fibrosis) remodeling. pAF was initiated by rapidly pacing the right (RSPV) and left (LSPV) superior pulmonary veins during sinus rhythm, and rotor dynamics quantified by PS analysis. Three RFA strategies were studied: (i) PVI, roof, and mitral lines; (ii) circles, perforated circles, lines, and crosses 0.5-1.5 cm in diameter/length administered near rotor locations/pathways identified by PS mapping; and (iii) 4-8 lines streamlining the sequence of electrical activation during sinus rhythm. As in pAF patients, 2 ± 1 rotors with cycle length 185 ± 4 ms and short PS duration 452 ± 401 ms perpetuated simulated pAF. Spatially, PS density had weak to moderate positive correlations with fibrosis density (RSPV: r = 0.38, p = 0.35, LSPV: r = 0.77, p = 0.02). RFA PVI, mitral, and roof lines failed to terminate pAF, but RFA perforated circles and lines 1.5 cm in diameter/length terminated meandering rotors from RSPV pacing when placed at locations with high PS density. Similarly, RFA circles, perforated circles, and crosses 1.5 cm in diameter/length terminated stationary rotors from LSPV pacing. The most effective strategy for terminating pAF was to streamline the sequence of activation during sinus rhythm with >4 RFA lines. These results demonstrate that co-localizing 1.5 cm RFA lesions with locations of high PS density is a promising strategy for terminating pAF rotors. For patients immune to PVI, roof, mitral, and PS guided RFA strategies, streamlining patient-specific activation sequences during sinus rhythm is a robust but challenging alternative.

Gender, Race, and Health Insurance Status in Patients Undergoing Catheter Ablation for Atrial Fibrillation

Catheter ablation for atrial fibrillation (AF) has emerged as a popular procedure. The purpose of this study was to examine whether there exist differences or disparities in ablation utilization across gender, socioeconomic class, insurance, or race. Using the Nationwide Inpatient Sample (2000 to 2012), we identified adults hospitalized with a principal diagnosis of AF by ICD 9 code 427.31 who had catheter ablation (ICD 9 code-37.34). We stratified patients by race, insurance status, age, gender, and hospital characteristics. A hierarchical multivariate mixed-effect model was created to identify the independent predictors of AF ablation. Among an estimated total of 3,508,122 patients (extrapolated from 20% Nationwide Inpatient Sample) hospitalized with a diagnosis of AF in the United States from the year 2000 to 2012, 102,469 patients (2.9%) underwent catheter ablations. The number of ablations was increased by 940%, from 1,439 in 2000 to 15,090 in 2012. There were significant differences according to gender, race, and health insurance status, which persisted even after adjustment for other risk factors. Female gender (0.83 [95% CI 0.79 to 0.87; p <0.001]), black (0.49 [95% CI 0.44 to 0.55; p <0.001]), and Hispanic race (0.64 [95% CI 0.56 to 0.72; p <0.001]) were associated with lower likelihoods of undergoing an AF ablation. Medicare (0.93, 0.88 to 0.98, <0.001) or Medicaid (0.67, 0.59 to 0.76, <0.001) coverage and uninsured patients (0.55, 0.49 to 0.62, <0.001) also had lower rates of AF ablation compared to patients with private insurance. In conclusion we found differences in utilization of catheter ablation for AF based on gender, race, and insurance status that persisted over time.

Presence and stability of rotors in atrial fibrillation: evidence and therapeutic implications

Rotor-guided ablation has opened new perspectives into the therapy of atrial fibrillation (AF). Analysis of the spatio-temporal cardiac excitation patterns in the frequency and phase domains has demonstrated the importance of rotors in research models of AF, however, the dynamics and role of rotors in human AF are still controversial. In this review, the current knowledge gained through research models and patient data that support the notion that rotors are key players in AF maintenance is summarized. We report and discuss discrepancies regarding rotor prevalence and stability in various studies, which can be attributed in part to methodological differences among mapping systems. Future research for validation and improvement of current clinical electrophysiology mapping technologies will be crucial for developing mechanistic-based selection and application of the best therapeutic strategy for individual AF patient, being it, pharmaceutical, ablative, or other approach.

