Ventricular fibrillation in hypertrophic cardiomyopathy is associated with increased fractionation of paced right ventricular electrograms.

BACKGROUND. Intraventricular conduction in hypertrophic cardiomyopathy (HCM) has been characterized to test the hypothesis that myofibrillar disarray will cause dispersion of activation throughout the ventricular myocardium. METHODS AND RESULTS. Of 37 patients with HCM, four had spontaneous ventricular fibrillation (VF), five had nonsustained ventricular tachycardia (VT), 13 had no risk factors, and 15 had a family history of sudden death. These patients and four controls were studied by pacing one site in the right ventricle and recording electrograms from three other right ventricular sites. These electrograms were high-pass filtered to emphasize small deflections due to activation of small bundles of myocytes close to the electrode. Intraventricular conduction curves were obtained with S1S2 coupling intervals decreasing in 1-msec steps from 479 msec to ventricular effective refractory period (VERP). These curves were repeated by pacing each RV site in turn and were characterized by two parameters: the point at which latency increased by 0.75 msec/20 msec reduction of the S1S2 coupling interval and an increase in electrogram duration between an S1S2 of 350 msec and VERP. Patients with VF, VT, and family history of sudden death had a mean increase in electrogram duration of 12.8 (2.9-32.3) msec versus 4.6 (-4.2 to 14.0) msec in low-risk patients and controls. Electrogram latency increased at an S1S2 of 363 msec in the VF group (342-386), 269 msec in the controls (266-279), and 326 msec in the non-VF group (260-399). Discriminant analysis separated VF patients from the remainder (p less than 0.0001) and VF, VT, and family history of sudden death patients from the low-risk and control groups (p less than 10(-6)). CONCLUSIONS. Patients with HCM who are at risk of sudden death have increased dispersion and inhomogeneity of intraventricular conduction, and this may create the conditions for reentry and arrhythmogenesis.     

Prolonged and fractionated right atrial electrograms during sinus rhythm in patients with paroxysmal atrial fibrillation and sick sinus node syndrome

Intraatrial catheter mapping of the right atrium was performed during sinus rhythm in 92 patients: Group I = 43 control patients without paroxysmal atrial fibrillation or sick sinus node syndrome; Group II = 31 patients with paroxysmal atrial fibrillation but without sick sinus node syndrome; and Group III = 18 patients with both paroxysmal atrial fibrillation and sick sinus node syndrome. Atrial electrograms were recorded at 12 sites in the right atrium. The duration and number of fragmented deflections of the atrial electrograms were quantitatively measured. The mean duration and number of fragmented deflections of the 516 atrial electrograms in Group I were 74 +/- 11 ms and 3.9 +/- 1.3, respectively. The criteria for an abnormal atrial electrogram were defined as a duration of greater than or equal to 100 ms or eight or more fragmented deflections, or both. Abnormal atrial electrograms were observed in 10 patients (23.3%) in Group I, 21 patients (67.7%) in Group II and 15 patients (83.3%) in Group III (Group II versus Group I, p less than 0.001; Group III versus Group I, p less than 0.001). The mean number of abnormal electrograms per patient with an abnormal electrogram was 1.3 +/- 0.7 in Group I, 2.5 +/- 1.9 in Group II and 3.5 +/- 2.5 in Group III (Group I versus Group II, p less than 0.01; Group II versus Group III, p less than 0.05). A prolonged and fractionated atrial electrogram characteristic of paroxysmal atrial fibrillation can be closely related to the vulnerability of the atrial muscle.(ABSTRACT TRUNCATED AT 250 WORDS)     

Extended distribution of prolonged and fractionated right atrial electrograms predicts development of chronic atrial fibrillation in patients with idiopathic paroxysmal atrial fibrillation

