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Ifedili I, Maturana M, Kayali S, Levine Y, Kabra R, Jha SK. A case of short QT-interval postventricular arrhythmia arrest from Torsade De Pointes, a new phenotype, or the result of tachycardia-mediated imbalance. J Cardiovasc Electrophysiol 2024; 35:501-504. [PMID: 38174843 DOI: 10.1111/jce.16164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 12/03/2023] [Accepted: 12/15/2023] [Indexed: 01/05/2024]
Abstract
INTRODUCTION We report the case of an 18-year-old female with recurrent syncope that was discovered to have congenital long QT syndrome (LQTS) and episodes of a transiently short QT interval after spontaneous termination of polymorphic ventricular tachycardia. METHODS & RESULTS A cardiac event monitor revealed a long QT interval and initiation of polymorphic ventricular tachycardia by a premature ventricular complex on the preceding T-wave. After 1 minute of ventricular fibrillation, her arrhythmia spontaneously terminated with evidence of a short QT interval. CONCLUSIONS A transient, potentially artificial, short QT interval following Torsades de Pointes can occur in patients with LQTS.
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Affiliation(s)
- Ikechukwu Ifedili
- Department of Cardiovascular Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Miguel Maturana
- Department of Cardiovascular Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Sharif Kayali
- Department of Cardiovascular Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Yehoshua Levine
- Department of Cardiovascular Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Rajesh Kabra
- Department of Cardiovascular Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, USA
- Kansas City Heart Rhythm Institute, Overland Park, Kansas, USA
| | - Sunil K Jha
- Department of Cardiovascular Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, USA
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Holter Recordings at Initial Assessment for Long QT Syndrome: Relationship to Genotype Status and Cardiac Events. J Cardiovasc Dev Dis 2022; 9:jcdd9050164. [PMID: 35621875 PMCID: PMC9147587 DOI: 10.3390/jcdd9050164] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 05/19/2022] [Accepted: 05/20/2022] [Indexed: 11/17/2022] Open
Abstract
Background: The relationship of Holter recordings of repolarization length to outcome in long QT syndrome (LQTS) is unknown. Methods: Holter recordings and initial 12 lead ECG QTc were related to outcome in 101 individuals with LQTS and 28 gene-negative relatives. Mean QTc (mQTc) and mean RTPc (R-wave to peak T-wave, mRTPc) using Bazett correction were measured, analyzing heart rates 40 to 120 bpm. Previously reported upper limit of normal (ULN) were: women and children (<15 years), mQTc 454, mRTPc 318 ms; men mQTc 446 ms, mRTPc 314 ms. Results: Measurements in LQTS patients were greatly prolonged; children and women mean mQTc 482 ms (range 406−558), mRTPc 351 ms (259−443); males > 15 years mQTc 469 ms (407−531), mRTPc 338 ms (288−388). Ten patients had cardiac arrest (CA), and 24 had arrhythmic syncope before or after the Holter. Holter values were more closely related to genotype status and symptoms than 12 lead QTc, e.g., sensitivity/specificity for genotype positive status, mRTPc > ULN (89%/86%); CA, mRTPc > 30 ms over ULN (48%/100%). Of 34 symptomatic (CA/syncope) patients, only 9 (26%) had 12 lead QTc > 500 ms, whereas 33/34 (94%) had an mRTPc or mQTc above ULN. In 10 with CA, all Holter measurements were > 15 ms above ULN, but only two had 12 lead QTc > 500 m. Conclusions: Holter average repolarization length, particularly mRTPc, reflects definite LQTS status and clinical risk better than the initial 12 lead QTc. Values below ULN indicate both a low risk of having LQTS and a low risk of cardiac events in the small percentage that do.
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Shi B, Motin MA, Wang X, Karmakar C, Li P. Bivariate Entropy Analysis of Electrocardiographic RR-QT Time Series. ENTROPY 2020; 22:e22121439. [PMID: 33419293 PMCID: PMC7766536 DOI: 10.3390/e22121439] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/15/2020] [Accepted: 12/17/2020] [Indexed: 11/16/2022]
Abstract
QT interval variability (QTV) and heart rate variability (HRV) are both accepted biomarkers for cardiovascular events. QTV characterizes the variations in ventricular depolarization and repolarization. It is a predominant element of HRV. However, QTV is also believed to accept direct inputs from upstream control system. How QTV varies along with HRV is yet to be elucidated. We studied the dynamic relationship of QTV and HRV during different physiological conditions from resting, to cycling, and to recovering. We applied several entropy-based measures to examine their bivariate relationships, including cross sample entropy (XSampEn), cross fuzzy entropy (XFuzzyEn), cross conditional entropy (XCE), and joint distribution entropy (JDistEn). Results showed no statistically significant differences in XSampEn, XFuzzyEn, and XCE across different physiological states. Interestingly, JDistEn demonstrated significant decreases during cycling as compared with that during the resting state. Besides, JDistEn also showed a progressively recovering trend from cycling to the first 3 min during recovering, and further to the second 3 min during recovering. It appeared to be fully recovered to its level in the resting state during the second 3 min during the recovering phase. The results suggest that there is certain nonlinear temporal relationship between QTV and HRV, and that the JDistEn could help unravel this nuanced property.
