New simplified algorithm for abnormal pathway detection in ecg patients with overt pre-excitation for the clinical cardiologist

Abstract

The aims of this study were: to generate a new simplified diagnostic algorithm to identify accessory pathways in ECGs presenting ventricular pre-excitation; to compare it with the result of radiofrequency (RF) ablation; and to validate this simplified algorithm with the Fitzpatrick algorithm. Material and Methods: There were 47 consecutive patients included, with successful ablation of Wolf-Parkinson-White syndrome (WPW). Two observers blinded to the ablation results evaluated 12-lead ECGs for all patients. The proposed simplified algorithm comprises only 4 steps: 1) Observing QRS in V1; if Rs / R, the path is left, if rS / QS the path is right. 2) Evaluating R wave transition in the precordial leads (passage from rS / QS to Rs / R), if it occurs before V3 the path is septal, if it does not then it is septal. 3) Evaluating QRS in DII, DIII, and AVF; if they are R / Rs the path is anterior, if they are QS / Qr it is posterior, and if one of them differs, it is medial 4) Evaluating if the QRS in DI and / or AVL Is QS / Qr; then it is left lateral pathway. Once the ECGs were analyzed, a comparison was made between what was observed by these physicians and the result of the ablation. In a second stage, we performed a comparative evaluation of the simplified and Fitzpatrick algorithms (the latter is the most disseminated at present) with two physicians blinded to the results of the ablation. Results: The study population had an average of 24 years of age (10-57 years), with 73% being males. The correlation of the simplified algorithm with the ablation showed high degree of correspondence (0.83 ± 0.079; 95% CI 0.68-0.99) to discriminate between the right and left pathways and between septal and nonseptal pathways, with a lower correlation for the midseptal and posteroseptal pathways. Comparison of the simplified algorithm with the Fitzpatrick algorithm revealed smaller inter-observer differences (0.73 ± 0.073; 95% CI 0.59-0.87) and greater specificity in differentiating septal and non-septal pathways with the simplified algorithm. Conclusions: The proposed simplified algorithm is a new tool, useful, simple and valid for the clinical cardiologist in decision making in patients with WPW syndrome.