PO-04-038 ULTRA HIGH DENSITY MAPPING TO IDENTIFY MICRO-REENTRANT LEFT ATRIAL FLUTTER CIRCUITS WITHIN LOW BIPOLAR VOLTAGE REGIONS: A CASE SERIES

Abstract

Micro-reentrant (MR) atrial flutter (AFL) circuits may not be evident with standard bipolar or multipolar mapping. We report 3 cases of left atrial (LA) AFL where HD Grid + Omnipolar technology (Ensite X, Abbott) revealed MR circuits within an area of scar as noted by standard multipolar mapping. N/A Three patients with prior LA ablation presented with symptomatic AFL. LA mapping was done using the Ensite X system in Voxel mode. Bipolar voltage cutoff was set at 0.3 to 0.05 mV. A 65-year-old presented with AFL CL of 335 ms. Mapping with an Advisor spiral showed a large posterior wall scar and no AFL circuit in LA or RA. Remapping with HD Grid identified a 12 mm MR circuit with entire CL in the low LA posterior wall which showed dense scar by spiral mapping (Figure 1A). A 59-year-old male presented with AFL CL of 340 ms with proximal to distal CS activation. HD grid mapping identified a 21 mm MR circuit in the mid LA posterior with fractionated mid-diastolic electrograms (Figure 1B and 1C). Third patient was a 54-year-old male who had a MR circuit in the posterolateral mitral annulus, otherwise noted as scar by bipolar mapping. Successful ablation sites in all 3 cases did not have an identifiable bipolar electrogram on ablation catheter (<0.05 mV, Figure 1 D). Low voltage cut off during HD mapping was manually adjusted and had to be lowered to 0.04 to identify the circuit in all cases. This case series demonstrates that ultra high-density mapping with HD Grid + Omnipolar technology, with dynamic adjustment of low voltage threshold, enables identification of MR AFL circuits, leading to successful ablation, where critical isthmi were not identified by standard bipolar or multipolar mapping.