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Affiliation(s)
- Bo Shi
- School of Medical Imaging, Bengbu Medical College, Bengbu 233030, China;
| | - Mohammod Abdul Motin
- Department of Electrical and Electronic Engineering, University of Melbourne, Melbourne, VIC 3110, Australia;
| | - Xinpei Wang
- School of Control Science and Engineering, Shandong University, Jinan 250061, China;
| | - Chandan Karmakar
- School of Information Technology, Deakin University, Geelong, VIC 3225, Australia
- Correspondence: (C.K.); (P.L.)
| | - Peng Li
- Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
- Correspondence: (C.K.); (P.L.)
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Waddell-Smith KE, Chaptynova AA, Li J, Crawford JR, Hinds H, Skinner JR. Normative Heart-Rate Corrected Values for Repolarisation Length From Holter Recordings in Children and Adults. Heart Lung Circ 2020; 29:1469-1475. [PMID: 31983548 DOI: 10.1016/j.hlc.2019.12.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 10/17/2019] [Accepted: 12/05/2019] [Indexed: 11/26/2022]
Abstract
BACKGROUND Normative values for heart-rate corrected repolarisation length are not available in children and are scarce in adults. We wished to define repeatability and normative values of Holter recording measurements of repolarisation length in healthy individuals using a commercially available system, and compare measurements with those from 12-lead electrocardiograms (ECGs). METHODS Twenty-four-hour (24-) Holter recordings were made on 99 Healthy volunteers: 52 children (7 months to 14 years) and 47 adults (≥15 yrs). Mean and peak values of QTc, and RTPc (R-wave to peak T-wave) were assessed. Bazett heart rate correction was employed for each measurement and only heart rates between 40 and 120 bpm were analysed. The end of the T-wave was defined from the zero-crossing point. QTc was also determined from 12-lead ECGs from the same population by manual measurement recording the longest QTc of leads 2 and V5. The tangent technique was used to define the end of the T-wave. RESULTS Interobserver repeatability: mean QTc ±15 ms (CI 3.5%), peak QTc ±25 ms (CI 4.5%), mean RTPc ±3 ms (CI 1%), peak RTPc ±44 ms (CI 11%). Mean values were very similar for <15 years and all females and were therefore amalgamated: mean (±2 SD); mean QTc 424 ms (394-454), mean RTPc 291ms (263-319). Values were lower in males ≥15 years; (mean QTc 408 ms (370-446), p<0.01; mean RTPc 274 ms (234-314), p<0.01. The highest mean QTc value was 467 ms in an adult female. QTc from 12-lead ECG: females <15 years 409 ms (384-434) males <15 years 408 ms (383-433), females ≥15 years 426 ms (401-451), males ≥15 years 385 ms (362-408). CONCLUSIONS Holter measurements of mean QTc and RTPc are highly repeatable. Males ≥15 years have shorter mean repolarisation length over 24 hours than males <15 years and all females. Mean QTc Holter values were on average 15-17 ms longer than QTc from 12-lead ECGs except in females >15 years.
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Affiliation(s)
- Kathryn E Waddell-Smith
- Green Lane Paediatric and Congenital Cardiac Services, Starship Children's Hospital Auckland New Zealand; The University of Auckland, Department of Child Health, Auckland, New Zealand; Green Lane Cardiovascular Services, Auckland City Hospital, Auckland, New Zealand
| | | | - Jian Li
- Green Lane Paediatric and Congenital Cardiac Services, Starship Children's Hospital Auckland New Zealand
| | - Jackie R Crawford
- Green Lane Paediatric and Congenital Cardiac Services, Starship Children's Hospital Auckland New Zealand
| | - Halina Hinds
- Green Lane Cardiovascular Services, Auckland City Hospital, Auckland, New Zealand
| | - Jonathan R Skinner
- Green Lane Paediatric and Congenital Cardiac Services, Starship Children's Hospital Auckland New Zealand; The University of Auckland, Department of Child Health, Auckland, New Zealand; Green Lane Cardiovascular Services, Auckland City Hospital, Auckland, New Zealand.
