Fine versus coarse atrial fibrillation in rheumatic mitral stenosis: The impact of aging and the clinical significance

Background

Atrial fibrillation (AF) as the most rhythm disturbance in patients with rheumatic mitral stenosis (MS), is classified in to coarse and fine subtypes according to the height of fibrillatory wave amplitude. The aim of this study is to identify the factors associated with the presence of fine versus coarse morphology in patients with rheumatic MS.

Methods

In this cross‐sectional study, patients with confirmed diagnosis of severe rheumatic MS admitted between March 2013 and March 2017 were screened. Patients were categorized to sinus rhythm (SR) and AF rhythm (coarse and fine subtypes) groups according to the admission electrocardiogram. The association between various clinical and echocardiographic factors and the development of fine versus coarse AF were examined.

Results

Among 754 patients with the diagnosis of rheumatic MS, 288 (198 female) were found to have AF (38%). Among them 206 (71.5%), and 82 (28.5%) patients had fine and coarse morphology respectively. Patient in these two groups were quite similar in terms of echocardiographic parameters and comorbidities. However, patients with fine morphology AF were significantly older. (p‐Value=.007).

Conclusion

Coarse morphology of AF is common in patients with rheumatic MS. While echocardiographic or most clinical parameters do not seem to associate with the occurrence of coarse or fine morphology, age seems to be the only independent factor correlated with the presence of fine subtype of AF in this population.

     

Coarse fibrillatory waves in atrial fibrillation predict success of electrical cardioversion

Background

To determine whether the presence of “coarse” fibrillatory waves (Fw) seen on surface ECGs of patients with persistent atrial fibrillation (AF) predict maintenance of sinus rhythm (SR) at 6 weeks after electrical cardioversion (ECV).

Methods

Preprocedure ECGs from 94 consecutive patients with persistent AF scheduled to undergo ECV at a single centre were classified as having coarse Fw (≥0.1 mV) or fine Fw (<0.1 mV) in leads II or V₁. The primary outcome was ECG rhythm at 6‐week clinical follow‐up. Demographic and echocardiographic data were also collected.

Results

Thirty‐two patient ECGs (34%) had coarse Fw on baseline ECG in either or both leads II or V₁ with no significant differences in baseline demographics compared to those patients with fine Fw. At 6 weeks post‐ECV, in the coarse Fw group 72% of patients maintained SR vs. 42% in the fine Fw group (χ², p = .006) with the odds ratio (OR) of maintaining SR at 6 weeks in the presence of coarse Fw being 3.5 (95% CI: 1.4–8.9, p = .007). Across the overall study population, there were no other significant univariate predictors of SR at 6 weeks post‐ECV.

Conclusion

Classifying persistent AF using the maximal Fw amplitude on a surface ECG is a simple and reproducible method of predicting medium‐term success of ECV, independent of traditional risk factors.

     

Catheter Ablation for Long-Standing Persistent Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia worldwide and represents a major burden to health care systems. Atrial fibrillation is associated with a 4- to 5-fold increased risk of thromboembolic stroke. The pulmonary veins have been identified as major sources of atrial triggers for AF. This is particularly true in patients with paroxysmal AF but not always the case for those with long-standing persistent AF (LSPAF), in which other locations for ectopic beats have been well recognized. Structures with foci triggering AF include the coronary sinus, the left atrial appendage (LAA), the superior vena cava, the crista terminalis, and the ligament of Marshall. More than 30 studies reporting results on radiofrequency ablation of LSPAF have been published to date. Most of these are observational studies with very different methodologies using different strategies. As a result, there has been remarkable variation in short- and long-term success, which suggests that the optimal ablation technique for LSPAF is still to be elucidated. In this review we discuss the different approaches to LSPAF catheter ablation, starting with pulmonary vein isolation (PVI) through ablation lines in different left atrial locations, the role of complex fractionated atrial electrograms, focal impulses and rotor modulation, autonomic modulation (ganglionated plexi), alcohol ablation, and the future of epicardial mapping and ablation for this arrhythmia. A stepwise ablation approach requires several key ablation techniques, such as meticulous PVI, linear ablation at the roof and mitral isthmus, electrogram-targeted ablation with particular attention to triggers in the coronary sinus and LAA, and discretionary right atrial ablation (superior vena cava, intercaval, or cavotricuspid isthmus lines).     

