Electrocardiographic Markers of Hypertrophy in Children: Revisiting R/S Overlap and the Katz-Wachtel Phenomenon

Nikola Owsianka¹Lukas Schober¹Hannes Sallmon¹Daniel Scherr²Martin Koestenberger¹Martin Manninger^2*Nathalie Öffl¹Stefan Kurath-Koller¹

• ¹Clinical Department of Pediatric Cardiology, Department of Pediatrics and Adolescent Medicine, Medical University Graz, Graz, Austria
• ²Division of Cardiology, Department of Medicine, Medizinische Universitat Graz, Graz, Austria

Background: Many children show R/S overlap in ECG chest leads. The Katz-Wachtel phenomenon, described in the 1960s, characterizes high R and S waves ≥ 50 mm as an ECG feature of biventricular cardiac hypertrophy. This study investigates the KWP and the association between an R/S overlap and cardiac hypertrophy. Methods: Retrospective study including 800 pediatric patients, treated at the Division of Pediatric Cardiology, University Hospital Graz, between 2016 and 2022. ECG measurements with regard to R/S overlap and voltage in chest leads and review of echocardiography findings of cardiac hypertrophy. ECG measurements were manually obtained and and reviewed by two blinded pediatric cardiologists. Results: Of the 500 patients with an R/S overlap, 4% had confirmed cardiac hypertrophy compared to 1% of children without confirmed R/S overlap. Sensitivity was highest in leads V3/4 (69%), while specificity was highest in leads V1/V2 (93%) and V5/V6 (96%), respectively. A statistically significant correlation between R/S overlap and hypertrophy was found. Conclusion: R/S overlap correlates with myocardial hypertrophy in children. While it demonstrates high sensitivity, its limited specificity prevents its use as a standalone diagnostic parameter. It may contribute to early identification when combined with other ECG features and echocardiographic evaluation.