Coronary Sinus Isolation for High-Burden Atrial Fibrillation: A Randomized Clinical Trial

BACKGROUND

The coronary sinus is an arrhythmogenic structure that can initiate and maintain atrial fibrillation (AF). Coronary sinus ablation has been shown to be effective in prolonging the AF cycle length and terminating AF in patients with both paroxysmal and persistent AF who have persistent AF after pulmonary vein isolation (PVI).

OBJECTIVES

The objective of this study was to undertake a randomized controlled trial to investigate the efficacy of coronary sinus isolation (CSI) as an adjunctive ablation strategy for the treatment of high-burden AF.

METHODS

Consecutive patients presenting with symptomatic long episodes of paroxysmal AF (≥48 h but ≤7 days) or persistent AF (>7 days and ≤12 months) referred for first-time ablation were enrolled. Participants were randomized to either PVI, roofline ablation, and CSI (CSI group) or PVI and roofline ablation only (non-CSI group). Participants were assessed postprocedurally via clinical follow-up and 7-day Holter monitoring at regular intervals. The primary outcome was single-procedure drug-free atrial arrhythmia-free survival at 2 years.

RESULTS

One hundred participants were recruited to the study; 48 were randomized to the CSI group and 52 to the non-CSI group. Acutely successful CSI was achieved in 45 of the 48 patients in the CSI group. At 2 years follow up, 30 of 48 patients (62.5%) in the CSI group and 33 of 52 (63.4%) in the non-CSI group were free from arrhythmia recurrence. Single-procedure drug-free survival at 2 years was no different between groups (P = 0.91). Similarly, multiple procedure drug assisted survival at 5 years was not different between groups (P = 0.80). Complication rates were not significantly different between groups (P = 0.19).

CONCLUSIONS

Adjunctive CSI as part of a de novo ablation strategy does not confer any additional benefit greater than PVI and roofline for the treatment of high-burden AF.

Coronary sinus diverticulum: Importance, function, and treatment

The importance of venous structure in the heart is usually overshadowed by that of the arterial system. Coronary sinus (CS) is a part of cardiac venous apparatus and connects left atria to the right atria. Other than having role in physiological contractions of both atria, it contributes substantially to cardiac electrical conduction system. Due to unique placement and connections of the CS, it has become growing interest in clinical cardiology. It is used in cardiac resynchronization therapy with biventricular pacing, left-sided catheter ablation of arrhythmias, and administration of retrograde cardioplegia in cardiac surgery. In some individuals, CS is presented with anatomical variants. CS diverticulum is a congenital outpouching that provides muscular connection between atria and ventricle. This connection provides a suitable substrate for occurrence of arrhythmias, which even results in life-threatening events such as sudden cardiac death. Early diagnosis leads to treatment with ablation techniques, which ultimately eliminates origins of arrhythmias.

Beyond Pulmonary Vein Isolation in Nonparoxysmal Atrial Fibrillation: Posterior Wall, Vein of Marshall, Coronary Sinus, Superior Vena Cava, and Left Atrial Appendage

The optimal ablation strategy for non-paroxysmal atrial fibrillation remains controversial. Non-PV triggers have been shown to have a major arrhythmogenic role in these patients. Common sources of non-PV triggers are: posterior wall, left atrial appendage, superior vena cava, coronary sinus, vein of Marshall, interatrial septum, crista terminalis/Eustachian ridge, and mitral and tricuspid valve annuli. These sites are targeted empirically in selected cases or if significant ectopy is noted (with or without a drug challenge), to improve outcomes in patients with non-paroxysmal atrial fibrillation. This article focuses on summarizing the current evidence and the approach to mapping and ablation of these frequent non-PV trigger sites.