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Vesely P, Stracina T, Hlavacova M, Halamek J, Kolarova J, Olejnickova V, Mrkvicova V, Paulova H, Novakova M. Haloperidol affects coupling between QT and RR intervals in guinea pig isolated heart. J Pharmacol Sci 2018; 139:23-28. [PMID: 30528680 DOI: 10.1016/j.jphs.2018.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 11/08/2018] [Accepted: 11/12/2018] [Indexed: 11/25/2022] Open
Abstract
Prolonged QT interval is an independent risk factor for development of ventricular arrhythmias. Haloperidol is one of the drugs inducing QT prolongation. Previous studies showed that haloperidol affects not only QT duration but also heart rate (RR interval). The present work focused on relationship between QT and RR and its changes under acute and chronic haloperidol administration. The study included 14 male guinea pigs divided into control and haloperidol-treated group. After 21-days administration of haloperidol or vehiculum, electrograms in isolated hearts were recorded. QT/RR and dQT/dRR coupling were calculated. Chronic haloperidol administration significantly decreases the coupling between QT and RR. Acute haloperidol exposure significantly decreases the dQT/dRR coupling in both treated and untreated guinea pig hearts. Flatter QT/RR relationship reveals a lack of QT adaptation to increased heart rate. It should be emphasized that in such situation ECG recording will not show significant QT prolongation evaluated according to clinical rules. However, if QT interval does not adapt to increased heart rate sufficiently, the risk of ventricular arrhythmias may be increased despite practically normal QT interval length. The results are supported by findings in biochemical analyses, which proved eligibility of the used model.
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Affiliation(s)
- Petr Vesely
- International Clinical Research Center, St. Anne's Faculty Hospital, Brno, Czech Republic; Department of Biomedical Engineering, Brno University of Technology, Brno, Czech Republic
| | - Tibor Stracina
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic.
| | - Miroslava Hlavacova
- Department of Biochemistry, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Josef Halamek
- Institute of Scientific Instruments, Academy of Sciences, Brno, Czech Republic
| | - Jana Kolarova
- Department of Biomedical Engineering, Brno University of Technology, Brno, Czech Republic
| | - Veronika Olejnickova
- Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Veronika Mrkvicova
- Department of Sports Medicine and Rehabilitation (KFDR), St. Anne's Faculty Hospital, Masaryk University, Brno, Czech Republic; Department of Public Health, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Hana Paulova
- Department of Biochemistry, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Marie Novakova
- International Clinical Research Center, St. Anne's Faculty Hospital, Brno, Czech Republic; Department of Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
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Potapov I, Latukka J, Kim J, Luukko P, Aalto-Setälä K, Räsänen E. Information transfer in QT-RR dynamics: Application to QT-correction. Sci Rep 2018; 8:14992. [PMID: 30301929 PMCID: PMC6178346 DOI: 10.1038/s41598-018-33359-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 09/27/2018] [Indexed: 01/10/2023] Open
Abstract
The relation between the electrical properties of the heart and the beating rate is essential for the heart functioning. This relation is central when calculating the “corrected QT interval” — an important measure of the risk of potentially lethal arrhythmias. We use the transfer entropy method from information theory to quantitatively study the mutual dynamics of the ventricular action potential duration (the QT interval) and the length of the beat-to-beat (RR) interval. We show that for healthy individuals there is a strong asymmetry in the information transfer: the information flow from RR to QT dominates over the opposite flow (from QT to RR), i.e. QT depends on RR to a larger extent than RR on QT. Moreover, the history of the intervals has a strong effect on the information transfer: at sufficiently long QT history length the information flow asymmetry inverts and the RR influence on QT dynamics weakens. Finally, we demonstrate that the widely used QT correction methods cannot properly capture the changes in the information flows between QT and RR. We conclude that our results obtained through a model-free informational perspective can be utilised to improve and test the QT correction schemes in clinics.
