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El-Hamad FJ, Bonabi SY, Müller A, Steger A, Schmidt G, Baumert M. Augmented Oscillations in QT Interval Duration Predict Mortality Post Myocardial Infarction Independent of Heart Rate. Front Physiol 2020; 11:578173. [PMID: 33240101 PMCID: PMC7680963 DOI: 10.3389/fphys.2020.578173] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 10/16/2020] [Indexed: 11/13/2022] Open
Abstract
Objective This study seeks to decompose QT variability (QTV) into physiological sources and assess their role for risk stratification in patients post myocardial infarction (MI). We hypothesize that the magnitude of QTV that cannot be explained by heart rate or respiration carries important prognostic information. Background Elevated beat-to-beat QTV is predictive of cardiac mortality, but the underlying mechanisms, and hence its interpretation, remain opaque. Methods We decomposed the QTV of 895 patients post MI into contributions by heart rate, respiration, and unexplained sources. Results Cox proportional hazard analysis demonstrates that augmented oscillations in QTV and their level of dissociation from heart rate are associated with a higher 5-year mortality rate (18.4% vs. 4.7%, p < 0.0001). In patients with left ventricular ejection fraction (LVEF) > 35%, a higher QTV risk score was associated with a significantly higher 5-year mortality rate (16% vs. 4%, p < 0.0001). In patients with a GRACE score ≥ 120, a higher QTV risk score was associated with a significantly higher 5-year mortality (25% vs. 11%, p < 0.001). Conclusion Augmented oscillations in QTV and discordance from heart rate, possibly indicative of excessive sympathetic outflow to the ventricular myocardium, predict high risk in patients post MI independent from established risk markers. Clinical Trial Registration www.ClinicalTrials.gov, identifier NCT00196274.
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Affiliation(s)
- Fatima J El-Hamad
- School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA, Australia
| | - Safa Y Bonabi
- School of Electronic and Telecommunications Engineering, RMIT University, Melbourne, VIC, Australia
| | - Alexander Müller
- Internal Medicine I Department, Technical University of Munich, Munich, Germany
| | - Alexander Steger
- Internal Medicine I Department, Technical University of Munich, Munich, Germany
| | - Georg Schmidt
- Internal Medicine I Department, Technical University of Munich, Munich, Germany
| | - Mathias Baumert
- School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA, Australia
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Tse G, Du Y, Hao G, Li KHC, Chan FYW, Liu T, Li G, Bazoukis G, Letsas KP, Wu WKK, Cheng SH, Wong WT. Quantification of Beat-To-Beat Variability of Action Potential Durations in Langendorff-Perfused Mouse Hearts. Front Physiol 2018; 9:1578. [PMID: 30538638 PMCID: PMC6277547 DOI: 10.3389/fphys.2018.01578] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 10/22/2018] [Indexed: 12/27/2022] Open
Abstract
Background: Beat-to-beat variability in action potential duration (APD) is an intrinsic property of cardiac tissue and is altered in pro-arrhythmic states. However, it has never been examined in mice. Methods: Left atrial or ventricular monophasic action potentials (MAPs) were recorded from Langendorff-perfused mouse hearts during regular 8 Hz pacing. Time-domain, frequency-domain and non-linear analyses were used to quantify APD variability. Results: Mean atrial APD (90% repolarization) was 23.5 ± 6.3 ms and standard deviation (SD) was 0.9 ± 0.5 ms (n = 6 hearts). Coefficient of variation (CoV) was 4.0 ± 1.9% and root mean square (RMS) of successive differences in APDs was 0.3 ± 0.2 ms. The peaks for low- and high-frequency were 0.7 ± 0.5 and 2.7 ± 0.9 Hz, respectively, with percentage powers of 39.0 ± 20.5 and 59.3 ± 22.9%. Poincaré plots of APDn+1 against APDn revealed ellipsoid shapes. The ratio of the SD along the line-of-identity (SD2) to the SD perpendicular to the line-of-identity (SD1) was 8.28 ± 4.78. Approximate and sample entropy were 0.57 ± 0.12 and 0.57 ± 0.15, respectively. Detrended fluctuation analysis revealed short- and long-term fluctuation slopes of 1.80 ± 0.15 and 0.85 ± 0.29, respectively. When compared to atrial APDs, ventricular APDs were longer (ANOVA, P < 0.05), showed lower mean SD and CoV but similar RMS of successive differences in APDs and showed lower SD2 (P < 0.05). No difference in the remaining parameters was observed. Conclusion: Beat-to-beat variability in APD is observed in mouse hearts during regular pacing. Atrial MAPs showed greater degree of variability than ventricular MAPs. Non-linear techniques offer further insights on short-term and long-term variability and signal complexity.