Atrial fibrillation management: evaluating rate vs rhythm control

Atrial fibrillation (AF) is an increasing global issue leading to increased hospitalizations, adverse health related events and mortality. This review focuses on the management of atrial fibrillation, in particular in the past decade, comparing two major strategies, rate or rhythm control. We evaluate the evidence for each strategy, pharmacological options and the increasing utilization of invasive techniques, in particular catheter ablation and use of implantable cardiac pacing devices. Pharmacological comparative trials evaluating both strategies have shown rate control being non-inferior to rhythm control for clinical outcomes of mortality and other cardiovascular events (including stroke). Catheter ablation techniques, involving radiofrequency ablation and recently cryoablation, have shown promising results in particular with paroxysmal AF. However, persistent AF provides ongoing challenges and will be a particular focus of continued research.

Rate Versus Rhythm Control for Atrial Fibrillation

Treatment of patients with symptomatic atrial fibrillation (AF) with antiarrhythmic drug therapy in general improves their symptom scores and exercise tolerance; however, large randomized trials have failed to show a mortality benefit with a rhythm-control compared with a rate-control strategy. Catheter ablation in patients who have failed or not tolerated medical therapy has been shown to alleviate symptoms and improve quality of life. However, catheter ablation cannot undo the structural remodeling that contributed to the arrhythmia in the first place. Patients should be alerted to modifiable factors that may decrease the likelihood of unchecked structural remodeling and AF recurrence.

Ablation as First-Line Therapy for Atrial Fibrillation: Yes

This article addresses the use of catheter ablation (CA) as first-line therapy for atrial fibrillation (AF). CA increases long-term freedom from AF, reduces hospitalizations, and improves quality of life compared with antiarrhythmic drug (AAD) therapy in patients with symptomatic AF who have already failed one AAD. The role of CA as first-line therapy for AF, however, is still controversial. Evidence from randomized controlled trials shows that CA is definitely superior to AADs as first-line therapy for relatively young patients with paroxysmal AF, with comparable complication rates and results consistently reproducible across different institutions, operators, and types of ablation approaches.

Optimizing contact force during ablation of atrial fibrillation: available technologies and a look to the future

In a select atrial fibrillation population, catheter ablation is considered first-line therapy. Prevention of early reconnection of the isolated pulmonary veins is an important goal for a successful treatment. Here, adequate catheter–tissue contact is crucial. One of the most promising new advances, therefore, is contact force (CF) sensing technology. The aim of this review is to provide an overview of innovations regarding catheter ablation of atrial fibrillation with a special focus on CF optimization. Both experimental and human studies show how CF sensing catheters lead to a reduction of fluoroscopy time, increased procedural safety and a better clinical outcome. Possible future developments include new parameters combining real-time ablation data, direct visualization of lesion formation and incorporation of robotics.

Assessing quality-of-life outcomes in cardiovascular clinical research

The field of quality-of-life (QOL) measurement grew out of attempts in the 1960s and 1970s to connect the ever-increasing levels of public expenditure on technology-based health care for chronic diseases with evidence of the benefits and harms to patients. Most of the concepts, methods, and standards for measuring QOL were derived from psychometrics, but the degree to which current tools adhere to these methods varies greatly. Despite the importance of QOL, patient-reported outcomes are not measured in most cardiovascular clinical trials. Lack of familiarity with QOL measures and their interpretation, and unrealistic expectations about the information these measures can provide, are obstacles to their use. Large clinical trials of revascularization therapy for coronary artery disease and medical treatments for heart failure show small-to-moderate QOL effects, primarily detected with disease-specific instruments. Larger treatment effects, seen in trials of device therapy for heart failure and ablation therapy for atrial fibrillation, have been detected with both generic and disease-specific instruments. A large gap remains between the parameters currently being measured in clinical research and the data needed to incorporate the 'patient's voice' into therapeutic decision-making.

A Patient With Asymptomatic Cerebral Lesions During AF Ablation: How Much Should We Worry?