Contraction-excitation feedback in human atrial fibrillation

Background: Contraction-excitation feedback, that is, electrophysiologic changes that are caused or preceded by mechanical changes of the myocardium, has been extensively studied in the ventricles. The role of contraction-excitation feedback in the atria, and more particularly in the genesis and maintenance of atrial fibrillation, has been less adequately investigated. Hypothesis: The aim of the present study was to determine whether increased right atrial pressure (RAP) facilitates the induction of atrial fibrillation (AF) in patients with a history of lone AF. Methods: Sixteen patients with a history of paroxysmal AF but without structural heart disease were included in the study. All patients underwent electrophysiologic study at both a lower (3.1 ± 2.0 mmHg) and (in 13 cases) a higher (6.4 ± 2.5 mmHg) RAP. “Higher” was considered the pressure following rapid (in about 30 min) intravenous administration of normal saline or before the administration of a diuretic. Results: Rapid atrial pacing induced AF in 19 of 29 attempts. At a lower pressure, rapid pacing induced brief (3 s to 3 min) AF in 3 of 16 patients, long-lasting (>3 min) AF in 3 of 16 patients, and no AF in 10 of 16 patients. At a higher pressure, brief AF was induced in 3 of 10 patients in whom no AF could be induced at a lower pressure, and long-lasting AF in 10 patients in whom either brief AF (3 cases) or no AF (7 cases) was induced at a lower pressure. In 11 patients, in whom Wenckebach periodicity was determined at both higher and lower pressure, the critical cycle length at which atrioventricular block appeared was significantly (p<0.001, paired t-est) longer(349.1 ± 44.4 ms, i.e.,+15.5 ± 11.3 ms)at higher than at lower atrial pressure (333.6 ±41.0 ms). In nine patients, in whom Wenckebach periodicity was determined and two rhythms occurred at different pressures, the critical cycle length was 332.2 ± 45.8 ms when associated with sinus rhythm, and significantly (p<0.01) longer (344.4 ± 48.0 ms, i.e., +12.2 ± 8.3 ms) when associated with induction of AF. Conclusion: In patients with lone atrial fibrillation, modest increases in atrial pressure may facilitate the induction of atrial fibrillation.     

Temporal aspects of Ca(2+) and myosin phosphorylation during myogenic and norepinephrine-induced arteriolar constriction

Previous studies demonstrated that maintenance of steady-state myogenic tone requires Ca(2+)-dependent myosin phosphorylation. The present studies furthered these observations by examining temporal relationships among Ca(2+), myosin phosphorylation and vessel diameter during acute increases in intraluminal pressure and norepinephrine stimulation. Rat cremaster muscle arterioles were cannulated and loaded with the Ca(2+)-sensitive indicator fura-2. The extent of myosin phosphorylation was measured using two-dimensional gel electrophoresis. Acute increases in intraluminal pressure caused a biphasic increase in intracellular Ca(2+) ([Ca(2+)](i)), characterized by a transient peak followed by a decline to a steady-state level which remained significantly higher than control values. Peak [Ca(2+)](i) was significantly related to vessel distension and increased with the change in wall tension. Increased intraluminal pressure resulted in a monophasic increase in myosin phosphorylation that was significantly correlated with instantaneous wall tension. In general, norepinephrine induced larger [Ca(2+)](i) transients and a biphasic myosin phosphorylation pattern. The results demonstrate: (a) major roles for Ca(2+) and myosin phosphorylation in arteriolar myogenic and norepinephrine-induced responses; (b) that changes in Ca(2+) and phosphorylation during a myogenic response are related to changes in wall tension, and (c) differences in Ca(2+) and phosphorylation patterns between the two modes of contraction reflect possible differences in underlying signaling mechanisms. The data further emphasize that spontaneous arteriolar tone represents a state of maintained smooth muscle activation that requires increases in [Ca(2+)](i) and myosin light-chain phosphorylation.     