INTRODUCTION: This study evaluates whether electrophysiologic abnormalities in patients with idiopathic paroxysmal atrial fibrillation (PAF) predict the transition to chronic atrial fibrillation (CAF). METHODS AND RESULTS: Ninety-six patients with idiopathic PAF underwent electrophysiologic study and were followed up. During electrophysiologic study, endocardial mapping was performed at 12 sites in the right atrium (four aspects of the high, middle, and low right atrium). During follow-up of 60 to 130 months, conversion from PAF to CAF was observed in 17 patients (CAF group). The remaining 79 patients remained in sinus rhythm (PAF group). Although a high frequency of abnormal atrial electrograms was observed in the high right atrium in both groups, the frequency of those recorded from the middle right atrium was significantly higher in the CAF group than in the PAF group (70.6% vs 13.9%, P < 0.0005). Kaplan-Meier analysis showed that >50% of the patients with abnormal atrial electrograms in the middle right atrium developed CAF after 10 years, whereas only 7% of patients without those developed CAF (P < 0.0001). CONCLUSION: Our data suggest that extended distribution of abnormal atrial electrograms from the high to middle right atrium is predictive of the development of CAF in patients with idiopathic PAF.     

老年对慢性心房颤动患者左房复杂碎裂电位的影响

目的 评价老年对非瓣膜病心房颤动（简称房颤）患者左房复杂碎裂电位（CFAEs）的影响。方法 前瞻性入选116例行导管消融的慢性房颤患者。 以60岁为界,分为老年组（n=48）与非老年组（n=68）。 在CARTO系统指导下记录局部稳定的心内膜电图。 应用CARTO系统内置的CFAEs分析软件进行分析。 以间期置信水平（ICL）来评估CFAEs的特点。 CFAEs指数定义为 ICL≥7 区域的面积与左房表面积的比值。 将左房分为前壁、后壁、顶部、下壁、外侧壁、间隔六个部分,评价CFAEs在左房不同位置的分布特征。 结果 老年组男性患者比例显著低于非老年组,合并高血压、脑卒中的比例显著高于非老年组（P均〈0. 05）。 老年组最大ICL显著大于非老年组[（16.7±2.0） vs （15.7±2.2）,P=0. 014）],老年组CFAEs指数显著高于非老年组[（60. 4%±22.9% ） vs （48. 6%±22. 3% ）,P=0. 007）]。 老年组左房前壁、间隔的CFAEs的分布比例显著大于非老年组。 年龄与CFAEs指数呈正相关（r=0. 244, P=0. 008）。 结论 老年慢性房颤具有广泛的 CFAEs。     

Mechanism of conversion of atypical right atrial flutter to atrial fibrillation

The purpose of this study was to explore the mechanisms of conversion from atypical atrial flutter (AFL) to atrial fibrillation (AF), and the long-term results of cavotricuspid isthmus ablation in these patients. We retrospectively reviewed the records of 221 patients with typical AFL referred to our hospital for ablation. A total of 25 patients had atypical AFL, and cavotricuspid isthmus ablation was performed in 23 with isthmus-dependent atypical AFL, as well as in 180 patients with typical counterclockwise and/or clockwise AFL. In all, 13 spontaneous transitions from atypical AFL to AF were documented in 11 of 17 patients. Before AF, a pattern of lower loop reentry was observed in 11 of 13 patients (85%) and upper loop reentry in 3 (1 had both). Multiple early breaks along the tricuspid annulus during AFL were noted in 6 of 13 patients (46%). Among the 13 transitions, discrete atrial premature complexes before AF were found in 5 patients with lower loop reentry and in 1 with upper loop reentry (46%). In the remaining patients, a more rapid atrial rhythm was involved in the development of AF with a pulmonary venous focus in 2. In some cases, additional "breaks" in the functional line of block occurred before the development of AF. There was a significant increased incidence of AF (68%) in those with atypical AFL compared with those with typical AFL (38%) (p = 0.004). After a mean follow-up of 28 +/- 9 months for the atypical group and 18 +/- 11 months for the typical group, the AF recurrence rate was similar (57% vs 48%, p = 0.4). Discrete atrial premature complexes or atrial tachycardia may initiate AF either directly or by producing further breaks in lines of functional block. Bidirectional cavotricuspid isthmus block is associated with cure or control of AF in approximately 50% of patients with AFL.     

Autonomic modulation of complex fractionated atrial electrograms in patients with paroxysmal atrial fibrillation

Aims  

In patients with atrial fibrillation (AF), complex fractionated atrial electrograms (CFAE) have been shown to be located at the anatomic sites of ganglionated plexi (GP). This study aimed at investigating the contribution of parasympathetic activity to formation of CFAE.     

