Quantitative analyses of the distal bipolar electrogram for focal premature ventricular contraction ablation

Background

Accurate interpretation of the distal bipolar electrogram (bi-EGM) is essential for successful ablation of idiopathic focal PVC. Sharp, early, and fractionated bi-EGM is often considered to be near-field and targeted, but in an empiric fashion rather than by quantitative criteria.

Objectives

To quantify the distal bi-EGM with five parameters to elucidate quantitative criteria distinguishing near-field from far-field bi-EGM.

Methods

The distal bi-EGM was quantified and analyzed using: half time of activation (t_½), slope factor (S, derived by fitting the Boltzmann equation), linear slope (dV/dt), time from onset of bi-EGM to surface ECG (T_s) and number of deflections (De#).

Results

Among 41 patients, 26 were ablated successfully and 15 unsuccessfully. t_½ and S, defining the sharpness of the activation process, were significantly different between the two groups (3.2 ± 0.3 vs. 5.9 ± 0.6 ms, p < 0.001 and 0.8 ± 0.1 vs. 4.8 ± 2.0, p = 0.01). T_s was earlier in the successful group (35.6 ± 1.3 vs. 25.8 ± 1.6 ms, p < 0.01). dV/dt and De# were not statistically different (0.2 ± 0.04 vs. 0.1 ± 0.02 mV/ms, p = 0.06; and 2.7 ± 0.2 vs. 2.3 ± 0.3, p = 0.22). The 5 parameters showed indifference across anatomic locations. AUCs of ROC curve are >0.8 (t_½ 0.85, S 0.85 and T_s 0.87).

Conclusion

t_½, S and T_s are precise in quantifying the sharpness and earliness of distal bi-EGM; therefore, discriminating the near-field from far-field bi-EGM for guiding successful ablation.