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Address reprint requests and correspondence: Dr Satoshi Yanagisawa, Department of Cardiology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya, Aichi, 466-8550, Japan.
Affiliations
Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
Although endocardial and epicardial asynchronous activation may be an important feature for arrhythmia maintenance, the extent of the lesion reaching the epicardial surface and transmural block after cryoballoon roofline ablation have not been well evaluated.
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This is the first case report demonstrating transmural lesion formation and complete conduction block confirmed by endocardial and epicardial mapping after cryoballoon roofline ablation.
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A roofline block can be readily achieved using a cryoballoon, thus demonstrating the efficacy of cryoballoons in suppressing residual epicardial gaps and arrhythmogenesis.
Introduction
Pulmonary vein isolation (PVI) using a cryoballoon (CB) has been a well-established treatment for paroxysmal atrial fibrillation (AF).
Long-term outcomes after ablation for paroxysmal atrial fibrillation using the second-generation cryoballoon: final results from STOP AF Post-Approval study.
Although the efficacy of CB PVI for persistent AF has been cumulatively reported, the effectiveness of freedom from atrial tachyarrhythmias is limited.
An additional roofline ablation by CB may achieve a high success rate of complete conduction block and improve the clinical outcomes as compared with PVI alone in patients with persistent AF.
Cryoballoon ablation of persistent atrial fibrillation: feasibility and safety of left atrial roof ablation with generation of conduction block in addition to antral pulmonary vein isolation.
Recent studies have demonstrated that endocardial and epicardial (endo-epi) asynchronous activation may be an important feature for arrhythmia maintenance based on a simultaneous endo-epi mapping assessment.
Herein, we present a case of persistent AF evaluating simultaneous endo-epi mapping before and after PVI plus roofline ablation by CB.
Case report
A 78-year-old man complained of dyspnea and was referred to Chukyo Hospital for the treatment of congestive heart failure with persistent AF. On admission, chest computed tomography revealed a moderate pericardial effusion. After medical therapy with diuretics, beta-blockers, and angiotensin-converting enzyme inhibitors, and conversion of AF to sinus rhythm by electrical cardioversion, his symptoms improved. He had no history of cardiac disease or abnormalities on coronary angiography. The absence of pericardial effusion and the presence of sinus rhythm on an examination were confirmed at least 1 year before admission. As both recently developed persistent AF and pericardial effusion were thought to be contributing to the patient’s presentation of decompensated heart failure, the patient was scheduled for CB ablation for AF and pericardial drainage. Because of the persistent nature of AF, ablation was conducted to achieve PVI and additional left atrial (LA) roofline ablation using a 28-mm CB (Arctic Front Advance Pro; Medtronic, Minneapolis MN). Prior to the procedure, informed consent was obtained from the patient.
First, pericardiocentesis was performed with the removal of 275 mL of pericardial effusion, resulting in an increase in systolic blood pressure by 20 mm Hg. After drainage, the drain tube was replaced with a long catheter sheath to facilitate the epicardial LA mapping.
Prior to cryoablation, a high-density map of the endo-epi atria was created using an Advisor HD Grid catheter and 3-dimentional mapping system (EnSite X; Abbott, North Chicago, IL). A preablation epicardial substrate map from the oblique sinus showed epicardial electrical potentials on the LA roof (Figure 1). A sparkle propagation map with the high right atrial septum pacing revealed that the endocardial roof and epicardial roof both displayed propagation (Supplemental Videos 1 and 2). PVI was achieved with a freeze cycle of 180 seconds for each lesion. Subsequently, a roofline ablation was completed with 4 overlapping cryoapplications of 150-second cycles along with the grid catheter placed on the epicardial surface of the LA roof. The amplitudes of the epicardial roof’s potential adjacent to the CB gradually decreased until 60 seconds from the start of freezing. Thereafter, the epicardial potentials recorded in the A1, A2, B1, and B2 electrodes of the grid catheter disappeared (Figure 2). After freezing was stopped, the amplitudes of electrical potentials were unchanged. A postablation endo-epi substrate map demonstrated scar regions (defined as amplitudes of <0.05 mV) on the endo-epi roof, indicating an achievement of a transmural lesion (Figures 3A and 3B). The grid catheter located on the epicardial scar area at the LA roof showed no electrical potentials (Figure 3C). No local atrial captures from both endo-epi scar regions were confirmed on the grid catheter by 10 V high-output pacing. A post–sparkle propagation map with LA appendage pacing also confirmed complete transmural block of the LA roof (Supplemental Video 3). The patient completed the ablation procedure because there were no other low-voltage areas on the endo-epi posterior wall that did not require an additional LA floor ablation for posterior wall isolation.
Figure 1Preablation epicardial substrate map. Epicardial substrate map with high right atrial pacing demonstrated epicardial potentials on the epicardial left atrial roof. The dark purple and gray colors represent voltage amplitudes of 0.5 mV and 0.05 mV, respectively. The purple color represents a healthy area with an electrogram amplitude of ≥0.5 mV.
Figure 2Changes in epicardial potentials of the left atrial roof pre- and postfreezing. A: Epicardial potentials of the left atrial roof recorded by the electrode catheter with high right atrial (RA) pacing. The amplitudes of the epicardial potentials decreased during freezing and persisted thereafter. The red arrowheads indicate the disappearance of epicardial potentials. B: Relationship of the electrode catheters and cryoballoon in the left anterior oblique (left) and right anterior oblique (right) fluoroscopic views. Electrodes A and B of the mapping catheter are seen on the opposing surface where the cryoballoon was attached. CS = coronary sinus.
