Catheter ablation is preferred over surgery for persistent atrial fibrillation

There are important limitations that can hinder outcomes of surgical ablation in nonparoxysmal patients with atrial fibrillation (AF), which is the typical AF population undergoing concomitant cardiac surgery for valve or ischemic heart disease. Incomplete lesions with recovered conduction or gaps as well as arrhythmias originating from areas not targeted by surgical ablation are commonly seen at the time of recurrence. Therefore, while it might be reasonable to perform AF surgery in this cohort, it is important to know these limitations and establish adequate postoperative rhythm monitoring to detect recurrences, which can be effectively addressed by catheter ablation.     

Role of repolarization restitution in the development of coarse and fine atrial fibrillation in the isolated canine right atria

INTRODUCTION: Although the role of action potential duration restitution (APD-R) in the initiation and maintenance of ventricular fibrillation (VF) has been the subject of numerous investigations, its role in the generation of atrial fibrillation (AF) is less well studied. The cellular and ionic basis for coarse versus fine AF is not well delineated. METHODS AND RESULTS: We measured APD-R during acetylcholine-mediated AF as well as during pacing (standard and dynamic protocols) in crista teriminalis, pectinate muscle, superior vena cava, and appendage of isolated canine arterially perfused right atria (n = 15). Transmembrane action potential (TAP), pseudo-ECG, and isometric tension development were simultaneously recorded. Acetylcholine flattened APD-R measured by both standard and dynamic protocols, but promoted induction of AF. AF was initially coarse, converting to fine within 3-15 minutes of AF. Coarse, but not fine AF was associated with dramatic fluctuations in tension development, reflecting wide variations in intracellular calcium activity ([Ca(2+)](i)). During coarse AF, APD-R data displayed a cloud-like distribution pattern, with a wide range of maximum APD-R slope (from 1.21 to 0.35). A maximum APD-R slope >1 was observed only in crista terminalis (3/10). The APD-R relationship was relatively linear and flat during fine AF. Reduction of [Ca(2+)](i) was associated with fine AF whereas augmentation of [Ca(2+)](i) with coarse AF. CONCLUSIONS: Our data indicate that while APD-R may have a limited role in the maintenance of coarse AF, it is unlikely to contribute to the maintenance of fine AF and that [Ca(2+)](i) dynamics determine the degree to which AF is coarse or fine.     

A comparison of clinical characteristics and long-term prognosis in asymptomatic and symptomatic patients with first-diagnosed atrial fibrillation: The Belgrade Atrial Fibrillation Study

Background

To investigate baseline characteristics and long-term prognosis of carefully characterized asymptomatic and symptomatic patients with atrial fibrillation (AF) in a ‘real-world’ cohort of first-diagnosed non-valvular AF over a 10-year follow-up period.

Methods and results

We conducted an observational, non-interventional, and single-centre registry-based study of consecutive first-diagnosed AF patients. Of 1100 patients (mean age 52.7 ± 12.2 years and mean follow-up 9.9 ± 6.1 years), 146 (13.3%) had asymptomatic AF.Persistent or permanent AF, slower ventricular rate during AF (< 100/min), CHA₂DS₂–VASc score of 0, history of diabetes mellitus and male gender were independent baseline risk factors for asymptomatic AF presentation (all p < 0.01) with a good predictive ability of the multivariable model (c-statistic 0.86, p < 0.001).Kaplan–Meier 10-year estimates of survival free of progression of AF (log-rank test = 33.4, p < 0.001) and ischemic stroke (log-rank test = 6.2, p = 0.013) were significantly worse for patients with asymptomatic AF compared to those with symptomatic arrhythmia. In the multivariable Cox regression analysis, intermittent asymptomatic AF was significantly associated with progression to permanent AF (Hazard Ratio 1.6; 95% CI, 1.1–2.2; p = 0.009).

Conclusions

In a ‘real-world’ setting, patients with asymptomatic presentation of their first-diagnosed AF could have different risk profile and long-term outcomes compared to those with symptomatic AF. Whether more intensive monitoring and comprehensive AF management including AF ablation at early stage following the incident episode of AF and increased quality of oral anticoagulation could alter the long-term prognosis of these patients requires further investigation.     

Update on atrial fibrillation: part II

Antiarrhythmic drugs are an essential tool in the management of atrial fibrillation (AF). Although we are already on the threshold of a large expansion in the use of ablation therapies, these will not, however, be appropriate for all patients, and pharmacological therapies will continue to have an important place in the management of atrial fibrillation. The plethora of antiarrhythmic drugs currently available for the treatment of atrial fibrillation is a reflection that none is wholly satisfactory, each having limited efficacy combined with poor safety and tolerability. Improved class III antiarrhythmic drugs, such as dronedarone, new classes of antiarrhythmic agents, such as atrial repolarization delaying agents, and upstream therapies dealing with substrate, represent potential sources of new pharmacological therapies.     