Coronary Sinus Ablation Is a Key Player Substrate in Recurrence of Persistent Atrial Fibrillation

Atrial fibrillation (AF) is the most frequent atrial arrhythmia. During the last few decades, owing to numerous advancements in the field of electrophysiology, we reached satisfactory outcomes for paroxysmal AF with the help of ablation procedures. But the most challenging type is still persistent AF. The recurrence rate of AF in patients with persistent AF is very high, which shows the inadequacy of pulmonary vein isolation (PVI). Over the last few decades, we have been trying to gain insight into AF mechanisms, and have come to the conclusion that there must be some triggers and substrates other than pulmonary veins. According to many studies, PVI alone is not enough to deal with persistent AF. The purpose of our review is to summarize updates and to clarify the role of coronary sinus (CS) in AF induction and propagation. This review will provide updated knowledge on developmental, histological, and macroscopic anatomical aspects of CS with its role as arrhythmogenic substrate. This review will also inform readers about application of CS in other electrophysiological procedures.

Novel concepts and approaches in ablation of atrial fibrillation: the role of non-pulmonary vein triggers

Ablation of non-pulmonary vein (PV) triggers is an important step to improve outcomes in atrial fibrillation ablation. Non-pulmonary vein triggers typically originates from predictable sites (such as the left atrial posterior wall, superior vena cava, coronary sinus, interatrial septum, and crest terminalis), and these areas can be ablated either empirically or after observing significant ectopy (with or without drug challenge). In this review, we will focus on ablation of non-PV triggers, summarizing the existing evidence and our current approach for their mapping and ablation.

Association of Rate-Dependent Conduction Block Between Eccentric Coronary Sinus to Left Atrial Connections With Inducible Atrial Fibrillation and Flutter

BACKGROUND

We sought to describe the prevalence and variability of coronary sinus (CS) and left atrial (LA) myocardium connections, their susceptibility to rate-dependent conduction block, and association with atrial fibrillation (AF) and flutter induction.

METHODS AND RESULTS

The study cohort included 30 consecutive AF patients (age 63.3±10.5 years, 63% male). Multipolar catheters were positioned in the CS, high right atrium (HRA), and LA parallel to and near the CS. Trains of 10 pacing stimuli were delivered during sinus rhythm from each of the following sites: CS proximal (CSp), CS distal (CSd), LA septum (LAs), lateral LA (LAl), and HRA, at the following cycle lengths: 1000, 500, 400, 300, and 250 ms, while recording from the other catheters. With the CS 9 to 10 bipole just inside the CS ostium, CS-LA connections were observed in 100% at CS 9 to 10, 30% at CS 7 to 8, 23% at CS 5 to 6, 23% at CS 3 to 4, and 97% at CS 1 to 2. Eighteen patients (60%) had AF/atrial flutter induced. Rate-dependent conduction block of a CS-LA connection at cycle length of ≥250 ms was present in 17 (94%) of those with versus none of those without AF/atrial flutter induction (P<0.001).

CONCLUSIONS

Rate-dependent eccentric CS-LA conduction block is associated with AF/atrial flutter induction in patients with drug-refractory AF undergoing ablation. The presence of dual muscular CS-LA connections, coupled with unidirectional block in one limb, seems to serve as a substrate for single or multiple reentry beats, and arrhythmia induction.

Atrial Fibrillation Ablation Strategy: "Ready Made" or "Tailored"?

Atrial fibrillation (AF) is the most common arrhythmia leading to hospital admissions. Catheter ablation has evolved as an effective treatment strategy; however, ablation strategies continue to evolve due to the complex and multifactorial nature of atrial fibrillation. A standardized and primarily anatomical approach may not be sufficient to eliminate all mechanisms of atrial fibrillation. A tailored ablation strategy can target specific triggers and drivers of atrial fibrillation; however, it is limited by the accuracy and sensitivity of the methods used in identifying specific mechanisms of atrial fibrillation.

Confined thoracic vein fibrillation: prevalence and electrophysiological properties

INTRODUCTION

Confined thoracic vein fibrillation (cTVT) is a finding that suggests that thoracic vein acts as a rapid driver to maintain atrial fibrillation (AF). However, little is known about the cTVT.

