QTc evaluation in patients with bundle branch block

Harilaos Bogossian*, Dominik Linz, Jordi Heijman, Nana-Yaw Bimpong-Buta, Dirk Bandorski, Gerrit Frommeyer, Damir Erkapic, Melchior Seyfarth, Markus Zarse, Harry J. Crijns

*Corresponding author for this work

Research output: Contribution to journalReview articleAcademicpeer-review

1 Citation (Web of Science)

Abstract

Proper measurement of the QT interval on the 12-lead body-surface ECG is challenging in daily practice. Even more difficult is its correct estimation in the presence of repolarization abnormalities, arrhythmias or bundle-branch blocks (BBB). The QT interval results from two parts of the ECG: (1) the QRS complex, describing the excitation of the ventricles and (2) the JT interval, describing the repolarisation of the ventricles. Prolongation of the QRS width - like in the presence of BBB - entails prolongation of the QT interval, making the estimation of the true repolarisation time challenging. The US recommendations for the standardization and interpretation of the ECG suggest focusing on the JT interval in presence of BBB. However, in clinical practice physicians have become more familiar with the interpretation of QT-interval measurements than with the interpretation of the JT Interval.

In the last decade, a simple formula for the estimation of the "modified QT interval" in the presence of left or right BBB has been developed and evaluated. In this formula, the modified QT interval is calculated by subtracting 50% of the length of the BBB-QRS from the measured QT interval (QT(m) = QT(BBB) - 50% QRS(BBB)). Subsequently, rate-correction formula should be applied as usual. In this review, we discuss the determination of the QT-interval in the presence of BBB and summarize the origin and application of the modified QT-interval formula. (C) 2020 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Original languageEnglish
Article number100636
Number of pages5
JournalIJC Heart & Vasculature
Volume30
DOIs
Publication statusPublished - Oct 2020

Keywords

  • AHA/ACCF/HRS RECOMMENDATIONS
  • ARRHYTHMIAS COMMITTEE
  • CLINICAL CARDIOLOGY
  • CORRECTED QT
  • HEART-ASSOCIATION ELECTROCARDIOGRAPHY
  • INTERVAL
  • JT interval
  • Left bundle branch block
  • Long QT
  • OF-CARDIOLOGY-FOUNDATION
  • QT formula
  • QT interval
  • RHYTHM-SOCIETY
  • Right bundle branch block
  • SCIENTIFIC STATEMENT
  • STANDARDIZATION
  • COUNCIL

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