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Axelsson KJ, Gransberg L, Lundahl G, Bergfeldt L. Adaptation of ventricular repolarization dispersion during heart rate increase in humans: A roller coaster process. J Electrocardiol 2021; 68:90-100. [PMID: 34411881 DOI: 10.1016/j.jelectrocard.2021.07.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/10/2021] [Accepted: 07/24/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Regional differences in ventricular activation sequence and action potential duration and morphology result in dispersion in ventricular repolarization (VR). VR dispersion is a key factor in arrhythmogenesis. We studied the adaptation of global VR dispersion in humans during normal and abnormal ventricular activation, and the relation to the QT adaptation (hysteresis). METHODS We measured global VR dispersion as T amplitude, T area, and ventricular gradient (VG), using continuous Frank vectorcardiography, in response to abrupt and sustained atrial (AP) or ventricular pacing (VP) aiming at 120 bpm, in 21 subjects with permanent pacemakers. RESULTS Following pacing start, VR adaptation showed an initially rapid and complex tri-phasic pattern, most pronounced for T amplitude. There were major differences in the patterns of VR dispersion adaptation following abrupt AP vs VP, confirming that the adaptation pattern is activation dependent. In response to AP, an instantaneous decrease in VR dispersion occurred, followed by an increase and then a slow decrease, all at a lower level than baseline. In contrast, following VP there was an immediate increase to ~4× baseline in T amplitude and T area (but not in VG), with a subsequent biphasic adaptation lasting longer during VP than AP. The initial rapid changes occurred within the time for QT adaptation to reach steady-state. CONCLUSIONS Our results corroborate and expand data from animal and invasive human studies, showing similarities of the adaptation pattern on different scales. The initial rapidly changing VR adaptation phase presumably reflects a window of increased vulnerability to arrhythmias.
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Affiliation(s)
- Karl-Jonas Axelsson
- Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Region Västra Götaland, Department of Cardiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
| | - Lennart Gransberg
- Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Gunilla Lundahl
- Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lennart Bergfeldt
- Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Region Västra Götaland, Department of Cardiology, Sahlgrenska University Hospital, Gothenburg, Sweden
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2
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A comprehensive electrocardiographic analysis for young athletes. Med Biol Eng Comput 2021; 59:1865-1876. [PMID: 34342819 DOI: 10.1007/s11517-021-02401-2] [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: 12/12/2020] [Accepted: 07/01/2021] [Indexed: 10/20/2022]
Abstract
ECG-based differences between athletes and sedentary adolescents are a frequently investigated subject in sports medicine. Especially, training-induced ECG variations are common in adult athletes and sustained training often leads to anatomical changes in the heart that can yield abnormalities in ECG. Therefore, ECG screening in athletes is important in diagnosis of cardiac problems of young athletes. The present work investigated the ECG characteristics of young athletes in terms of both gender and sedentary healthy young control group differences. Besides comparison between groups, analysis parameters were also investigated within the groups using correlation analysis. ECG characteristics were extracted using wavelet transform-based adaptive algorithms. Results showed that ECGs of athletes demonstrate differences related to gender and compared to young sedentary. Athletes had significantly lower heart rate; higher QTc, P, and T amplitudes; ST segment; and ST, QT, and RR intervals compared to control group (p < 0.05). Proposed new parameter, namely "scalogram" of each wave, was lower in male athletes compared to other groups (p < 0.05). Negative correlation between T wave amplitude and RR interval could be an indicator of long QT syndrome for male athletes. Furthermore, prolongation of QRS interval in athletes could be the underlying reason of changes in T wave amplitude. Findings of this study can propose indicators for understanding the possible diseases as well as help evaluate the sudden changes in athlete's heart.
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Yodogawa K, Aiba T, Sumitomo N, Yamamoto T, Murata H, Iwasaki YK, Kokubo Y, Shimizu W. Differential diagnosis between LQT1 and LQT2 by QT/RR relationships using 24-hour Holter monitoring: A multicenter cross-sectional study. Ann Noninvasive Electrocardiol 2021; 26:e12878. [PMID: 34245193 PMCID: PMC8411756 DOI: 10.1111/anec.12878] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 05/16/2021] [Accepted: 06/29/2021] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND The clinical course and therapeutic strategies in the congenital long QT syndrome (LQTS) are genotype-specific. However, accurate estimation of LQTS genotype is often difficult from the standard 12-lead ECG. OBJECTIVES This study aims to evaluate the utility of QT/RR slope analysis by the 24-hour Holter monitoring for differential diagnosis of LQTS genotype between LQT1 and LQT2. METHODS This cross-sectional study enrolled 54 genetically identified LQTS patients (29 LQT1 and 25 LQT2) recruited from three medical institutions. The QT-apex (QTa) interval and the QT-end (QTe) interval at each 15-second were plotted against the RR intervals, and the linear regression (QTa/RR and QTe/RR slopes, respectively) was calculated from the entire 24-hour and separately during the day or night-time periods of the Holter recordings. RESULTS The QTe/RR and QTa/RR slopes at the entire 24-hour were significantly steeper in LQT2 compared to those in LQT1 patients (0.262 ± 0.063 vs. 0.204 ± 0.055, p = .0007; 0.233 ± 0.052 vs. 0.181 ± 0.040, p = .0002, respectively). The QTe interval was significantly longer, and QTe/RR and QTa/RR slopes at daytime were significantly steeper in LQT2 than in LQT1 patients. The receiver operating curve analysis revealed that the QTa/RR slope of 0.211 at the entire 24-hour Holter was the best cutoff value for differential diagnosis between LQT1 and LQT2 (sensitivity: 80.0%, specificity: 75.0%, and area under curve: 0.804 [95%CI = 0.68-0.93]). CONCLUSION The continuous 24-hour QT/RR analysis using the Holter monitoring may be useful to predict the genotype of congenital LQTS, particularly for LQT1 and LQT2.
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Affiliation(s)
- Kenji Yodogawa
- Department of Cardiovascular Medicine, Nippon Medical School, Tokyo, Japan
| | - Takeshi Aiba
- Department of Advanced Arrhythmia and Translational Medical Science, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Naotaka Sumitomo
- Department of Pediatric Cardiology, Saitama Medical University International Medical Center, Saitama, Japan
| | - Teppei Yamamoto
- Department of Cardiovascular Medicine, Nippon Medical School, Tokyo, Japan
| | - Hiroshige Murata
- Department of Cardiovascular Medicine, Nippon Medical School, Tokyo, Japan
| | - Yu-Ki Iwasaki
- Department of Cardiovascular Medicine, Nippon Medical School, Tokyo, Japan
| | - Yoshihiro Kokubo
- Department of Preventive Cardiology, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Wataru Shimizu
- Department of Cardiovascular Medicine, Nippon Medical School, Tokyo, Japan
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Miki T, Senoo K, Okura T, Shiraishi H, Shirayama T, Aiba T, Matoba S. First episode of ventricular fibrillation in an 84-year-old man with long-QT type 2 syndrome: A case report. J Cardiol Cases 2020; 22:257-259. [PMID: 33304416 PMCID: PMC7718543 DOI: 10.1016/j.jccase.2020.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 07/01/2020] [Accepted: 07/07/2020] [Indexed: 11/21/2022] Open
Abstract
Congenital long QT syndrome (LQTS) is associated with ventricular arrhythmia and an increased risk of sudden cardiac death in young people. However, it is extremely rare for an elderly man to experience ventricular fibrillation (VF) due to congenital LQTS as a first episode. We describe the case of an 84-year-old man who experienced syncope after urination. He had a medical history of hypertension and asthma, but no history of syncope. Electrocardiographic findings in 2017 showed QT prolongation (corrected QT = 505 ms). No medication that could induce QT prolongation was administered. Blood test results on admission showed no electrolyte abnormalities, and there were no abnormal findings on echocardiography. The second episode of loss of consciousness occurred during hospitalization, and electrocardiography revealed incessant torsade de pointes, caused by R-on-T with short-long-short (SLS) sequences due to bradyarrhythmia. Coronary angiography did not detect myocardial ischemia, and an implantable cardioverter-defibrillator was implanted for secondary prevention. Genetic testing revealed a mutation of the KCNH2 gene, indicating LQTS type 2. In summary, we report a rare case of prolonged QT interval with SLS sequences due to sick sinus syndrome triggering VF as the first attack in an elderly patient with LQTS type 2. .
