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.     

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.     

阵发房颤合并病窦综合征的射频消融治疗

目的总结顽固性阵发性房颤伴病窦综合征患者的心电图和动态心电图特点。评估心脏起搏和射频消融心房肺静脉电隔离治疗的结果。方法 5例阵发性房颤患者。年龄62(60.7±6.8)岁。4例有黑朦,1例有晕厥发作史,病史1~5(2.6±1.3)年。全部病例完行心内电生理检查和心房肺(或上腔)静脉电隔离。结果5例患者中,每周均有发作数次的3例,有2例植入DDD心脏起搏器,其中1例系导管射频消融术后1周植入起搏器,另1例系植入起搏器后房颤频繁发作行导管射频消融。动态心电图示房颤终止后的平均窦性停搏时间为5(5.0±1.9)s。心内电生理检查证实与房颤相关的靶静脉为上腔静脉1例,右上肺静脉1例,左上肺静脉2例,有1例未能确定起源点。作射频消融电隔离肺静脉共22根,平均随访3(2.78±1.59)月,无房颤发作。未植入起搏器的3例多次动态心电图复查无窦性停搏发生,24h总心率均在正常范围。结论部分阵发性房颤伴病态窦综合征的患者,导管射频消融电隔离肺静脉后能有效地消除房颤发作,窦房结功能可以恢复。建议对这些患者首先行肺静脉电隔离治疗控制房颤,然后根据自身心率的变化评估心脏起搏治疗的必要。     

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 fractionation of paced right atrial electrograms in patients with atrial flutter and fibrillation

OBJECTIVES: This study investigated the extent of fractionation of paced right atrial electrograms in patients with and without paroxysmal atrial flutter (AFL) or atrial fibrillation (AF). BACKGROUND: Slow conduction through nonuniform anisotropic atrial muscles, represented by fractionated electrograms, may favor the generation of atrial tachyarrhythmias. METHODS: This study included 10 control patients (Group 1), 8 patients with documented paroxysmal AFL (Group 2) and 10 patients with documented paroxysmal AF (Group 3). Five electrode catheters were placed in the different sites of the right atrium and one catheter was positioned at the coronary sinus ostium. Atrial pacing from one site was done by a constant drive train with an extrastimulus inserted every fourth beat while recording at the other five sites was performed. The delay of each fractionated potential in the high-pass filtered atrial electrogram in response to extrastimulation was determined and used to construct conduction curves of delay versus the S1S2 interval. RESULTS: The mean increase in electrogram duration between a coupling interval of 350 ms and 10 ms above atrial refractoriness was significantly greater in Groups 2 and 3 compared with that in Group 1 (8.5 +/- 2.5 vs. 11.0 +/- 2.7 vs. 5.9 +/- 2.3 ms, respectively, p < 0.001). The mean S1S2 interval at which delay increased suddenly was also longer in Groups 2 and 3 compared with Group 1 (326 +/- 9 vs. 343 +/- 12 vs. 307 +/- 17 ms, respectively, p < 0.001). CONCLUSIONS: Increased delays in the individual potential of the fractionated atrial electrograms may be related to the development of AFL and AF.     

Functional characterization of atrial electrograms in sinus rhythm delineates sites of parasympathetic innervation in patients with paroxysmal atrial fibrillation.

OBJECTIVES: This study sought to characterize left atrial (LA) sinus rhythm electrogram (EGM) patterns and their relationship to parasympathetic responses during atrial fibrillation (AF) ablation. BACKGROUND: The mechanistic basis of fractionated LA EGMs in patients with paroxysmal AF is not well understood. METHODS: We analyzed 1,662 LA ablation sites from 30 patients who underwent catheter ablation for paroxysmal AF. Pre-ablation EGM characteristics (number of deflections, amplitude, and duration) were measured in sinus rhythm. Parasympathetic responses during radiofrequency application (increase of atrial-His interval by > or =10 ms or decrease of sinus rate by > or =20%) were assessed at all sites. We also prospectively studied the effect of adenosine, a pharmacological agent mimicking acetylcholine signaling in myocytes, on LA EGMs. Finally, we performed mathematical simulations of atrial tissue to delineate possible mechanisms of fractionated EGMs in sinus rhythm. RESULTS: A specific pattern of pre-ablation sinus rhythm EGM (deflections > or =4, amplitude > or =0.7 mV, and duration > or =40 ms) was strongly associated with parasympathetic responses (sensitivity 72%, specificity 91%). The sites associated with these responses were found to be located mainly in the posterior wall of the LA. Adenosine administration and mathematical simulation of the effect of acetylcholine were able to reproduce a similar EGM pattern. CONCLUSIONS: Parasympathetic activation during AF ablation is associated with the presence of pre-ablation high-amplitude fractionated EGMs in sinus rhythm. Local acetylcholine release could potentially explain this phenomenon.     

