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QT interval measurement in ventricular pacing: Implications for assessment of drug effects and pro-arrhythmia risk. J Electrocardiol 2021; 70:13-18. [PMID: 34826635 DOI: 10.1016/j.jelectrocard.2021.11.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 11/08/2021] [Accepted: 11/12/2021] [Indexed: 11/22/2022]
Abstract
QT interval prolongation is a known risk factor for development of malignant ventricular arrhythmias. Measurement of the QT interval is difficult in the setting of ventricular pacing (VP), which can prolong depolarization and increase the QT interval, overestimating repolarization time. VP and cardiac resynchronization therapies have become commonplace in modern cardiac care and may contribute to repolarization heterogeneity and subsequent increased risk for ventricular arrhythmias including Torsades de Pointes. It is imperative for the clinician caring for acutely ill cardiac patients to understand the relationship between QT interval prolongation, both drug-induced and pacing-induced, and repolarization changes with subsequent ventricular arrhythmia risk. In this review, we discuss the components of QT interval assessment for arrhythmogenic risk including arrhythmogenic QT prolongation, methods for adjusting the QT interval to identify repolarization changes, methods to adjust for heart rate, and propose a framework for medication management to assess for drug-induced long QT syndrome in patients with VP.
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2
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Ibisoglu E, Boyraz B. Comparison of ventricular repolarization parameters of Covid-19 patients diagnosed with chest CT and RT-PCR. Acta Cardiol 2021; 76:1013-1018. [PMID: 34254875 DOI: 10.1080/00015385.2021.1950366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
BACKGROUND AND OBJECTIVES The aim of the comparison is to evaluate the marker of ventricular repolarization parameters such as QT, QTc, cQT, Tp-e, Tp-e/QT, Tp-e/QTc, Tp-e/JT and Tp-e/JTc ratios and the risk of ventricular arrhtythmias in patients with newly diagnosed Covid-19. METHODS The study included 2 separate groups. The first one consisted of 96 positive reverse transcriptase polymerase chain reaction (RT-PCR) Covid-19 patients and the second one of 106 patients with negative PCR but positive chest computed tomography (CT) findings consistent with Covid-19. We measured QTmax, QTmin, QRS, JT and Tp-e intervals and estimated Tp-e/QT max, Tp- e/QTc max, Tp-e/JT and Tp-e/JTc rates and QTc max, QTc min, cQTd and JTc intervals. RESULTS QT max, QT min, JT, cQTd, Tp-e, Tp-e/QT max, Tp-e/QTc max, Tp-e/JT, Tp-e/JTc values were significantly higher in RT-PCR Covid-19 patient group. CONCLUSION Positive RT-PCR Covid-19 patients should be followed more closely, in terms of high ventricular repolarization parameters and preventing ventricular arrhythmias that may develop due to this.
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Affiliation(s)
- Ersin Ibisoglu
- Cardiology Department, Başakşehir Çam and Sakura City Hospital, İstanbul, Turkey
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Funk MC, Cates KW, Rajagopalan A, Lane CE, Lou J. Assessment of QTc and Risk of Torsades de Pointes in Ventricular Conduction Delay and Pacing: A Review of the Literature and Call to Action. J Acad Consult Liaison Psychiatry 2021; 62:501-510. [PMID: 34489062 DOI: 10.1016/j.jaclp.2021.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 11/04/2020] [Accepted: 01/27/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND Assessment of the heart rate-corrected QT-interval on the 12-lead electrocardiogram when prescribing medications known to increase the risk of Torsades de Pointes has become a common part of consultation-liaison psychiatry practice. OBJECTIVES Highlighted by a patient who experienced psychiatric decompensation due to inaccurate interpretation of QTc prolongation in the setting of a wide QRS complex, we aimed to describe the approach to QTc interpretation in patients with ventricular conduction delay. METHODS We reviewed the current literature on the approach to assessment of prolonged repolarization in patients with ventricular conduction delay due to bundle branch block (BBB) and ventricular pacing. RESULTS Physicians of any specialty may perform initial electrocardiogram interpretation and should be proficient in the definition, recognition, and understanding of the basic pathophysiology of electrocardiographic abnormalities. We discuss current approaches to assessment of the QT-interval in patients with a wide QRS complex due to bundle branch block and ventricular pacing, including bivariate QTc modification, univariate QT-interval modifications, and use of the JT-interval. CONCLUSIONS The QT-interval is prolonged ipso facto in patients with a wide QRS complex from ventricular conduction delay/ventricular pacing and must be adjusted for QRS duration. Multiple formulae have been proposed to account for wide QRS complex in this setting with no single universally accepted methodology. We suggest the use of either the Bogossian formula or JT-interval followed by Hodges or Framingham heart-rate correction to adjust for a wide QRS complex. It is critical that the C-L psychiatrist be able to identify a wide QRS complex on the electrocardiogram, understand implications for accurate assessment of prolonged depolarization, and apply an appropriate correction methodology.