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Affiliation(s)
- Tomonori Miki
- Department of Cardiovascular Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Keitaro Senoo
- Department of Cardiovascular Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
- Department of Cardiac Arrhythmia Research and Innovation, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Takashi Okura
- Department of Cardiovascular Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Hirokazu Shiraishi
- Department of Cardiovascular Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
- Department of Cardiac Arrhythmia Research and Innovation, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Takeshi Shirayama
- Department of Cardiovascular Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
- Department of Cardiac Arrhythmia Research and Innovation, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Takeshi Aiba
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Satoaki Matoba
- Department of Cardiovascular Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan
- Department of Cardiac Arrhythmia Research and Innovation, Kyoto Prefectural University of Medicine, Kyoto, Japan
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Extramiana F, Badilini F, Denjoy I, Vaglio M, Green CL, Kligfield P, Leenhardt A, Maison-Blanche P. Sex influences on ventricular repolarization duration in normal subjects and in type 1, 2 and 3 long QT syndrome patients: Different effect in acquired and congenital type 2 LQTS. J Electrocardiol 2020; 62:148-154. [PMID: 32905894 DOI: 10.1016/j.jelectrocard.2020.08.016] [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: 05/27/2020] [Revised: 07/31/2020] [Accepted: 08/18/2020] [Indexed: 01/08/2023]
Abstract
AIM To evaluate the interaction between sex and rate corrected QT interval (QTc) duration in normal subjects after drug-induced QT prolongation and in LQTS patients. METHODS Semi-automated measurements were performed on 875 digital ECGs (200 normal subjects off drugs (100 females), 200 normal subjects on Moxifloxacin (100 females), 259 LQT1 patients (161 females), 183 LQT2 patients (100 females) and 33 LQT3 patients (15 females)). A sex specific coefficient was calculated in each group and was used to calculate group specific corrected QT intervals (QTci). RESULTS The mean sex difference (female minus male) in QTci interval duration was 17 ms 95%CI(12.7; 21.3) in normal subjects, 19 ms (14.5; 23.5) on Moxifloxacin, and 13 ms (4.8; 21.2) in LQT1 patients. The mean difference was 2 ms (-7.9; 11.9) in LQT2 and - 5 ms (-32.2; 22.2) in LQT3 patients (p = 0.0067 for the group and sex interaction). In the subgroup of patients above 15 years and without beta blocker treatment, the sex effect (female minus male) on QTci interval duration was 17 ms (4.1; 29.9) in LQT1 patients. QTc duration was not different between sex in LQT2 and in LQT3 patients (mean difference - 3 ms (-21.6; 15.6) and 12 ms (-28.4; 52.4), respectively) (p = 0.0191 for group and sex interaction). CONCLUSIONS The interaction between sex and QTc interval is preserved in type 1 LQTS and drug-induced QTc prolongation but blurred in type 2 LQTS. Further experimental studies are warranted to better understand the interaction of sexual hormones with malfunctioning KCNH2 encoded repolarizing potassium channel.
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Affiliation(s)
- Fabrice Extramiana
- Université de Paris, CNMR, Maladies Cardiaques Héréditaires Rares, Hôpital Bichat, INSERMU1166, 75018 Paris, France.
| | | | - Isabelle Denjoy
- Université de Paris, CNMR, Maladies Cardiaques Héréditaires Rares, Hôpital Bichat, INSERMU1166, 75018 Paris, France
| | | | - Cynthia L Green
- Duke Clinical Research Institute, Duke University Medical Center, Durham, NC, United States of America
| | - Paul Kligfield
- Division of Cardiology, Weill Cornell Medical College, New York, NY, United States of America
| | - Antoine Leenhardt
- Université de Paris, CNMR, Maladies Cardiaques Héréditaires Rares, Hôpital Bichat, INSERMU1166, 75018 Paris, France
| | - Pierre Maison-Blanche
- Université de Paris, CNMR, Maladies Cardiaques Héréditaires Rares, Hôpital Bichat, INSERMU1166, 75018 Paris, France
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Comparison of automated interval measurements by widely used algorithms in digital electrocardiographs. Am Heart J 2018; 200:1-10. [PMID: 29898835 DOI: 10.1016/j.ahj.2018.02.014] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 02/21/2018] [Indexed: 01/08/2023]
Abstract
BACKGROUND Automated measurements of electrocardiographic (ECG) intervals by current-generation digital electrocardiographs are critical to computer-based ECG diagnostic statements, to serial comparison of ECGs, and to epidemiological studies of ECG findings in populations. A previous study demonstrated generally small but often significant systematic differences among 4 algorithms widely used for automated ECG in the United States and that measurement differences could be related to the degree of abnormality of the underlying tracing. Since that publication, some algorithms have been adjusted, whereas other large manufacturers of automated ECGs have asked to participate in an extension of this comparison. METHODS Seven widely used automated algorithms for computer-based interpretation participated in this blinded study of 800 digitized ECGs provided by the Cardiac Safety Research Consortium. All tracings were different from the study of 4 algorithms reported in 2014, and the selected population was heavily weighted toward groups with known effects on the QT interval: included were 200 normal subjects, 200 normal subjects receiving moxifloxacin as part of an active control arm of thorough QT studies, 200 subjects with genetically proved long QT syndrome type 1 (LQT1), and 200 subjects with genetically proved long QT syndrome Type 2 (LQT2). RESULTS For the entire population of 800 subjects, pairwise differences between algorithms for each mean interval value were clinically small, even where statistically significant, ranging from 0.2 to 3.6milliseconds for the PR interval, 0.1 to 8.1milliseconds for QRS duration, and 0.1 to 9.3milliseconds for QT interval. The mean value of all paired differences among algorithms was higher in the long QT groups than in normals for both QRS duration and QT intervals. Differences in mean QRS duration ranged from 0.2 to 13.3milliseconds in the LQT1 subjects and from 0.2 to 11.0milliseconds in the LQT2 subjects. Differences in measured QT duration (not corrected for heart rate) ranged from 0.2 to 10.5milliseconds in the LQT1 subjects and from 0.9 to 12.8milliseconds in the LQT2 subjects. CONCLUSIONS Among current-generation computer-based electrocardiographs, clinically small but statistically significant differences exist between ECG interval measurements by individual algorithms. Measurement differences between algorithms for QRS duration and for QT interval are larger in long QT interval subjects than in normal subjects. Comparisons of population study norms should be aware of small systematic differences in interval measurements due to different algorithm methodologies, within-individual interval measurement comparisons should use comparable methods, and further attempts to harmonize interval measurement methodologies are warranted.
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7
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Bergfeldt L, Lundahl G, Bergqvist G, Vahedi F, Gransberg L. Ventricular repolarization duration and dispersion adaptation after atropine induced rapid heart rate increase in healthy adults. J Electrocardiol 2017; 50:424-432. [DOI: 10.1016/j.jelectrocard.2017.03.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Indexed: 11/16/2022]
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Sugrue A, Noseworthy PA, Kremen V, Bos JM, Qiang B, Rohatgi RK, Sapir Y, Attia ZI, Brady P, Caraballo PJ, Asirvatham SJ, Friedman PA, Ackerman MJ. Automated T-wave analysis can differentiate acquired QT prolongation from congenital long QT syndrome. Ann Noninvasive Electrocardiol 2017; 22. [PMID: 28429460 DOI: 10.1111/anec.12455] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 03/18/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Prolongation of the QT on the surface electrocardiogram can be due to either genetic or acquired causes. Distinguishing congenital long QT syndrome (LQTS) from acquired QT prolongation has important prognostic and management implications. We aimed to investigate if quantitative T-wave analysis could provide a tool for the physician to differentiate between congenital and acquired QT prolongation. METHODS Patients were identified through an institution-wide computer-based QT screening system which alerts the physician if the QTc ≥ 500 ms. ECGs were retrospectively analyzed with an automated T-wave analysis program. Congenital LQTS was compared in a 1:3 ratio to those with an identified acquired etiology for QT prolongation (electrolyte abnormality and/or prescription of known QT prolongation medications). Linear discriminant analysis was performed using 10-fold cross-validation to statistically test the selected features. RESULTS The 12-lead ECG of 38 patients with congenital LQTS and 114 patients with drug-induced and/or electrolyte-mediated QT prolongation were analyzed. In lead V5 , patients with acquired QT prolongation had a shallower T wave right slope (-2,322 vs. -3,593 mV/s), greater T-peak-Tend interval (109 vs. 92 ms), and smaller T wave center of gravity on the x axis (290 ms vs. 310 ms; p < .001). These features could distinguish congenital from acquired causes in 77% of cases (sensitivity 90%, specificity 58%). CONCLUSION T-wave morphological analysis on lead V5 of the surface ECG could successfully differentiate congenital from acquired causes of QT prolongation.