Silent brain lesions due to thrombogenicity of the procedure represent recognized side effects of atrial fibrillation (AF) catheter ablation. Embolic risk is higher if anticoagulation is inadequate and recent studies suggest that uninterrupted anticoagulation, ACT levels above 300 seconds and administration of a pre-transeptal bolus of heparin might significantly reduce the incidence of silent cerebral ischemia (SCI) to 2%. Asymptomatic new lesions during AF ablation should suggest worse neuropsychological outcome as a result of the association between silent cerebral infarcts and increased long-term risk of dementia in non-ablated AF patients. However, the available data are discordant. To date, no study has definitely linked post-operative asymptomatic cerebral events to a decline in neuropsychological performance. Larger volumes of cerebral lesions have been associated with cognitive decline but are uncommon findings acutely in post-ablation AF patients. Of note, the majority of acute lesions have a small or medium size and often regress at a medium-term follow-up. Successful AF ablation has the potential to reduce the risk of larger SCI that may be considered as part of the natural course of AF. Although the long-term implications of SCI remain unclear, it is conceivable that strategies to reduce the risk of SCI may be beneficial.

Novel perspectives on arrhythmia-induced cardiomyopathy: pathophysiology, clinical manifestations and an update on invasive management strategies

Arrhythmia-induced cardiomyopathy is a partially or completely reversible form of myocardial dysfunction due to sustained supraventricular and ventricular arrhythmias. Asynchrony, rapid cardiac rates and rhythm irregularities are the main factors involved in the development of the disease. The reversible nature of arrhythmia-induced cardiac dysfunction allows only for a retrospective diagnosis of the disease once cardiac function is restored following heart rate control. A high level of suspicion is needed to make a diagnosis at an early stage and prevent further progression of the disease. Although reversible, arrhythmia-induced cellular and molecular changes may remain, increasing the risk for sudden death even when normal ejection fraction is restored as well as causing rapid deterioration of cardiac function and development of heart failure symptoms if arrhythmia recurs. Appropriate management based on a combination of pharmacologic and nonpharmacologic strategies to achieve rate control and prevent arrhythmia recurrence is pivotal to avoid further cardiac function deterioration and to control symptoms, significantly reducing the risk of heart failure and sudden cardiac death.

Atrial fibrillation ablation and left appendage closure in heart failure patients

PURPOSE OF REVIEW

Patients with atrial fibrillation and heart failure experience an increased morbidity and mortality from the hemodynamic consequences of atrial fibrillation and an increased stroke risk. Consequently, there has been increased attention to procedural alternatives to pharmacologic rhythm control and anticoagulation for stroke prevention. This review aims to evaluate the evidence for atrial fibrillation ablation and left atrial appendage closure in heart failure patients.

RECENT FINDINGS

Several randomized control trials and systematic reviews demonstrate the safety and efficacy of atrial fibrillation ablation in patients with heart failure and left ventricular systolic dysfunction. In multiple trials, these patients have shown clinical benefit from atrial fibrillation ablation including improved left ventricular systolic function, quality of life, and clinical heart failure symptoms. The evidence of clinical benefit of atrial fibrillation ablation in heart failure patients with preserved ejection fraction remains limited. Only a handful of randomized controlled trials have been performed evaluating left atrial appendage closure, and there is insufficient data regarding the safety and efficacy of these procedures in heart failure patients.

SUMMARY

Atrial fibrillation ablation in heart failure patients remains well tolerated with an overall efficacy comparable to atrial fibrillation ablation in patients without heart failure. There is consistent evidence for the clinical benefit of atrial fibrillation ablation in heart failure patients with left ventricular systolic dysfunction and limited evidence for atrial fibrillation ablation in heart failure patients with preserved ejection fraction. Currently, there is insufficient data regarding the safety and efficacy of left atrial appendage closure devices in heart failure patients.