Lone atrial fibrillation: influence of familial disease on gender predilection

Introduction: Epidemiological studies report a male predominance in lone atrial fibrillation (LAF). Phenotypic differences between sporadic and familial LAF could aid in deciding which cases should undergo family screening. We sought to determine gender distribution in sporadic and familial LAF, gender-based differences, and phenotypic differences between sporadic and familial LAF.
Methods: Since November 2000, 192 unrelated LAF probands were recruited. Sporadic LAF was defined as the absence of a family history of LAF. Familial LAF was classified as possible if one first- or second-degree relative had LAF, or confirmed if ≥ 2 relatives had LAF. Affected relatives (n = 87) of 34 confirmed familial probands were also evaluated. For unrelated LAF probands, differences in proportions and means were tested using χ² and ANOVA, respectively. Difference in gender ratio among the family history groups was tested using mixed models.
Results: Male proportion was greater among sporadic (82%) and possible familial probands (84%) than confirmed familial probands (62%), and affected relatives (54%), P < 0.001. Sporadic LAF was more common in men (62%) than women (51%), P = 0.03. More women were affected by palpitation and nocturnal symptoms than men. More patients had permanent AF in the confirmed familial group (27%), compared with the possible familial (7%) and the sporadic LAF group (8%), P = 0.05, but no other phenotypic discriminators were identified.
Conclusions: Male predilection for LAF is attenuated as the likelihood of dominant Mendelian inheritance increases. Increased frequency of "sporadic" LAF among men could be partially due to X-linked recessive inheritance. Finally, sporadic and familial LAF are clinically indistinguishable.     

Occam's razor and the unraveling of atrial fibrillation

The search for a mechanism to explain atrial fibrillation (AF) has lasted for over a century and continues. Significant progress in understanding this arrhythmia accelerated with the era of operative treatment of this arrhythmia and intensified with the advent of catheter ablation. Through considerable trial and some error, effective "curative" therapies have evolved for paroxysmal AF and are evolving for persistent AF. It is becoming clear that no single mechanism suffices to explain AF in all its forms and multiple mechanisms are playing a role in the most complicated cases.     

心房颤动的基础研究和临床治疗新进展

近年来,心房颤动的基础研究和临床治疗有很多新的进展,现对此作一综述。     

Atrial fibrillation: mechanistic insights from biatrial (and triatrial) mapping

Percutaneous radiofrequency ablation of pulmonary vein potentials has been shown to eliminate atrial fibrillation in a subset of patients characterized by frequent and repetitive paroxysms of atrial fibrillation. However, pulmonary vein disconnection has had only limited success at curing patients with persistent atrial fibrillation. In those patients, left atrial substrate modification and linear ablation strategies have had substantially higher success rates. Furthermore, in other patients, elimination of right atrial triggers (superior vena cava) or modification of right atrial substrate has been required for elimination of atrial fibrillation. Finally, the realization that the coronary sinus is a third atrial chamber that can both initiate and maintain atrial fibrillation has provided new understanding to the pathogenesis of atrial fibrillation. From a clinical perspective, only careful anatomic and mapping strategies specifically aimed at each subset of patients with atrial fibrillation will allow for pattern recognition and establish which mechanisms are responsible for initiation and maintenance of atrial fibrillation. Only the latter will allow for increased long-term success rates of ablation of atrial fibrillation.     

120例房颤患者24h动态心电图分析

目的：分析房颤患者12导联动态心电图,探讨其伴发的异常表现与年龄、疾病诊断情况及心脏器质性病变的关系,进一步认识阵发性房颤。方法收集我院动态心电图检测诊断为房颤（AF）及阵发性房颤（PAF）的120例患者的动态心电图,采用回顾性分析方法,根据动态心电图记录房颤中伴发的异常表现,结合临床资料进行分析和总结。结果①120例房颤患者中,动态心电图检测显示68例伴发有不同类型的心电图异常,异常发生率为68／120（56．7％）,其中以快速心室率及室性早搏最多见,分别占37／120（30．8％）和35／120（29．2％）,其次分别为：ST-T 改变占32／120（26．7％）;传导阻滞占29／120（24．2％）;＞2．0 s 的长 R-R 间期占23／120（19．2％）和室性心动过速7／120（4．2％）。在65岁以上的房颤患者中,心电图伴发的异常表现在同一患者有时可达两种或两种以上。②120例房颤患者中阵发性房颤有18例,占15％（18／120）,多由房性早搏触发所致。肺心病组、冠心病组、外科检查组和风心病组都以室性早搏最多见,分别占45％（5／11）、50．0％（11／22）、42．9％（2／7）和30．0％（3／10）;高血压组以ST-T 改变最多见,占44．1％（15／34）;胸闷、心悸组、甲亢组及糖尿病组都以快速心室率最多见,分别占38．0％（8／21）、33．3％（1／3）和22．2％（2／9）;晕厥组中1例伴发快速心室率,1例伴发＞2．0 s 的长 R-R 间期。有器质性心脏病房颤患者动态心电图伴发异常表现率可高达67．4％。结论动态心电图可准确显示房颤患者伴发的心电图异常表现,在合并器质性心脏病和／或65岁以上的房颤患者中有时达两种甚至更多,可确定阵发性房颤的心电始动因素及其部位。     