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Affiliation(s)
- Alan Sugrue
- Department of Internal Medicine, Mayo Clinic, Rochester, MN, USA.,Department of Cardiovascular Diseases, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA
| | - Peter A Noseworthy
- Department of Cardiovascular Diseases, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA
| | - Vaclav Kremen
- Department of Cardiovascular Diseases, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA.,Czech Institute of Informatics, Robotics, and Cybernetics, Czech Technical University in Prague, Prague, Czech Republic
| | - J Martijn Bos
- Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN, USA.,Department of Molecular Pharmacology & Experimental Therapeutics Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Bo Qiang
- Department of Cardiovascular Diseases, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA
| | - Ram K Rohatgi
- Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN, USA
| | - Yehu Sapir
- Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Zachi I Attia
- Department of Cardiovascular Diseases, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA.,Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Peter Brady
- Department of Cardiovascular Diseases, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA
| | | | - Samuel J Asirvatham
- Department of Cardiovascular Diseases, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA.,Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN, USA
| | - Paul A Friedman
- Department of Cardiovascular Diseases, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA
| | - Michael J Ackerman
- Department of Cardiovascular Diseases, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA.,Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN, USA.,Department of Molecular Pharmacology & Experimental Therapeutics Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA
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Electrocardiographic Predictors of Torsadogenic Risk During Dofetilide or Sotalol Initiation: Utility of a Novel T Wave Analysis Program. Cardiovasc Drugs Ther 2016; 29:433-41. [PMID: 26411977 DOI: 10.1007/s10557-015-6619-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
INTRODUCTION Initiation of class III anti-arrhythmic medications requires telemetric monitoring for ventricular arrhythmias and QT prolongation to reduce the risk of torsades de pointes (TdP). Heart rate-corrected QT interval (QTc) is an indicator of risk, however it is imperfect, and subtle abnormalities of repolarization have been linked with arrhythmogenesis. PURPOSE Identification of electrocardiographic predictors of torsadogenic risk through the application of a novel T wave analysis tool. METHODS Among all patients admitted to Mayo Clinic for initiation of dofetilide or sotalol, we identified 13 cases who developed drug-induced TdP and 26 age and sex matched controls that did not develop TdP. The immediate pre-TdP ECG of those with TdP was compared to the last ECG performed prior to hospital discharge in controls using a novel T wave program that quantified subtle changes in T wave morphology. RESULTS The QTc and 12 T wave parameters successfully distinguished TdP cases from controls. The top performing parameters were the QTc in lead V3 (mean case vs control 480 vs 420 msec, p < 0.001, r = 0.72) and T wave right slope in lead I (mean case vs control -840.29 vs -1668.71 mV/s, p = 0.002, r = 0.45). The addition of T wave right slope to QTc improved prediction accuracy from 79 to 88 %. CONCLUSION Our data demonstrate that, in addition to QTc, the T wave right slope is correlated strongly with TdP risk. This suggests that a computer-based repolarization measurement tool that integrates additional data beyond the QTc may identify patients with the greatest torsadogenic potential.
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Ferber G, Zhou M, Dota C, Garnett C, Keirns J, Malik M, Stockbridge N, Darpo B. Can Bias Evaluation Provide Protection Against False-Negative Results in QT Studies Without a Positive Control Using Exposure-Response Analysis? J Clin Pharmacol 2016; 57:85-95. [DOI: 10.1002/jcph.779] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 06/02/2016] [Accepted: 06/02/2016] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | - Christine Garnett
- Division of Cardiovascular and Renal Products; Center for Drug Evaluation and Research; US Food and Drug Administration; Silver Spring MD USA
| | - James Keirns
- Clinical Pharmacology & Exploratory Development; Astellas Pharma Global Development, Inc; Northbrook IL USA
| | - Marek Malik
- St Paul's Cardiac Electrophysiology; University of London, and Imperial College; London UK
| | - Norman Stockbridge
- Division of Cardiovascular and Renal Products; Center for Drug Evaluation and Research; US Food and Drug Administration; Silver Spring MD USA
| | - Borje Darpo
- iCardiac Technologies; Inc; Rochester NY USA
- Karolinska Institutet; Division of Cardiovascular Medicine; Department of Clinical Sciences; Danderyd's Hospital; Stockholm Sweden
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Yamaguchi Y, Mizumaki K, Hata Y, Sakamoto T, Nakatani Y, Kataoka N, Ichida F, Inoue H, Nishida N. Latent pathogenicity of the G38S polymorphism of KCNE1 K + channel modulator. Heart Vessels 2016; 32:186-192. [PMID: 27255646 DOI: 10.1007/s00380-016-0859-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 05/27/2016] [Indexed: 01/08/2023]
Abstract
KCNE1 encodes a modulator of KCNQ1 and KCNH2 channels. Although KCNE1(G38S), a single-nucleotide polymorphism (SNP) causing a G38S substitution in KCNE1, is found frequently, whether and how this SNP causes long QT syndrome (LQTS) remains unclear. We evaluated rate-dependent repolarization dynamics using Holter electrocardiogram (ECG) to assess the pathogenicity of KCNE1(G38S). Forty-five patients exhibiting long QT intervals, as assessed by their baseline ECGs, and 16 control subjects were enrolled. KCNE1(G38S) carriers were identified using genome sequencing. LQTS patients were classified into LQT1 or LQT2 using genetic analysis or epinephrine test. QT-RR relations were determined using 24-h Holter ECG recordings. Among the 15 patients (33.3 %) with KCNE1(G38S), four patients without any mutations or amino acid changes in other major cardiac ion channels were categorized as KCNE1(G38S) carriers. In the QT-RR regression lines, the QT-RR slope was greater in the KCNE1(G38S) carriers and the LQT2 patients (0.215 ± 0.021 and 0.207 ± 0.032, respectively) than in the LQT1 patients (0.163 ± 0.014, P < 0.05) and the control subjects (0.135 ± 0.025, P < 0.001). The calculated QT intervals at an RR interval of 1200 ms were longer in the KCNE1(G38S) carriers and LQT1 and LQT2 patients than in the control subjects. Patients with KCNE1(G38S) had a rate-dependent repolarization abnormality similar to patients with LQT2 and, therefore, may have a potential risk to develop lethal arrhythmias.
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Affiliation(s)
- Yoshiaki Yamaguchi
- Second Department of Internal Medicine, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan
| | - Koichi Mizumaki
- Clinical Research and Ethics Center, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan.
| | - Yukiko Hata
- Department of Legal Medicine, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan
| | - Tamotsu Sakamoto
- Second Department of Internal Medicine, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan
| | - Yosuke Nakatani
- Second Department of Internal Medicine, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan
| | - Naoya Kataoka
- Second Department of Internal Medicine, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan
| | - Fukiko Ichida
- Department of Pediatrics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan
| | - Hiroshi Inoue
- Second Department of Internal Medicine, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan
| | - Naoki Nishida
- Department of Legal Medicine, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan
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12
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Hodkinson EC, Neijts M, Sadrieh A, Imtiaz MS, Baumert M, Subbiah RN, Hayward CS, Boomsma D, Willemsen G, Vandenberg JI, Hill AP, De Geus E. Heritability of ECG Biomarkers in the Netherlands Twin Registry Measured from Holter ECGs. Front Physiol 2016; 7:154. [PMID: 27199769 PMCID: PMC4850154 DOI: 10.3389/fphys.2016.00154] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 04/11/2016] [Indexed: 11/17/2022] Open
Abstract
Introduction: The resting ECG is the most commonly used tool to assess cardiac electrophysiology. Previous studies have estimated heritability of ECG parameters based on these snapshots of the cardiac electrical activity. In this study we set out to determine whether analysis of heart rate specific data from Holter ECGs allows more complete assessment of the heritability of ECG parameters. Methods and Results: Holter ECGs were recorded from 221 twin pairs and analyzed using a multi-parameter beat binning approach. Heart rate dependent estimates of heritability for QRS duration, QT interval, Tpeak–Tend and Theight were calculated using structural equation modeling. QRS duration is largely determined by environmental factors whereas repolarization is primarily genetically determined. Heritability estimates of both QT interval and Theight were significantly higher when measured from Holter compared to resting ECGs and the heritability estimate of each was heart rate dependent. Analysis of the genetic contribution to correlation between repolarization parameters demonstrated that covariance of individual ECG parameters at different heart rates overlap but at each specific heart rate there was relatively little overlap in the genetic determinants of the different repolarization parameters. Conclusions: Here we present the first study of heritability of repolarization parameters measured from Holter ECGs. Our data demonstrate that higher heritability can be estimated from the Holter than the resting ECG and reveals rate dependence in the genetic—environmental determinants of the ECG that has not previously been tractable. Future applications include deeper dissection of the ECG of participants with inherited cardiac electrical disease.