Time- and frequency-domain characteristics of atrial electrograms during sinus rhythm and atrial fibrillation

Ablation and Spectral Characteristics of Fibrillation. Background: Complex fractionated atrial electrograms (CFAE) have been considered to be helpful during catheter ablation of atrial fibrillation (AF). The purpose of this study was to analyze the characteristics of CFAEs recorded during sinus rhythm (SR) and AF, and to determine their relationship to perpetuation of AF and clinical outcome. Methods and Results: Antral pulmonary vein isolation (APVI) was performed in 34 consecutive patients (age = 59 ± 10 years) with paroxysmal AF who presented in SR. Time‐ and frequency‐domain characteristics of electrograms recorded from the same sites in the coronary sinus (CS) were analyzed during SR and AF, before and during isoproterenol infusion. There was a modest correlation in fractionation index (FI: change in the direction of depolarization, r = 0.40, P = 0.001) and complexity index (CI: change in the polarity of depolarization, r = 0.41, P = 0.001), but not in the dominant frequency (DF) between SR and AF. There was no relationship between the DF and CI or FI during AF. Isoproterenol was associated with an increase in DF during AF (6.6 ± 0.9 vs 5.1 ± 0.6 Hz, P < 0.001) but had no effect on CI or FI (P = 0.6). A higher CI (58.3 ± 21.0/s vs 38.0 ± 21.0/s, P < 0.01), and FI (123.5 ± 44.8/s vs 75.6 ± 44.6/s, P < 0.01) during AF were associated with a lower likelihood of termination of AF during APVI and a higher probability of recurrent AF after ablation. Ratio of FI during AF to SR was also higher when AF persisted than terminated after APVI (29.7 ± 12.4 vs 19.1 ± 9.7, P = 0.002). However, time‐ or frequency‐domain parameters during SR were not predictive of termination or clinical outcome. Conclusions: Structural and functional properties of the atrial myocardium during AF contribute to electrogram complexity, which may indicate the presence of extra‐PV mechanisms of AF that are not eliminated by APVI. Mapping of complex electrograms in SR is not likely to be sufficient to identify drivers of AF. (J Cardiovasc Electrophysiol, Vol. 22, pp. 851‐857, August 2011)     

High-density activation mapping of fractionated electrograms in the atria of patients with paroxysmal atrial fibrillation

BACKGROUND: Areas of complex fractionated atrial electrograms (CFAEs) have been implicated in the atrial substrate of atrial fibrillation (AF). The mechanisms underlying CFAE in humans are not well investigated. OBJECTIVES: The purpose of this study was to investigate the regional activation pattern associated with CFAE using a high-density contact mapping catheter. METHODS: Twenty patients with paroxysmal AF were mapped using a high-density multielectrode catheter. CFAE were mapped at 10 different sites (left atrium [LA]: inferior, posterior, roof, septum, anterior, lateral; right atrium [RA]: anterior, lateral, posterior, septum). Local atrial fibrillation cycle length (AFCL) was measured immediately before and after the occurrence of CFAE, and the longest electrogram duration (CFAEmax) was assessed. RESULTS: Longer electrogram durations were recorded in the LA compared with the RA (CFAEmax 118 +/- 21 ms vs 104 +/- 23 ms, P = .001). AFCL significantly shortened before the occurrence of CFAEmax compared with baseline (LA: 174 +/- 32 ms vs 186 +/- 32 ms, P = .0001; RA: 177 +/- 31 ms vs 188 +/- 31 ms, P = .0001) and returned to baseline afterwards. AFCL shortened by >or=10 ms in 91% of mapped sites. Two different local activation patterns were associated with occurrence of CFAEmax: a nearly simultaneous activation in all spines in 84% indicating passive activation, and a nonsimultaneous activation sequence suggesting local complex activation or reentry. CONCLUSION: Fractionated atrial electrograms during AF demonstrate dynamic changes that are dependent on regional AFCL. Shortening of AFCL precedes the development of CFAE; thus, cycle length is a major determinant of fractionation during AF. High-density mapping in AF may help to differentiate passive activation of CFAE from CFAE associated with an active component of the AF process.     