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Affiliation(s)
- Ilya Potapov
- Laboratory of Physics, Tampere University of Technology, P.O. Box 692, FI-33101, Tampere, Finland.
| | - Joonas Latukka
- Laboratory of Physics, Tampere University of Technology, P.O. Box 692, FI-33101, Tampere, Finland
| | - Jiyeong Kim
- Laboratory of Physics, Tampere University of Technology, P.O. Box 692, FI-33101, Tampere, Finland
| | - Perttu Luukko
- Laboratory of Physics, Tampere University of Technology, P.O. Box 692, FI-33101, Tampere, Finland.,FirstBeat Technologies Ltd, Yliopistonkatu 28a, Jyväskylä, 40100, Finland
| | - Katriina Aalto-Setälä
- Heart Group, Faculty of Medicine and Life Sciences, University of Tampere, P.O. Box 100, FI-33014, Tampere, Finland.,Heart Hospital, Tampere University Hospital, P.O. Box 2000, FI-33521, Tampere, Finland
| | - Esa Räsänen
- Laboratory of Physics, Tampere University of Technology, P.O. Box 692, FI-33101, Tampere, Finland
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Imam MH, Karmakar CK, Palanaiswami M, Khandoker AH. A novel technique to investigate the effect of ageing on ventricular repolarization characteristics in healthy and LQTS subjects. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2018; 2015:2796-9. [PMID: 26736872 DOI: 10.1109/embc.2015.7318972] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Ventricular repolarization(VR) characteristics is affected by ageing alongside several other factors like Heart rate(HR),respiration, modulation of autonomic nervous system, different drug effects, genetical factors affecting the cardiac ion channel characteristics, gender etc. Therefore, total VR variability (i.e. QT interval variability in surface ECG) consists of two components: one dependent on HR variability (HRV) and another independent of HRV. Analysis of QT interval variability (QTV) is crucial for both healthy and pathological conditions as increase in VR variability measured by QTV increases cardiac repolarization instability, which might lead to arrhythmogenesis. Analyzing the effect of ageing using a widely used measure of QTV (i.e. QTVI) is reported inconsistently in Healthy subjects whereas the same for Long QT Syndrome (LQTS) subjects is not widely reported. In this study, we propose a novel time domain measure from beat-tobeat QT-RR distribution to analyze how ageing affects VR in both Healthy and a group of genotyped LQTS1 subjects. A total of 139 Healthy subjects and 134 LQTS1 subjects of three different age groups (i.e. Young: age 20-35, Middle-aged: 40-55 and Old: age<;60) were analyzed for this study. The proposed measure is also compared with other existing widely used measures of QTV like SDQT and QTVI in differentiating different age groups. The proposed measure stands out to be more discriminatory than other existing variability measures of QT interval.
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Gravel H, Jacquemet V, Dahdah N, Curnier D. Clinical applications of QT/RR hysteresis assessment: A systematic review. Ann Noninvasive Electrocardiol 2017; 23. [PMID: 29083088 DOI: 10.1111/anec.12514] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 09/17/2017] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND QT/RR hysteresis (QT-hys) is an index of the time accommodation of ventricular repolarization to heart rate changes. This report comprehensively reviews studies addressing QT-hys as a biomarker of medical conditions. METHODS This is a secondary analysis of data from a recent systematic review pertaining to methods of assessment of QT-hys. Articles included in the former review were filtered in order to select original articles investigating the association of QT-hys with medical conditions in humans. RESULTS Nineteen articles fulfilled our inclusion criteria. Given the heterogeneity of the methods and investigated conditions, no pooled analysis of data could be implemented. QT-hys was mostly studied as a risk marker of severe arrhythmias, as a predictor of the long QT syndrome (LQTS) phenotypes and genotypes and as a marker of exercise-induced ischemia. An increased QT-hys appears to be implicated in arrhythmogenesis, although the evidence in this regard relies on few human studies. An augmented QT-hys was reported in the LQTS, predominantly in the LQT2 genotype, but conflicting results were obtained between studies using different methods of assessment. In addition, QT-hys appears to be a useful marker of stress-induced myocardial ischemia in patients suspected of coronary artery disease. CONCLUSIONS QT-hys evaluation has potential clinical utility in at least some clinical conditions. Further studies of the clinical validity of QT-hys assessment are warranted, particularly condition specific studies based on QT-hys evaluation methods that provide separate estimates of QT-hys and QT/RR dependency.