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Affiliation(s)
- Emily C Hodkinson
- Molecular Cardiology and Biophysics, Victor Chang Cardiac Research InstituteDarlinghurst, NSW, Australia; St Vincent's Clinical School, University of New South WalesSydney, NSW, Australia
| | - Melanie Neijts
- Department of Biological Psychology, EMGO+ Institute, VU University and VU Medical Center Amsterdam, Netherlands
| | - Arash Sadrieh
- Molecular Cardiology and Biophysics, Victor Chang Cardiac Research InstituteDarlinghurst, NSW, Australia; St Vincent's Clinical School, University of New South WalesSydney, NSW, Australia
| | - Mohammad S Imtiaz
- Molecular Cardiology and Biophysics, Victor Chang Cardiac Research InstituteDarlinghurst, NSW, Australia; St Vincent's Clinical School, University of New South WalesSydney, NSW, Australia
| | - Mathias Baumert
- School of Electrical and Electronic Engineering, University of Adelaide Adelaide, SA, Australia
| | - Rajesh N Subbiah
- St Vincent's Clinical School, University of New South Wales Sydney, NSW, Australia
| | | | - Dorret Boomsma
- Department of Biological Psychology, EMGO+ Institute, VU University and VU Medical Center Amsterdam, Netherlands
| | - Gonneke Willemsen
- Department of Biological Psychology, EMGO+ Institute, VU University and VU Medical Center Amsterdam, Netherlands
| | - Jamie I Vandenberg
- Molecular Cardiology and Biophysics, Victor Chang Cardiac Research InstituteDarlinghurst, NSW, Australia; St Vincent's Clinical School, University of New South WalesSydney, NSW, Australia
| | - Adam P Hill
- Molecular Cardiology and Biophysics, Victor Chang Cardiac Research InstituteDarlinghurst, NSW, Australia; St Vincent's Clinical School, University of New South WalesSydney, NSW, Australia
| | - Eco De Geus
- Department of Biological Psychology, EMGO+ Institute, VU University and VU Medical Center Amsterdam, Netherlands
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Yamaguchi Y, Mizumaki K, Hata Y, Inoue H. Abnormal repolarization dynamics in a patient with KCNE1(G38S) who presented with torsades de pointes. J Electrocardiol 2015; 49:94-8. [PMID: 26520166 DOI: 10.1016/j.jelectrocard.2015.10.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Indexed: 11/29/2022]
Abstract
Risk of G38S, major KCNE1 polymorphism [KCNE1(G38S)], for long QT syndrome (LQTS) remains unclear. A 72-year-old woman was admitted with recurrent torsades de pointes (TdP). She had remarkable QT prolongation (corrected QT interval 568 ms) under conditions of hypokalemia and hypomagnesemia. After correction of this electrolytic imbalance, TdP was suppressed and metoprolol was started. The QT-RR slope in 24-hour Holter electrocardiogram was steep and this enhanced bradycardia-dependent QT prolongation was similar to that in LQTS. She carried KCNE1(G38S). Patients with KCNE1(G38S) could have similar potential risk of ventricular arrhythmia as with LQTS. Analysis of QT-RR relationship could also evaluate the latent arrhythmogenicity of KCNE1(G38S).
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Affiliation(s)
- Yoshiaki Yamaguchi
- Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan
| | - Koichi Mizumaki
- Clinical Research and Ethics Center, University of Toyama, Toyama, Japan.
| | - Yukiko Hata
- Legal Medicine, University of Toyama, Toyama, Japan
| | - Hiroshi Inoue
- Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan
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14
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Yamaguchi Y, Mizumaki K, Nishida K, Sakamoto T, Kataoka N, Nakatani Y, Inoue H. Time-Dependent Changes in QT Dynamics after Initiation and Termination of Paroxysmal Atrial Fibrillation. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2015; 38:1418-24. [PMID: 26391623 DOI: 10.1111/pace.12746] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2015] [Revised: 08/18/2015] [Accepted: 08/18/2015] [Indexed: 11/27/2022]
Abstract
BACKGROUND Little is known about time-dependent changes in QT dynamics after initiation of atrial fibrillation (AF) and after restoration of sinus rhythm (SR) in patients with paroxysmal AF. METHODS Beat-to-beat QT and RR intervals in CM5 lead were measured automatically in 13 patients with both AF and SR on the single 24-hour Holter electrocardiology recording. QT-RR relation was analyzed at six periods of time: 1 hour before AF onset (Pre(0-1h)), 0-1 hour and 4-5 hours after AF onset (AF(0-1h) and AF(4-5h)), and 0-1 hour, 2-3 hours, and 4-5 hours after the restoration of SR (SR(0-1h), SR(2-3h), and SR(4-5h)). RESULTS QT-RR slope was gradually decreased after AF onset and gradually returned to the baseline level after restoration of SR. The slope became greater at SR(4-5h) than at AF(4-5h) and AF(0-1h). In patients receiving antiarrhythmic drugs (AADs; n = 5), QT-RR slope was greater at SR(4-5h) than in those not receiving AADs (n = 8). CONCLUSION In patients with paroxysmal AF, bradycardia-dependent QT prolongation was attenuated during AF, and was corrected and gradually augmented along with continuation of SR, especially in patients receiving AADs. This could increase the risk of developing torsade de pointes.
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Affiliation(s)
- Yoshiaki Yamaguchi
- Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan
| | - Koichi Mizumaki
- Clinical Research and Ethics Center, University of Toyama, Toyama, Japan
| | - Kunihiro Nishida
- Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan
| | - Tamotsu Sakamoto
- Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan
| | - Naoya Kataoka
- Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan
| | - Yosuke Nakatani
- Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan
| | - Hiroshi Inoue
- Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan
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15
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Vicente J, Johannesen L, Mason JW, Crumb WJ, Pueyo E, Stockbridge N, Strauss DG. Comprehensive T wave morphology assessment in a randomized clinical study of dofetilide, quinidine, ranolazine, and verapamil. J Am Heart Assoc 2015; 4:e001615. [PMID: 25870186 PMCID: PMC4579946 DOI: 10.1161/jaha.114.001615] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Accepted: 03/06/2015] [Indexed: 12/19/2022]
Abstract
BACKGROUND Congenital long QT syndrome type 2 (abnormal hERG potassium channel) patients can develop flat, asymmetric, and notched T waves. Similar observations have been made with a limited number of hERG-blocking drugs. However, it is not known how additional calcium or late sodium block, that can decrease torsade risk, affects T wave morphology. METHODS AND RESULTS Twenty-two healthy subjects received a single dose of a pure hERG blocker (dofetilide) and 3 drugs that also block calcium or sodium (quinidine, ranolazine, and verapamil) as part of a 5-period, placebo-controlled cross-over trial. At pre-dose and 15 time-points post-dose, ECGs and plasma drug concentration were assessed. Patch clamp experiments were performed to assess block of hERG, calcium (L-type) and late sodium currents for each drug. Pure hERG block (dofetilide) and strong hERG block with lesser calcium and late sodium block (quinidine) caused substantial T wave morphology changes (P<0.001). Strong late sodium current and hERG block (ranolazine) still caused T wave morphology changes (P<0.01). Strong calcium and hERG block (verapamil) did not cause T wave morphology changes. At equivalent QTc prolongation, multichannel blockers (quinidine and ranolazine) caused equal or greater T wave morphology changes compared with pure hERG block (dofetilide). CONCLUSIONS T wave morphology changes are directly related to amount of hERG block; however, with quinidine and ranolazine, multichannel block did not prevent T wave morphology changes. A combined approach of assessing multiple ion channels, along with ECG intervals and T wave morphology may provide the greatest insight into drug-ion channel interactions and torsade de pointes risk. CLINICAL TRIAL REGISTRATION URL: http://clinicaltrials.gov/ Unique identifier: NCT01873950.
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Affiliation(s)
- Jose Vicente
- Office of Science and Engineering Laboratories, CDRH, US FDA, Silver Spring, MD (J.V., L.J., E.P., D.G.S.)
- Division of Cardiovascular and Renal Products, Office of New Drugs, CDER, US FDA, Silver Spring, MD (J.V., N.S.)
- BSICoS Group, Aragón Institute for Engineering Research (I3A), IIS Aragón, University of Zaragoza, Zaragoza, Spain (J.V., E.P.)
| | - Lars Johannesen
- Office of Science and Engineering Laboratories, CDRH, US FDA, Silver Spring, MD (J.V., L.J., E.P., D.G.S.)