Consistency of complex fractionated atrial electrograms during atrial fibrillation

BACKGROUND: Temporal variation in complex fractionated atrial electrograms (CFAEs) exists during atrial fibrillation (AF). OBJECTIVE: This study sought to quantify the variation in CFAEs using a fractionation interval (FI) algorithm and to define the shortest optimal recording duration required to consistently characterize the magnitude of the fractionation. METHODS: Twenty-seven patients undergoing AF mapping in the left atrium were studied. The FI and frequency analysis were performed at each mapped site for recording durations of 1 to 8 seconds. The magnitude of the fractionation was quantified by the FI algorithm, which calculated the mean interval between multiple, discrete deflections during AF. The results from each duration were statistically compared with the maximal-duration recording, as a standard. The FI values were compared with the dominant frequency values obtained from the associated frequency spectra. RESULTS: The FIs obtained from recording durations between 5 and 8 seconds had a smaller variation in the FI (P < .05) and, for those sites with a FI < 50 ms, the fractionation was typically continuous. The fast-Fourier Transform spectra obtained from the CFAE sites with recording durations of >5 seconds harbored higher dominant frequency values than those with shorter recording durations (8.1 +/- 2.5 Hz vs. 6.8 +/- 0.98 Hz, P < .05). The CFAE sites with continuous fractionation were located within the pulmonary veins and their ostia in 77% of patients with paroxysmal AF, and in only 29% of patients with nonparoxysmal AF (P < .05). CONCLUSION: The assessment of fractionated electrograms requires a recording duration of > or =5 seconds at each site to obtain a consistent fractionation. Sites with the shortest FIs consistently identified sites with the fastest electrogram activity throughout the entire left atrium and pulmonary veins.     

厄贝沙坦对病态窦房结综合征患者双腔起搏后阵发性心房颤动的影响

目的观察厄贝沙坦对病态窦房结综合征（SSS）患者双腔起搏后阵发性心房颤动（Af）的影响。方法入选84例双腔起搏术后1个月仍有阵发性Af的SSS患者,随机分为治疗组（n=42）和对照组（n=42）。在治疗基础疾病的基础上,治疗组给予厄贝沙坦150mg/d,对照组不予血管紧张素转化酶抑制剂（ACEI）或血管紧张素受体拮抗剂（ARB）。随诊1年,观察左房内径、血清高敏C反应蛋白（hsCRP）水平、Af发作次数（次/d）及Af负荷（h/d）等。结果起搏器置入术后1年,治疗组左房内径、hsCRP、Af发作次数及Af负荷显著低于对照组,分别为[（3.91±0.22）cmvs.（4.48±0.46）cm],[（3.42±1.63）mg/Lvs.（5.23±2.11）mg/L],[（3.15±2.83）次/dvs.（6.46±4.28）次/d],[（0.46±0.28）h/dvs.（0.69±0.32）h/d]（P均〈0.05）;同时显著低于同组厄贝沙坦用药前水平（P均〈0.05）;对照组上述指标厄贝沙坦治疗前后变化无显著性差异（P〉0.05）。结论厄贝沙坦可减轻SSS双腔起搏后心房重构、降低hsCRP水平,减少阵发性Af的发生。     

Left atrial systolic function assessed by left atrial ejection force in patients with sick sinus syndrome and paroxysmal atrial fibrillation

We evaluated left atrial systolic function using left atrial ejection force (LAEF) in 19 patients with sick sinus syndrome (SSS) and in 20 with paroxysmal atrial fibrillation (Paf) whose ages ranged from 48 to 80 years. We also evaluated 35 normal individuals for comparison. The LAEF was calculated as 1/3 x mitral valve area x (peak velocity of A wave)2 using two-dimensional and pulsed-Doppler echocardiography according to Newton's law of motion and hydrodynamics. In normal individuals, LAEF positively correlated with age (r = 0.82, p < 0.01). Normal LAEF was calculated as 0.098 x age - 0.74 (kdynes) from the regression line. Because of this correlation, we used age-corrected LAEF (%LAEF) that was calculated as (measured LAEF / normal LAEF) x 100. The results showed that this value was 53+/-26% in patients with SSS and 54+/-26% in patients with Paf. Both were significantly lower than normal individuals (p < 0.001). Among SSS subtypes, %LAEF was lower in types II and III than in type I (51+/-14%, 37+/-19%, and 81+/-35%, respectively). In conclusion, left atrial systolic function is depressed in patients with Paf and SSS, in particular, types II and III. These results suggest that the pathological abnormalities extend not only to the sinus node but also to the left atrial muscle in patients with SSS and Paf.     