Atrial fibrosis and substrate based characterization in atrial fibrillation: Time to move forwards

Atrial fibrillation (AF) is the most commonly encountered cardiac arrhythmia in clinical practice. However, current therapeutic interventions for atrial fibrillation have limited clinical efficacy as a consequence of major knowledge gaps in the mechanisms sustaining atrial fibrillation. From a mechanistic perspective, there is increasing evidence that atrial fibrosis plays a central role in the maintenance and perpetuation of atrial fibrillation. Electrophysiologically, atrial fibrosis results in alterations in conduction velocity, cellular refractoriness, and produces conduction block promoting meandering, unstable wavelets and micro-reentrant circuits. Clinically, atrial fibrosis has also linked to poor clinical outcomes including AF-related thromboembolic complications and arrhythmia recurrences post catheter ablation. In this article, we review the pathophysiology behind the formation of fibrosis as AF progresses, the role of fibrosis in arrhythmogenesis, surrogate markers for detection of fibrosis using cardiac magnetic resonance imaging, echocardiography and electroanatomic mapping, along with their respective limitations. We then proceed to review the current evidence behind therapeutic interventions targeting atrial fibrosis, including drugs and substrate-based catheter ablation therapies followed by the potential future use of electro phenotyping for AF characterization to overcome the limitations of contemporary substrate-based methodologies.     

钙信号调节异常在房颤电重构过程中的作用

心房颤动（AF）是一种多因素导致的疾病,持续性AF后期不可避免要有结构上出现相应的改变,故在早期电重构期进行针对性的治疗很有必要。本文主要从AF电重构产生的生理基础、AF患者钙信号的改变及AF药物治疗的新思想方面做一综述。     

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.     

Prospective Clinical Evaluation of Programmed Atrial Stimulation Protocol for Induction of Sustained Atrial Fibrillation and Flutter

We sought to define a minimum standardized protocol for induction of atrial fibrillation [AF] and/or atrial flutter. In contrast to ventricular stimulation protocols, a stimulation protocol for induction of AF or atrial flutter has not been critically evaluated. Since suppression of inducible AF or atrial flutter is used as one of the endpoints of success of pharmacologic and ablation therapies, there is an obvious need to define minimally appropriate electrical stimulation protocol for induction of AF or atrial flutter. We prospectively evaluated 70 patients, 44 with spontaneous atrial flutter or AF and 26 controls without documented atrial arrhythmias. A standardized programmed stimulation protocol, which employed up to three atrial extrastimuli delivered at two atrial sites at two atrial drive pacing lengths, was used in attempt to reproduce sustained AF and atrial flutter. The study endpoint was induction of sustained (>30 s) AF or atrial flutter. Sustained AF or atrial flutter was induced in 39/44 (89%) patients and 2/26 (7%) of controls (p <0.01). The arrhythmia induced was atrial flutter in 19/21 (91%) of atrial flutter patients, AF in 17/18 (94%) AF patients, both atrial flutter and AF in 5 AF/atrial flutter patients (100%). Two patients with atrial flutter had both AF/atrial flutter and 1 patient with AF had atrial flutter induced. The arrhythmia was induced from first stimulation site in 37 patients (85%) using a single in 9 (20%) patients, double 18 (41%) patients and triple extrastimuli in 10 (23%) patients. Two patients (5%) required stimulation from second site with two and three extrastimuli, respectively. The overall sensitivity and specificity of this stimulation protocol were 89% and 92%, respectively with a positive predictive accuracy of 95%.Conclusions. 1. Up to three atrial extrastimuli and two atrial sites are needed to increase yield of AF/atrial flutter induction at electrophysiologic study. 2. Induction of either AF or atrial flutter correlates well with presence of a similar spontaneous arrhythmia. 3. A baseline determination of the induction mode may be desirable prior to evaluation of interventions directed at AF or atrial flutter.     

