Elsevier

Heart Rhythm

Volume 7, Issue 9, September 2010, Pages 1200-1204
Heart Rhythm

Focus issue: Atrial fibrillation
Clinical
Prevalence of fractionated electrograms in the coronary sinus: Comparison between patients with persistent or paroxysmal atrial fibrillation and a control population

https://doi.org/10.1016/j.hrthm.2010.05.011Get rights and content

Background

Complex fractionated atrial electrograms (CFAEs) are often identified as targets for radiofrequency ablation in the coronary sinus (CS) of patients with atrial fibrillation (AF).

Objective

The purpose of this study was to determine whether similar features are present in a normal control population.

Methods

Twenty-four patients with AF (12 paroxysmal, 12 persistent) were compared with 12 controls (undergoing radiofrequency ablation for supraventricular tachycardia) in whom at least 1 minute of AF was induced by rapid atrial pacing. Electrogram comparisons during sinus rhythm and AF were made offline. A random 10-second window of AF was used for analysis of fractionation and dominant frequency.

Results

The three groups were age matched. CFAEs during AF were less prevalent in the control versus the AF groups (control = 30% ± 28%, paroxysmal AF = 63% ± 34%, persistent AF = 62% ± 29%, P = .01). This difference was significant for the proximal to mid-CS only. Conduction velocity within the CS was slower in AF versus control patients (paroxysmal AF = 51 ± 6 cm/s, persistent AF = 52 ± 6 cm/s, control = 73 ± 11 cm/s, P <.001). Minimum AF cycle length was shorter in the AF groups versus the control group (paroxysmal AF = 132 ± 34 ms, persistent AF = 127 ± 34 ms, control = 168 ± 30 ms, P = .01). No differences in dominant frequency or prevalence of sinus rhythm CFAE was seen among the three groups.

Conclusion

AF patients have a higher prevalence of CFAE and short cycle length activation within the proximal CS than control patients with nonclinical AF. CFAE are associated with slowed CS conduction in AF patients. No difference in the dominant frequency during AF was seen. CS CFAEs are common in a control population with induced AF and are unlikely to signify clinically important AF drivers in this setting.

Introduction

Nademanee et al1 were the first to demonstrate that complex fractionated atrial electrograms (CFAEs) could be targeted for successful ablation of atrial fibrillation (AF). Since that seminal observation, CFAE ablation has been incorporated into a range of ablation procedures for treatment of both paroxysmal and persistent AF, with varying success.2, 3, 4, 5, 6 The coronary sinus (CS) has been identified as a common site of fractionated electrograms, and in many centers extensive CS ablation is an integral part of the procedure for persistent AF ablation.2, 3, 4, 7 However, the significance of fractionated electrograms is unclear, and whether they represent recordings from active drivers in the AF process or are simply passive is uncertain. Simultaneous recording of signals from CS musculature and adjacent left atrium further confuses this analysis. In the current study, we compared the prevalence of fractionated CS electrograms in paroxysmal and persistent AF populations with a control supraventricular tachycardia population in whom AF was induced during electrophysiologic study. This control population had not previously experienced a clinical episode of AF.

Section snippets

Study population

Twelve patients with paroxysmal AF and 12 patients with persistent AF were compared with 12 age-matched control patients undergoing radiofrequency ablation for supraventricular tachycardia in whom AF of at least 1-minute duration was induced by rapid atrial pacing.

All patients provided written informed consent according to a study protocol approved by the Melbourne Health research and ethics committee. With the exception of amiodarone, all antiarrhythmic medications were withheld at least five

Results

The AF and control patient groups were well matched for age (Table 1).

Discussion

This study demonstrates that both paroxysmal and persistent AF patients have a higher prevalence of CFAE and shortest cycle length activation within the proximal CS compared with control patients with induced AF. However, CFAEs within the CS also were common in control patients without clinical AF (28% of electrograms). Furthermore, at distal CS sites (bipoles 1,2 and 3,4), no difference in the prevalence of fractionated electrograms was seen between the control population and the AF groups.

The

Conclusion

This study demonstrates that both paroxysmal and persistent AF patients have a higher prevalence of CFAE and short cycle length activation associated with slowed conduction within the proximal CS compared with control patients with induced AF. However, CFAEs within the CS are also common in control patients and, as these patients have no underlying atrial “substrate,” are unlikely to signify the presence of clinically important AF drivers in this setting. Our observation that fractionated

References (17)

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    Clinically, this presents itself as a progression from paroxysmal AF to persistent and subsequently permanent forms of AF. The progressive nature of the atrial substrate underlying this natural progression of AF has been confirmed in atrial mapping studies; persistent AF is associated with larger left atrial dimensions, lower atrial regional voltages, increased proportion of low voltage areas, and increased proportion of complex signals (fractionated electrograms) within the left atrium.50,51 It is likely that these progressive changes explain the fact that catheter ablation of persistent AF is associated with higher attrition rates and poorer long-term maintenance of sinus rhythm in comparison to paroxysmal AF.2

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  • Morphology and pathophysiology of target anatomical sites for ablation procedures in patients with atrial fibrillation. Part I: Atrial structures (atrial myocardium and coronary sinus)

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    It has been shown that CFAEs are often targets for radiofrequency ablation in the CS of patients with AF, and so CFAE ablation has been included in a series of ablation procedures for the treatment of paroxysmal and persistent AF, albeit with varying rates of success. CFAEs are associated with slowed CS conduction and show arrhythmogenesis after PV isolation in AF patients [107,121,122]. Catheter and surgical ablation of the atrial myocardium have had a significant impact on the practice of cardiology especially in the case of supraventricular arrhythmia.

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Dr. Teh is the recipient of a postgraduate research scholarship from the National Heart Foundation of Australia. Dr. Lee is the recipient of a postgraduate research scholarship from the Cardiac Society of Australia and New Zealand. Drs. Teh and Lee are the recipients of a cardiovascular and lipid research grant from Pfizer. Dr. Kistler is supported by a Research Investigatorship from the Cardiac Society of Australia and New Zealand.

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