Original Article

Electrocardiographic Criteria for Differentiating Endocardial from Epicardial Posterseptal Accessory Pathways to Guide Catheter Ablation

Abstract

Background: Radiofrequency (RF) catheter ablation is the standard treatment for symptomatic patients with Wolff-Parkinson-White (WPW) syndrome. Successful RF ablation of an accessory pathway (AP) depends on accurate localization of its site.
Methods: This retrospective, observational, cross-sectional study included all consecutive patients who underwent successful RF ablation of a single manifest posteroseptal AP at the Cardiac Electrophysiology Laboratory of the Cardiovascular Department, Cairo University Hospitals. Twelve-lead electrocardiograms were collected and analyzed to identify electrocardiographic criteria that differentiate epicardial from endocardial posteroseptal APs to guide mapping and ablation strategies.
Results: Seventy-three patients with a posteroseptal AP were included: 47 were ablated from the right posteroseptal endocardium; 6 from the left posteroseptal endocardium; and 20 were ablated epicardially (from the coronary sinus or its branches). Epicardial posteroseptal APs were predicted by a negative delta wave in lead II, a positive delta wave in lead aVR, a positive delta wave in lead V1, and/or QRS complex notching in lead II. Endocardial posteroseptal APs were predicted by a negative delta wave in lead V1 and/or an R/S ratio less than 1 in lead V1. Double QRS transition was not useful for differentiation unless combined with a Q wave or predominantly negative QRS complex in lead V1.
Conclusion: Epicardial and endocardial posteroseptal APs can be differentiated based on delta wave polarity in leads II, aVR, and V1; R/S ratio in lead V1; and QRS complex notching in lead II.