Critical Atrial Site for Ablation of Pacing-Induced Atrial Fibrillation in the Normal Dog Heart

Site for Ablation of AF in Dogs. Introduction: Radiofrequency catheter ablation (RFA) has been used recently to treat atrial fibrillation (AF). The purpose of this study was to investigate a new approach to preventing AF by RFA.
Methods and Results: In open chest, anesthetized dogs, AF (lasting > 30 sec) was induced after burst stimulation, and electrophysiologic parameters were recorded before and after RFA. In group 1 (9 dogs) we performed selective and combined slow and fast pathway RFA, whereas in group 2(11 dogs) RFA was applied as a linear lesion at the mid-atrial septum between the inferior vena cava and the fossa ovalis. After ablation, the Wenckebach cycle length was significantly prolonged only in group 1 (194 ± 23 vs 282 ± 35 msec, P = 0.002). whereas the interval between the stimulus (S) artifact applied at the high right atrium to the His hundle (H) (SH interval) prolonged to the same extent in both groups (162 ± 14 vs 146 ± 45 msec. P = NS); group 1 due to an A-H prolongation whereas in group 2 it was due to an intra-atrial conduction delay. In group 1 AF still remained inducible, although with a longer mean R-R interval (215 ± 16 vs 433 ± 88 msec, P < 0.05). No instance of complete AV block developed. In group 2, sustained AF was noninducible in 10 dogs and its duration was markedly shorter in the remaining one (8 sec). Gross anatomy and histology did not reveal any damage inside of Koch's triangle, and particularly to the compact AV node.
Conclusion: These findings suggest that RFA at the mid-atrial septum prevents AF in the normal dog heart. This approach might also be successful in those clinical settings in which the atrial septum plays a critical role in the maintenance of sustained AF.     

持续性心房颤动患者无症状心房颤动的发生情况及影响因素

目的 分析持续性心房颤动(房颤)患者中无症状房颤的发生情况及影响因素.方法 收集经24 h动态心电图监测确诊的持续性房颤患者82例,观察症状的有无及发生比例.经抗心律失常药物治疗3个月后复查24 h动态心电图监测,观察症状的变化情况.采用多无logistic回归分析持续性房颤症状与临床特征的相关性.结果 82例患者中34例(42%)无症状房颤发作,48例有症状房颤发作.应用抗心律失常药物治疗3个月后,48例有症状患者中31例症状完全消失,其中4例转复为窦性心律,27例为无症状房颤发作.34例无症状患者中,5例转复为窦性心律,24例仍为无症状房颤发作.持续性房颤中有症状和无症状患者年龄,瓣膜病比较差异有统计学意义(P＜0.05).其症状与瓣膜病呈正相关(b=1.959,P=0.001),与年龄呈负相关(b=-0.837,P=0.032).结论 持续性房颤患者中无症状房颤的发生率较高.抗心律失常药物既可减少房颤发作,又可减少房颤症状.高龄和非瓣膜病房颤患者易发生无症状房颤.     

Factors predicting success rate and recurrence of atrial fibrillation after first electrical cardioversion in patients with persistent atrial fibrillation

BACKGROUND: The recurrence rate of atrial fibrillation (AF) after elective cardioversion is high. HYPOTHESIS: The study aimed to identify clinical predictors for successful electrical cardioversion and maintenance of sinus rhythm after a first electrical cardioversion in patients with persistent AF without concomitant antiarrhythmic drugs of class I and III. METHODS: Consecutive outpatients (n = 166) with persistent AF for > 1 month, scheduled for elective cardioversion, were prospectively included in the study. A clinical investigation, echocardiographic assay, and Holter electrocardiogram (ECG) before and ECG 4 weeks after cardioversion, were performed in all patients. RESULTS: The mean age of the patients was 68 years (range 45-83) and duration of AF was 5 (1-48) months. Sinus rhythm was established in 124 (75%) patients. In multivariate analysis, only duration of AF < 6 months (p < 0.04, odds ratio [OR] 2.2, 95% confidence interval [CI] 1.1 to 4.7) and patients weight (p < 0.03, OR 2.3, 95% CI 1.1 to 4.8 for weight < 80 kg) were identified as independent predictors of successful cardioversion. At 4 weeks after cardioversion, only 46 (37%) of 124 patients maintained sinus rhythm. Independent factors for maintenance of sinus rhythm, in multivariate analysis, were AF <3 months (p < 0.04, OR 2.5, 95% CI 1.1 to 5.6), treatment with beta blockers (p < 0.00001, OR 7.0, 95% CI 3.0 to 16.3) or verapamil/diltiazem (p < 0.04, OR 3.6, 95% CI 1.1 to 12.1), and right atrial dimension < 37 mm (p < 0.02, OR 5.9, 95% CI 1.4 to 25.4). CONCLUSIONS: In patients with persistent AF, the patient's weight and the duration of AF are independent predictors for a successful cardioversion. Short duration of AF, treatment with beta blockers or verapamil/diltiazem, and right atrial area/dimension are independent predictors for maintenance of sinus rhythm.     

