A Simple Algorithm for Predicting the Location of Right-Sided Accessory Pathways Based on ECG in WPW Patients

Several algorithms have been designed for the localization of pre-ablation accessory pathways (APs) in Wolff–Parkinson–White (WPW) syndrome based on QRS or delta-wave polarity in different (electrocardiographic) ECG leads. Due to the difficulty of catheter placement in the tricuspid ring, leading to increased likelihoods of ablation failure and recurrence in right-sided APs, it is essential to design an algorithm to correctly predict the location of these APs before ablation.

In this retrospective study, 294 known WPW patients with right-sided APs who had clear pre-excitation in the 12-lead ECG were divided into 8 anatomic zones and were then studied using ECG and electrophysiological characteristics.

An algorithm was designed based on the sum of QRS and delta-wave polarity in the V1 and inferior leads. The sensitivity and specificity of the proposed algorithm for predicting free-wall APs, including posterolateral and posterior APs, were 95% and 25%, respectively. Sensitivity and specificity were 72.7% and 95.8% for anterolateral and anterior APs, respectively, and 100% and 60% for lateral APs, respectively. In septal APs, the respective rates of sensitivity and specificity of the algorithm were 60% and 80% for the posteroseptal AP, 61% and 98% for the anteroseptal AP, and 31% and 90% for the midseptal AP. 

The proposed algorithm provides a precise and simple way to differentiate between right-sided APs before performing ablation, thereby reducing ablation failure and recurrence. (Iranian Heart Journal 2021; 22(4): 71-79)