Local Atrial/Ventricular Ratio as an Adjuvant Marker for Catheter Ablation of Atrioventricular Accessory Pathways

Background and Objectives: The earliest atrial (A)/ventricular (V) activation potential, or accessory pathway (AP) potential are commonly used as ablation targets for atrioventricular (AV) APs. However, these targets are sometimes ambiguous. Subjects and Methods: We reviewed 119 catheter ablation cases in 112 patients diagnosed with orthodromic atrioventricular reentrant tachycardia (AVRT) or Wolff-Parkinson-White (WPW) syndrome. Local A/V amplitude potentials with the earliest activation or AP potential were measured shortly before achieving antegrade AP conduction block, ventriculoatrial block during right ventricle (RV) pacing, or AVRT termination with no AP conduction. Results: APs were located in the left lateral (55.5%), left posterior (17.6%), left posteroseptal (10.1%), midseptal (1.7%), right posteroseptal (7.6%), right posterior (1.7%), and right lateral (5.9%) regions. The mean earliest activation time was $16.7{\pm}15.5ms$, mean A/V potential was $1.1{\pm}0.9/1.0{\pm}0.9mV$, and mean A/V ratio was $1.7{\pm}2.0$. There was no statistically significant difference between the activation methods (antegrade vs. RV pacing vs. orthodromic AVRT) or AP locations (left vs. right atrium). However, when the local A/V ratio was divided into 3 groups (${\leq}0.6$, $1.0{\pm}0.3$, and ${\geq}1.4$), the antegrade approach resulted in an A/V ratio greater than $1.0{\pm}0.3$ (86.7%, p=0.007), and the orthodromic AVRT state resulted in a ratio of less than $1.0{\pm}0.3$ (87.5%, p<0.001). Conclusion:The mean local A/V potential and ratio did not differ by activation method or AP location. However, a different A/V ratio based on activation method (${\geq}1.0{\pm}0.3$, antegrade approach; and ${\leq}1.0{\pm}0.3$, orthodromic AVRT state) could be a good adjuvant marker for targeting AV APs.