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Qtc Interval Measurement in Patients With Right Bundle Branch Block: A Practical Method Publisher Pubmed



Alizadeh A1 ; Shahrbaf MA2 ; Khorgami M1 ; Zeighami M1 ; Keikhavani A1 ; Mokhtaritorshizi H3 ; Teimourijervekani Z4
Authors
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Authors Affiliations
  1. 1. Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, Iran
  2. 2. Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
  3. 3. Department of Biomedical Engineering and Physics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
  4. 4. Cardiac Rehabilitation Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran

Source: Annals of Noninvasive Electrocardiology Published:2023


Abstract

Background and Aim: Prolonging the QT interval in the right bundle branch block (RBBB) can create challenges for electrophysiologists in estimating repolarization time and eliminating the effect of depolarization changes on QT interval. In this study, we aimed to develop a practice formula to eliminate the effect of depolarization changes on QT interval in patients with RBBB. Methods: This prospective study evaluated accidentally induced RBBB in patients undergoing electrophysiological study. Two expert electrophysiologists recorded the ECG parameters, including QRS duration, QT interval, and cycle length, in the patients. The formula was developed based on QT interval differences (with and without RBBB) and its proportion to QRS. Additionally, the Bazzet, Rautaharju, and Hodge formulas were used to evaluate QTc. Results: We evaluated 96 patients in this study. The mean QT interval without RBBB was 369.39 ± 37.38, reaching 404.22 ± 39.23 after inducing RBBB. ΔQT was calculated as 34.83 ± 17.61, and the ratio of ΔQT/QRS with RBBB was almost 23%. Our formula is: (QTwith RBBB − 23% × QRS). Subtraction of 25% instead of 23% seems more straightforward and practical. Our formula could also predict the QTc interval in RBBB based on the Bazzet, Rautaharju, and Hodge formulas. Conclusion: Previous formulas for QT correction were hard to apply in the clinical setting or were not specified for RBBB. Our new formula allows a rapid and practical method for QT correction in RBBB in clinical practice. © 2023 The Authors. Annals of Noninvasive Electrocardiology published by Wiley Periodicals LLC.
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