Introduction: Complex atrial tachycardias (AT) are frequently encountered in patients after left atrial catheter abaltions. We aimed to evaluate the HD grid technology for high-resolution mapping of these challenging arrhythmias.
Methods: Prospective observational study including consecutive patients undergoing de novo or redo catheter ablation for AT. Electroanatomical mapping during AT was performed using the Advisor HD grid catheter (HD Wave Solution), and a separate map was created using a conventional bipolar electrode configuration. The total number of collected points and the mean voltage amplitude at the critical isthmus for macro-/micro-reentry AT or at the earliest site of activation for focal AT were recorded and compared in both the maps (i.e. HD Wave Solution vs. standard bipolar configuration). Response to ablation and entrainment was used to confirm the correct location of the critical isthmus (post pacing interval <20ms).
Results: 40 patients (62.6±10.0 years, 70% male) were enrolled and a total of 42 ATs (mean cycle length 323±74ms) were mapped. The mechanism of AT was macro-reentry in 24 cases (57.1%), focal in 16 (38.1%), and micro-reentry in 2 (4.8%). The mean number of electrograms acquired per map was significantly higher for HD wave vs. standard bipolar (23251±12711 vs. 12812±8608, p<0.05). The mean voltage at the critical isthmus/earliest activation point was measured for a total of 22 left-sided ATs and was numerically higher for HD wave vs. standard bipolar (2.60±5.66 vs. 2.18±5.18, p=0.16). After 239±168 days of follow up, 72.5% of patients were free from AT recurrences.
Conclusions: The HD grid is an effective and useful technology for mapping complex AT. This system allows an increased mapping density and resolution compared to conventional bipoles, and as such might optimise the ability to localise critical isthmuses. Success rate of catheter ablation guided by HD grid mapping appears to be high.