New formula for evaluation of the QT interval in patients with left bundle branch block

Harilaos Bogossian; Gerrit Frommeyer; Ilias Ninios; Fuad Hasan; Quy Suu Nguyen; Zana Karosiene; Dejan Mijic; Axel Kloppe; Hawal Suleiman; Dirk Bandorski; Melchior Seyfarth; Bernd Lemke; Lars Eckardt; Markus Zarse

doi:10.1016/j.hrthm.2014.08.026

New formula for evaluation of the QT interval in patients with left bundle branch block

Harilaos Bogossian, Gerrit Frommeyer, Ilias Ninios, Fuad Hasan, Quy Suu Nguyen, Zana Karosiene, Dejan Mijic, Axel Kloppe, Hawal Suleiman, Dirk Bandorski, Melchior Seyfarth, Bernd Lemke, Lars Eckardt, Markus Zarse

Research output: Contribution to journal › Article › peer-review

54 Scopus citations

Abstract

Background Left bundle branch block (LBBB) and QT prolongation both are associated with a worse prognosis. LBBB lengthens the QT interval. To date it is not known whether QT prolongation during LBBB differs in repolarization from QT prolongation during narrow QRS.

Methods Sixty consecutive patients with sinus rhythm (SR) and narrow QRS underwent electrophysiologic study for ablation. In all patients, the intrinsic QRS,QT, and JT times were measured during SR, and ventricular pacing from both the right ventricular apex (RVA) and the right ventricular outflow tract (RVOT) caused LBBB. We determined prolongation of the QT during as compared to SR (ΔQT). ΔQT was then divided by the QRS length during pacing QRS (QRSb). This describes the percentage of the QRS duration at LBBB, which must be subtracted from the measured QT (QTb) to determine the modified QT interval (QTm).

Results The ratio of ΔQT to paced QRS was calculated as 48.3% (RVA) and 48.8% (RVOT) (mean 48.5%). The ratio intrinsic of JTi to paced JT was 1.0055 (RVA) and 1.0087 (RVOT). There was no significant difference in intrinsic JT vs paced JT (P =.2).

Conclusion Right ventricular pacing causes prolongation of the QT due to a paced LBBB without prolongation of the JT time. In our study, we showed that QT prolongation caused by LBBB constitutes 48.5% of the QRS width. This is the value that must be subtracted from the measured QT in LBBB in order to estimate the modified QT. Thus, the resulting formula for "modified QT" estimation in LBBB is QTm = QTb - 48.5%∗ (QRSb).

Original language	English
Pages (from-to)	2273-2277
Number of pages	5
Journal	Heart Rhythm
Volume	11
Issue number	12
DOIs	https://doi.org/10.1016/j.hrthm.2014.08.026
State	Published - 1 Dec 2014
Externally published	Yes

Keywords

JT interval
Left bundle branch block
Long QT
QT formula
QT interval
QT prolongation

Access to Document

10.1016/j.hrthm.2014.08.026

Cite this

@article{6a9ee39125574a4691d2a7d87c6d2a29,

title = "New formula for evaluation of the QT interval in patients with left bundle branch block",

abstract = "Background Left bundle branch block (LBBB) and QT prolongation both are associated with a worse prognosis. LBBB lengthens the QT interval. To date it is not known whether QT prolongation during LBBB differs in repolarization from QT prolongation during narrow QRS.Methods Sixty consecutive patients with sinus rhythm (SR) and narrow QRS underwent electrophysiologic study for ablation. In all patients, the intrinsic QRS,QT, and JT times were measured during SR, and ventricular pacing from both the right ventricular apex (RVA) and the right ventricular outflow tract (RVOT) caused LBBB. We determined prolongation of the QT during as compared to SR (ΔQT). ΔQT was then divided by the QRS length during pacing QRS (QRSb). This describes the percentage of the QRS duration at LBBB, which must be subtracted from the measured QT (QTb) to determine the modified QT interval (QTm).Results The ratio of ΔQT to paced QRS was calculated as 48.3% (RVA) and 48.8% (RVOT) (mean 48.5%). The ratio intrinsic of JTi to paced JT was 1.0055 (RVA) and 1.0087 (RVOT). There was no significant difference in intrinsic JT vs paced JT (P =.2).Conclusion Right ventricular pacing causes prolongation of the QT due to a paced LBBB without prolongation of the JT time. In our study, we showed that QT prolongation caused by LBBB constitutes 48.5% of the QRS width. This is the value that must be subtracted from the measured QT in LBBB in order to estimate the modified QT. Thus, the resulting formula for {"}modified QT{"} estimation in LBBB is QTm = QTb - 48.5%∗ (QRSb).",

keywords = "JT interval, Left bundle branch block, Long QT, QT formula, QT interval, QT prolongation",

author = "Harilaos Bogossian and Gerrit Frommeyer and Ilias Ninios and Fuad Hasan and Nguyen, {Quy Suu} and Zana Karosiene and Dejan Mijic and Axel Kloppe and Hawal Suleiman and Dirk Bandorski and Melchior Seyfarth and Bernd Lemke and Lars Eckardt and Markus Zarse",

note = "Publisher Copyright: {\textcopyright} 2014 Heart Rhythm Society. All rights reserved. Objective The purpose of the present proof-of-concept-study was to develop a formula that allows comparison of the adjusted QT interval during LBBB with reference values and thereby allows interpretation of the QT interval irrespective of QRS widening.",

year = "2014",

month = dec,

day = "1",

doi = "10.1016/j.hrthm.2014.08.026",

language = "English",

volume = "11",

pages = "2273--2277",

journal = "Heart Rhythm",

issn = "1547-5271",

publisher = "Elsevier B.V.",

number = "12",

}

TY - JOUR

T1 - New formula for evaluation of the QT interval in patients with left bundle branch block

