Evaluation of Left Atrial Lesions After Initial and Repeat Atrial Fibrillation Ablation

Abstract

Background We evaluated scar lesions following initial and repeat catheter ablation of atrial fibrillation (AF) and correlated these regions to low-voltage tissue on repeat electroanatomical (EA) mapping. We also identified gaps in lesion sets that could be targeted and closed during repeat procedures. Methods and Results One hundred forty-four patients underwent AF ablation and received a delayed-enhancement MRI (DE-MRI) at three months post-ablation. The number of pulmonary veins (PV) with circumferential lesions were assessed and correlated with procedural outcome. Eighteen patients with AF recurrence underwent repeat ablation. MRI scar regions were compared to electroanatomical (EA) maps during the repeat procedure. Regions of incomplete scar around the PVs were then identified and targeted during repeat ablation in order to ensure complete circumferential lesions. Following the initial procedure, complete circumferential scarring of all 4 PVA was achieved in only 7% of patients, with the majority of patients (69%) having <2 completely scarred PVA. After the first procedure, the number of PVs with complete circumferential scarring and total LA wall scar burden was associated with better clinical outcome. Patients with successful AF termination had higher average total LA wall scar of 16.4% ± 9.8 (p = 0.004) and percent PVA scar of 66.2 ± 25.4 (p = 0.01) compared to patients with AF recurrence who had an average total LA wall scar 11.3% ± 8.1 and PVA percent scar 50.0 ± 24.7. In patients who underwent repeat ablation, the PV antra scar percentage was 56.1% ± 21.4 after the first procedure compared to 77.2% ± 19.5 after the second procedure. The average total LA scar after the first ablation was 11.0% ± 4.1, while the average total LA scar after second ablation was 21.2% ± 7.4. All patients had increased number of completely scarred pulmonary vein antra after the second procedure. MRI scar after the first procedure and low voltage regions on EA obtained during repeat ablation demonstrated a positive quantitative correlation of R2 = 0.57. Conclusions Complete circumferential PV lesions is difficult to achieve but is associated with better clinical outcome. DE-MRI can accurately define scar lesions following AF ablation and can be used to target breaks in lesion sets during repeat ablation.

The Role of Multimodality Cardiac Imaging in the Management of Patients with Atrial Fibrillation

“…13) [74]. However, this is difficult to achieve, with only 7% of the patients having complete scarring of all veins in one study [75].…”

Myocardial Fibrosis and the Risk of Recurrence in Atrial Fibrillation

“…In many patients, only repeated procedures can suppress the arrhytmia. 10 A prospective multicenter study that included 167 patients with paroxysmal atrial fibrillation, comparing PVI with antiarrhythmic medication, showed that 66% of subjects had better results following ablation during the 9 months of follow-up, compared to patients that had received antiarrhythmic drugs. 11 Currently the most challenging task is to parallelly improve ablation techniques, as well as to find new arrhythmia substrates and to reduce the recurrence rates of atrial fibrillation.…”

Closing the Knowledge Gaps

“…The ability to perform gap visualization post ablation remains an issue of ongoing debate, and in this study similar to the study by Sprague et al, 8 CMR was not able to reliably identify conducting gaps. In contrast, studies by Bisbal et al, 7 Badger et al, 9 and Taclas et al 10 showed good correlation between electroanatomic mapping and LGE CMR to predict gap location (Table). Some reasons may be technical and the different image acquisition protocols, scar reconstruction algorithms, LGE and electroanatomic mapping threshold values, scan resolution and magnetic resonance imaging scan timing make a comparison difficult.…”

“…6 Identification of such gaps by noninvasive techniques, such as cardiac magnetic resonance imaging (CMR), would have high clinical utility. [7][8][9][10][11] Article see p 270…”