- Department of Clinical Physiology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden (L.J., D.G.S.)
| | - Jay W. Mason
- Spaulding Clinical Research, West Bend, WI (J.W.M.)
| | | | - Esther Pueyo
- Office of Science and Engineering Laboratories, CDRH, US FDA, Silver Spring, MD (J.V., L.J., E.P., D.G.S.)
- BSICoS Group, Aragón Institute for Engineering Research (I3A), IIS Aragón, University of Zaragoza, Zaragoza, Spain (J.V., E.P.)
- Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER‐BBN), Zaragoza, Spain (E.P.)
| | - Norman Stockbridge
- Division of Cardiovascular and Renal Products, Office of New Drugs, CDER, US FDA, Silver Spring, MD (J.V., N.S.)
| | - David G. Strauss
- Office of Science and Engineering Laboratories, CDRH, US FDA, Silver Spring, MD (J.V., L.J., E.P., D.G.S.)
- Department of Clinical Physiology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden (L.J., D.G.S.)
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16
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Sadrieh A, Mann SA, Subbiah RN, Domanski L, Taylor JA, Vandenberg JI, Hill AP. Quantifying the origins of population variability in cardiac electrical activity through sensitivity analysis of the electrocardiogram. J Physiol 2013; 591:4207-22. [PMID: 23551947 DOI: 10.1113/jphysiol.2013.251710] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Altered function of ion channels in the heart can increase the risk of sudden arrhythmic death. Hundreds of genetic variants exist in these cardiac ion channel genes. The challenge is how to interpret the effects of multiple conductance perturbations on the complex multi-variable cardiac electrical system? In theory, sensitivity analysis can address this question. However, to date this approach has been restricted by computational overheads to analysis of isolated cells, which has limited extrapolation to physiologically relevant scales. The goal of this study was to extend existing sensitivity analyses to electrocardiogram (ECG) signals derived from multicellular systems and quantify the contribution of ionic conductances to emergent properties of the ECG. To achieve this, we have developed a highly parallelised simulation environment using unconventional high performance computing architectures to analyse the emergent electrical properties of a multicellular system. This has permitted the first systematic analysis of the molecular basis of the T wave amplitude, revealing important but distinct roles for delayed rectifier and inward rectifier K(+) currents. In addition to quantifying how interactions between multiple ion channels influence ECG parameters we show that these sensitivities are dynamic functions of heart rate. This study provides a significant advance in our understanding both of how individual ion conductances define ECG signals and of epistatic modification of cardiac electrical phenotypes. The parallelised simulation environment we have developed removes the computational roadblock that has limited this approach and so provides the framework for future analysis of more complex tissue and whole organ systems.
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Affiliation(s)
- Arash Sadrieh
- A. P. Hill: Victor Chang Cardiac Research Institute, 405, Liverpool Street, Darlinghurst, NSW 2010, Australia.
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17
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Abrahamsson C, Dota C, Skallefell B, Carlsson L, Frison L, Berggren A, Edvardsson N, Duker G. Assessment of ventricular repolarization variability with the DeltaT50 method improves identification of patients with congenital long QT syndromes. Ann Noninvasive Electrocardiol 2012; 18:240-50. [PMID: 23714082 DOI: 10.1111/anec.12016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
BACKGROUND We analyzed ventricular repolarization variability in genotyped long QT syndrome (LQTS) patients and in healthy volunteers (HV). METHOD The deltaT50, that is, the temporal variability of ventricular repolarization at 50% of the T-wave downslope, was analyzed every 15th minute on 175 and 390 Holter electrocardiogram (ECG) recordings from HV and genotyped LQTS patients, respectively. The average deltaT50 and QTcF were calculated in each subject. RESULTS DeltaT50 was 2.26 ± 0.71 ms (mean ± SD) in the HV and 5.74 ± 2.30 ms in the LQTS population (P < 0.0001). The sensitivity and specificity of QTcF (cutoff value 450 ms) to discriminate between the LQTS patients and the HV were 51.5% and 98.9%, and for deltaT50 (cutoff value 3 ms) 93.9% and 88.6%, respectively. The combination of both variables improved the diagnosis of the LQTS patients even further. Subgroups of LQTS patients at higher risk of cardiac events (with LQTS3, JLN, QTc > 500 ms or symptoms) had higher deltaT50 than subgroups at lower risk (with LQTS1, QTc < 450 ms or without symptoms). The variation in deltaT50 between day and night was concordant with the risk of symptoms; patients with LQTS1 had higher deltaT50 in the daytime and patients with LQTS3 had higher deltaT50 during the night. CONCLUSION DeltaT50 more accurately distinguished between LQTS patients and HV than QTcF and was higher in LQTS patients with a higher risk of cardiac events. DeltaT50 can be used together with QTcF to improve the diagnosis in patients with the LQTS phenotype and tentatively also be of value for risk assessment in such patients.
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18
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Graff C, Struijk JJ, Kanters JK, Andersen MP, Toft E, Tyl B. Effects of bilastine on T-wave morphology and the QTc interval: a randomized, double-blind, placebo-controlled, thorough QTc study. Clin Drug Investig 2012; 32:339-51. [PMID: 22393898 DOI: 10.2165/11599270-000000000-00000] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND AND OBJECTIVES The International Conference of Harmonisation (ICH) E14 guideline for thorough QT studies requires assessing the propensity of new non-antiarrhythmic drugs to affect cardiac repolarization. The present study investigates whether a composite ECG measure of T-wave morphology (Morphology Combination Score [MCS]) can be used together with the heart rate corrected QT interval (QTc) in a fully ICH E14-compliant thorough QT study to exclude clinically relevant repolarization effects of bilastine, a novel antihistamine. METHODS Thirty participants in this crossover study were randomly assigned to receive placebo, moxifloxacin 400 mg, bilastine at therapeutic and supratherapeutic doses (20 and 100 mg) and bilastine 20 mg co-administered with ketoconazole 400 mg. Resting ECGs recorded at 12 nominal time points before and after treatments were used to determine Fridericia corrected QTc (QTcF) and MCS from the T-wave characteristics: asymmetry, flatness and notching. RESULTS There were no effects of bilastine monotherapy (20 and 100 mg) on MCS or QTcF at those study times where the bilastine plasma concentrations were highest. MCS changes for bilastine monotherapy did not exceed the normal intrasubject variance of T-wave shapes for triplicate ECG recordings. Maximum QTcF prolongation for bilastine monotherapy was 5 ms or less: 3.8 ms (90% CI 0.3, 7.3 ms) for bilastine 20 mg and 5.0 ms (90% CI 2.0, 8.0 ms) for bilastine 100 mg. There were no indications of bilastine inducing larger repolarization effects on T-wave morphology as compared with the QTcF interval, as evidenced by the similarity of z-score equivalents for placebo-corrected changes in MCS and QTcF values. CONCLUSION This study shows that bilastine, at therapeutic and supratherapeutic dosages, does not induce any effects on T-wave morphology or QTcF. These results confirm the absence of an effect for bilastine on cardiac repolarization.
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Affiliation(s)
- Claus Graff
- Medical Informatics Group, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
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19
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Methodologies to characterize the QT/corrected QT interval in the presence of drug-induced heart rate changes or other autonomic effects. Am Heart J 2012; 163:912-30. [PMID: 22709743 DOI: 10.1016/j.ahj.2012.02.023] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 02/20/2012] [Indexed: 01/08/2023]
Abstract
This White Paper, written collaboratively by members of the Cardiac Safety Research Consortium from academia, industry, and regulatory agencies, discusses different methods to characterize the QT effects for drugs that have a substantial direct or indirect effect on heart rate. Descriptions and applications are provided for individualized QT-R-R correction, Holter bin, dynamic QT beat-to-beat, pharmacokinetic-pharmacodynamic modeling, and QT assessment at constant heart rate. Most of these techniques are optimally performed using continuous electrocardiogram data obtained in clinical studies designed to characterize a drug's effect on the QT interval. An important study design element is the collection of drug-free data over a range of heart rates seen on treatment. The range of heart rates is increased at baseline by using ambulatory electrocardiogram recordings in addition to those collected under semisupine, resting conditions. Discussions in this study summarize areas of emerging consensus and other areas in which consensus remains elusive and provide suggestions for additional research to further increase our knowledge and understanding of this topic.
