Background
- Achieving bidirectional mitral isthmus (MI) block using radiofrequency catheter ablation (RFCA) alone is challenging, and MI reconnection is common. Adjunctive vein of Marshall (VOM) ethanol infusion (VOM-Et) can facilitate acute MI block. However, little is known regarding its long-term success. This study sought to evaluate the impact of adjunctive VOM-Et on MI block achievement and durability compared to RFCA alone.
Methods
- Patients undergoing a first attempt of posterior MI ablation were grouped according to their MI block index strategy: adjunctive VOM-Et and RFCA alone. Rates of acute MI block and MI reconnection observed during repeat procedures were compared between the two groups.
Results
- The VOM-Et group consisted of 152 patients (63.8 ± 9.4 years) undergoing adjunctive VOM-Et for MI block. The RFCA group consisted of 110 patients (60.9 ± 9.2 years) undergoing MI ablation using RFCA alone. Acute MI block was more frequently achieved in the VOM-Et group (98.7% [150/152] vs. 63.6% [70/110]; p < 0.001) with shorter RFCA duration (5.00 [3.00-7.00] vs. 19.0 [13.6-22.0] mins; p < 0.001). Of the 220 patients with MI block achieved during the index procedure, 81 underwent a repeat procedure during follow-up (VOM-Et group: 23.3% [35/150] vs. RFCA group: 65.7% [46/70], respectively; p < 0.001). A significantly greater number of patients exhibited durable MI block in the VOM-Et group (62.9% [22/35] vs. 32.6% [15/46], respectively; p = 0.008).
Conclusions
- Beyond facilitating acute MI block, VOM-Et is associated with greater lesion durability as evidenced by higher rates of MI block during repeat procedures.
Aims
Pulsed field ablation (PFA), a non-thermal ablative modality, may show different effects on the myocardial tissue compared to thermal ablation. Thus, this study aimed to compare the left atrial (LA) structural and mechanical characteristics after PFA vs. thermal ablation.
Methods and results
Cardiac magnetic resonance was performed pre-ablation, acutely (<3 h), and 3 months post-ablation in 41 patients with paroxysmal atrial fibrillation (AF) undergoing pulmonary vein (PV) isolation with PFA (n = 18) or thermal ablation (n = 23, 16 radiofrequency ablations, 7 cryoablations). Late gadolinium enhancement (LGE), T2-weighted, and cine images were analysed. In the acute stage, LGE volume was 60% larger after PFA vs. thermal ablation (P < 0.001), and oedema on T2 imaging was 20% smaller (P = 0.002). Tissue changes were more homogeneous after PFA than after thermal ablation, with no sign of microvascular damage or intramural haemorrhage. In the chronic stage, the majority of acute LGE had disappeared after PFA, whereas most LGE persisted after thermal ablation. The maximum strain on PV antra, the LA expansion index, and LA active emptying fraction declined acutely after both PFA and thermal ablation but recovered at the chronic stage only with PFA.
Conclusion
Pulsed field ablation induces large acute LGE without microvascular damage or intramural haemorrhage. Most LGE lesions disappear in the chronic stage, suggesting a specific reparative process involving less chronic fibrosis. This process may contribute to a preserved tissue compliance and LA reservoir and booster pump functions.
Introduction
Human atria comprise distinct layers. One layer can bypass another, and lead to a downstream centrifugal propagation at their interface. We sought to characterize anatomical substrates, electrophysiological properties, and ablation outcomes of "pseudo‐focal" atrial tachycardias (ATs), defined as macroreentrant ATs mimicking focal ATs.
Methods and Results
We retrospectively analyzed left atrial ATs showing centrifugal propagation with postpacing intervals (PPIs) after entrainment pacing suggestive of a macroreentrant mechanism. A total of 22 patients had pseudo‐focal ATs consisting of 15 perimitral and 7 roof‐dependent flutters. A low‐voltage area was consistently found at the collision site and colocalized with distinct anatomical structures like the: (1) coronary sinus‐great cardiac vein bundle (27%), (2) vein of Marshall bundle (18%), (3) Bachmann bundle (27%), (4) septopulmonary bundle (18%), and (5) fossa ovalis (9%). The mean missing tachycardia cycle length (TCL) was 65 ± 31 ms (22%) on the endocardial activation map. PPI was 0 [0–15] ms and 0 [0–21] ms longer than TCL at the breakthrough site and the opposite site, respectively. While feasible in 21 pseudo‐focal ATs (95%), termination was better achieved by blocking the anatomical isthmus than ablating the breakthrough site [20/21 (95%) vs. 1/5 (20%); p < .001].
