Validation of qrs-polarity algorithm with special emphasis in parahisian pathways

Jorge R. Gómez-Flores, Departamento de Electrofisiología, Instituto Nacional de Cardiología Ignacio Chávez, Ciudad de México, México
Ángel Cueva-Parra, Electrophysiology Department, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico
Antonio Gallegos-Cortéz, Electrophysiology Department, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico
Santiago Nava, Electrophysiology Department, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico
Manlio F. Márquez, Departamento de Cardiología, Sociedad interamericana de Cardiología, Ciudad de México, México; Departamento de Cardiología, Instituto Nacional de Cardiología Ignacio Chávez, Ciudad de México, México; Departamento de Cardiología, Consejo Interamericano de Electrocardiográfica y Arritmias, Ciudad de México. México
Pedro Iturralde-Torres, Electrophysiology Department, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico

Background: In 1996 Iturralde et al. published an algorithm based on the QRS polarity to determine the location of the accessory pathways (AP), this algorithm was developed before the massive practice of invasive electrophysiology. Purpose: To validate the QRS-Polarity algorithm in a modern cohort of subjects submitted to radiofrequency catheter ablation (RFCA). Our objective was to determinate its global accuracy and its accuracy for parahisian AP. Methods: We conducted a retrospective analysis of patients with Wolff-Parkinson-White (WPW) syndrome who underwent an electrophysiological study (EPS) and RFCA. We employed the QRS-Polarity algorithm to predict the AP anatomical location and we compared this result with the real anatomic location determined in the EPS. To determine accuracy, the Cohen’s kappa coefficient (κ) and the Pearson correlation coefficient were used. Results: A total of 364 patients were included (mean age 30 years, 57% male). The global κ score was 0.78 and the Pearson’s coefficient was 0.90. The accuracy for each zone was also evaluated, the best correlation was for the left lateral AP (κ of 0.97). There were 26 patients with a parahisian AP, who showed a great variability in the ECG features. Employing the QRS-Polarity algorithm, 34.6% patients had a correct anatomical location, 42.3% had an adjacent location and only 23% an incorrect location. Conclusion: The QRS-Polarity algorithm has a good global accuracy; its precision is high, especially for left lateral AP. This algorithm is also useful for the parahisian AP.

Keywords: Wolff-Parkinson-White syndrome. Accessory pathways. Parahisian accessory pathways. QRS-Polarity algorithm.