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Sauer A, Wilcox JE, Andrei AC, Passman R, Goldberger JJ, Shah SJ. Diastolic electromechanical coupling: association of the ECG T-peak to T-end interval with echocardiographic markers of diastolic dysfunction. Circ Arrhythm Electrophysiol 2012; 5:537-43. [PMID: 22467673 DOI: 10.1161/circep.111.969717] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Electromechanical coupling, a well-described phenomenon in systolic dysfunction, has not been well studied in diastole. We hypothesized that the ECG T-peak to T-end (TpTe) interval, representing transmural dispersion of repolarization, is associated with echocardiographic markers of diastolic dysfunction (DD). METHODS AND RESULTS We performed a prospective, cross-sectional study of the association between TpTe and markers of DD in 84 consecutive, unselected patients referred for exercise echocardiography. We systematically measured TpTe on the resting ECG, and we performed comprehensive assessment of DD at rest and at peak stress. ECGs and echocardiograms were analyzed independently, blinded to each other and to all clinical data. By univariable analysis, increased TpTe was associated with older age, increased E/e' ratio, and DD (P<0.05 for all associations after correcting for multiple comparisons). Increased TpTe was inversely associated with reduced tissue Doppler e' velocity, a marker of DD (R=-0.66, P<0.0001). This association persisted after adjusting for age, QTc, exercise-induced wall motion abnormalities, and left ventricular mass index (β=-0.41 [95% confidence interval, -0.70 to -0.12] cm/s per 10-ms increase in TpTe; P=0.006). Baseline TpTe was also independently associated with resting DD (adjusted odds ratio, 3.9 [95% confidence interval, 1.4-10.7]; P=0.009) and peak exercise E/e' ratio (P<0.0001). CONCLUSIONS Increased TpTe is associated with both resting and exercise-induced DD. Electromechanical coupling may represent a pathophysiologic link between electrical transmural dispersion of repolarization and abnormal myocardial relaxation, and may be a novel therapeutic target.
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Affiliation(s)
- Andrew Sauer
- Division of Cardiology, Department of Medicine, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
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21
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Vahedi F, Haney MF, Jensen SM, Näslund U, Bergfeldt L. Effect of heart rate on ventricular repolarization in healthy individuals applying vectorcardiographic T vector and T vector loop analysis. Ann Noninvasive Electrocardiol 2011; 16:287-94. [PMID: 21762257 DOI: 10.1111/j.1542-474x.2011.00444.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Ventricular repolarization (VR) is strongly influenced by heart rate (HR) and autonomic nervous activity, both of which also are important for arrhythmogenesis. Their relative influence on VR is difficult to separate, but might be crucial for understanding while some but not other individuals are at risk for life-threatening arrhythmias at a certain HR. This study was therefore designed to assess the "pure" effect of HR increase by atrial pacing on the ventricular gradient (VG) and other vectorcardiographically (VCG) derived VR parameters during an otherwise unchanged condition. METHODS In 19 patients with structurally normal hearts, a protocol with stepwise increased atrial pacing was performed after successful arrhythmia ablation. Conduction intervals were measured on averaged three-dimensional (3D) QRST complexes. In addition, various VCG parameters were measured from the QRS and T vectors as well as from the T loop. All measurements were performed after at least 3 minutes of rate adaptation of VR. RESULTS VR changes at HR from 80 to 120 bpm were assessed. The QRS and QT intervals, VG, QRSarea, Tarea, and Tamplitude were markedly rate dependent. In contrast, the Tp-e/QT ratio was rate independent as well as the T-loop morphology parameters Tavplan and Teigenvalue describing the bulginess and circularity of the loop. CONCLUSIONS In healthy individuals, the response to increased HR within the specified range suggests a decreased heterogeneity of depolarization instants, action potential morphology, and consequently of the global VR.
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Affiliation(s)
- Farzad Vahedi
- Department of Molecular and Clinical Medicine/Cardiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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22
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Couderc JP, Garnett C, Li M, Handzel R, McNitt S, Xia X, Polonsky S, Zareba W. Highly automated QT measurement techniques in 7 thorough QT studies implemented under ICH E14 guidelines. Ann Noninvasive Electrocardiol 2011; 16:13-24. [PMID: 21251129 DOI: 10.1111/j.1542-474x.2010.00402.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Thorough QT (TQT) studies are designed to evaluate potential effect of a novel drug on the ventricular repolarization process of the heart using QTc prolongation as a surrogate marker for torsades de pointes. The current process to measure the QT intervals from the thousands of electrocardiograms is lengthy and expensive. In this study, we propose a validation of a highly automatic-QT interval measurement (HA-QT) method. We applied a HA-QT method to the data from 7 TQT studies. We investigated both the placebo and baseline-adjusted QTc interval prolongation induced by moxifloxacin (positive control drug) at the time of expected peak concentration. The comparative analysis evaluated the time course of moxifloxacin-induced QTc prolongation in one study as well. The absolute HA-QT data were longer than the FDA-approved QTc data. This trend was not different between ECGs from the moxifloxacin and placebo arms: 9.6 ± 24 ms on drug and 9.8 ± 25 ms on placebo. The difference between methods vanished when comparing the placebo-baseline-adjusted QTc prolongation (1.4 ± 2.8 ms, P = 0.4). The differences in precision between the HA-QT and the FDA-approved measurements were not statistically different from zero: 0.1 ± 0.1 ms (P = 0.7). Also, the time course of the moxifloxacin-induced QTc prolongation adjusted for placebo was not statistically different between measurements methods.
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Affiliation(s)
- Jean-Philippe Couderc
- Heart Research Follow-up Program, Cardiology Department, University of Rochester Medical Center, Rochester, NY 14642, USA.
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Abstract
The short and long QT syndromes are inherited diseases associated with an increased risk for life-threatening arrhythmias. The first case of long QT syndrome (LQTS) was reported more than 150 years ago, and the study of this disease led to crucial advancement of our understanding of channelopathies and associated ventricular arrhythmias. Ten years ago, Gussak et al. reported four cases of idiopathic ventricular fibrillation in individuals from a family with a history of sudden cardiac death exhibited very short QT interval and labeled the disease: short QT syndrome (SQTS). Over this decade, the SQTS was found to be a rare inherited syndrome with the potential to provide novel insights into the main mechanisms of cardiac arrhythmogenicity. In this review, we discuss these mechanisms and provocatively question the role of the QT interval duration as a surrogate marker of increased risk for arrhythmia in both the LQTS and the SQTS.
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Tereshchenko LG, Han L, Cheng A, Marine JE, Spragg DD, Sinha S, Dalal D, Calkins H, Tomaselli GF, Berger RD. Beat-to-beat three-dimensional ECG variability predicts ventricular arrhythmia in ICD recipients. Heart Rhythm 2010; 7:1606-13. [PMID: 20816873 DOI: 10.1016/j.hrthm.2010.08.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2010] [Accepted: 08/29/2010] [Indexed: 10/19/2022]
Abstract
BACKGROUND Methodological difficulties associated with QT measurements prompt the search for new electrocardiographic markers of repolarization heterogeneity. OBJECTIVE We hypothesized that beat-to-beat 3-dimensional vectorcardiogram variability predicts ventricular arrhythmia (VA) in patients with structural heart disease, left ventricular systolic dysfunction, and implanted implantable cardioverter-defibrillators (ICDs). METHODS Baseline orthogonal electrocardiograms were recorded in 414 patients with structural heart disease (mean age 59.4 ± 12.0; 280 white [68%] and 134 black [32%]) at rest before implantation of ICD for primary prevention of sudden cardiac death. R and T peaks of 30 consecutive sinus beats were plotted in 3 dimensions to form an R peaks cloud and a T peaks cloud. The volume of the peaks cloud was calculated as the volume within the convex hull. Patients were followed up for at least 6 months; sustained VA with appropriate ICD therapies served as an end point. RESULTS During a mean follow-up time of 18.4 ± 12.5 months, 61 of the 414 patients (14.73% or 9.6% per person-year of follow-up) experienced sustained VA with appropriate ICD therapies: 41 of them were white and 20 were black. In the multivariate Cox model that included inducibility of VA and use of beta-blockers, the highest tertile of T/R peaks cloud volume ratio significantly predicted VA (hazard ratio 1.68, 95% confidence interval 1.01 to 2.80; P = .046) in all patients. T peaks cloud volume and T/R peaks cloud volume ratio were significantly smaller in black subjects (median 0.09 [interquartile range 0.04 to 0.15] vs. median 0.11 [interquartile range 0.06 to 0.22], P = .002). CONCLUSION A relatively large T peaks cloud volume is associated with increased risk of VA in patients with structural heart disease and systolic dysfunction.
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Affiliation(s)
- Larisa G Tereshchenko
- Division of Cardiology, Department of Medicine, Johns Hopkins Hospital, Baltimore, Maryland, USA.
