Background

Omnipolar mapping (OT) is a novel tool to acquire omnipolar signals for electroanatomical mapping. In conjunction with the Advisor HD Grid mapping catheter, OT maps consist of a higher point density and accuracy as compared to previous enhanced mapping algorithms (bipolar (SD) and HD wave (HDW).

By integration of omnipolar signals, OT enables display of true voltage, real-time wavefront direction and speed, independent of catheter orientation and external reference. These properties make it possible to overcome the so called conventional "bipolar blindness” (wavefront detection only along and across the electrodes). Therefore, OT potentially improves atrial and ventricular scar assessment, comprehension of tachycardia mechanisms and gap detection after previous catheter ablation.

Aims

The aim of our study was to analyze previously performed left atrial (LA) and left ventricular (LV) maps for differences using automated OT vs. SD vs. the previously published HDW algorithm that automatically integrates an additional orthogonal bipole compared to SD configuration. 

Methods

Maps of patients undergoing catheter ablation (CA) for atrial or ventricular arrhythmia were initially acquired using HDW settings in conjunction with the Advisor HD Grid mapping catheter. These maps were then analyzed retrospectively applying the automated OT algorithm vs. HDW vs. SD. to reveal differences in voltage and point density. Additionally, in all LA maps, detection of pulmonary vein (PV) gaps was evaluated. For LV maps, a comparison of scar area, defined by the fraction of mapping points below scar threshold in relation to the total number of mapping points, was performed. 

Results

In 45 consecutive patients 135 maps were analyzed. The study population undergoing CA consisted of: 30 (22.2%) patients undergoing repeated CA for recurrence of persistent atrial fibrillation (persAF)/left atrial tachycardia (AT) and 15 (11.1%) patients with ventricular tachycardia (VT) or premature ventricular contractions (PVC). In total, 135 maps were analyzed.

Atrial maps revealed significantly higher point densities using OT (21471) vs. SD (6682) or HDW (12189, p<0.001). Mean voltage was significantly higher using OT (0.75mV) vs. SD (0.61mV) or HDW (0.64mV, p<0.001). OT maps detected significantly more PV gaps vs. SD (4 vs. 2, p=0.001).

In LV maps, OT revealed significantly higher point densities (25951) vs. SD (8582) and HDW (17071), p<0.001. Mean voltage was significantly higher for OT (1.49mV) vs. SD (1.19mV) and HDW (1.2mV), p<0.001. Detected scar area was significantly smaller using OT (25.3%) vs. SD (33.9%, p<0.001). 

Conclusion

In a subset of patients that has previously been treated by CA using substrate mapping by HDW, application of OT led to significant differences in substrate mapping results. Most importantly, OT provided a higher voltage and point density compared to SD and HDW, with more PV gaps detected. First data indicate a possible benefit for scar definition. Application of OT could provide a novel tool in improving substrate characterization for substrate-based ablation techniques especially in low-voltage areas and could ultimately lead to improvements in arrhythmia recurrence rates, procedure times and procedural safety.