Harilaos Bogossian1, Gerrit Frommeyer2, Ilias Ninios3, Fuad Hasan3, Quy Suu Nguyen3, Zana Karosiene3, Dejan Mijic3, Axel Kloppe3, Hawal Suleiman3, Dirk Bandorski3, Melchior Seyfarth4, Bernd Lemke3, Lars Eckardt2, Markus Zarse5. 1. Märkische Kliniken GmbH, Department of Cardiology and Angiology, Klinikum Lüdenscheid, Lüdenscheid, Germany; Department of Cardiology, Witten/Herdecke University, Witten, Germany. Electronic address: Harilaos.bogossian@klinikum-luedenscheid.de. 2. Division of Electrophysiology, Department of Cardiovascular Medicine, University of Münster, Münster, Germany. 3. Märkische Kliniken GmbH, Department of Cardiology and Angiology, Klinikum Lüdenscheid, Lüdenscheid, Germany. 4. Department of Cardiology, Witten/Herdecke University, Witten, Germany; Department of Cardiology, Helios Klinikum Wuppertal, Wuppertal, Germany. 5. Märkische Kliniken GmbH, Department of Cardiology and Angiology, Klinikum Lüdenscheid, Lüdenscheid, Germany; Department of Cardiology, Witten/Herdecke University, Witten, Germany.
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. 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. 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).
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. 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. 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).
Authors: K F Weipert; H Bogossian; P Conzen; G Frommeyer; C Gemein; I Helmig; R Chasan; L Eckardt; M Seyfarth; B Lemke; M Zarse; C W Hamm; J Schmitt; D Erkapic Journal: Clin Res Cardiol Date: 2018-05-11 Impact factor: 5.460
Authors: M Bianco; C A Biolè; S Campagnuolo; F Pietrangiolillo; A Spirito; A Galluzzo; I Nuñez-Gil; P Destefanis; A Luciano; P Carvalho; G P Varalda; A Previti; M Gravellone; A Travieso Gonzalez; F Ugo; G Pivano; F Rametta; A Perboni; R Pozzi; L Montagna; E Cerrato Journal: Int J Cardiol Heart Vasc Date: 2020-09-11
Authors: Santiago Colunga; Remigio Padrón; Daniel García-Iglesias; José Manuel Rubín; Diego Pérez; Raquel Del Valle; Pablo Avanzas; César Morís; David Calvo Journal: J Clin Med Date: 2019-09-09 Impact factor: 4.241