Figure 3Endocardial and epicardial substrate map after left atrial roof ablation. A: Epicardial substrate map showing the scar region on the left atrial roof. B: Combined endocardial and epicardial substrate map showing the transmural lesion induced by cryofreezing sufficiently reaching the epicardium. C: The grid catheter positioned at epicardial roof demonstrated no electrical potentials in the electrodes located at the scar region (electrodes A1–A4, B1–B2). Endo = endocardium; Epi = epicardium; ECG = electrocardiogram; LAA = left atrial appendage; LSPV = left superior pulmonary vein; RSPV = right superior pulmonary vein.
No perioperative complications developed, and the patient was free from AF recurrence and hospitalization for heart failure during a 4-month follow-up. The patient had no symptoms related to gastroesophageal disorder during the follow-up, though we did not monitor the esophageal temperature during the procedure. Pericardial effusion did not recur after the follow-up echocardiography. Histological examination of the pericardial effusion suggested transudative effusion with no evidence of malignancy or other specific diseases.
Discussion
We present a case of complete transmural lesion formation and conduction block of the LA roof after PVI plus roofline ablation using a 28-mm CB. Before ablation, the epicardial surface of the LA roof possessed sharp epicardial potentials that might be different from the far-field potentials of that endocardial surface, and activation could propagate through the endo-epi roof. Monitoring the epicardial potentials adjacent to the CB located at the endocardial LA roof revealed that epicardial lesion was created until 60-second cryoapplication, which might also be durable after stop of 150-second freezing. The endo-epi conduction block in the post–sparkle propagation map suggested transmural lesion formation on the LA roof after endocardial CB ablation, although some parts of the LA epicardium such as the front half of the LA roof and around the right pulmonary veins were inaccessible from the oblique sinus.
Unfortunately, we could not confirm the real-time sequence changes during the final freezing of the LA roof because the grid catheter was positioned away from the epicardial posterior wall due to difficulty fixing it to the LA roof space. However, our findings including postsubstrate and propagation maps after CB ablation were the evidence to confirm transmural lesion formation and complete conduction block consistently.
An insufficient transmural conduction block during roofline ablation might be associated with incomplete substrate modification with residual epicardial arrhythmogenesis and recurrence of atrial tachyarrhythmias. A previous report showed that the conduction gap of the roofline occasionally could remain after endocardial ablation, which may be related to incomplete transmural lesions with preserved epicardial connection via the septopulmonary bundle.
To the best of our knowledge, this is the first case report demonstrating transmural lesion formation and complete conduction block by endo-epi mapping after CB roofline ablation. A roofline block using a CB can be readily achieved with an appropriate balloon size and shape. Recent large-scale multicenter randomized controlled trials failed to show the improved outcomes of additional radiofrequency linear ablation or posterior wall isolation, in addition to PVI in patients with persistent AF.
Effect of catheter ablation using pulmonary vein isolation with vs without posterior left atrial wall isolation on atrial arrhythmia recurrence in patients with persistent atrial fibrillation: the CAPLA Randomized Clinical Trial.
In contrast, regarding CB ablation, 2 small randomized controlled trials demonstrated a benefit of additional linear ablation including posterior wall isolation.
Does isolation of the left atrial posterior wall using cryoballoon ablation improve clinical outcomes in patients with persistent atrial fibrillation? A prospective randomized controlled trial.
Esophageal injury is a major concern during the additional CB ablation, while these studies revealed that CB linear ablation did not increase the risk of gastroesophageal complications compared with PVI alone.
Does isolation of the left atrial posterior wall using cryoballoon ablation improve clinical outcomes in patients with persistent atrial fibrillation? A prospective randomized controlled trial.
Additional linear ablation including posterior wall isolation using CB may be beneficial for persistent AF with specific substrates, based on the balance of the efficacy and safety of CB linear ablation, which will be validated by further large-scale studies. Whether cryoablation is more or less likely to leave epicardial conduction gaps compared with radiofrequency ablation remains unknown but may warrant further investigation.
Conclusion
Simultaneous endo-epi mapping after LA roof CB ablation demonstrated complete transmural lesion formation on the LA roof, which might represent the efficacy of CB in suppressing residual epicardial arrhythmogenesis and connection.
Acknowledgments
The authors express their appreciation to Drs Kenji Kada and Naoya Tsuboi for their valuable guidance and generous help with the electrophysiological study.
Funding Sources
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Disclosures
Satoshi Yanagisawa is affiliated with a department sponsored by Medtronic Japan. The other authors have no conflicts of interest.
Authorship
All authors attest they meet the current ICMJE criteria for authorship.
Patient Consent
Informed consent was obtained from the patient before catheter ablation.
Ethics Statement
The research reported in this paper adhered to CARE case report guidelines.
Long-term outcomes after ablation for paroxysmal atrial fibrillation using the second-generation cryoballoon: final results from STOP AF Post-Approval study.
Cryoballoon ablation of persistent atrial fibrillation: feasibility and safety of left atrial roof ablation with generation of conduction block in addition to antral pulmonary vein isolation.
Effect of catheter ablation using pulmonary vein isolation with vs without posterior left atrial wall isolation on atrial arrhythmia recurrence in patients with persistent atrial fibrillation: the CAPLA Randomized Clinical Trial.
Does isolation of the left atrial posterior wall using cryoballoon ablation improve clinical outcomes in patients with persistent atrial fibrillation? A prospective randomized controlled trial.
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