1
|
Reynard JT, Oshodi OM, Lai JC, Lai RW, Bazoukis G, Fragakis N, Letsas KP, Korantzopoulos P, Liu FZ, Liu T, Xia Y, Tse G, Li CK. Electrocardiographic conduction and repolarization markers associated with sudden cardiac death: moving along the electrocardiography waveform. Minerva Cardioangiol 2019; 67:131-144. [PMID: 30260143 DOI: 10.23736/s0026-4725.18.04775-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
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.
Collapse
Affiliation(s)
- Jack T Reynard
- Faculty of Medicine, Newcastle University, Newcastle Upon Tyne, UK
| | | | - Jenny C Lai
- Faculty of Medicine, Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong, China
- Department of Medicine and Therapeutics, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China
| | - Rachel W Lai
- Faculty of Medicine, Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong, China
- Department of Medicine and Therapeutics, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China
| | - George Bazoukis
- Laboratory of Cardiac Electrophysiology, Second Department of Cardiology, Evangelismos General Hospital of Athens, Athens, Greece
| | - Nikolaos Fragakis
- Third Department of Cardiology, Hippokration Hospital, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
- First Department of Cardiology, Medical School, University of Ioannina, Ioannina, Greece
| | - Konstantinos P Letsas
- Laboratory of Cardiac Electrophysiology, Second Department of Cardiology, Evangelismos General Hospital of Athens, Athens, Greece
| | - Panagiotis Korantzopoulos
- Third Department of Cardiology, Hippokration Hospital, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
- First Department of Cardiology, Medical School, University of Ioannina, Ioannina, Greece
| | - Fang-Zhou Liu
- Department of Cardiovascular Surgery, Guangdong Cardiovascular Institute, Guangdong General Hospital affiliated to South China University of Technology, Guangzhou, China
| | - Tong Liu
- 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
| | - Yunlong Xia
- Department of Cardiology, First Affiliated Hospital of Dalian Medical University, Dalian, China
| | - Gary Tse
- Faculty of Medicine, Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong, China
- Department of Medicine and Therapeutics, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China
| | - Christien K Li
- Faculty of Medicine, Newcastle University, Newcastle Upon Tyne, UK -
- Faculty of Medicine, Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong, China
- Department of Medicine and Therapeutics, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China
| |
Collapse
|
2
|
Tse G, Yan BP. Traditional and novel electrocardiographic conduction and repolarization markers of sudden cardiac death. Europace 2018; 19:712-721. [PMID: 27702850 DOI: 10.1093/europace/euw280] [Citation(s) in RCA: 107] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 08/11/2016] [Indexed: 12/20/2022] Open
Abstract
Sudden cardiac death, frequently due to ventricular arrhythmias, is a significant problem globally. Most affected individuals do not arrive at hospital in time for medical treatment. Therefore, there is an urgent need to identify the most-at-risk patients for insertion of prophylactic implantable cardioverter defibrillators. Clinical risk markers derived from electrocardiography are important for this purpose. They can be based on repolarization, including corrected QT (QTc) interval, QT dispersion (QTD), interval from the peak to the end of the T-wave (Tpeak - Tend), (Tpeak - Tend)/QT, T-wave alternans (TWA), and microvolt TWA. Abnormal repolarization properties can increase the risk of triggered activity and re-entrant arrhythmias. Other risk markers are based solely on conduction, such as QRS duration (QRSd), which is a surrogate marker of conduction velocity (CV) and QRS dispersion (QRSD) reflecting CV dispersion. Conduction abnormalities in the form of reduced CV, unidirectional block, together with a functional or a structural obstacle, are conditions required for circus-type or spiral wave re-entry. Conduction and repolarization can be represented by a single parameter, excitation wavelength (λ = CV × effective refractory period). λ is an important determinant of arrhythmogenesis in different settings. Novel conduction-repolarization markers incorporating λ include Lu et al.' index of cardiac electrophysiological balance (iCEB: QT/QRSd), [QRSD× (Tpeak - Tend)/QRSd] and [QRSD × (Tpeak - Tend)/(QRSd × QT)] recently proposed by Tse and Yan. The aim of this review is to provide up to date information on traditional and novel markers and discuss their utility and downfalls for risk stratification.
Collapse
Affiliation(s)
- Gary Tse
- Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, SAR, P.R. China
| | - Bryan P Yan
- Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, SAR, P.R. China.,Department of Epidemiology and Preventive Medicine, Monash University, Clayton, VIC, Australia
| |
Collapse
|