Impact of mitral isthmus anatomy on the likelihood of achieving linear block in patients undergoing catheter ablation of persistent atrial fibrillation

Yokokawa, Miki; Sundaram, Baskaran; Garg, Anubhav; Stojanovska, Jadranka; Oral, Hakan; Morady, Fred; Chugh, Aman

doi:10.1016/j.hrthm.2011.04.030

Cited by 82 publications

(101 citation statements)

References 13 publications

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“…14,15 In addition, it also recently has been shown that when the circumflex coronary artery courses between the mitral isthmus and the coronary sinus, there is a higher likelihood of failure to achieve MI block. 16 The circumflex coronary artery and the great cardiac vein both pass in close proximity to the MI and may act as a heat sink, preventing adequate tissue heating by radiofrequency delivery and preventing the development of a transmural lesion. This may be why, in the majority of patients, recovery was felt to be in the epicardium, with coronary sinus ablation required in 33 of 38 patients in this study to achieve bidirectional MI block at repeat ablation.…”

Section: Discussionmentioning

confidence: 99%

Recovery of Mitral Isthmus Conduction Leads to the Development of Macro-Reentrant Tachycardia After Left Atrial Linear Ablation for Atrial Fibrillation

Sawhney

Anand

Robertson

et al. 2011

Circ: Arrhythmia and Electrophysiology

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Background-Left atrial linear ablation for atrial fibrillation (AF) may be proarrhythmic, leading to left atrial macro-reentrant tachycardia (LAT). Whether due to failure to achieve block initially or to recovery of conduction after ablation is unknown. This study was designed to evaluate the frequency of recovery of mitral isthmus (MI) conduction compared with cavo-tricuspid isthmus (CTI) conduction, and the relationship between recovery of MI conduction and postablation LAT. Methods and Results-Of 163 patients with AF who underwent circumferential pulmonary vein ablation plus left atrial linear ablation, in whom MI and CTI ablation produced bidirectional conduction block, 52 underwent repeat ablation for recurrent atrial arrhythmias (AF or LAT). Of these 52 patients, coronary sinus ablation was required in 48 to achieve bidirectional MI block at the index ablation. During repeat ablation, MI and CTI conduction was assessed in sinus rhythm. At repeat ablation, MI conduction had recovered in 38 of 52 patients, as compared with CTI conduction which recovered in only 12 of 52 patients (Pϭ0.001). At repeat ablation, the recurrent clinical arrhythmia in 12 patients was MI-dependent LAT. Recovery of MI conduction was associated with development of MI-dependent LAT (Pϭ0.01). Conclusions-Despite using bidirectional conduction block as a procedural end point, recovery of MI conduction is common and may lead to LAT after left atrial linear ablation for AF. The reason for greater recovery of MI versus CTI conduction is unknown but could be due to differences in isthmus anatomy or lower power used for ablation in the left versus right atrium. (Circ Arrhythm Electrophysiol. 2011;4:832-837.)

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Section: Discussionmentioning

confidence: 99%

Recovery of Mitral Isthmus Conduction Leads to the Development of Macro-Reentrant Tachycardia After Left Atrial Linear Ablation for Atrial Fibrillation

Sawhney

Anand

Robertson

et al. 2011

Circ: Arrhythmia and Electrophysiology

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“…11,14 However, the circuitry can be complex in some patients, making for long procedures. Furthermore, linear block may be challenging to achieve in some patients, 15 which may be met with arrhythmia recurrence. Whether it is possible to eliminate persistent AF without these intervening ATs remains unknown.…”