Electrophysiological Perspectives on Hybrid Ablation of Atrial Fibrillation

To overcome limitations of minimally invasive surgical ablation as a standalone procedure in eliminating atrial fibrillation (AF), hybrid approaches incorporating adjunctive endovascular catheter ablation have been proposed in recent years. The endovascular component targets residual conduction gaps and identifies additional electrophysiological targets with the goal of minimizing recurrent atrial arrhythmia. We performed a systematic review of published studies of hybrid AF ablation, analyzing 432 pooled patients (19% paroxysmal, 29% persistent, 52% long-standing persistent) treated using three different approaches: A. bilateral thoracoscopy with bipolar radiofrequency (RF) clamp-based approach; B. right thoracoscopic suction monopolar RF catheter-based approach; and C. subxiphoid posterior pericardioscopic ("convergent") approach. Freedom from recurrence off antiarrhythmic medications at 12 months was seen in 88.1% [133/151] for A, 73.4% [47/64] for B, and 59.3% [80/135] for C, with no significant difference between paroxysmal (76.9%) and persistent/long-standing persistent AF (73.4%). Death and major surgical complications were reported in 8.5% with A, 0% with B and 8.6% with C. A critical appraisal of hybrid ablation is presented, drawing from experiences and insights published over the years on catheter ablation of AF, with a discussion of the rationale underlying hybrid ablation, its strengths and limitations, where it may have a unique role in clinical management of patients with AF, which questions remain unanswered and areas for further investigation.

Combined catheter ablation for atrial fibrillation and Watchman® left atrial appendage occlusion procedures: Five-year experience

Background

Patients with atrial fibrillation (AF) may benefit from undergoing concomitant interventions of left atrial catheter ablation and device occlusion of the left atrial appendage (LAA) as a two-pronged strategy for rhythm control and stroke prevention. We report on the outcome of combined procedures in a single center case series over a 5-year timeframe.

Methods

Ninety-eight patients with non-valvular AF and a mean CHA₂DS₂-VASc score 2.6±1.0 underwent either first time, or redo pulmonary vein isolation (PVI) procedures, followed by successful implant of a Watchman® device.

Results

All procedures were generally uncomplicated with a mean case time of 213±40 min. Complete LAA occlusion was achieved at initial implant in 92 (94%) patients. Satisfactory LAA occlusion was achieved in 100% of patients at 12 months, with a complete LAA occlusion rate of 86%. All patients discontinued oral anticoagulation. Persistent late peri-device leaks were more frequently associated with device angulation or shoulder protrusion, and were associated with a significantly lower achieved device compression of 12±3% vs. 15±5% (p<0.01) than complete occlusion. One ischemic stroke was recorded over a mean follow-up time of 802±439 days. Twelve months׳ freedom from detectable AF was achieved in 77% of patients.

Conclusions

Combined procedures of catheter ablation for AF and Watchman® LAA implant appear to be feasible and safe, with excellent rates of LAA occlusion achieved and an observed stroke rate of 0.5% per year during mid-term follow-up. Incomplete occlusion was associated with lower achieved device compression and was more frequently associated with suboptimal device position.

CoolLoop® First: A First In Man Study To Test A Novel Circular Cryoablation System In Paroxysmal Atrial Fibrillation

INTRODUCTION

Pulmonary vein (PV) isolation is the mainstay of catheter treatment of paroxysmal atrial fibrillation (AF). The CoolLoop® cryoablation catheter (AFreeze® GmbH; Innsbruck, Austria) was developed to create wide and complete circular lesions around the PVs. In this study we evaluated feasibility and safety of this novel ablation system in humans.

METHODS

10 patients (6M/4F; 57.6±7.6y) with paroxysmal AF were included in 2 referral centers. The CoolLoop® catheter was positioned at each PV antrum using a steerable transseptal sheath. Subsequently, 2-6 double-freezes over 5min were performed at each vein and PV-isolation was assessed thereafter using a circular mapping catheter. During cryoablation of the right PVs, pacing was used to monitor phrenic nerve function.

RESULTS

The CoolLoop® catheter could be successfully positioned at each PV. A mean of 5.6±1.8 cryoablations were performed in the LSPV, 5.2±1.6 in the LIPV, 6.3±2.5 in the RSPV and 5.4±1.6 in the RIPV, respectively. Mean procedure time was 251±60min and mean fluoroscopy time was 44.0±13.2min. 6 / 10 LSPV, 6 / 10 LIPV, 5 / 10 RSPV and 6 / 10 RIPV could be isolated exclusively using the novel cryoablation system. One patient developed groin hematoma and a brief episode of ST-elevation due to air embolism was observed in another subject. No other clinical complications occurred during 3 months of follow up.

CONCLUSIONS

PV-isolation for paroxysmal atrial fibrillation using the CoolLoop® catheter is feasible and appears safe. Clinical long term efficacy still needs to be evaluated and will be compared with established catheters used for AF ablation.