阵发性心房颤动合并病态窦房结综合征的导管射频消融心房-大静脉电隔离

目的 　总结顽固性阵发性心房颤动 (房颤 )伴病态窦房结综合征 (病窦综合征 )患者的心电图和动态心电图特点 ,评估心脏起搏和导管射频消融进行心房 肺静脉电隔离治疗的结果。　方法　 8例阵发性房颤患者 ,年龄 (6 0 7± 6 8)岁 ,5例有黑、 1例有晕厥发作史 ,病史 1～ 2 0 (7 6±6 0 )年。全部病例完成各项临床常规检查后行心内电生理检查和导管射频消融作心房 肺 (或上腔 )静脉电隔离治疗。　结果　 8例患者中 ,房颤每天均有发作的 5例 ,每周发作数次的 3例 ,有 4例植入心脏起搏器后不能控制发作。动态心电图示房颤终止后的平均窦性停搏时间为 (5 0± 1 9)s。心内电生理检查证实与房颤相关的靶静脉为上腔静脉 2例 ,左上肺静脉 3例 ,有 3例未能确定起源点。作射频消融电隔离大静脉共 2 2根 ,平均随访 (2 78±15 9)d ,无房颤发作 6例 (75 % ) ,2例复发病例行第 2次电隔离后分别随访 2个月和 2 5个月 ,均再无房颤发生。其中未植入起搏器的 4例多次动态心电图复查无窦性停搏发生 ,2 4h总心率均在正常范围。　结论　部分阵发性房颤伴病窦综合征的患者 ,导管射频消融电隔离大静脉能够完全消除房颤的发作 ,窦房结功能可以恢复 ,这一现象说明部分慢 快综合征患者的病窦综合征表现可能是继发性和可逆性的     

High-density mapping of left atrial endocardial activation during sinus rhythm and coronary sinus pacing in patients with paroxysmal atrial fibrillation

INTRODUCTION: This study was designed to record global high-density maps of left atrial endocardial activation during sinus rhythm and coronary sinus pacing. METHOD AND RESULTS: Noncontact mapping of the left atrium was performed in nine patients with paroxysmal atrial fibrillation undergoing pulmonary vein ablation procedures. High-density isopotential and isochronal activation maps were superimposed on three-dimensional reconstructions of left atrial geometry. Mapping was repeated during pacing from sites within the coronary sinus. Earliest left atrial endocardial activation occurred anterior to the right pulmonary veins in seven patients and on the anterosuperior septum in two patients. A line of conduction block was seen in the posterior wall and inferior septum in all patients. The direction of activation in the left atrial myocardium overlying the coronary sinus was different from the electrogram sequence in the coronary sinus catheter in 6 of 9 patients. During coronary sinus pacing, activation entered the left atrium a mean (SD) of 41 (13) ms after the pacing stimulus at a site 12 (10) mm from the endocardium overlying the pacing electrode. Lines of conduction block were present in the posterior wall and inferior septum. CONCLUSION: In patients with paroxysmal atrial fibrillation, lines of conduction block are present in the left atrium during sinus rhythm and coronary sinus pacing. Electrograms recorded in the coronary sinus infrequently correspond to the direction of activation in the overlying left atrial myocardium.     

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。     

永久性心脏起搏器对病态窦房结综合征患者合并阵发性心房颤动的预防作用

心房颤动(AF)是临床最常见的一种持续性心律失常，心脏起搏预防AF是目前AF治疗的新途径之一。近年来的研究证明，双腔起搏或心房起搏能降低AF的发生率。vitairon 900E型永久起搏器具有房室顺序起搏和4种预防AF发作的起搏程序。现对我院16例植入Vitaron 900E起搏器的患者定期随访，报道如下。     

