Mapping and ablation of left atrial roof-dependent tachycardias using an ultra-high resolution mapping system.

BACKGROUND: Left atrial roof-dependent tachycardias (LARTs) are common macroreentrant atrial tachycardias (ATs). We sought to characterize clinical LARTs using an ultra-high resolution mapping system. METHODS: This study included 22 consecutive LARTs in 21 patients who underwent AT mapping/ablation using Rhythmia systems. RESULTS: Three, 13, 4, and 2 LART patients were cardiac intervention naïve (Group-A), post-roof line ablation (Group-B), post-atrial fibrillation ablation without linear ablation (Group-C), and post-cardiac surgery (Group-D), respectively. The mean AT cycle length was 244 ± 43 ms. Coronary sinus activation was proximal-to-distal or distal-to-proximal in 16 (72.7%) ATs. The activation map revealed 13 (59.1%) clockwise and 9 (40.9%) counter-clockwise LARTs. A 12-lead synchronous isoelectric interval was observed in 10/19 (52.6%) LARTs. The slow conduction area was identified on the LA roof, anterior/septal wall, and posterior wall in 18, 6, and 2 ATs, respectively. Twenty concomitant ATs among 13 procedures were also eliminated, and peri-mitral AT coexisted in 7 of 9 non-group-B patients. In group-B, the conduction gap was predominantly located on the mid-roof. Sustained LARTs were terminated by a single application and linear ablation in 6 (27.3%) and 9 (40.9%), while converting to other ATs in 7 (31.8%) LARTs. Complete linear block was created without any complications in all, however, ablation at the mid-posterior wall was required to achieve block in 4 (18.2%) procedures. During 14.0 (6.5-28.5) months of follow-up, 17 (81.0%) and 19 (90.5%) patients were free from any atrial tachyarrhythmias after single and last procedures. CONCLUSIONS: The LART mechanisms were distinct in individual patients, and elimination of all concomitant ATs was required for the management.

SVC Mapping Using an Ultra-High Resolution 3-Dimensional Mapping System in Patients With and Without AF.

OBJECTIVES: This study aimed to characterize the superior vena cava (SVC) sleeve in patients with and without atrial fibrillation (AF). BACKGROUND: A few studies have examined the morphological characteristics of atrial myocardial extensions into the human SVC using autopsied hearts. METHODS: Thirty-four patients with AF and 30 without AF underwent SVC mapping during sinus rhythm using ultra-high-resolution mapping. In 18 patients with AF, SVC isolation was added, and the SVC mapping was repeated. RESULTS: The median acquisition time was 7.7 min (interquartile range [IQR]: 5.5 to 11.2 min), and 2,478 data points (IQR: 1,620 to 3,350 data points) were automatically annotated. The electrically activated SVC sleeve length was asymmetric and longest at the anteroseptal SVC (27.0 to 28.0 mm) and shortest at the posterolateral SVC (22.0 to 23.0 mm). The sleeve length at each segment was similar in patients with and without AF, however, conduction time in the sleeve was significantly longer (76.1 ± 26.4 ms vs. 61.0 ± 19.1 ms; p = 0.036) and conduction block more frequently pre-existing in patients with AF than in those without (3 of 34 vs. 0 of 30; p = 0.047). The conduction velocity from sinus node was slower in upper direction (to SVC) than in other directions. Electrical SVC isolations were successfully achieved in all 18 patients without any complications. The conventional isolation line was a median of 20 mm (IQR: 13.9 to 29.0 mm) apart from and superior to the earliest activation sites during sinus rhythm. The isolated SVC sleeve length was longest at the septal SVC (median: 19.1 mm [IQR: 11.8 to 24.2 mm]) and shortest at the anterolateral SVC (median: 6.4 mm [IQR: 0 to 11.3 mm]). CONCLUSIONS: Ultra-high-resolution human SVC mapping demonstrated asymmetric SVC musculature sleeves and variations in the sleeve length in individual patients. Conduction disturbances were more prominent in patients with AF than in those without.