1. Wang X. Sites of successful radiofrequency ablation of posteroseptal accessory pathways. PACE. 1992;15:535.
2. Oren J. Epicardial posteroseptal accessory pathways requiring ablation from the middle cardiac vein. PACE. 1992;15:535.
3. Arruda MS, Beckman KJ, McClelland JH, Wang X, Nakagawa H, Widman LE, et al. Coronary sinus anatomy and anomalies in patients with posteroseptal accessory pathway requiring ablation within a venous branch of the coronary sinus. J Am Coll Cardiol. 1994;23:224A.
4. Dhala AA, Deshpande SS, Bremner S, Hempe S, Sra JS, Blanck Z, Akhtar M, Jazayeri MR. Transcatheter ablation of posteroseptal accessory pathways using a venous approach and radiofrequency energy. Circulation. 1994 Oct;90(4):1799-810.
5. Jazayeri MR, Dhala AN, Deshpande SA, Blanck ZA, Sra JA, Akhtar MA. Posteroseptal accessory pathways: an overview of anatomical characteristics, electrocardiographic patterns, electrophysiological features, and ablative therapy. Journal of Interventional Cardiology. 1995 Feb 1;8(1):89-101.
6. Warin JF, Haissaguerre M, Lemetayer P, Guillem JP, Blanchot P. Catheter ablation of accessory pathways with a direct approach. Results in 35 patients. Circulation. 1988 Oct;78(4):800-15.
7. Jackman WM, Wang X, Friday KJ, Roman CA, Moulton KP, Beckman KJ, et al. Catheter ablation of accessory atrioventricular pathways (Wolff–Parkinson–White syndrome) by radiofrequency current. New England Journal of Medicine. 1991 Jun 6;324(23):1605-11.
8. Kuck KH, Schluter M, Geiger M, Siebels J, Duckeck W. Radiofrequency current catheter ablation of accessory atrioventricular pathways. The Lancet. 1991 Jun 29;337(8757):1557-61.
9. Calkins H, Sousa J, El-Atassi R, Rosenheck S, de Buitleir M, Kou WH, et al. Diagnosis and cure of the Wolff–Parkinson–White syndrome or paroxysmal supraventricular tachycardias during a single electrophysiologic test. New England Journal of Medicine. 1991 Jun 6;324(23):1612-8.
10. Lesh MD. Curative percutaneous catheter ablation using radiofrequency energy for accessory pathway in all locations: results in 100 consecutive patients. J Am Coll Cardiol. 1992;70:1490-1.
11. Kuck KH, Schluter M, Chiladakis I. Accessory pathways anatomically related to the coronary sinus. InCirculation 1992 Oct 1 (Vol. 86, No. 4, pp. 782-782). 7272 GREENVILLE AVENUE, DALLAS, TX 75231-4596: AMER HEART ASSOC.
12. Langberg JJ, Man KC, Vorperian VR, Williamson B, Kalbfleisch SJ, Strickberger SA, Hummel JD, et al. Recognition and catheter ablation of subepicardial accessory pathways. Journal of the American College of Cardiology. 1993 Oct 1;22(4):1100-4.
13. Arruda MS, McCLELLAND JH, Wang X, Beckman KJ, Widman LE, Gonzalez MD, et al. Development and validation of an ECG algorithm for identifying accessory pathway ablation site in Wolff‐Parkinson‐White syndrome. Journal of cardiovascular electrophysiology. 1998 Jan;9(1):2-12.
14. Sun Y, Arruda M, Otomo K, Beckman K, Nakagawa H, Calame J, et al. Coronary sinus-ventricular accessory connections producing posteroseptal and left posterior accessory pathways: incidence and electrophysiological identification. Circulation. 2002 Sep 10;106(11):1362-7.
15. Takahashi A, Shah DC, Jais P, Hocini M, Clementy J, Haissaguerre M. Specific electrocardiographic features of manifest coronary vein posteroseptal accessory pathways. Journal of cardiovascular electrophysiology. 1998 Oct;9(10):1015-25.
16. Haghjoo M, Mahmoodi E, FARJAM FAZELIFAR AM, Alizadeh A, JAFAR HASHEMI MO, Emkanjoo Z, et al. Electrocardiographic and electrophysiologic predictors of successful ablation site in patients with manifest posteroseptal accessory pathway. Pacing and Clinical Electrophysiology. 2008 Jan;31(1):103-11.
17. Kobza R, Hindricks G, Tanner H, Piorkowski C, Wetzel U, Schirdewahn P, et al. Paraseptal accessory pathway in Wolff-Parkinson-White-Syndrom: ablation from the right, from the left or within the coronary sinus/middle cardiac vein? Journal of interventional cardiac electrophysiology. 2005 Jan;12(1):55-60.
18. Pascale P, Hunziker S, Denis A, Gómez Flores JR, Roten L, Shah AJ, et al. The ‘double transition’: a novel electrocardiogram sign to discriminate posteroseptal accessory pathways ablated from the right endocardium from those requiring a left-sided or epicardial coronary venous approach. EP Europace. 2020 Nov;22(11):1703-11.
19. Chiang CE, Chen SA, Teo WS, Tsai DS, Wu TJ, Cheng CC, et al. An accurate stepwise electrocardiographic algorithm for localization of accessory pathways in patients with Wolff-Parkinson-White syndrome from a comprehensive analysis of delta waves and R/S ratio during sinus rhythm. The American journal of cardiology. 1995 Jul 1;76(1-2):40-6.
20. Mathieu Lebloa, Patrizio Pascale. Preprocedural Discrimination of Posteroseptal Accessory Pathways Ablated from the Right Endocardium from Those Requiring a Left-sided or Epicardial Coronary Venous Approach, Arrhythmia & Electrophysiology Review 2022;11:e07.
21. Pambrun T, El Bouazzaoui R, Combes N, Combes S, Sousa P, Le Bloa M et al. Maximal Pre-excitation based algorithm for localization of manifest accessory pathways in adults. JACC Clin Electrophysiol 2018; 4:1052–61.
22. Bera D. CE-542-01 PRECORDIAL ‘REVERSE PATTERN BREAK’: A NOVEL PREDICTOR FOR EPICARDIAL POSTEROSEPTAL ACCESSORY PATHWAYS. Heart Rhythm. 2022 May 1;19(5):S70-1.1
Files
IssueVol 21 No 4 (2026) QRcode
SectionOriginal Article(s)
DOI https://doi.org/10.18502/rhythm.v21i4.23091
Keywords
Electrocardiogram Catheter Ablation Posteroseptal Accessory Pathway
Rights and permissions
Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
How to Cite
1.
Hassan A, Rashad M, Aziz E, Al Damaty A. Electrocardiographic Criteria for Differentiating Endocardial from Epicardial Posterseptal Accessory Pathways to Guide Catheter Ablation. Res Heart Yield Transl Med. 2026;21(4):286-296.