Time- and frequency-domain analyses of atrial fibrillation activation rate: The optical mapping reference

Background

Time- and frequency-domain estimates of activation rate have been proposed to guide atrial fibrillation (AF) ablation in patients, but their electrophysiological correlates are unclear.

Objective

This study sought to examine the relative correlation of average electrical cycle length (CL) and dominant frequency (DF) during AF with reference optical mapping measures.

Methods

Eight sheep hearts were Langendorff-perfused and superfused with oxygenated Tyrode solution inside a tank representing the human thorax. Optical mapping (DI-4-ANEPPS) of 4 × 4 cm² in the left atrium was performed at 0.5 mm/pixel and 600 fps. A 20-pole catheter was placed in the optical field of view to acquire 1.2-kHz unipolar recordings by the EnSite NavX System (ENS; St. Jude Medical, St. Paul, MN) optimized for CL and DF calculation. During AF, 5-second-long simultaneous optical and electrical signals were analyzed for CL and DF.

Results

During pacing, DF measurements had fewer false results than CL (6.6% to 2.5% vs. 21.5% to 4.4% depending on filtering, P <.001). During AF in regions showing periodic waves on both sides of the catheter optical 1,000/CL versus DF correlation showed 95% confidence identity and was better than unipolar measurements in the ENS (adjusted R²: 0.58879 vs. 0.12902; P < 10⁻⁶). DFs of unipolar signals correlated better than CLs with DFs of optical signals. Similarly, bipolar DF correlation with optical DF was not different from identity (P >.157), but the bipolar CL showed smaller identity with the optical CL (P <.0004).

Conclusion

DF values of unipolar and bipolar signals correlate with those of optical signals better than CL values for the respective signals.

Keywords: Ablation, Atrial fibrillation, Complex fractionated electrogram, Cycle length, Dominant frequency

Abbreviations: AF, atrial fibrillation, AR, adjusted regression coefficient, CFE, complex fractionated electrograms, CL, cycle length, DF, dominant frequency, ENS, EnSite NavX system