AU - Bogossian, Harilaos

AU - Frommeyer, Gerrit

AU - Ninios, Ilias

AU - Hasan, Fuad

AU - Nguyen, Quy Suu

AU - Karosiene, Zana

AU - Mijic, Dejan

AU - Kloppe, Axel

AU - Suleiman, Hawal

AU - Bandorski, Dirk

AU - Seyfarth, Melchior

AU - Lemke, Bernd

AU - Eckardt, Lars

AU - Zarse, Markus

N1 - Publisher Copyright: © 2014 Heart Rhythm Society. All rights reserved. Objective The purpose of the present proof-of-concept-study was to develop a formula that allows comparison of the adjusted QT interval during LBBB with reference values and thereby allows interpretation of the QT interval irrespective of QRS widening.

PY - 2014/12/1

Y1 - 2014/12/1

N2 - Background Left bundle branch block (LBBB) and QT prolongation both are associated with a worse prognosis. LBBB lengthens the QT interval. To date it is not known whether QT prolongation during LBBB differs in repolarization from QT prolongation during narrow QRS.Methods Sixty consecutive patients with sinus rhythm (SR) and narrow QRS underwent electrophysiologic study for ablation. In all patients, the intrinsic QRS,QT, and JT times were measured during SR, and ventricular pacing from both the right ventricular apex (RVA) and the right ventricular outflow tract (RVOT) caused LBBB. We determined prolongation of the QT during as compared to SR (ΔQT). ΔQT was then divided by the QRS length during pacing QRS (QRSb). This describes the percentage of the QRS duration at LBBB, which must be subtracted from the measured QT (QTb) to determine the modified QT interval (QTm).Results The ratio of ΔQT to paced QRS was calculated as 48.3% (RVA) and 48.8% (RVOT) (mean 48.5%). The ratio intrinsic of JTi to paced JT was 1.0055 (RVA) and 1.0087 (RVOT). There was no significant difference in intrinsic JT vs paced JT (P =.2).Conclusion Right ventricular pacing causes prolongation of the QT due to a paced LBBB without prolongation of the JT time. In our study, we showed that QT prolongation caused by LBBB constitutes 48.5% of the QRS width. This is the value that must be subtracted from the measured QT in LBBB in order to estimate the modified QT. Thus, the resulting formula for "modified QT" estimation in LBBB is QTm = QTb - 48.5%∗ (QRSb).

AB - Background Left bundle branch block (LBBB) and QT prolongation both are associated with a worse prognosis. LBBB lengthens the QT interval. To date it is not known whether QT prolongation during LBBB differs in repolarization from QT prolongation during narrow QRS.Methods Sixty consecutive patients with sinus rhythm (SR) and narrow QRS underwent electrophysiologic study for ablation. In all patients, the intrinsic QRS,QT, and JT times were measured during SR, and ventricular pacing from both the right ventricular apex (RVA) and the right ventricular outflow tract (RVOT) caused LBBB. We determined prolongation of the QT during as compared to SR (ΔQT). ΔQT was then divided by the QRS length during pacing QRS (QRSb). This describes the percentage of the QRS duration at LBBB, which must be subtracted from the measured QT (QTb) to determine the modified QT interval (QTm).Results The ratio of ΔQT to paced QRS was calculated as 48.3% (RVA) and 48.8% (RVOT) (mean 48.5%). The ratio intrinsic of JTi to paced JT was 1.0055 (RVA) and 1.0087 (RVOT). There was no significant difference in intrinsic JT vs paced JT (P =.2).Conclusion Right ventricular pacing causes prolongation of the QT due to a paced LBBB without prolongation of the JT time. In our study, we showed that QT prolongation caused by LBBB constitutes 48.5% of the QRS width. This is the value that must be subtracted from the measured QT in LBBB in order to estimate the modified QT. Thus, the resulting formula for "modified QT" estimation in LBBB is QTm = QTb - 48.5%∗ (QRSb).

KW - JT interval

KW - Left bundle branch block

KW - Long QT

KW - QT formula

KW - QT interval

KW - QT prolongation

UR - http://www.scopus.com/inward/record.url?scp=84919422442&partnerID=8YFLogxK

U2 - 10.1016/j.hrthm.2014.08.026

DO - 10.1016/j.hrthm.2014.08.026

M3 - Article

C2 - 25149024

AN - SCOPUS:84919422442

SN - 1547-5271

VL - 11

SP - 2273

EP - 2277

JO - Heart Rhythm

JF - Heart Rhythm

IS - 12

ER -

New formula for evaluation of the QT interval in patients with left bundle branch block

Abstract

Keywords

Access to Document

Other files and links

Fingerprint

Cite this