Simple electrocardiography algorithm for localizing accessory pathway in patients with Wolff-Parkinson-White syndrome.

Background: Existing algorithms to predict the location of an accessory pathway (AP) in Wolff-Parkinson-White Syndrome (WPW) have good sensitivity and specificity but complex with various accuracy and inter-observer agreement rates. A simple algorithm with high accuracy and inter-observer agreement rates is needed.

Methods: This was a cross-sectional and retrospective diagnostic study. The data were collected by total population sampling from January 2015 to January 2017. Forty-seven patients were included in the study. Data collected were pre-ablation 12-lead ECGs and ablation reports. These ECGs were evaluated by two independent observers using the simplified algorithm and compared with ablation results.

Results: The algorithm had a sensitivity of 45% on the left free wall, 80% on septal, 92% on the right free wall, and the specificity of 96% on the left free wall, 69% on the septal, 85% on the right free wall for AP prediction. The positive predictive value was 90% on the left free wall, 55% on the septal, and 67% on the right free wall APs. The negative predictive value was 70% on the left free wall, 88% on the septal, and 97% on right free wall AP. The positive likelihood ratio was 11.23 on the left free wall, 2.23 on septal and 6.57 on right free wall APs, and the negative likelihood ratio was 0.57 on left free wall APs, 0.28 on septal, and 0.09 on the right free wall APs. Algorithm accuracy varied from 73-87%. Inter-observer agreement calculation was kappa 0.93 for left free wall AP, 0.78 for septal AP, and 0.74 for right free wall AP.

Conclusion: This simple algorithm has a remarkable accuracy and inter-observer agreement; therefore, it may prove to be helpful even to non-electrophysiologists and has the potential to be integrated into clinical practice.