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Affiliation(s)
- Gary Tse
- Department of Medicine and Therapeutics, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China.,Li Ka Shing Institute of Health Sciences, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China.,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China
| | - Yimei Du
- Research Center of Ion Channelopathy, Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Guoliang Hao
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | | | - Fiona Yin Wah Chan
- School of Biological Sciences, University of Cambridge, Cambridge, United Kingdom
| | - 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
| | - Guangping Li
- 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
| | - George Bazoukis
- Laboratory of Cardiac Electrophysiology, Second Department of Cardiology, Evangelismos General Hospital of Athens, Athens, Greece
| | - Konstantinos P Letsas
- Laboratory of Cardiac Electrophysiology, Second Department of Cardiology, Evangelismos General Hospital of Athens, Athens, Greece
| | - William K K Wu
- State Key Laboratory of Digestive Disease, Department of anesthesia and Intensive Care, LKS Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Shuk Han Cheng
- Department of Biomedical Sciences, College of Veterinary Medicine and Life Science, City University of Hong Kong, Hong Kong, China.,State Key Laboratory of Marine Pollution at City University of Hong Kong, Hong Kong, China.,Department of Materials Science and Engineering, College of Science and Engineering, City University of Hong Kong, Hong Kong, China
| | - Wing Tak Wong
- State Key Laboratory of Agrobiotechnology, School of Life Sciences, Chinese University of Hong Kong, Hong Kong, China
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Baumert M, Porta A, Vos MA, Malik M, Couderc JP, Laguna P, Piccirillo G, Smith GL, Tereshchenko LG, Volders PGA. QT interval variability in body surface ECG: measurement, physiological basis, and clinical value: position statement and consensus guidance endorsed by the European Heart Rhythm Association jointly with the ESC Working Group on Cardiac Cellular Electrophysiology. Europace 2016; 18:925-44. [PMID: 26823389 PMCID: PMC4905605 DOI: 10.1093/europace/euv405] [Citation(s) in RCA: 140] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 11/05/2015] [Indexed: 12/20/2022] Open
Abstract
This consensus guideline discusses the electrocardiographic phenomenon of beat-to-beat QT interval variability (QTV) on surface electrocardiograms. The text covers measurement principles, physiological basis, and clinical value of QTV. Technical considerations include QT interval measurement and the relation between QTV and heart rate variability. Research frontiers of QTV include understanding of QTV physiology, systematic evaluation of the link between QTV and direct measures of neural activity, modelling of the QTV dependence on the variability of other physiological variables, distinction between QTV and general T wave shape variability, and assessing of the QTV utility for guiding therapy. Increased QTV appears to be a risk marker of arrhythmic and cardiovascular death. It remains to be established whether it can guide therapy alone or in combination with other risk factors. QT interval variability has a possible role in non-invasive assessment of tonic sympathetic activity.
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Affiliation(s)
- Mathias Baumert
- School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA, Australia
| | - Alberto Porta
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, Milan, Italy
| | - Marc A Vos
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marek Malik
- St Paul's Cardiac Electrophysiology, University of London, and National Heart and Lung Institute, Imperial College, Dovehouse Street, London SW3 6LY, UK
| | - Jean-Philippe Couderc
- Heart Research Follow-Up Program, University of Rochester Medical Center, Rochester, NY, USA
| | - Pablo Laguna
- Zaragoza University and CIBER-BBN, Zaragoza, Spain
| | - Gianfranco Piccirillo
- Dipartimento di Scienze Cardiovascolari, Respiratorie, Nefrologiche, Anestesiologiche e Geriatriche, Università 'La Sapienza' Rome, Rome, Italy
| | - Godfrey L Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
| | - Larisa G Tereshchenko
- Oregon Health and Science University, Knight Cardiovascular Institute, Portland, OR, USA
| | - Paul G A Volders
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, Maastricht, The Netherlands