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Affiliation(s)
- Margo C Funk
- Harvard Medical School, Boston, MA; VA Boston Healthcare System, Brockton, MA.
| | - Kevin W Cates
- Harvard Medical School, Boston, MA; VA Boston Healthcare System, Brockton, MA
| | | | - Chadrick E Lane
- Boston University School of Medicine, Boston, MA; VA Boston Healthcare System, Brockton, MA
| | - Junyang Lou
- Harvard Medical School, Boston, MA; Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA
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Chen H, Wang X, Xiong C, Zou H. The negative effects of obesity on heart, especially the electrophysiology of the heart. ARTIFICIAL CELLS NANOMEDICINE AND BIOTECHNOLOGY 2021; 48:1055-1062. [PMID: 32696673 DOI: 10.1080/21691401.2020.1770269] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Obesity is associated with ventricular arrhythmia and sudden cardiac death. Numerous studies have shown that obesity may have effects on the heart by affecting the ventricular re-polarisation (VR). As an effective detection method for VR the measurement of the QT interval has been extensively studied in obese patients (OP). This review aims to investigate the relationship between obesity and obesity-related diseases; including diabetes, hypertension and cardiovascular diseases (CVD). This review compares the advantages and disadvantages of different QT interval measurement methods, as well as explores the possible mechanisms of obesity leading to heart disease. Finally, it also reviews the feasibility of various weight loss methods to reverse the risk of obesity leading to heart disease is discussed.
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Affiliation(s)
- Haishan Chen
- Department of Nephrology, The Third Affiliated Hospital, Southern Medical University, Guangzhou, China
| | - Xin Wang
- Department of Nephrology, The Third Affiliated Hospital, Southern Medical University, Guangzhou, China
| | - Chongxiang Xiong
- Department of Nephrology, The Third Affiliated Hospital, Southern Medical University, Guangzhou, China
| | - Hequn Zou
- Department of Nephrology, The Third Affiliated Hospital, Southern Medical University, Guangzhou, China
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5
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Validation of using cardioplegic solutions for preserving cardiac function in isolated rabbit heart assays. J Pharmacol Toxicol Methods 2021; 111:107082. [PMID: 34082139 DOI: 10.1016/j.vascn.2021.107082] [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: 02/01/2021] [Revised: 04/29/2021] [Accepted: 05/23/2021] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Cardioplegic solutions were first developed to preserve heart function during cardiac surgeries and heart transplants but have application in the nonclinical setting. Due to lack of lab space in the vivarium, cardioplegic solution was used to conserve cardiac function for ex-vivo studies performed in a separate building. All studies in this report were conducted with isolated female rabbit hearts (IRHs) via retrograde perfusion using the Langendorff apparatus to investigate if cardioplegia usage affects cardiac function. METHODS Cardioplegia was achieved with a hyperkalemia (27 mM KCL) solution kept at 4 °C. Cardiac function was assessed by measuring ECG parameters, left ventricular contractility, and coronary flow under constant perfusion pressure. IRHs were cannulated with Krebs Henseleit buffer (KH) either fresh or after cardioplegic solution storage (C-IRH). Three comparisons were performed with and without cardioplegia; (i) direct side-by side studies of cardiac function; (ii) pharmacological responses to typical ion channels blockers, dofetilide, flecainide, and diltiazem; (iii) retrospective evaluation of cardiac functions in a large sample of hearts. RESULTS In the side-by-side comparisons, cardioplegia-stored IRHs (C-IRH; storage time 90 min) had similar electrocardiographic (ECG) and hemodynamic parameters to fresh-cannulated hearts with KH buffer (KH-IRH). In addition, responses to dofetilide, flecainide, and diltiazem, were similar for C-IRH and KH-IRH hearts. Over the years (2006-2011), baseline data was collected from 79 hearts without cardioplegia and 100 hearts with cardioplegia (C-IRH; storage time 15 min), which showed no meaningful differences in a retrospective analysis. DISCUSSION Cardiac function was preserved after cardioplegic treatment, however, coronary flow rates were decreased (-19.3%) in C-IRH hearts which indicated an altered coronary vascular tone. In conclusion, storage in cardioplegic solution preserves rabbit cardiac function, a practice that enables heart tissues to be collected at one site (e.g., vivarium) and transported to a laboratory in a separate location.
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Ibisoglu E, Tekin DDN, Kızılırmak F, Güneş ST, Boyraz B, Özdenkaya Y, Çakal S, Çakal B, Savur Ü, Erdoğan A, Olgun FE, Güneş HM. Evaluation of Changes in Ventricular Repolarization Parameters in Morbidly Obese Patients Undergoing Bariatric Surgery. Obes Surg 2021; 31:3138-3143. [PMID: 33856635 DOI: 10.1007/s11695-021-05385-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 03/24/2021] [Accepted: 03/24/2021] [Indexed: 12/31/2022]
Abstract
BACKGROUND Weight loss after bariatric surgery has been associated with reduced cardiovascular mortality and overall mortality in obese patients. In this study, we aimed to analyze the changes between pre-operation and post-operation ventricular arrhythmia predictors in patients who underwent bariatric surgery. MATERIALS AND METHODS The study included 58 patients who underwent bariatric surgery. We measured QT max, QT min, QRS, JT, and Tp-e intervals, and we estimated Tp-e/QT max, Tp-e/QTc max, Tp-e/JT, Tp-e/JTc rates, QTc max, QTc min, cQTd, and JTc intervals both pre-op and 6 months post-op. RESULTS Heart rate, PR, QT max, QTc max, QTc min, cQTd, JTc, Tp-e, Tp-e/QT max, Tp-e/QTc max, Tp-e/JT, and Tp-e/JTc values, which were close to the upper limit in the pre-op period, showed statistically significant decreases at 6 months post-op. CONCLUSION The results of our study showed that bariatric surgery had positive effects on the regression of ventricular repolarization parameters and the possible development of ventricular arrhythmia.
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Affiliation(s)
- Ersin Ibisoglu
- Cardiology Department, Başakşehir Çam and Sakura City Hospital, Başakşehir Mahallesi G-434 Caddesi No: 2L, 34480 Başakşehir, İstanbul, Turkey.