Atrial fibrillation in patients with a dual defibrillator: characteristics of spontaneous and induced episodes and effect of ventricular tachyarrhythmia induction

BACKGROUND: The pattern of FF intervals during atrial fibrillation (AF) has been analyzed in induced and spontaneous AF episodes, after the induction of ventricular fibrillation (VF) and after atrial shock, in order to suggest practical considerations for AF management in patients implanted with antitachycardia devices. METHODS: In 13 patients implanted with a dual-chamber defibrillator, FF intervals were analyzed during two separate induced AF episodes, before and after VF induction over AF, as well as during spontaneous AF episodes and after unsuccessful atrial shocks. The following parameters were considered: mean atrial cycle length (CL), atrial CL stability, and standard deviation of the atrial cycle. RESULTS: The AF pattern had comparable characteristics considering two separate inductions of AF, as well as spontaneous AF episodes. Ventricular tachyarrhythmia induction resulted in a shortening of atrial CL (P < 0.02) and in a less organized AF pattern (P < 0.005). Changes in the FF interval after ineffective shock therapy showed a shortening of AF cycles after shocks with energies far below the defibrillation threshold. CONCLUSIONS: (a) The AF pattern is reproducible in separate inductions of sustained AF and in spontaneous episodes, (b) dynamic changes involving a shortening of the AF cycle and an evolution to a less homogeneous pattern occur after VF induction, revealing a complex interplay between AF and VF, and (c) FF interval analysis after ineffective shock delivery may allow the relationship between delivered shock energy and effective defibrillation energy to be estimated, thereby providing practical suggestions for step-up protocols in atrial cardioversion.     

血浆抵抗素水平与心房颤动关系的临床研究

目的：通过测定血浆抵抗素的水平,研究其在孤立性心房颤动（房颤）的发生与维持中的作用;同时分析影响其水平的相关因素及房颤的风险因素。方法研究对象为2014年6月至12月因心悸等不适就诊我院心内科的患者140例,其中试验组为房颤人群,分为孤立性房颤（60例）和房颤合并高血压（55例）;根据发病时间不同,孤立性房颤又分为阵发性与持续性房颤,各30例。正常对照组为正常人群,共25例。使用单因素方差分析比较房颤人群与正常人群血浆抵抗素水平的差异。用 Pearson 及多重线性回归法分析影响房颤患者抵抗素水平的相关因素。用 Logistic 回归分析影响房颤的风险因素。结果①超敏 C 反应蛋白（hs-CRP）及血浆抵抗素水平：所有房颤组的水平均高于对照组,其中孤立性房颤组低于房颤合并高血压组;阵发性房颤组低于持续性房颤组。② Pearson 相关分析：血浆抵抗素水平与hs-CRP 水平、左房内径大小及收缩压均呈正相关（分别为 r ＝0．530,P ＝0．000;r ＝0．265,P ＝0．004;r ＝0．364,P ＝0．000）。多重线性回归分析进一步显示收缩压（SBP）、hs-CRP 水平与血浆抵抗素的水平存在线性关系：Y ＝－2．172＋0．089 SBP ＋1．347 hs-CRP（R2＝0．307,P ＜0．05）。③ Logistic 回归分析表明血浆抵抗素水平、hs-CRP 水平均被纳入回归方程,且 OR 值均＞1。结论①血浆抵抗素水平孤立性房颤组明显高于对照组,其中又以持续性房颤组增高为著,表明抵抗素与房颤的发生、节律的维持相关。②血浆抵抗素水平与 hs-CRP 的水平呈正相关,间接表明房颤的发生可能与抵抗素具有某种炎性特质相关,提示抵抗素可引起炎症反应并和炎症介质一起参与了房颤发生、维持。③血浆抵抗素水平在房颤合并高血压患者中升高明显,且具有协同效应,提示抵抗素也许具有独立表达高血压与房颤疾病的潜质。同时本研究也证实了高血压为房颤的风险因素,可推测抵抗素通过高血压影响房颤。     