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Imam MH, Karmakar CK, Jelinek HF, Palaniswami M, Khandoker AH. Analyzing Systolic-Diastolic Interval Interaction Characteristics in Diabetic Cardiac Autonomic Neuropathy Progression. IEEE JOURNAL OF TRANSLATIONAL ENGINEERING IN HEALTH AND MEDICINE-JTEHM 2015; 3:1900510. [PMID: 27170895 PMCID: PMC4848101 DOI: 10.1109/jtehm.2015.2462339] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 05/25/2015] [Accepted: 07/16/2015] [Indexed: 11/23/2022]
Abstract
Cardiac autonomic neuropathy (CAN), one of the major complications in diabetes, if detected at the subclinical stage allows for effective treatment and avoiding further complication including cardiovascular pathology. Surface ECG (Electrocardiogram)-based diagnosis of CAN is useful to overcome the limitation of existing cardiovascular autonomic reflex tests traditionally used for CAN identification in clinical settings. The aim of this paper is to analyze the changes in the mechanical function of the ventricles in terms of systolic-diastolic interval interaction (SDI) from a surface ECG to assess the severity of CAN progression [no CAN, early CAN (ECAN) or subclinical CAN, and definite CAN (DCAN) or clinical CAN]. ECG signals recorded in supine resting condition from 72 diabetic subjects without CAN (CAN-) and 70 diabetic subjects with CAN were analyzed in this paper. The severity of CAN was determined by Ewing’s Cardiovascular autonomic reflex tests. Fifty-five subjects of the CAN group had ECAN and 15 subjects had DCAN. In this paper, we propose an improved version of the SDI parameter (i.e., TQ/RR interval ratio) measured from the electrical diastolic interval (i.e., TQ interval) and the heart rate interval (i.e., RR interval). The performance of the proposed SDI measure was compared with the performance of the existing SDI measure (i.e., QT/TQ interval ratio). The proposed SDI parameter showed significant differences among three groups (no CAN, ECAN, and DCAN). In addition, the proposed SDI parameter was found to be more sensitive in detecting CAN progression than other ECG interval-based features traditionally used for CAN diagnosis. The modified SDI parameter might be used as an alternative measure for the Ewing autonomic reflex tests to identify CAN progression for those subjects who are unable to perform the traditional tests. These findings could also complement the echocardiographic findings of the left ventricular diastolic dysfunction by providing additional information about alteration in systolic and diastolic intervals in heart failure.
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RIBEIRO ANTONIOLUIZPINHO, ROCHA MANOELOTÁVIODACOSTA, TERRANOVA PAOLO, CESARANO MARCO, NUNES MARIADOCARMOPEREIRA, LOMBARDI FEDERICO. T-Wave Amplitude Variability and the Risk of Death in Chagas Disease. J Cardiovasc Electrophysiol 2011; 22:799-805. [DOI: 10.1111/j.1540-8167.2010.02000.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Couderc JP. Measurement and regulation of cardiac ventricular repolarization: from the QT interval to repolarization morphology. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2009; 367:1283-99. [PMID: 19324709 PMCID: PMC2635501 DOI: 10.1098/rsta.2008.0284] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Ventricular repolarization (VR) is a crucial step in cardiac electrical activity because it corresponds to a recovery period setting the stage for the next heart contraction. Small perturbations of the VR process can predispose an individual to lethal arrhythmias. In this review, I aim to provide an overview of the methods developed to analyse static and dynamic aspects of the VR process when recorded from a surface electrocardiogram (ECG). The first section describes the list of physiological and clinical factors that can affect the VR. Technical aspects important to consider when digitally processing ECGs are provided as well. Special attention is given to the analysis of the effect of heart rate on the VR and its regulation by the autonomic nervous system. The final section provides the rationale for extending the analysis of the VR from its duration to its morphology. Several modelling techniques and measurement methods will be presented and their role within the arena of cardiac safety will be discussed.
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Affiliation(s)
- Jean-Philippe Couderc
- Heart Research Follow-Up Program, Cardiology Department, Box 653, University of Rochester Medical Center, 601 Elmwood Avenue, University of Rochester, Rochester, NY 14642, USA.