Long-term stroke rates after catheter ablation or antiarrhythmic drug therapy for atrial fibrillation: a meta-analysis of randomized trials

BACKGROUND

Atrial fibrillation (AF) is an independent risk factor for ischemic stroke and is associated with increased risk of death. Randomized studies suggest improved quality of life for patients with AF after successful catheter ablation compared to antiarrhythmic drug therapy. The value of ablation in long-term risk of ischemic stroke, however, has not been assessed. We conducted a meta-analysis to determine whether AF ablation reduces the long-term risk of stroke compared to antiarrhythmic drug therapy in randomized controlled trials.

METHODS & RESULTS

PubMed and the Cochrane Central Register were searched for randomized trials from January 1990 to December 2014 comparing AF catheter ablation to drug therapy. The results are reported as risk differences (RDs) and 95% CI. Thirteen trials were analyzed with 1097 patients treated by catheter ablation and 855 patients received antiarrhythmic drug therapy. Overall, seven patients (0.64%) in the catheter ablation group had ischemic stroke or transient ischemic attacks vs. two patients (0.23%) in the drug therapy group. No difference was shown in the rate of stroke or transient ischemic attack between ablation and drug therapy (RD: 0.003, 95% CI: -0.006 to 0.012, P = 0.470), and no evidence of heterogeneity was observed (I (2) = 0, P = 0.981). No potential publication bias was found. There was also no difference in mortality between the two groups (RD: -0.004, 95% CI: -0.014 to 0.006, P = 0.472).

CONCLUSIONS

This meta-analysis of randomized controlled trials showed similar rates of ischemic stroke or transient ischemic attack and death in AF patients undergoing catheter ablation compared to drug therapy. A larger prospective randomized trial to confirm this finding is warranted.

Prevalence and distribution of focal triggers in persistent and long-standing persistent atrial fibrillation

BACKGROUND

The relevance of focal triggers in persistent atrial fibrillation (PerAF) and long-standing persistent atrial fibrillation (LSPAF) has not been previously investigated.

OBJECTIVE

We prospectively evaluated the prevalence and distribution of AF triggers in patients referred for catheter ablation of PerAF and LSPAF.

METHODS

We analyzed consecutive patients undergoing first time AF ablation who underwent a standardized trigger protocol including cardioversion of induced or spontaneous AF and infusion of up to 20 μg of isoproterenol for 15-20 minutes either before or after pulmonary vein (PV) isolation accomplished. Triggers were defined as AF/sustained atrial tachyarrhythmia or repetitive atrial premature depolarizations.

RESULTS

A total of 2168 patients were included (mean age 57 ± 11 years; 1636 [75%] men), with 1531 patients having paroxysmal AF (PAF) (71%), 496 having PerAF (23%), and 141 having LSPAF (7%). PV triggers were found in 1398 patients with PAF (91%), 449 patients with PerAF (91%), and 129 patients with LSPAF (91%) (P = .856 for comparison across groups). Non-PV triggers were elicited in a total of 234 patients (11%), and the prevalence was similar across the different types of AF (PAF, 165 [11%]; PerAF, 54 [11%]; LSPAF, 15 [11%]; P = .996 for comparison across groups).

CONCLUSION

PVs are the main AF trigger site in patients with PerAF and LSPAF, with an overall prevalence similar to that found in patients with PAF. These results support the current recommendations for PV isolation as the cornerstone of catheter ablation to eliminate AF triggers in PerAF and LSPAF.

Differences in Quality of Life Between Atrial Fibrillation Patients with Low Stroke Risk Treated With and Without Catheter Ablation

BACKGROUND

Impacts of a single radiofrequency ablation (RFA) on quality of life (QoL) were not well investigated in atrial fibrillation (AF) patients with low stroke risk.

METHODS AND RESULTS

Nine hundred AF patients with low CHADS2 score (ie, CHADS2 ≤1) who completed both a baseline and 6-month Atrial Fibrillation Effect on QualiTy-of-life (AFEQT) questionnaire were selected from The Chinese Atrial Fibrillation Registry between 2011 and 2013. A final cohort of 222 patients was constructed after a propensity score matching with 74 in the RFA group and 148 in the non-RFA group. Domains of AFEQT were balanced at baseline between the 2 groups. No statistically significant differences were noted in QoL (all P>0.05) when AFEQT at 6 months was compared between groups, except for the symptoms domain (83.07±12.37 units in the RFA group vs. 77.68±17.14 units in the non-RFA group; P=0.008) and treatment satisfaction domain (76.34±14.92 units in the RFA group vs. 70.38±16.81 units in the non-RFA group; P=0.01). Within-group changes in all domains and the global score of the questionnaire were moderate to large, whereas between-group comparisons in baseline to 6-month changes and QoL at 6 months were small to moderate according to Cohen effect sizes.