CT定量评价左心耳解剖结构与心房颤动射频消融术后复发的相关性研究

目的:采用256层螺旋CT定量评价左心耳解剖结构与心房颤动(房颤)射频消融术后复发的关系。方法:研究纳入83例首次进行射频消融术的房颤患者,平均年龄(60.36±10.11)岁,男性49例(59.04%)。所有患者术前均行256层螺旋CT检查,测量左心房体积、左心耳体积、左心耳开口周长、短径、长径、深径并收集患者临床资料。83例房颤患者行射频消融术后中位随访时间19(4~24)个月,27例(32.53%)患者复发。根据有无复发分为复发组(n=27例)和未复发组(n=56例)。结果:对83例患者的临床资料进行分析,复发组持续性房颤患者及心力衰竭(心衰)患者较未复发组比例更高,CHA2DS2-VASc评分更高(P均<0.05);对左心耳解剖结构分析,左心房体积、左心耳体积、左心耳开口周长、短径、长径、深径,复发组均大于未复发组(P均<0.05);多因素Cox比例风险回归分析显示较大的左心耳体积是房颤复发的独立预测因子(HR=1.160,95%CI:1.095~1.229,P<0.001);左心耳体积>9.25 ml对射频消融术后复发具有一定预测价值,敏感度85.2%、特异度67.9%、AUC 0.82,房颤复发率较高(P<0.00l)。结论:房颤会造成心脏结构重构,左心耳各解剖径线明显增大可能是房颤射频消融术后复发的原因,并且发现左心耳体积增大是房颤射频消融术后复发的独立预测因子。     

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.     

Temporal changes in atrial refractoriness following DC cardioversion of persistent atrial fibrillation in man.

AIMS: Studies have demonstrated shortening of the atrial effective refractory period (ERP) after episodes of atrial fibrillation (AF). This is termed atrial remodelling. It is unclear whether restoration of SR after persistent AF in patients with a clinical substrate results in reversal of this shortening and whether this is maintained long term. METHODS AND RESULTS: The ERP was determined at mid-lateral right atrial wall (MLRA) and right atrial appendage (RAA) at 600 ms and 400 ms drive cycle lengths and at basic sinus cycle length in 81 patients with persistent AF immediately, 24 h and 2 weeks following external DC cardioversion. All atrially active drugs were stopped for at least 5 half lives. (1) Prolongation of the ERP was observed at both atrial sites and all cycle lengths up to 24 h post cardioversion (p < 0.0001). (2) However, between 24 h and 2 weeks a subsequent shortening occurred in the ERP returning it to near post cardioversion levels. (3) The ERP was significantly longer at 24 h post cardioversion in patients who remained in SR for 2 weeks or longer compared with those who reverted to AF. CONCLUSION: Prolongation of the atrial ERP occurred following restoration of SR in persistent AF patients but was not maintained and displayed a biphasic pattern such that by 2 weeks the ERP had returned to baseline values. Despite this finding, a longer ERP at 24 h post cardioversion was associated with maintenance of SR in the medium-term.     

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.     

钙离子通道与老龄心房颤动心房电重构的研究进展

随着心房颤动电生理机制研究的广泛深人,已经认识到离子通道重构在心房颤动的发生和维持过程中起重要作用。L-型钙通道及其基因表达的改变可能是老年人容易发生心房颤动电生理重建的离子和分子基础。现就心脏钙离子通道及年龄与心房颤动的研究进展予以综述。