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Kalisnik JM, Avbelj V, Trobec R, Vidmar G, Troise G, Gersak B. Ventricular repolarization dynamicity and arrhythmic disturbances after beating-heart and arrested-heart revascularization. Heart Surg Forum 2009; 11:E194-201. [PMID: 18782696 DOI: 10.1532/hsf98.20081025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Arrhythmias attributable to altered autonomic modulation of the heart, with elevated sympathetic and depressed vagal modulation, occur to a similar extent after surgery performed on beating or arrested hearts. Coronary artery bypass grafting (CABG) with cardiopulmonary bypass has been associated with more frequent occurrence of arrhythmic events than surgery performed without CABG, even with comparable levels of postoperative cardiac autonomic (dis) regulation after arrested- and beating-heart revascularization. We explored the effects of arrested- and beating-heart revascularization procedures on the dynamics of ventricular repolarization and on increased postoperative arrhythmic events. METHODS Study participants included 57 CABG patients; 28 underwent on-pump and 29 underwent off-pump procedures. The 2 groups were comparable regarding clinical and postoperative characteristics. With high-quality 15-minute digital electrocardiograms, we assessed ventricular repolarization dynamics using RR and QT intervals and analyzed QT variability (QTV) and QT-RR interdependence. RR and QT intervals were determined from stationary 5-minute segments. QT-interval variability was determined by a T-wave template-matching algorithm. We used linear regression to compute the slope/correlation of the QT/RR interval. The Fisher exact test, nonpaired t-test, and ANOVA were applied to test the results; P <.05 was considered significant. RESULTS Postoperative arrhythmic events were significantly more frequent in both groups. One week postoperatively these events were significantly more frequent in the on-pump group. In both groups, the RR interval was shorter after CABG (P <.001). The QT variability index increased from -1.2 + or - 0.6 to -0.8 + or - 0.4 after off-pump CABG and from -1.3 + or - 0.5 to -0.5 + or - 0.6 on day 4 after surgery (P <.05), further deteriorating to -0.2 + or - 0.6 one week after CABG in the on-pump group only (P <.05). QT-RR correlations decreased from 0.39 to 0.24 in the off-pump vs 0.34 to 0.17 in the on-pump group (P <.05), and in both groups they remained significantly reduced for as long as 4 weeks after CABG. CONCLUSIONS For both on- and off-pump CABG, beat-to-beat heart-rate changes and rate-dependent ventricular repolarization adaptation showed disparities that worsened after surgery. The observed repolarization lability after CABG procedures seems to be transient but more pronounced after on-pump CABG. The association of arrhythmic events with ventricular repolarization lability changes in the setting of faster heart rates offers novel insights into the mechanisms of perioperative proarrhythmia after beating- and arrested-heart revascularization.
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Affiliation(s)
- Jurij M Kalisnik
- Department of Cardiovascular Surgery, University Medical Center, Ljubljana, Slovenia.
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Almeida R, Gouveia S, Rocha AP, Pueyo E, Martínez JP, Laguna P. QT variability and HRV interactions in ECG: quantification and reliability. IEEE Trans Biomed Eng 2006; 53:1317-29. [PMID: 16830936 DOI: 10.1109/tbme.2006.873682] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In this paper, a dynamic linear approach was used over QT and RR series measured by an automatic delineator, to explore the interactions between QT interval variability (QTV) and heart rate variability (HRV). A low-order linear autoregressive model allowed to separate and quantify the QTV fractions correlated and not correlated with HRV, estimating their power spectral density measures. Simulated series and artificial ECG signals were used to assess the performance of the methods, considering a respiratory-like electrical axis rotation effect and noise contamination with a signal-to-noise ratio (SNR) from 30 to 10 dB. The errors found in the estimation of the QTV fraction related to HRV showed a nonrelevant performance decrease from automatic delineation. The joint performance of delineation plus variability analysis achieved less than 20% error in over 75% of cases for records presenting SNRs higher than 15 dB and QT standard deviation higher than 10 ms. The methods were also applied to real ECG records from healthy subjects where it was found a relevant QTV fraction not correlated with HRV (over 40% in 19 out of 23 segments analyzed), indicating that an important part of QTV is not linearly driven by HRV and may contain complementary information.
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Affiliation(s)
- Rute Almeida
- Departamento de Matemática Aplicada, Faculdade de Ciências da Universidade do Porto and Centro de Matemática da UP, Rua Campo Alegre 687, 4169-007 Porto, Portugal.
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Boriani G, Biffi M, Martignani C, Bartolini P, Branzi A. Implantable Cardioverter Defibrillators for Ventricular Tachyarrhythmia: Current Status and Technological Evolution. Int J Artif Organs 2001. [DOI: 10.1177/039139880102400701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- G. Boriani
- Institute of Cardiology, University of Bologna, Bologna - Italy
| | - M. Biffi
- Institute of Cardiology, University of Bologna, Bologna - Italy
| | - C. Martignani
- Institute of Cardiology, University of Bologna, Bologna - Italy
| | - P. Bartolini
- Biomedical Engineering, Istituto Superiore di Sanità, Rome - Italy
| | - A. Branzi
- Institute of Cardiology, University of Bologna, Bologna - Italy
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