CONCLUSIONS

QoL was balanced at baseline and improved at 6 months in both groups from this observational propensity-matched cohort based on the AFEQT questionnaire. However, RFA treatment was only associated with small-to-moderate superiorities over non-RFA treatment. The role of RFA in QoL improvement among AF patients with low stroke risk requires further research.

Atrial fibrillation in the elderly: a review

Atrial fibrillation (AF) is common in the elderly population. Elderly patients with AF are often asymptomatic, may have atypical presentation or may present with heart failure or thromboembolic complications. The optimal management strategy of AF in the elderly population is challenging. We present an overview of AF in elderly patients, in particular addressing the pros and cons of various management strategies, and provide a practical approach within the guidelines.

Non-compliance with randomised allocation and missing outcome data in randomised controlled trials evaluating surgical interventions: a systematic review

Background

Randomised controlled trials are widely acknowledged as the gold standard in medical research although their validity can be undermined by non-compliance with the randomly allocated treatment and missing data. Due to the nature of the intervention, surgical trials face particular threat to compliance and data collection. For example, ineligibility for the intervention may only become apparent once the operation has commenced. It is unclear how such cases are reported and handled.

Objective

The objective was to assess non-compliance and missing data in reports of trials of surgical interventions.

Methods

Searches for reports of trials involving at least one surgical procedure and published in 2010 were carried out in the Medical Literature Analysis and Retrieval System Online (MEDLINE^®). Data on missing data, non-compliance and methods of handling missing data were extracted from full texts. Descriptive data analyses were carried out on the data.

Results

Forty-five (55 %) studies reported non-compliance with treatment allocation and 52 (63 %) reported primary outcome missing data. The median levels of non-compliance and missing data were 2 % [IQR (0, 5), range (0–29)] and 6 % [IQR (0, 15), range (0–57)], respectively. Fifty-two (63 %) studies analysed as randomised, 17 (21 %) analysed per protocol and 3 (4 %) analysed as treated. Complete case analysis was the most common method used to deal with missing data, 35/52 (67 %).

Conclusions

The reporting of non-compliance to allocation and the handling of missing data were typically suboptimal. There is still room for improvement on the use of the CONSORT statement particularly in accounting for study participants. Transparency in reporting would facilitate evidence synthesis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-015-1364-9) contains supplementary material, which is available to authorized users.

Outcomes Of Cryoballoon Ablation Of Atrial Fibrillation: A Comprehensive Review

Over the last decade, cryoballoon ablation has emerged as an effective alternate strategy to point-by-point radiofrequency ablation for treatment of symptomatic atrial fibrillation. There are several reasons for this. First, the acute and long-term safety and efficacy associated with cryoablation appear comparable to that of radiofrequency ablation in patients with both paroxysmal and also persistent atrial fibrillation. Second, cryoablation offers certain advantages over conventional radiofrequency ablation including a gentler learning curve, shorter ablation and procedure times as well as lack of need for costly electroanatomical mapping technologies commonly utilized with radiofrequency ablation. Lastly, with the recent advent of the second-generation cryoballoon, the effectiveness of cryoablation has further improved dramatically. This comprehensive review examines the gradual evolution of the cryoablation tools as well as the rationale and data in support of the currently-available cryoballoon technologies for catheter ablation of atrial fibrillation.

Adenosine-guided pulmonary vein isolation for the treatment of paroxysmal atrial fibrillation: an international, multicentre, randomised superiority trial

BACKGROUND

Catheter ablation is increasingly used to manage atrial fibrillation, but arrhythmia recurrences are common. Adenosine might identify pulmonary veins at risk of reconnection by unmasking dormant conduction, and thereby guide additional ablation to improve arrhythmia-free survival. We assessed whether adenosine-guided pulmonary vein isolation could prevent arrhythmia recurrence in patients undergoing radiofrequency catheter ablation for paroxysmal atrial fibrillation.