Efficacy and safety of dofetilide in patients with atrial fibrillation and atrial flutter

Background  Dofetilide, an I_Kr blocker has been demonstrated to be effective in terminating persistent atrial fibrillation and flutter (AF/AFL), and in maintaining sinus rhythm after direct current cardioversion (CV). It is not known, however, whether pharmacological conversion with dofetilide predicts maintenance of sinus rhythm. In addition, there is limited information comparing the efficacy of dofetilide in persistent versus paroxysmal AF/AFL. Methods and Results  Eighty consecutive patients with AF/AFL (51 persistent, 29 paroxysmal) admitted for initiation of dofetilide were studied. Termination of persistent AF/AFL occurred in 61% of patients while 39% required CV. After 21 ± 19 months of follow-up, 37% of patients with persistent AF/AFL were free of recurrence. Acute conversion with dofetilide did not predict long term efficacy. Dofetilide was more effective in maintaining sinus rhythm in patients with AFL (65%) than in those with AF (25%) (p < 0.05). Dofetilide was more likely to maintain sinus rhythm in patients with persistent than paroxysmal AF/AFL (37 vs. 14%; p < 0.05). Torsades de Pointes developed in two patients despite careful dosing and monitoring of QT changes. Conclusions  Dofetilide is more effective in patients with persistent than in those with paroxysmal AF/AFL. Importantly, short-term response does not necessarily predict long-term efficacy. Significant proarrhythmia can occur even with careful in-hospital monitoring. Dr. Banchs and Dr. Wolbrette contributed equally to this study. Presented in abstract form at the XIII World Congress on Cardiac Pacing and Electrophysiology; December 3, 2007; Rome and published in abstract form (Giornale Italiano di Aritmologia e Cardiostimolazione 2007;10(3):26).     

静脉地尔硫治疗快速房颤、房扑的疗效分析

为检验静脉地尔硫艹卓控制房颤、房扑心室率的有效性和安全性，对４７例快速房颤、房扑患者一次静脉注射０．２５ｍｇ／ｋｇ地尔硫艹卓后以５ｍｇ／ｈ～１０ｍｇ／ｈ微泵维持，平均起效时间５．２±２．７ｍｉｎ，总有效率９３．６％，心功能较用药前明显改善（Ｐ＜０．０５），对血压无明显影响，副作用发生率为１０．６％，均不严重。结果提示地尔硫艹卓是一种能迅速、安全、有效控制房颤、房扑患者心室率的药物     

The effects of aging on atrial endocardial electrograms in patients with paroxysmal atrial fibrillation

BACKGROUND: The prevalence of atrial fibrillation (AF) has been reported to increase with advancing age. Histologic studies in AF have demonstrated that the percentage of fibrosis and degenerative changes in the atrial muscle increase significantly with age. HYPOTHESIS: This study was undertaken to assess the influence of advancing age on atrial endocardial electrograms recorded during sinus rhythm in patients with paroxysmal atrial fibrillation (PAF), which had not been assessed previously. METHODS: Right atrial endocardial catheter mapping during sinus rhythm was performed in 111 patients with PAF to evaluate the influence of advancing age on atrial endocardial electrograms. The bipolar electrograms were recorded at 12 sites in the right atrium, and an abnormal atrial electrogram was defined as lasting > or = 100 ms, and/or showing eight or more fragmented deflections. RESULTS: In all, 1,332 right atrial endocardial electrograms were assessed and measured quantitatively. The number of abnormal atrial electrograms in patients with PAF showed a significantly positive correlation with age (r = 0.34; p < 0.0005). Patients aged > 60 years had a significantly greater mean number of abnormal electrograms (2.58 +/- 2.05) than those aged < 60 years (1.43 +/- 2.03; p < 0.004). The longest duration (r = 0.35; p < 0.0005) and the maximal number of fragmented deflections (r = 0.29; p < 0.005) of atrial electrograms among the 12 right atrial sites also showed a significantly positive correlation with age. CONCLUSIONS: Aging alters the electrophysiologic properties of the atrial muscle in patients with PAF. Elderly patients have a significantly greater abnormality of atrial endocardial electrograms than do younger ones. There is a progressive increment in the extension of altered atrial muscle with advancing age in patients with PAF.     

