This paper presents an analysis of the Arruda accessory pathway localization method for patients suffering from Wolff-Parkinson-White syndrome, with modifications to increase the overall performance. The Arruda method was tested on a total of 79 cases, and 91.1 % localization performance was reached. After a deeper analysis of each decision point of the Arruda localization method, we considered that the lead aVF is not as relevant as other used leads (I, II, III, V1). The branch of the decision tree, which evaluates the left ventricle positions, was entirely replaced using different decision criteria based of the same biological parameters. The modified algorithm significantly improves the localization performance in the left ventricle. The overall performance reaches 94.9 %. A high localization performance of non-invasive methods is relevant because it can enlighten the necessary invasive interventions, and also reduces the discomfort caused to the patient.