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Affiliation(s)
- Hugo Gravel
- Department of Kinesiology, University of Montreal, Montreal, QC, Canada
| | - Vincent Jacquemet
- Department of Pharmacology and Physiology, Faculty of Medicine, University of Montreal, Montreal, QC, Canada
| | - Nagib Dahdah
- Division of Pediatric Cardiology and CHU Ste-Justine Research Center, CHU Ste-Justine, Montreal, QC, Canada
| | - Daniel Curnier
- Department of Kinesiology, University of Montreal, Montreal, QC, Canada
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Gravel H, Curnier D, Dahdah N, Jacquemet V. Categorization and theoretical comparison of quantitative methods for assessing QT/RR hysteresis. Ann Noninvasive Electrocardiol 2017; 22. [PMID: 28510313 DOI: 10.1111/anec.12463] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 03/27/2017] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND In the human electrocardiogram, there is a lag of adaptation of the QT interval to heart rate changes, usually termed QT/RR hysteresis (QT-hys). Subject-specific quantifiers of QT-hys have been proposed as potential biomarkers, but there is no consensus on the choice of the quantifier. METHODS A comprehensive literature search was conducted to identify original articles reporting quantifiers of repolarization hysteresis from the surface ECG in humans. RESULTS Sixty articles fulfilled our inclusion criteria. Reported biomarkers were grouped under four categories. A simple mathematical model of QT/RR loop was used to illustrate differences between the methods. Category I quantifiers use direct measurement of QT time course of adaptation. They are limited to conditions where RR intervals are under strict control. Category IIa and IIb quantifiers compare QT responses during consecutive heart rate acceleration and deceleration. They are relevant when a QT/RR loop is observed, typically during exercise and recovery, but are not robust to protocol variations. Category III quantifiers evaluate the optimum RR memory in dynamic QT/RR relationship modeling. They estimate an intrinsic memory parameter independent from the nature of RR changes, but their reliability remains to be confirmed when multiple memory parameters are estimated. Promising approaches include the differentiation of short-term and long-term memory and adaptive estimation of memory parameters. CONCLUSION Model-based approaches to QT-hys assessment appear to be the most versatile, as they allow separate quantification of QT/RR dependency and QT-hys, and can be applied to a wide range of experimental settings.
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Affiliation(s)
- Hugo Gravel
- Department of Kinesiology, University of Montreal, Montréal, QC, Canada
| | - Daniel Curnier
- Department of Kinesiology, University of Montreal, Montréal, QC, Canada
| | - Nagib Dahdah
- Division of Pediatric Cardiology and CHU Ste-Justine Research Center, CHU Ste-Justine, Montréal, QC, Canada
| | - Vincent Jacquemet
- Department of Pharmacology and Physiology, Faculty of Medicine, University of Montreal, Montréal, QC, Canada
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Quinteiro RA, Biagetti MO, Fernandez A, Borzone FR, Gargano A, Casabe HJ. Can QT/RR relationship differentiate between low- and high-risk patients with hypertrophic cardiomyopathy? Ann Noninvasive Electrocardiol 2015; 20:386-93. [PMID: 25639818 DOI: 10.1111/anec.12230] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Abnormal dynamicity of repolarization is considered to be a marker of myocardial vulnerability contributing to increased risk of arrhythmic events and sudden death. However, little is known about QT dynamics in hypertrophic cardiomyopathy (HCM). In this study, we aimed to evaluate ventricular repolarization by QT dynamicity in patients with HCM, focusing on its value to define if it is able to differentiate among low- and high-risk HCM patients. METHODS The linear regression slopes of the QT interval, measured to the apex and to the end of the T wave plotted against RR intervals (QTapex/RR and QTend/RR slopes, respectively) were calculated from 24-hour Holter recordings using a standard algorithm in 36 HCM patients and 64 control subjects. RESULTS QTapex/RR and QTend/RR slopes were significantly steeper in the HCM patients in contrary to healthy control subjects (QTapex/RR = 0.22 + 0.08 vs 0.20 + 0.05, P = 0.0367; QTend/RR = 0.25 + 0.10 vs 0.20 + 0.06, P = 0.023). Moreover, the slopes of QTend/RR and QTapex/RR of high-risk patients were significantly steeper than those of control subjects while no significant differences were found among low-risk HCM patients and control subjects and only QTe/RR of high-risk patients was significantly different between low- and high-risk HCM patients. CONCLUSIONS Our study results suggest that QT dynamicity is impaired in patients with HCM and may help to differentiate among low- and high-risk patients. Further studies are needed to elucidate the prognostic significance and clinical implications of impaired ventricular repolarization in patients with HCM.
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Affiliation(s)
- Ricardo A Quinteiro
- Cardiac Electrophysiology Laboratory, Favaloro University, Buenos Aires, Argentina
| | - Marcelo O Biagetti
- Cardiac Electrophysiology Laboratory, Favaloro University, Buenos Aires, Argentina
| | - Adrian Fernandez
- the Cardiology Division of the University Hospital, Favaloro University, Buenos Aires, Argentina
| | - Francisco R Borzone
- Cardiac Electrophysiology Laboratory, Favaloro University, Buenos Aires, Argentina
| | - Agustina Gargano
- the Cardiology Division of the University Hospital, Favaloro University, Buenos Aires, Argentina
| | - Horacio J Casabe
- the Cardiology Division of the University Hospital, Favaloro University, Buenos Aires, Argentina
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