Incidence of atrial flutter and atrial fibrillation in patients with implanted physiological pacemakers

Atrial flutter (AF) is a troublesome arrhythmia for patients with an implanted pacemaker. Although it has recently become possible to eliminate AF by radiofrequency catheter ablation (RF-CA), the incidence of AF before and after pacemaker implantation has not been clarified. The present study was conducted with 123 consecutive patients (69.3+/-11.6 (SD) years old) implanted with pacemakers, excluding patients who had chronic atrial fibrillation (AFib) when the pacemaker was implanted; 69 patients with atrioventricular (AV) block and 54 patients with sick sinus syndrome (including 29 patients with bradycardia-tachycardia syndrome). All patients were implanted with physiological pacemakers. The follow-up period was 4.7+/-1.9 years. In 11 of the 123 patients (8.9%), AF was observed before pacemaker implantation and the incidence was significantly higher in patients with sick sinus syndrome than in those with AV block (16.7 vs 2.9%, p<0.01). Nine of the 29 patients with bradycardia-tachycardia syndrome (31%) had AF. After physiological pacemaker implantation, AF recurred in 9 of the 11 patients, and AF was newly observed in 1 patient. Thus, 10 of the 123 patients (8.1%) had AF after physiological pacemaker implantation. Recurrence of AF was not suppressed by physiological pacing. Thirty of the 123 patients had AFib before implantation of a pacemaker and its occurrence was reduced by physiological pacing (from 24.4% to 12.2%, p<0.05). The incidence of AFib in patients with AF was significantly higher than in those without AF (90.0 vs 5.3%, p<0.001). In conclusion, the recurrence of AF is not prevented by physiological pacing and is closely related to the occurrence of AFib. RF-CA should be considered in patients who have AF before pacemaker implantation.     

起搏术后心房颤动的影响因素及心房颤动与心钠素的关系

目的观察心脏起搏术后发生心房颤动(简称房颤)的影响因素及房颤与血心钠素(ANP)的关系。方法选择安装心脏起搏器的患者103例进行随访,分析房颤与年龄、起搏方式、心律失常类型、左房内径(LAD)、左室射血分数(LVEF)和血ANP的关系。结果①65岁以下患者房颤发生率低于65岁以上组(P<0.05)。②VVI组房颤发生率高于DDD组(P<0.05)。③慢快综合征组房颤发生率较缓慢型病窦综合征和房室传导阻滞组高(P<0.05)。④VVI房颤组术后LAD增大、LVEF下降(P<0.05),VVI房颤组术后与DDD组比较有差异(P<0.05)。⑤VVI房颤组和VVI窦性心律组ANP浓度较DDD组高(P<0.05);各组不同心功能级别(NYHA)之间ANP浓度随着心功能级别的加重而升高。结论长期心脏起搏术后房颤的发生可能与年龄大、VVI起搏、病窦综合征(慢快型)、LAD增大、LVEF降低及ANP浓度升高相关。     

Fragmented electrograms and continuous electrical activity in atrial flutter

Multiple endocardial bipolar electrograms were recorded in 13 patients with atrial flutter (AF) to locate areas of fragmented electrical activity. Stable fragmentation patterns were found in each case, covering between 36% and 100% of the flutter cycle. Double or triple spike patterns were common. The direction of atrial activation was approximately defined in 11 patients, and in all of them at least part of the areas showing fragmentation was included in the circuit. In 1 patient an area of continuous electrical activity was found. AF circuits appeared to be included in the right atrium in 12 patients and in the left atrium in 1 patient. During atrial stimulation changes in fragmented electrograms coincided with changes in AF pattern before its interruption, while restoration of stable AF after stimulation was accompanied by reappearance of previous stable fragmented electrograms. In 6 patients electrograms were recorded after sinus rhythm was reestablished, and all showed marked decreases or disappearance of fragmentation. It is concluded that fragmented electrograms are often found in AF and may be related to abnormal local conduction in relation to the reentrant activation circuits.     

Long-term outcome of patients with drug-refractory atrial flutter and fibrillation after single- and dual-site right atrial pacing for arrhythmia prevention

Objectives. An initial crossover study comparing dual- and single-site right atrial pacing was performed followed by a long-term efficacy and safety evaluation of dual-site right atrial pacing in patients with drug-refractory atrial fibrillation (AF). Also examined was the efficacy of two single-site right atrial pacing modes (high right atrium and coronary sinus ostium) and the long-term need for cardioversion, antithrombotic and antiarrhythmic drug therapies during dual-site atrial pacing.