Conclusion
Perimitral and roof‐dependent flutters with centrifugal propagation are favored by a low‐voltage area located at well‐identified anatomical structures. Comprehensive entrainment pacing maneuvers are crucial to distinguish pseudo‐focal ATs from true focal ATs. Blocking the anatomical isthmus is a better therapeutic option than ablating the breakthrough site.
Introduction
The optimal strategy after a failed ablation for persistent atrial fibrillation (perAF) is unknown. This study evaluated the value of an anatomically guided strategy using a systematic set of linear lesions with adjunctive ethanol infusion into the vein of Marshall (Et‐VOM) in patients referred for second perAF ablation procedures.
Methods and Results
Patients with perAF who underwent a second procedure were grouped according to the two strategies. The first strategy was an anatomically guided approach using systematic linear ablation with adjunctive Et‐VOM, with bidirectional blocks at the posterior mitral isthmus (MI), roof, and cavotricuspid isthmus (CTI) as the procedural endpoint (Group I). The second one was an electrophysiology‐guided strategy, with atrial tachyarrhythmia termination as the procedural endpoint (Group II). Arrhythmia behavior during the procedure guided the ablation strategy. Groups I and II consisted of 96 patients (65 ± 9 years; 71 men) and 102 patients (63 ± 10 years; 83 men), respectively. Baseline characteristics were comparable. In Group I, Et‐VOM was successfully performed in 91/96 (95%), and procedural endpoint (bidirectional block across all three anatomical lines) was achieved in 89/96 (93%). In Group II, procedural endpoint (atrial tachyarrhythmia termination) was achieved in 80/102 (78%). One‐year follow‐up demonstrated Group I (21/96 [22%]) experienced less recurrence compared to Group II (38/102 [37%], Log‐rank p = .01). This was driven by lower AT recurrence in Group I (Group I: 10/96 [10%] vs. Group II: 29/102 [28%]; p = .002).
Conclusion
Anatomically guided strategy with adjunctive Et‐VOM is superior to an electrophysiology‐guided strategy for second procedures in patients with perAF at 1‐year follow‐up.
Introduction: Ultra-high-density mapping for ventricular tachycardia
(VT) is increasingly used. However, manual annotation of local abnormal
ventricular activities (LAVAs) is challenging in this setting.
Therefore, we assessed the accuracy of the automatic annotation of LAVAs
with the Lumipoint algorithm of the Rhythmia system (Boston Scientific).
Methods and Results: One hundred consecutive patients undergoing
catheter ablation of scar-related VT were studied. Areas with LAVAs and
ablation sites were manually annotated during the procedure and compared
with automatically annotated areas using the Lumipoint features for
detecting late potentials (LP), fragmented potentials (FP), and double
potentials (DP). The accuracy of each automatic annotation feature was
assessed by re-evaluating local potentials within automatically
annotated areas. Automatically annotated areas matched with manually
annotated areas in 64 cases (64%), identified an area with LAVAs missed
during manual annotation in 15 cases (15%), and did not highlight areas
identified with manual annotation in 18 cases (18%). Automatic FP
annotation accurately detected LAVAs regardless of the cardiac rhythm or
scar location; automatic LP annotation accurately detected LAVAs in
sinus rhythm, but was affected by the scar location during ventricular
pacing; automatic DP annotation was not affected by the mapping rhythm,
but its accuracy was suboptimal when the scar was located on the right
ventricle or epicardium. Conclusion: The Lumipoint algorithm was as/more
accurate than manual annotation in 79% of patients. FP annotation
detected LAVAs most accurately regardless of mapping rhythm and scar
location. The accuracy of LP and DP annotations varied depending on
mapping rhythm or scar location.
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