METHODS

We did this randomised trial at 18 hospitals in Australia, Europe, and North America. We enrolled patients aged older than 18 years who had had at least three symptomatic atrial fibrillation episodes in the past 6 months, and for whom treatment with an antiarrhythmic drug failed. After pulmonary vein isolation, intravenous adenosine was administered. If dormant conduction was present, patients were randomly assigned (1:1) to additional adenosine-guided ablation to abolish dormant conduction or to no further ablation. If no dormant conduction was revealed, randomly selected patients were included in a registry. Patients were masked to treatment allocation and outcomes were assessed by a masked adjudicating committee. Patients were followed up for 1 year. The primary outcome was time to symptomatic atrial tachyarrhythmia after a single procedure in the intention-to-treat population. The trial is registered with ClinicalTrials.gov, number NCT01058980.

FINDINGS

Adenosine unmasked dormant pulmonary vein conduction in 284 (53%) of 534 patients. 102 (69·4%) of 147 patients with additional adenosine-guided ablation were free from symptomatic atrial tachyarrhythmia compared with 58 (42·3%) of 137 patients with no further ablation, corresponding to an absolute risk reduction of 27·1% (95% CI 15·9-38·2; p<0·0001) and a hazard ratio of 0·44 (95% CI 0·31-0·64; p<0·0001). Of 115 patients without dormant pulmonary vein conduction, 64 (55·7%) remained free from symptomatic atrial tachyarrhythmia (p=0·0191 vs dormant conduction with no further ablation). Occurrences of serious adverse events were similar in each group. One death (massive stroke) was deemed probably related to ablation in a patient included in the registry.

INTERPRETATION

Adenosine testing to identify and target dormant pulmonary vein conduction during catheter ablation of atrial fibrillation is a safe and highly effective strategy to improve arrhythmia-free survival in patients with paroxysmal atrial fibrillation. This approach should be considered for incorporation into routine clinical practice.

FUNDING

Canadian Institutes of Health Research, St Jude Medical, Biosense-Webster, and M Lachapelle (Montreal Heart Institute Foundation).

Randomized, Controlled Trial of the Safety and Effectiveness of a Contact Force-Sensing Irrigated Catheter for Ablation of Paroxysmal Atrial Fibrillation: Results of the TactiCath Contact Force Ablation Catheter Study for Atrial Fibrillation (TOCCASTAR) Study

BACKGROUND

Contact force (CF) is a major determinant of lesion size and transmurality and has the potential to improve efficacy of atrial fibrillation ablation. This study sought to evaluate the safety and effectiveness of a novel irrigated radiofrequency ablation catheter that measures real-time CF in the treatment of patients with paroxysmal atrial fibrillation.

METHODS AND RESULTS

A total of 300 patients with symptomatic, drug-refractory, paroxysmal atrial fibrillation were enrolled in a prospective, multicenter, randomized, controlled trial and randomized to radiofrequency ablation with either a novel CF-sensing catheter or a non-CF catheter (control). The primary effectiveness end point consisted of acute electrical isolation of all pulmonary veins and freedom from recurrent symptomatic atrial arrhythmia off all antiarrhythmic drugs at 12 months. The primary safety end point included device-related serious adverse events. End points were powered to show noninferiority. All pulmonary veins were isolated in both groups. Effectiveness was achieved in 67.8% and 69.4% of subjects in the CF and control arms, respectively (absolute difference, -1.6%; lower limit of 1-sided 95% confidence interval, -10.7%; P=0.0073 for noninferiority). When the CF arm was stratified into optimal CF (≥90% ablations with ≥10 g) and nonoptimal CF groups, effectiveness was achieved in 75.9% versus 58.1%, respectively (P=0.018). The primary safety end point occurred in 1.97% and 1.40% of CF patients and control subjects, respectively (absolute difference, 0.57%; upper limit of 1-sided 95% confidence interval, 3.61%; P=0.0004 for noninferiority).

CONCLUSIONS

The CF ablation catheter met the primary safety and effectiveness end points. Additionally, optimal CF was associated with improved effectiveness.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov. Unique identifier: NCT01278953.