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Halámek J, Jurák P, Bunch TJ, Lipoldová J, Novák M, Vondra V, Leinveber P, Plachy M, Kara T, Villa M, Frána P, Soucek M, Somers VK, Asirvatham SJ. Use of a novel transfer function to reduce repolarization interval hysteresis. J Interv Card Electrophysiol 2010; 29:23-32. [PMID: 20625805 DOI: 10.1007/s10840-010-9500-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 06/14/2010] [Indexed: 10/19/2022]
Abstract
BACKGROUND Cardiac repolarization is assessed by the QT interval on the surface electrocardiogram and varies with the heart rate. Standard QT corrections (QTc) do not account for the lag in QT change following a change in heart rate (QT hysteresis). Our group has developed and tested a transfer function (TRF) model to assess the effectiveness of a dynamic model of QT/RR coupling in eliminating hysteresis. METHODS We studied three groups: group I, healthy volunteers (n = 23, 41 ± 17 years); group II, hypertensive patients (n = 25, 45 ± 11 years); and group III, patients in a predominately paced rhythm (n = 5, 75 ± 6 years). To vary the heart rate, either exercise bicycling in the supine position (groups I and II) or manipulation of the pacemaker parameters (group III) was done. We then compared a dynamic TRF model with a model based on weighted averages of previous RR intervals. Two parameters were tested: root mean square (RMS) of the error signal between measured and computed QT and the elimination of hysteretic loops. RESULTS TRF-based measurements eliminated hysteresis in 22/23 (95%) group I patients, 21/25 (84%) group II patients, and 4/5 (80%) group III patients. When hysteresis elimination was not complete, the QT drift that followed RR intervals was different before and after bicycling (100 ms). In these patients, the corresponding QT interval did not significantly change during this period. The TRF model was found superior to the other tested models with respect to both analyzed parameters (RMS and hysteresis elimination). CONCLUSION The TRF model limited QT hysteresis in healthy, hypertensive, and pacemaker-dependent patients. In addition, an important finding of QT drift in patients with hypertension was identified. With further study in these and other diseased states, the TRF model may improve our ability to measure accurately cardiac repolarization and to determine arrhythmia risk.
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Graff C, Struijk JJ, Matz J, Kanters JK, Andersen MP, Nielsen J, Toft E. Covariate analysis of QTc and T-wave morphology: new possibilities in the evaluation of drugs that affect cardiac repolarization. Clin Pharmacol Ther 2010; 88:88-94. [PMID: 20485337 DOI: 10.1038/clpt.2010.51] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This study adds the dimension of a T-wave morphology composite score (MCS) to the QTc interval-based evaluation of drugs that affect cardiac repolarization. Electrocardiographic recordings from 62 subjects on placebo and 400 mg moxifloxacin were compared with those from 21 subjects on 160 and 320 mg D,L-sotalol. T-wave morphology changes, as assessed by DeltaMCS, are larger after 320 mg D,L-sotalol than after 160 mg D,L-sotalol; and the changes associated with 160 mg D,L-sotalol are, in turn, larger than those associated with moxifloxacin and placebo. Covariate analyses of DeltaQTc and DeltaMCS showed that changes in T-wave morphology are a significant effect of D,L-sotalol. By contrast, moxifloxacin was found to have no significant effect on T-wave morphology (DeltaMCS) at any given change in QTc. This study offers new insights into the repolarization behavior of a drug associated with low cardiac risk vs. one associated with a high risk and describes the added benefits of a T-wave MCS as a covariate to the assessment of the QTc interval.
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Affiliation(s)
- C Graff
- Department of Health Science and Technology, Aalborg University, Aalborg, Denmark.
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Challenges of Diagnosing Long QT Syndrome in Patients With Nondiagnostic Resting QTc. J Am Coll Cardiol 2010; 55:1962-4. [DOI: 10.1016/j.jacc.2010.02.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 02/09/2010] [Indexed: 11/23/2022]
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Extramiana F, Dubois R, Vaglio M, Roussel P, Dreyfus G, Badilini F, Leenhardt A, Maison-Blanche P. The time course of new T-wave ECG descriptors following single- and double-dose administration of sotalol in healthy subjects. Ann Noninvasive Electrocardiol 2010; 15:26-35. [PMID: 20146779 PMCID: PMC6932454 DOI: 10.1111/j.1542-474x.2009.00336.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
INTRODUCTION The aim of the study was to assess the time course effect of IKr blockade on ECG biomarkers of ventricular repolarization and to evaluate the accuracy of a fully automatic approach for QT duration evaluation. METHODS Twelve-lead digital ECG Holter was recorded in 38 healthy subjects (27 males, mean age = 27.4 + or - 8.0 years) on baseline conditions (day 0) and after administration of 160 mg (day 1) and 320 mg (day 2) of d-l sotalol. For each 24-hour period and each subject, ECGs were extracted every 10 minutes during the 4-hour period following drug dosage. Ventricular repolarization was characterized using three biomarker categories: conventional ECG time intervals, principal component analysis (PCA) analysis on the T wave, and fully automatic biomarkers computed from a mathematical model of the T wave. RESULTS QT interval was significantly prolonged starting 1 hour 20 minutes after drug dosing with 160 mg and 1 hour 10 minutes after drug dosing with 320 mg. PCA ventricular repolarization parameters sotalol-induced changes were delayed (>3 hours). After sotalol dosing, the early phase of the T wave changed earlier than the late phase prolongation. Globally, the modeled surrogate QT paralleled manual QT changes. The duration of manual QT and automatic surrogate QT were strongly correlated (R(2) = 0.92, P < 0.001). The Bland and Altman plot revealed a nonstationary systematic bias (bias = 26.5 ms + or - 1.96*SD = 16 ms). CONCLUSIONS Changes in different ECG biomarkers of ventricular repolarization display different kinetics after administration of a potent potassium channel blocker. These differences need to be taken into account when designing ventricular repolarization ECG studies.
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Affiliation(s)
- Fabrice Extramiana
- Lariboisière Hospital, APHP, Paris 7 University, INSERM U942, Paris, France.
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Cardiac regulation and electrocardiographic factors contributing to the measurement of repolarization variability. J Electrocardiol 2009; 42:494-9. [PMID: 19716566 DOI: 10.1016/j.jelectrocard.2009.06.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Indexed: 11/22/2022]
Abstract
Cellular and macroelectrical instability within the heart ventricles during repolarization is described as a potential triggering mechanism of life-threatening arrhythmias. Although this phenomenon was observed in animal and in vitro studies, significant efforts have been put into the design of computerized technologies to quantify very subtle variations of the repolarization signal from the surface electrocardiograms. These technologies aim at capturing repolarization instability of ventricular repolarization while controlling for the normal variability. Currently, the methods have focused on the autonomic regulation of the heart rate as a primary confounding factor (such as in the QT variability index). However, there are other factors that can influence the measurements of beat-to beat variability of the repolarization segment. Among them, the amplitude of the repolarization signal, the selected lead, and the heart vector orientation are very important and too often neglected in clinical investigations. We will discuss these factors and provocatively describe why they should be cautiously considered to avoid erroneous measurements of repolarization instability.
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Zhang ZM, Whitsel EA, Quibrera PM, Smith RL, Liao D, Anderson GL, Prineas RJ. Ambient fine particulate matter exposure and myocardial ischemia in the Environmental Epidemiology of Arrhythmogenesis in the Women's Health Initiative (EEAWHI) study. ENVIRONMENTAL HEALTH PERSPECTIVES 2009; 117:751-6. [PMID: 19479017 PMCID: PMC2685837 DOI: 10.1289/ehp.0800046] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Accepted: 01/23/2009] [Indexed: 05/02/2023]
Abstract
BACKGROUND Ambient particulate matter (PM) air pollution is associated with coronary heart disease, but the pathways underlying the association remain to be elucidated. METHODS We studied the association between PM and ischemia among 57,908 Women's Health Initiative clinical trial participants from 1999-2003. We used the Minnesota Code criteria to identify ST-segment and T-wave abnormalities, and estimated T amplitude (microvolt) from resting, standard 12-lead electrocardiogram (ECG). We used U.S. Environmental Protection Agency's monitor data to estimate concentrations of PM < 2.5 microm (PM(2.5)) at geocoded participant addresses over 6 days before the ECGs (lag0 through lag5). We excluded 2,379 women with ECG QRS duration > or = 120 msec. RESULTS Overall, 6% of the remaining 55,529 women (52-90 years of age; 83% non-Hispanic white) had ST abnormalities and 16% had T abnormalities. Lead-specific T amplitude was normally distributed (range of means from -14 to 349 microV). PM(2.5) (mean +/- SD) averaged over lag(0-2) was 14 +/- 7 microg/m(3). In logistic and linear regression models adjusted for demographic, clinical, temporal, and climatic factors, a 10-microg/m(3) increase in lag(0-2) PM(2.5) was associated with a 4% [95% confidence interval (CI), -3%, to 10%] increase in the odds of ST abnormality and a 5% (95% CI, 0% to 9%) increase in the odds of T abnormality. We observed corresponding decreases in T amplitude in all exam sites and leads except lead V1, reaching a minimum of -2 microV (95% CI, -5 to 0 microV) in lead V3. CONCLUSIONS Short-term PM(2.5) exposure is associated with ECG evidence of myocardial ischemia among postmenopausal women. The principal manifestations include subclinical but potentially arrhythmogenic ST-T abnormalities and decreases in T amplitude.
