The Relationship between the Profiles of SVC and Sustainability of SVC Fibrillation Induced by Provocative Electrical Stimulation

Role of electroanatomical mapping-guided superior vena cava isolation in paroxysmal atrial fibrillation patients without provoked superior vena cava triggers: a randomized controlled study

AIMS

Data about whether empirical superior vena cava (SVC) isolation (SVCI) improves the success rate of paroxysmal atrial fibrillation (PAF) are conflicting. This study sought to first investigate the characteristics of SVC-triggered atrial fibrillation and secondly investigate the impact of electroanatomical mapping-guided SVCI, in addition to circumferential pulmonary vein isolation (CPVI), on the outcome of PAF ablation in the absence of provoked SVC triggers.

METHODS AND RESULTS

A total of 130 patients undergoing PAF ablation underwent electrophysiological studies before ablation. In patients for whom SVC triggers were identified, SVCI was performed in addition to CPVI. Patients without provoked SVC triggers were randomized in a 1:1 ratio to CPVI plus SVCI or CPVI only. The primary endpoint was freedom from any documented atrial tachyarrhythmias lasting over 30 s after a 3-month blanking period without anti-arrhythmic drugs at 12 months after ablation. Superior vena cava triggers were identified in 30 (23.1%) patients with PAF. At 12 months, 93.3% of those with provoked SVC triggers who underwent CPVI plus SVCI were free from atrial tachyarrhythmias. In patients without provoked SVC triggers, SVCI, in addition to CPVI, did not increase freedom from atrial tachyarrhythmias (87.9 vs. 79.6%, log-rank P = 0.28).

CONCLUSION

Electroanatomical mapping-guided SVCI, in addition to CPVI, did not increase the success rate of PAF ablation in patients who had no identifiable SVC triggers.

REGISTRATION

ChineseClinicalTrials.gov: ChiCTR2000034532.

Efficacy, Safety and Feasibility of Superior Vena Cava Isolation in Patients Undergoing Atrial Fibrillation Catheter Ablation: An Up-to-Date Review

Pulmonary vein isolation (PVI) is the cornerstone in atrial fibrillation (AF) ablation; yet, the role of arrhythmogenic superior vena cava (SVC) is increasingly recognized and different ablation strategies have been employed in this context. SVC can act as a trigger or perpetuator of AF, and its significance might be more pronounced in patients undergoing repeated ablation. Several cohorts have examined efficacy, safety and feasibility of SVC isolation (SVCI) among AF patients. The majority of these studies explored as-needed SVCI during index PVI, and only a minority of them included repeated ablation subjects and non-radiofrequency energy sources. Studies of heterogeneous design and intent have explored both empiric and as-needed SVCI on top of PVI and reported inconclusive results. These studies have largely failed to demonstrate any clinical benefit in terms of arrhythmia recurrence, although safety and feasibility are undisputable. Mixed population demographics, small number of enrollees and short follow-up are the main limitations. Procedural and safety data are comparable between empiric SVCI and as-needed SVCI, and some studies suggested that empiric SVCI might be associated with reduced AF recurrences in paroxysmal AF patients. Currently, no study has compared different ablation energy sources in the setting of SVCI, and no randomized study has addressed as-needed SVCI on top of PVI. Furthermore, data regarding cryoablation are still in their infancy, and regarding SVCI in patients with cardiac devices more safety and feasibility data are needed. PVI non-responders, patients undergoing repeated ablation and patients with long SVC sleeves could be potential candidates for SVCI, especially via an empiric approach. Although many technical aspects remain unsettled, the major question to answer is which clinical phenotype of AF patients might benefit from SVCI?

Integrated Analysis of circRNA-miRNA-mRNA-Mediated Network and Its Potential Function in Atrial Fibrillation

Background

Atrial fibrillation (AF) is one of the most prevalent arrhythmias, characterized by a high risk of heart failure and embolic stroke. Competing endogenous RNA network has been reported to play an important role in cardiovascular diseases. The main objective of the present study was to construct a circRNA–miRNA–mRNA-mediated network and explore the potential function in AF.

Methods

The microarray data of circRNA, miRNA, and mRNA in AF were downloaded from the Gene Expression Omnibus database. The RobustRankAggreg method was used to screen the different expression circRNAs(DECs). Then the circRNA–miRNA–mRNA-mediated network was constructed by using the CircInteractome database and the miRWalk online tool. A quantitative real-time polymerase chain reaction was used to detect the circRNA expression level in plasma. The left atrial fibrosis was evaluated with the left atrial low voltage area (LVA) by using left atrial voltage matrix mapping.

Results

Three DECs (hsa_circRNA_102461, hsa_circRNA_103693, and hsa_circRNA_059880) and 4 miRNAs were screened. Then a circRNA–miRNA–mRNA-mediated network was constructed, which included 2 circRNAs, 4 miRNAs, and 83 genes. Furthermore, the plasma’s hsa_circ_0070391 expression level was confirmed to be upregulated and positively correlated with left atrial fibrosis in AF (r = 0.88, P < 0.001), whereas hsa_circ_0003935 was downregulated. Moreover, the ROC curve analysis revealed hsa_circ_0070391 and hsa_circ_0003935 could differentiate AF from the healthy controls with an AUC of 0.95 (95% sensitivity and 90% specificity) and 0.86 (70% sensitivity and 75% specificity), respectively. Finally, the free of atrial tachyarrhythmia rate was dramatically lower in the hsa_circ_0070391 high expression group than in the low expression group post catheter ablation (70.0 vs. 90.0%, p = 0.04).