Immediate Reinitiation of Atrial Fibrillation Following Internal Atrial Defibrillation

Immediate Reinitiation of AF. Introduction: Although the recurrence rate of atrial fibrillation has been reported to be similar to that after external and internal cardioversion, little is known about immediate reinitiation of atrial fibrillation (IRAF) following internal cardioversion. Methods and Results: Thirty-eight patients (24 men; mean age 63 ± 13 years) underwent internal atrial defibrillation. Catheter-based defibrillation electrodes were positioned in the anterolateral right atrium and the coronary sinus. All patients were cardioverted at a mean threshold of 4.6 ± 3.4 J. Five of 38 patients (13%) had 1 to 4 episodes of IRAF. No difference in clinical and echocardiographic characteristics were observed when patients with and without IRAF were compared. Atrial fibrillation was always reinitiated by an atrial premature beat. When the earliest atrial endocardial activation time on the defibrillation catheters was analyzed, these atrial premature heats did not seem to originate from the defibrillation catheters. Twenty-one patients had atrial premature heats without IRAF. When the coupling intervals of the first atrial premature heat in patients without and with IRAF after conversion were compared, a significant difference was found (661 ± 229 vs 418 ± 79 msec, P < 0.05). IRAF was successfully treated with repeated shock delivery after the administration of atropine in 1 patient and intravenous flecainide in 2. Only repeated shock delivery was sufficient to treat IRAF in another 2 patients. Late recurrences of atrial fibrillation occurred in 3 of 5 with IRAK and in 19 of 33 patients without IRAF (P = NS). Conclusion: IRAF after internal atrial defibrillation occurred in 13% of patients, was always initiated by an atrial premature heat having a short coupling interval not originating from the defibrillation catheters, and was prevented by repeated shock delivery with or without preceding administration of pharmacologic agents. IRAF did not predict early recurrences of the arrhythmia after discharge from the hospital, emphasizing the necessity to treat immediate reinitiation promptly to achieve a successful cardioversion.     

Heterogeneous changes in electrophysiologic properties in the paroxysmal and chronically fibrillating human atrium

INTRODUCTION: The regional changes in atrial electrophysiologic properties related to atrial fibrillation (AF) in patients with paroxysmal AF (PAF) and chronic AF (CAF) remain unclear. The purpose of this study was to investigate the regional changes in atrial electrophysiology in patients with AF. METHODS AND RESULTS: We evaluated the atrial electrophysiology at different sites (high right atrium, low right atrium [LRA], and distal coronary sinus [DCS]) in 11 patients with CAF, 8 patients with PAF, and 10 controls. Patients with CAF had significantly prolonged interatrial conduction and corrected sinus node recovery time, and shortened atrial effective refractory period (ERP) with loss of rate-related adaptation in the DCS, but had paradoxic prolongation of atrial ERP in the LRA, as compared with patients with PAF and the controls. As a result, the spatial distribution of atrial ERP that was observed in the controls and in patients with PAF was reversed in patients with CAF, without an increase in the dispersion of atrial refractoriness. Patients with PAF showed intermediate changes in atrial conduction times and atrial refractoriness as compared with patients with CAF and controls. CONCLUSION: There was a regional heterogeneity on the changes of atrial electrophysiology in different parts of the atrium, and the "normal" spatial distribution of atrial refractoriness was reversed in patients with CAF. The electrophysiologic changes observed in patients with PAF appear to behave as if in transition from the control state to CAF, suggesting progressive changes in atrial electrophysiologic properties.     

