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Minerva Cardioangiologica 2019 April;67(2):131-44

DOI: 10.23736/S0026-4725.18.04775-8

Copyright © 2018 EDIZIONI MINERVA MEDICA

language: English

Electrocardiographic conduction and repolarization markers associated with sudden cardiac death: moving along the electrocardiography waveform

Jack T. REYNARD 1, Oluwayemisi M. OSHODI 1, Jenny C. LAI 2, 3, Rachel W. LAI 2, 3, George BAZOUKIS 4, Nikolaos FRAGAKIS 5, 6, Konstantinos P. LETSAS 4, Panagiotis KORANTZOPOULOS 5, 6, Fang-Zhou LIU 7, Tong LIU 8, Yunlong XIA 9, Gary TSE 2, 3, Christien K. LI 1, 2, 3

1 Faculty of Medicine, Newcastle University, Newcastle Upon Tyne, UK; 2 Faculty of Medicine, Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong, China; 3 Department of Medicine and Therapeutics, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China; 4 Laboratory of Cardiac Electrophysiology, Second Department of Cardiology, Evangelismos General Hospital of Athens, Athens, Greece; 5 Third Department of Cardiology, Hippokration Hospital, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece; 6 First Department of Cardiology, Medical School, University of Ioannina, Ioannina, Greece; 7 Department of Cardiovascular Surgery, Guangdong Cardiovascular Institute, Guangdong General Hospital affiliated to South China University of Technology, Guangzhou, China; 8 Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin, China; 9 Department of Cardiology, First Affiliated Hospital of Dalian Medical University, Dalian, China



The QT interval along with its heart rate corrected form (QTc) are well-established ECG markers that have been found to be associated with malignant ventricular arrhythmogenesis. However, extensive preclinical and clinical investigations over the years have allowed for novel clinical ECG markers to be generated as predictors of arrhythmogenesis and sudden cardiac death. Repolarization markers include the older QTc, QT dispersion and newer Tpeak - Tend intervals, (Tpeak - Tend) / QT ratios, T-wave alternans (TWA), microvolt TWA and T-wave area dispersion. Meanwhile, conduction markers dissecting the QRS complex, such as QRS dispersion (QRSD) and fragmented QRS, were also found to correlate conduction velocity and unidirectional block with re-entrant substrates in various cardiac conditions. Both repolarization and conduction parameters can be combined into the excitation wavelength (λ). A surrogate marker for λ is the index of Cardiac Electrophysiological Balance (iCEB: QT / QRSd). Other markers based on conduction-repolarization are [QRSD x (Tpeak-Tend) / QRSd] and [QRSD x (Tpeak-Tend) / (QRSd x QT)]. Advancement in technology permitted sophisticated electrophysiological analyses such as principal component analysis and periodic repolarization dynamics to further improve risk stratification. This was closely followed by other novel indices including ventricular ectopic QRS interval, the f99 index and EntropyXQT, which integrates mathematical and physical calculations for determining the risk markers. Though proven to be effective in limited patient cohorts, more clinical studies across different cardiac pathologies are required to confirm their validity. As such, this review seeks to encapsulate the development of old and new ECG markers along with their associated utility and shortcomings in clinical practice.


KEY WORDS: Arrhythmias, cardiac; Death, sudden, cardiac; Electrocardiography

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