阿托伐他汀对血脂正常的病窦综合征患者心房颤动复发的影响

目的探讨阿托伐他汀对血脂正常的病窦综合征(SSS)患者心房颤动(AF)复发的防治作用。方法选择62例SSS合并阵发性AF(PAF)未行心脏永久起搏器植入术且血脂正常的患者,随机分为对照组(常规治疗组)和治疗组(常规治疗基础上加阿托伐他汀20 mg/d),随访观察12个月,观察AF发作次数、AF持续时间及血浆C反应蛋白(CRP)水平、血脂水平的变化。结果治疗后治疗组AF的发作次数、AF持续时间虽没有明显降低但显著低于对照组(13.4±2.8次/年vs 16.2±3.6次/年,62.4±7.2小时/年vs 66.3±4.7小时/年),血CRP水平显著降低(7.95±0.87 mg/L vs 9.52±1.31 mg/L)且显著低于对照组(7.95±0.87 mg/L vs 10.02±1.37mg/L)。治疗组的血脂在治疗12个月时较治疗前明显改善(P<0.05),而对照组的上述指标则无明显改善。结论阿托伐他汀对血脂正常、未行心脏永久起搏器植入术的SSS患者AF的复发具有明显的防治作用。其机制可能与他汀类药物抑制炎症反应及调脂有关。     

Atrial contractile function and fibrosis in patients with paroxysmal atrial fibrillation in sinus rhythm

Objectives:The aim of the study was to investigate atrial contractile function in patients with paroxysmal atrial fibrillation (AF) in sinus rhythm using transthoracic echocardiography (EchoCG).Methods and results:Thirty-five patients with paroxysmal AF and arterial hypertension (mean age 62 ± 10 years, 43% male) in sinus rhythm were enrolled in the study. The control group was composed of comparable patients with arterial hypertension without heart rhythm disturbances. EchoCG was performed during sinus rhythm according to an extended protocol, which included the ejection fraction (EF) of the left atrium (LA) and tissue Doppler measurements. Myocardial fibrosis was assessed quantitatively by videodensitometry in intraventricular and intraatrial (IAS) septa using an original image post-processing algorithm. We found a significant decrease in the left atrial contraction function during sinus rhythm in patients with AF when compared to controls. LA EF (34 ± 14 vs. 54 ± 17, p = 0.03) and A’ velocity (0.17 ± 0.04 vs. 0.22 ± 0.04, p = 0.008) decreased while A/A’ ratio (2.7 ± 0.2 vs. 1.9 ± 0.1, p = 0.006) increased. Peak A velocity was not affected. Videodensitometric analysis revealed a 2.3-fold increase in IAS fibrosis fraction in AF patients compared with controls (p = 0.01).Conclusion:Patients with AF in sinus rhythm have markedly depressed atrial contractile function. Videodensitometry of IAS has the potential to be used as inexpensive method of atrial fibrosis assessment in patients with AF.     

Comparative distribution of complex fractionated atrial electrograms, high dominant frequency (HDF) sites during atrial fibrillation and HDF sites during sinus rhythm

Purpose

Complex fractionated atrial electrograms (CFAEs) and high dominant frequency sites during atrial fibrillation (AF-HDF) are related to the maintenance of atrial fibrillation (AF). HDF sites in sinus rhythm (SR-HDF; as defined by frequencies of >70 Hz) are suggested to be abnormal atrial tissue. Relations between these electrophysiologic signals have not been elucidated.

Methods

We investigated the relations between SR-HDF and CFAE and AF-HDF sites during AF. NavX-based maps of CFAE and left atrium (LA)/pulmonary vein (PV) dominant frequency (DF) during AF and DF maps during SR were created for 23 patients with AF (paroxysmal AF (PAF), n?=?14; persistent AF (PerAF), n?=?9).

Results

The extent of overlap between SR-HDF and CFAE sites was 51?±?18 % (as calculated by the LA/PV segments containing both an SR-HDF site and a CFAE site/total LA/PV segments containing an CFAE site) and the extent of overlap between SR-HDF and AF-HDF sites was 50?±?35 % (P?=?0.7464). However, statistically poor agreement was noted for both (kappa values, 0.07?±?0.19 and 0.08?±?0.24, P?=?0.8794). The extent of overlap did not differ between PAF and PerAF patients (SR-HDF and CFAE, 52 % (interquartile range (IQR), 42–59) versus 57 % (IQR, 33–67), P?=?0.5842; SR-HDF and AF-HDF, 43 % (IQR, 25–85) versus 55 % (IQR, 13–83), P?=?0.9465). The bipolar voltage amplitudes of SR-HDF, CFAE, and AF-HDF sites revealed normal voltage areas (1.6 mV (IQR, 0.8–2.7), 1.9 mV (IQR, 1.1–2.8), and 1.5 mV (IQR, 1.7–2.7), respectively).

Conclusions

In both PAF and PerAF, most CFAE and AF-HDF sites did not correspond to the SR-HDF sites or low-voltage area during SR. Thus, most CFAE and DF signals during AF represent functional electrical activities rather than structural remodeling of the atria.