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

doi:10.1016/j.ijcha.2020.100636

QTc evaluation in patients with bundle branch block

Int J Cardiol Heart Vasc. 2020 Sep 19:30:100636. doi: 10.1016/j.ijcha.2020.100636. eCollection 2020 Oct.

Authors

Harilaos Bogossian^{1

2

3}, Dominik Linz³, Jordi Heijman³, Nana-Yaw Bimpong-Buta¹, Dirk Bandorski⁴, Gerrit Frommeyer⁵, Damir Erkapic⁶, Melchior Seyfarth^{2

7}, Markus Zarse², Harry J Crijns³

Affiliations

¹ Department of Cardiology and Rhythmology, Ev. Krankenhaus Hagen, Hagen, Germany.
² Department of Cardiology, University Witten/Herdecke, Witten, Germany.
³ Department of Cardiology, Maastricht University Medical Center (MUMC+) and Cardiovascular Research Institute Maastricht (CARIM), Maastricht, the Netherlands.
⁴ Faculty of Medicine, Semmelweis University Campus Hamburg, Hamburg, Germany.
⁵ Division of Electrophysiology, Department of Cardiovascular Medicine, University of Münster, Münster, Germany.
⁶ Diakonie Klinikum Siegen, Department of Cardiology and Electrophysiology, Siegen, Germany.
⁷ Department of Cardiology, Helios Klinikum Wuppertal, Germany.

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.

Keywords: JT interval; Left bundle branch block; Long QT; QT formula; QT interval; Right bundle branch block.

Publication types

Review