Implantable Atrial Defibrillators

Implantable Atrial Defibrillators. Due to the limited efficacy of antiarrhythmic drugs for atrial fibrillation, several nonpharmacologic therapeutic options have evolved. One of these is an implantable atrial defibrillator. Recent studies have shown that internal atrial defibrillation is feasible with relatively low energies. To date, the optimal electrode configuration involves large surface area catheters in the right atrium and coronary sinus. In humans, atrial defibrillation can generally be achieved with < 2 J using this electrode configuration and a biphasic shock waveform. For shocks < 5 J, there is no significant pathological damage to the atria or coronary sinus. Further investigation is needed to guarantee that atrial defibrillation shocks do not provoke ventricular arrhythmias. Preliminary data suggest that atrial defibrillation shocks synchronized to R waves that are not closely coupled are safe. In addition, the shocks are well tolerated if the shock energy is < 1.5 J. With additional studies to confirm the safety of implantable atrial defibrillators, further reduce shock energy, and improve patient tolerance, an implantable atrial defibrillator can become an acceptable therapy for patients with symptomatic, paroxysmal atrial fibrillation.     

ZV1,ZV5导联心室晚电位的检出率及临床意义

用Ｘ、Ｙ、Ｚ正交导联和改良的ＺＶ１、ＺＶ５导联，对３８例室性早搏病人进行心室晚电位检测。结果显示ＺＶ１、ＺＶ５导联法晚电位阳性率明显高于Ｘ、Ｙ、Ｚ正交导联法（ｕ＝４．６９，Ｐ〈０．０１），改进、弥补了Ｘ、Ｙ、Ｚ正交导联对晚电位“稀释”的不足。用ＤＣＧ同时记录，发现ＺＶ１导联法晚电位阳性与右室起源的早搏有关；ＺＶ５导联法记录的晚电位与左室起源的早搏有关。显示改良的ＺＶ１、ＺＶ５导联与传统的Ｘ、Ｙ、Ｚ     

Maintenance of Sinus Rhythm after Cardioversion of Atrial Fibrillation in Patients with Lone Atrial Fibrillation and Patients with Hypertension

Background: The success rate and prognosis of cardioversion of atrial fibrillation (AF) in patients with organic heart disease is well known. In contrast, little data exist about cardioversion success and maintenance of sinus rhythm (SR) in patients with lone AF and in patients with hypertension as the only underlying cardiovascular disease. Methods: In a prospective cardioversion registry 148 of 181 patients (81.8%) with lone AF (age 58 ± 13 years, duration of AF 7.6 ± 19 weeks) and 120 of 148 patients (81.1%) with hypertension (age 62 ± 10 years, duration of AF 6.6 ± 21 weeks) had successful cardioversion and were followed for 7.7 ± 1.9 months. Results: At follow-up, 120 patients (81.1%) with lone AF were in SR, and 18 of these patients had had repeated cardioversion during follow-up (AF total recurrence rate 31.1%). In stepwise regression analysis, the number of previous cardioversions was predictive of rhythm at follow-up (P = 0.0453). Rhythm at follow-up did not differ between patients who were or were not on antiarrhythmic drugs. At follow-up 96 patients (80%) with hypertension were in SR, and 9 of these had had repeated cardioversion during follow-up (AF total recurrence rate 27.5%). As in lone AF, the recurrence rate of AF did not differ between patients with or without antiarrhythmic drug treatment, and in multivariate regression analysis, the number of previous cardioversions was the only clinical predictor of rhythm at follow-up (P = 0.0284). Conclusions: Even in patients with such benign conditions as lone AF or hypertension as the only underlying disease, the prognosis of cardioversion in terms of maintenance of SR is poor. Future studies of rhythm control versus rate control need to include not only patients with organic heart disease but also patients with lone AF and patients with hypertension, since the long-term benefits of these two strategies remain unclear even in these subsets of patients.     

不同类型非瓣膜病性心房颤动并发缺血性脑卒中临床风险比较

目的研究非瓣膜病性心房颤动（房颤）患者中持续性房颤与阵发性房颤患者发生急性缺血性脑卒中的临床风险比较。方法将343例脑卒中患者分为重症（NIHSS评分≥22分）,轻症（NIHSS评分≤8分）,再将重症患者分为持续性房颤组、阵发性房颤组与非房颤组。轻症患者同样分组,进行临床资料分析。结果重症患者中房颤发生总例数明显增多,较非房颤差异有统计学意义,其中,持续性房颤组与阵发性房颤组比较差异无统计学意义。轻症患者中,非房颤例数明显增多,较房颤组差异有统计学意义,持续性房颤组与阵发性房颤组比较差异有统计学意义。在脑卒中危险因素中,D-二聚体及纤维蛋白原房颤患者较血栓形成脑卒中差异有统计学意义。结论房颤易造成大面积脑梗死,且病情危重,阵发性房颤与持续性房颤同样具有高风险,应得到及时有效的预防措施。