Section: Circ Arrhythm Electrophysiolmentioning

confidence: 99%

Atrial Tachycardia After Ablation of Persistent Atrial Fibrillation

Chugh

2013

Circ: Arrhythmia and Electrophysiology

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A rrhythmia recurrence after catheter ablation of persistent atrial fibrillation (AF) is not uncommon and frequently requires repeat ablation procedures. [1][2][3] However, the precise arrhythmia that recurs depends on the strategy that was used at the original session. Patients who undergo sole pulmonary vein (PV) isolation usually manifest recurrent AF. Patients who undergo substrate modification, in the form of electrogram based 4 or linear ablation, 5 frequently develop atrial tachycardia (AT) either during or after the procedure. Whether these organized arrhythmias represent underlying driver tachycardias that were responsible for maintaining AF or occur as a result of our intervention (that is, proarrhythmia) remains unresolved. Article see p 1059If we are truly unmasking underlying drivers, then our ablation strategy may be validated because it allows us to map and potentially eliminate sources of AF, which otherwise could not be identified during fibrillatory conduction. Alternatively, it is possible that substrate ablation, especially linear left atrial ablation, may result in macroreentrant ATs that were not present during or responsible for maintaining AF. In this case, either the original source(s) has been eliminated or simply grazed and is now supplanted by organized reentry related to zones of slow conduction created by ablation.The existing literature provides evidence for both hypotheses. A study using spectral analysis showed that the frequency (ie, the cycle length) of the AT that resulted after AF termination matched that of a spectral component that was already present in the baseline periodogram during AF.6 A follow-up study revealed that when linear ablation resulted in complete conduction block, it was accompanied by a decrease in the prevalence of these spectral components.7 These findings suggest that site-specific ATs may be present during ongoing AF, despite the fact that their frequency is lower than the dominant frequency during AF. These studies then support the contention that organized tachycardias are bound to be encountered after elimination of fibrillatory conduction and, therefore, are not brought on by ablation-related slowed conduction. They also imply that these underlying tachycardias may be responsible for maintaining AF in a hierarchical manner.However, there is also significant support for the competing argument that the ablation strategy determines whether organized reentrant arrhythmias will be encountered during or after ablation. For example, macroreentrant ATs using the mitral isthmus or the roof are frequently encountered when patients with paroxysmal AF undergo linear ablation, with 8 or without PV isolation.5 However, these tachycardias are rarely seen after simple antral PV isolation. If these ATs were truly responsible for maintaining AF, why is it possible to eliminate the arrhythmia in 90% of patients with paroxysmal AF 9 without ablation of the left atrial isthmi? An earlier study also showed that virtually all reentrant ATs originated from prior ablation ...

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“…However, complete bidirectional block of the mitral isthmus usually requires aggressive ablation with a combined endocardial and epicardial approach. Interposition of the circumflex artery between the mitral isthmus and the coronary sinus is associated with a lower probability of achieving complete mitral isthmus block [61,62]. Particularly in such cases, this may result in a higher risk of complications such as cardiac tamponade and damage to the circumflex artery [63].…”

Section: Atrial Tachycardia and Efficacy Of Linear Ablationmentioning

confidence: 99%

Catheter ablation of atrial fibrillation: Past, present, and future directions

Yoshida

Aonuma

2012

Journal of Arrhythmia

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a b s t r a c tAtrial fibrillation (AF) is the most common cardiac arrhythmia encountered in clinical practice. Because of inadequate efficacy of pharmacological therapy, catheter ablation of AF has evolved dramatically over the last decade. Although the success rate of ablation has improved, the ablation strategy is still extensive, and the ablation procedure is technically challenging. In the past decade, electrophysiologists were eager to obtain high success rates with extensive ablation. In the present decade, further clarification of the complex mechanism of AF is required to make ablation of AF safer and much more efficient. Because the mechanism of AF is very complex, and even somewhat mysterious, it may not be easy to attain a better understanding of the mechanism involved or to discover better guidance for catheter ablation. However, it is important to note that research into AF leads to better understanding of other cardiac and non-cardiac diseases because AF develops multifactorially in association with underlying systemic pathophysiologies.

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Impact of mitral isthmus anatomy on the likelihood of achieving linear block in patients undergoing catheter ablation of persistent atrial fibrillation

Cited by 82 publications

References 13 publications

Recovery of Mitral Isthmus Conduction Leads to the Development of Macro-Reentrant Tachycardia After Left Atrial Linear Ablation for Atrial Fibrillation

Recovery of Mitral Isthmus Conduction Leads to the Development of Macro-Reentrant Tachycardia After Left Atrial Linear Ablation for Atrial Fibrillation

Atrial Tachycardia After Ablation of Persistent Atrial Fibrillation

Catheter ablation of atrial fibrillation: Past, present, and future directions

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