A new interpretation of nonpulmonary vein substrates of the left atrium in patients with atrial fibrillation.

BACKGROUND

Substrate analysis of the left atrium in patients undergoing atrial fibrillation ablation has limitations when performed by means of simple bipolar acquisition.

OBJECTIVE

To evaluate the incidence of low-voltage zones (LVZs) through maps constructed by means of various catheters: multipolar (MC), omnipolar (OC), and circular catheters (CMCs) with the 3D electro-anatomical systems (3d-S) CARTO3 and EnSite Precision.

METHODS

To assess LVZs, we acquired maps by means of CMC and MC in the voltage range 0.05-0.5 mV in 70 consecutive patients in sinus rhythm. In the case of OC only, we made an intra-patient comparison of bipolar maps constructed by means of the along and across, and HD-Wave configurations of the EnSite 3d-S in the ranges of 0.05-0.5 and 0.5-1.0 mV. On the basis of this comparison, we chose the range that best identified LVZs as a set of different colors (SDC) compatible with patchy fibrosis (qualitative analysis). Subsequently, we detected the voltage values corresponding to purple and gray points, close to SDC, and the value inside corresponding to blue, green, and red colors, and we evaluated the color change in other voltage ranges. Finally, we performed a quantitative analysis of LVZs by applying the qualitative characteristics described above.

RESULTS

On the basis of our settings, for OC, the optimal range identifying LVZs was 0.3-0.6 mV. OC revealed smaller LVZs than MC ( < .05 or  < .001), except in the lateral wall. No significant differences were observed between CMCs.

CONCLUSIONS

In our experience, OC does not present the limits of bipolar HD maps, though further studies are needed in order to confirm that 0.3-0.6 mV is the optimal voltage range within which to identify LVZs.