METHODS AND RESULTS

Among consecutive 655 patients (age 62 ± 0 years, 492 men, 421 paroxysmal) who underwent circumferential pulmonary vein (PV) antrum isolation for AF, cTVT was identified in 28 (4.3%) patients. The prevalence was significantly higher in patients with paroxysmal AF than in those with nonparoxysmal AF (5.9% vs 1.3%, P = .002). The cTVT was observed in left PVs in 15 (53.6%), right PVs in 11 (39.3%), and superior vena cava in 2 (7.1%) patients. The median cycle length of cTVT was 150 (110-170) ms. The cTVT was recognized when sinus rhythm was restored from AF during vein isolation in 14 patients. Dissociated activity was seen after the termination of cTVT in 23 (82.1%) patients, and cTVT reinitiated spontaneously after the dissociated activity. In 2 patients, AF was not terminated by multiple cardioversions before the isolation, even with a maximal energy delivery. At a median follow-up of 12.0 (7.5-20.5) months, 26 patients (92.9%) were free from AF without antiarrhythmic drugs after a mean of 1.4 ± 0.5 procedures per patient. Notably, recurrent arrhythmia was not observed in any patient (n = 6), wherein cTVT was terminated by additional radiofrequency applications inside an isolated area after the achievement of vein isolation.

CONCLUSIONS

Confined thoracic vein fibrillation is not a rare finding in patients with paroxysmal AF, and its elimination results in an excellent clinical outcome.

Contemporary approaches to persistent atrial fibrillation

Atrial fibrillation (AF) is currently the most commonly treated cardiac arrhythmia. It is generally a progressive disease, often more difficult to control as electromechanical remodeling alters the underlying substrate. Patients typically evolve from infrequent, self-terminating episodes, to more frequent and sustained events. In addition, atrial remodeling may make sinus rhythm more challenging to achieve. Although an ablation strategy limited to pulmonary vein isolation may be curative in those with paroxysmal AF, a more extensive approach is often required in those with persistent AF. This article discusses the current approaches and most recent advances in the ablation of persistent and long-standing persistent AF.

Development of the cardiac venous system in prenatal human life

The human coronary sinus is an evolutionary modification of the terminal part of the left sinus horn. Anatomically, the coronary sinus is a short, broad vessel that runs along the coronary groove situated on the diaphragmatic surface of the heart. This structure, which opens into the right atrium, collects blood from the great cardiac vein and from other veins of the heart as well. In this study, we assessed the growth and dimensions of the coronary sinus at the fourth and eighth months of fetal development from whole material received from the Nicolaus Copernicus University, Collegium Medicum, Department of Histology and Embryology in Bydgoszcz. A group of 219 specimens, 105 male and 114 female fetuses, presented no visible malformations or developmental abnormalities. The results of this study determined that the dimension of the coronary sinus during prenatal development is not sexually dimorphic. Furthermore, following a monthly period of rapid growth in length of this structure, there are no further increases in length after the six months gestation. Finally, we concluded that the dimensions of the coronary sinus obtained during autopsy are similar to those determined through intravital ultrasound examination. The diameter of the coronary sinus is the best parameter to monitoring the fetal age and the growing of the fetus. Accordingly, we suggest that the best way of estimate for proper blood drainage from heart veins is study of coronary sinus volume.

Ablation strategies for atrial fibrillation

Atrial fibrillation remains the most common arrhythmia in the USA and is associated with an increased risk for stroke, congestive heart failure and overall mortality. There has been a tremendous advance in the field of catheter ablation of atrial fibrillation that has resulted in better outcomes for patients. The approach for ablation of atrial fibrillation can be different depending on patients' presentation of paroxysmal or persistent atrial fibrillation. Pulmonary vein isolation remains the cornerstone of any ablation strategy for atrial fibrillation; however, further ablation, end points of the procedure, clinical end points for successful ablation and appropriate follow-up remain controversial. We aim to discuss these different approaches and the major controversies in catheter ablation of atrial fibrillation.