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Affiliation(s)
- Zhu-Ming Zhang
- Epidemiologic Cardiology Research Center, Department of Epidemiology and Prevention, Division of Public Health Sciences, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27104, USA.
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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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Automatic analysis of cardiac repolarization morphology using Gaussian mesa function modeling. J Electrocardiol 2009; 41:588-94. [PMID: 18954609 DOI: 10.1016/j.jelectrocard.2008.07.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Revised: 07/14/2008] [Accepted: 07/15/2008] [Indexed: 11/22/2022]
Abstract
A novel fully automated method for wave identification and extraction from electrocardiogram (ECG) waveforms is presented. This approach implements the combined use of a new machine-learning algorithm and of specified parameterized functions called Gaussian mesa functions (GMFs). Individual cardiac cycle waveforms are broken up into GMFs using a generalized orthogonal forward regression algorithm; each individual GMF is subsequently identified (wave labeling) and analyzed for feature and morphologic extraction. The GMF associated with the repolarization waveform of the main vector lead, based on principal components analysis, was analyzed, and a set of morphologic parameters were derived under 2 experimental settings: first, in 100 digital 12-lead ECG Holter recordings acquired during three 24-hour periods (baseline and after 160 and 320 mg of sotalol) from 38 healthy subjects; second, in drug-free 12-lead resting ECGs from 100 genotyped long QT syndrome (LQTS) patients (50 each with LQT1 and LQT2). QT-interval duration was measured using an on-screen method applied to the global representative beats and reviewed by a senior cardiologist. QTci (individual correction) was used for analysis. All parameters in the sotalol test showed highly significant differences between the time of peak plasma concentration (Tmax) and baseline ECGs; however, the dynamic pattern of individual parameters followed different patterns. The LQTS test confirmed the results of the sotalol test, showing that GMF-based repolarization parameters were strongly modified as compared with healthy controls. In particular, T-wave width and descending phase of repolarization were more prolonged in LQT2 compared to LQT1.
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Abstract
The hereditary Long QT syndrome (LQTS) is a genetic channelopathy with variable penetrance that is associated with increased propensity for polymorphic ventricular tachyarrhythmias and sudden cardiac death in young individuals with normal cardiac morphology. The diagnosis of this genetic disorder relies on a constellation of electrocardiographic, clinical, and genetic factors. Accumulating data from recent studies indicate that the clinical course of affected LQTS patients is time-dependent and age-specific, demonstrating important gender differences among age groups. Risk assessment should consider age-gender interactions, prior syncopal history, QT-interval duration, and genetic factors. Beta-blockers constitute the mainstay therapy for LQTS, while left cardiac sympathetic denervation and implantation of a cardioverter defibrillator should be considered in patients who remain symptomatic despite beta-blocker therapy. Current and ongoing studies are also evaluating genotype-specific therapies that may reduce the risk for life-threatening cardiac events in high-risk LQTS patients.
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Couderc JP, Zhou M, Sarapa N, Zareba W. Investigating the effect of sotalol on the repolarization intervals in healthy young individuals. J Electrocardiol 2008; 41:595-602. [DOI: 10.1016/j.jelectrocard.2008.06.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Revised: 06/24/2008] [Accepted: 06/25/2008] [Indexed: 10/21/2022]
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New descriptors of T-wave morphology are independent of heart rate. J Electrocardiol 2008; 41:557-61. [DOI: 10.1016/j.jelectrocard.2008.07.021] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Revised: 06/26/2008] [Accepted: 07/02/2008] [Indexed: 11/29/2022]
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The impact of varying autonomic states on the dynamic beat-to-beat QT-RR and QT-TQ interval relationships. Br J Pharmacol 2008; 154:1508-15. [PMID: 18663381 DOI: 10.1038/bjp.2008.123] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The beat-to-beat dynamicity of the QT-RR interval relationship is difficult to assess with the use of traditional correction factors (QTc) and changes in QTc do not accurately reflect or quantify arrhythmogenic risk. Further, the interpretation of arrhythmogenic risk is influenced by autonomic state. To visualize the QT-RR interval dynamics under varying conditions of autonomic state from impaired repolarization, we have developed a system to sequentially plot the beat-to-beat confluence of ECG data or 'clouds' obtained from conscious dogs and humans. To represent the non-uniformity of the clouds, a bootstrap sampling method that computes the mathematical centre of the uncorrected beat-to-beat QT value (QTbtb) and defines the upper and lower 95% confidence bounds is used. The same method can also be used to examine heterogeneity, hysteresis (both acceleration and deceleration) and restitution (beat-to-beat QT-TQ interval relationship). Impaired repolarization with the combination of E-4031 and L-768,673 (inhibitor of IKs current) increased heterogeneity of restitution at rest 55-91%; increased hysteresis during heart rate acceleration after isoproterenol challenge by approximately 40-60%; and dramatically diminished the minimum TQ boundary by 72% to only 28 ms. Impaired repolarization alters restitution during normal sinus rhythm and increases hysteresis/heterogeneity during heart rate acceleration following sympathetic stimulation. These findings are supported by similar clinical observations in LQT1 and LQT2 syndromes. Therefore, the assessment of the dynamic QT-RR and QT-TQ interval relationships through quantification of heterogeneity, hysteresis and restitution may allow a more accurate non-invasive evaluation of the conditions leading to cardiac arrhythmia.
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Vaglio M, Couderc JP, McNitt S, Xia X, Moss AJ, Zareba W. A quantitative assessment of T-wave morphology in LQT1, LQT2, and healthy individuals based on Holter recording technology. Heart Rhythm 2007; 5:11-8. [PMID: 18180017 DOI: 10.1016/j.hrthm.2007.08.026] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Accepted: 08/16/2007] [Indexed: 11/18/2022]
Abstract
BACKGROUND The clinical course and the precipitating risk factors in the congenital long QT syndrome (LQTS) are genotype specific. OBJECTIVES The goal of this study was to develop a computer algorithm allowing for electrocardiogram (ECG)-based identification and differentiation of LQT1 and LQT2 carriers. METHODS Twelve-lead ECG Holter monitor recordings were acquired in 49 LQT1 carriers, 25 LQT2 carriers, and 38 healthy subjects as controls. The cardiac beats were clustered based on heart-rate bin method. Scalar and vectorial repolarization parameters were compared for similar heart rates among study groups. The Q to Tpeak (QTpeak), the Tpeak to Tend interval, T-wave magnitude and T-loop morphology were automatically quantified using custom-made algorithms. RESULTS QTpeak from lead II and the right slope of the T-wave were the most discriminant parameters for differentiating the 3 groups using prespecified heart rate bin (75.0 to 77.5 beats/min). The predictive model utilizing these scalar parameters was validated using the entire spectrum of heart rates. Both scalar and vectorcardiographic models provided very effective identification of tested subjects in heart rates between 60 and 100 beats/min, whereas they had limited performance during tachycardia and slightly better discrimination in bradycardia. In the 60 to 100 beats/min heart rate range, the best 2-variable model identified correctly 89% of healthy subjects, 84% of LQT1 carriers, and 92% of LQT2 carriers. A model including 3 parameters based purely on scalar ECG parameters could correctly identify 90% of the population (89% of healthy subjects, 90% of LQT1 carriers, and 92% of LQT2 carriers). CONCLUSION Automatic algorithm quantifying T-wave morphology discriminates LQT1 and LQT2 carriers and healthy subjects with high accuracy. Such computerized ECG methodology could assist physicians evaluating subjects suspected for LQTS.
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Affiliation(s)
- Martino Vaglio
- Heart Research Follow-Up Program, University of Rochester Medical Center, Rochester, New York, USA
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