Methods. Thirty consecutive patients with drug-refractory symptomatic AF and documented primary or drug-induced bradycardia were implanted with a dual chamber rate-responsive pacemaker and two atrial leads. Single-site atrial pacing was performed at the high right atrium or the coronary sinus ostium. Continuous atrial pacing was maintained.

Results. Mean arrhythmia-free intervals increased from 9 ± 10 days in the control period preceding implant to 143 ± 110 days (p < 0.0001) in single-site right atrial pacing and 195 ± 96 days in dual-site right atrial pacing (p < 0.005 versus single-site pacing and p < 0.0001 versus control). Dual-site right atrial pacing significantly increased the proportion of patients free of AF recurrence (89%) as compared to single-site right atrial pacing (62%, p = 0.02). High right atrial pacing and coronary sinus ostial pacing had similar efficacy for AF prevention. Effective rhythm control was achieved in 86% of patients during dual right atrial pacing. Seventy-eight percent of patients at 1 year and 56% at 3 years remained free of symptomatic AF. The need for cardioversion was reduced after pacemaker implant (p < 0.05) and antithrombotic therapy was reduced (p < 0.06) without any thromboembolic event. Coronary sinus ostial lead dislodgement was not observed after discharge.

Conclusions. Atrial pacing in combination with antiarrhythmic drugs eliminates or markedly reduces recurrent AF. Prevention of AF is enhanced by dual-site right atrial pacing. High right atrial and coronary sinus ostial pacing do not differ in efficacy. Dual-site right atrial pacing is safe, achieves long-term rhythm control in most patients, decreases the need for cardioversion, and antithrombotic therapy can be selectively reduced.     

Characteristics and distribution of complex fractionated atrial electrograms in patients with paroxysmal and persistent atrial fibrillation

Introduction  

Substrate-based radiofrequency ablation for treatment of atrial fibrillation (AF) is still under development. The purpose of this study was to investigate the different characteristics and distribution of complex fractionated atrial electrograms (CFAE) in both atria in patients with paroxysmal and persistent AF.     

Prolonged atrial flutter in myotonic dystrophy

A case of myotonic dystrophy in a 47 year old white woman is described. Electrocardiographic abnormalities preceded clinical skeletal muscle involvement by 12 years. Electrocardiographic abnormalities included atrial flutter persisting over a three year period with return to sinus mechanism, incomplete atrioventricular block and a variable intraventricular conduction defect.     

Prevalence of atrial fibrillation and stroke in paced patients without prior atrial fibrillation: A prospective study

Background: Several reports suggest that the incidence of stroke and atrial fibrillation is reduced in patients receiving physiologic pacemakers, compared with patients receiving a ventricular pacemaker. Hypothesis: The study was undertaken to address the impact of different pacing modalities on the incidence of stroke and atrial fibrillation. Methods: We prospectively analyzed 210 consecutive patients. Those with previous episodes of cerebral ischemia and/ or atrial fibrillation were excluded from the study. The study population included 100 patients paced for total atrioventricular (AV) block or second-degree AV block (type II Mobitz) and 110 patients paced for sick sinus syndrome (SSS). The pacing mode was randomized. All patients underwent a brain computed tomography (CT) scan at the date of enrollment and after 1 and 2 years. Patients were followed for 2 years, and the incidence of atrial fibrillation and stroke was evaluated. Results: The incidence of atrial fibrillation was 10% at 1 year and 11% at 2 years. Comparing the different pacing modalities, we reported an increase in the incidence of atrial fibrillation in patients receiving ventricular pacing (p<0.05). On the other hand, no difference was found between patients paced for AV block and those paced for SSS. At the end of follow-up, we reported 29 cases of cerebral ischemia: 9 patients had AV block while 20 had SSS (p<0.05). Comparing the different pacing modalities, there was an increase in the incidence of stroke in patients receiving ventricular pacing (p< 0.05). Conclusion: There was an increase in the incidence of stroke and atrial fibrillation in patients with ventricular pacing.