Conclusion

This study provides a novel insight to further understand the AF pathogenesis from the perspective of the circRNA–miRNA–mRNA network, suggesting that plasma circRNAs could serve as a novel atrial fibrosis and prognosis biomarker for AF.

An anatomical approach to determine the location of the sinoatrial node during catheter ablation

INTRODUCTION

The sinoatrial node (SAN) should be identified before superior vena cava (SVC) isolation to avoid SAN injury. However, its location cannot be identified without restoring sinus rhythm. This study evaluated the usefulness of the anatomically defined SAN by comparing it with the electrically confirmed SAN (e-SAN) to predict the top-most position of e-SAN and thus establish a safe and more efficient anatomical reference for SVC isolation than the previously reported reference of the right superior pulmonary vein (RSPV) roof.

METHODS AND RESULTS

The e-SAN was identified as the earliest activation site in the electroanatomical map obtained during sinus rhythm. The anatomically defined SAN, the cranial edge of the crista terminalis (CT) visualized with intracardiac echocardiography (CT top), and the RSPV roof, which was obtained from the overlaid electroanatomical image of SVC and RSPV, were tagged on one map. The distance from the e-SAN to each reference was measured. Among 77 patients, the height of the e-SAN from the CT top was a median (interquartile range) of -2.0 (-8.0 to 4.0) mm. The e-SAN existed from 10 mm above the CT top or lower in 74 (96%) patients and from the RSPV roof or below in 73 (95%) patients. The reference of 10 mm above the CT top is more proximal to the right atrium than the RSPV roof and can provide longer isolatable SVC sleeves (30.0 [20.0-35.0] vs. 24.0 [18.0-30.0] mm, p < .001). The e-SAN tended to be found above the CT top when the heart rate during mapping was faster (adjusted odds ratio [95% confidence interval] per 10-bpm increase: 1.71 [1.20-2.43], p < .01).

CONCLUSION

The CT top is useful for predicting the upper limit of the e-SAN and can provide a better reference for SVC isolation than the RSPV roof.

Anatomical dilatation of the superior vena cava associated with an arrhythmogenic response induced by SVC scan pacing after atrial fibrillation ablation

Background

The relationship between pulmonary vein (PV) arrhythmogenicity and its anatomy has been reported. However, that of the superior vena cava (SVC) has not been well discussed. Arrhythmogenic response induced by pacing stimulation at SVC might help with identifying SVC arrhythmogenicity. The purpose of this study was to investigate the relationship between the anatomical dilatation of SVC and the arrhythmogenic response induced by pacing at SVC.

Methods

Forty-three patients who underwent atrial fibrillation (AF) ablation were enrolled in this study. After PV isolation, scan pacing (up to triple extra stimulation following intrinsic sinus beats) was performed at SVC. The arrhythmogenic response was defined as following: (1) repetitive atrial responses, (2) non-sustained, and (3) sustained AF/ atrial tachycardia. To assess the dilatation of SVC, we measured the cross-sectional area of the SVC (SVC-area) using multi-planar reconstruction CT imaging.

Results

Arrhythmogenic responses were documented in 24 patients (Group 1). No arrhythmogenic responses were documented in the remaining 19 patients (Group 2). The SVC-area was significantly larger in Group 1 than Group 2 (3.1±0.9 vs. 2.2±0.8 cm², P=0.004). A multivariate analysis revealed only SVC-area was associated with arrhythmogenic responses (odds ratio=2.87, CI 1.05–7.82, P=0.04). Furthermore, AF recurrence rate was significantly higher in patients with SVC-area>2.56 cm² than those with SVC-area <2.56 cm² (9 [42.9%] of 21 vs. 3 [13.6%] of 22, P=0.026).

Conclusion

Dilatation of SVC was associated with an arrhythmogenic response, and the AF recurrence rate was significantly higher in patients with large SVC-area. Adjunctive catheter intervention for the SVC might be indicated in patients with a dilated SVC and an arrhythmogenic response.

The Role of Superior Vena Cava Isolation in the Management of Atrial Fibrillation

The superior vena cava (SVC) has been identified as one of the most common sources of non-pulmonary vein triggers for atrial fibrillation (AF). SVC isolation has been shown to improve long-term maintenance of normal sinus rhythm in patients with paroxysmal AF. However, ablation at the SVC is associated with risks of phrenic nerve injury, sinus node dysfunction, and SVC stenosis. The use of electroanatomical mapping, intracardiac echocardiography, compound motor action potentials, and segmental (rather than circumferential) ablation are all strategies to reduce complications. Given these risks, SVC isolation is most effective as an adjunct to pulmonary vein isolation for patients with paroxysmal AF who have been found to have an arrhythmogenic SVC.