| | - Deniz Dilan Naki Tekin
- Cardiology Department, Başakşehir Çam and Sakura City Hospital, Başakşehir Mahallesi G-434 Caddesi No: 2L, 34480 Başakşehir, İstanbul, Turkey
| | - Filiz Kızılırmak
- Cardiology Department, İstanbul Medipol University, İstanbul, Turkey
| | - Saime Turgut Güneş
- Radiology Department, İstanbul Training and Research Hospital, İstanbul, Turkey
| | | | - Yaşar Özdenkaya
- General Surgery Department, İstanbul Medipol University, İstanbul, Turkey
| | - Sinem Çakal
- İstanbul Haseki Training and Research Hospital, İstanbul, Turkey
| | - Beytullah Çakal
- Cardiology Department, İstanbul Medipol University, İstanbul, Turkey
| | - Ümeyir Savur
- İstanbul Gaziosmanpaşa Training and Research Hospital, İstanbul, Turkey
| | - Aslan Erdoğan
- Cardiology Department, Başakşehir Çam and Sakura City Hospital, Başakşehir Mahallesi G-434 Caddesi No: 2L, 34480 Başakşehir, İstanbul, Turkey
| | - Fatih Erkam Olgun
- Cardiology Department, İstanbul Medipol University, İstanbul, Turkey
| | - H Murat Güneş
- Cardiology Department, İstanbul Medipol University, İstanbul, Turkey
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Isart FA, Mason JW, Isart-Infante FJ, Ramos FG. Surface Electrocardiographic Parameters of Children and Adolescents Diagnosed with Attention-Deficit/Hyperactivity Disorder in an Ambulatory Community Pediatric Center: A Focus on Cardiac Repolarization Electrocardiogram Intervals. J Child Adolesc Psychopharmacol 2021; 31:227-232. [PMID: 33635153 PMCID: PMC8066348 DOI: 10.1089/cap.2020.0092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Objectives: Our research aims were to determine if repolarization measures (QTcF, QTcB, JTcF, and JTcB) in attention-deficit/hyperactivity disorder (ADHD) children and adolescents differ from normal subjects and determine if the JTc interval duration, as a purer repolarization measure than QTc, strengthens the differentiation between ADHD and normal children and adolescents. Methods: This study included 418 subjects aged 5-18 years who were diagnosed with ADHD, and 1948 subjects in a historical normal control group. One-way analysis of variance (ANOVA) was performed to compare the independent groups on normal continuous outcomes. Means and standard deviations (SDs) were reported and interpreted for the ANOVA. Logistic regression analysis was performed to test the ability of four variables (QTcB, QTcF, JTcB, and JTcF) to predict an ADHD diagnosis, with age and gender as independent covariates. The log odds with standard errors for each variable were reported and interpreted for the logistic models. Results: In the nominal logistic regressions with JTcF ≥322 or JTcB ≥335 (values 1 SD above the mean of the control group), age and sex were significant contributors to the models that showed that subjects with a JTcF ≥322 ms had a statistically and significantly higher probability to be diagnosed with ADHD in comparison with normal control subjects (odds ratio [OR]: 2.6, 95% confidence interval [95% CI] 2.02-3.33, p < 0.0001). Similarly, those subjects with a JTcB ≥335 ms were 2.7 times more likely to be diagnosed with ADHD than normal control subjects (OR: 2.7, 95% CI 2.1-3.45, p < 0.0001). Conclusions: JTc provided a clearer separation of the groups than QTc. JTcB and JTcF 1 SD above the control group means are strong predictors of ADHD diagnosis and remain so even when strong demographic predictors of longer QTc (age and sex) are included in the regression models. Consideration should be given to recording a pretreatment electrocardiogram in all children and adolescents with ADHD, and to measuring and monitoring JTc in patients with ADHD, especially when considering the addition of QT prolonging drugs.
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Affiliation(s)
- Fernando A. Isart
- Baylor College of Medicine, Houston, Texas, USA.,Address correspondence to: Fernando A. Isart, MD, Kids'N Teens Clinics, PA, 2925 West T C Jester Blvd ste 1, Houston, TX 77018, USA
| | - Jay W. Mason
- University of Utah, Salt Lake City, Utah, USA.,Spaulding Clinical Research, Milwaukee, Wisconsin, USA
| | | | - Faustino G. Ramos
- Pediatric Cardiology, Department of Pediatrics, The University of Texas Health Science Center at Houston, Houston, Texas, USA
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8
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Inanir M, Sincer I, Erdal E, Gunes Y, Cosgun M, Mansiroglu AK. Evaluation of electrocardiographic ventricular repolarization parameters in extreme obesity. J Electrocardiol 2018; 53:36-39. [PMID: 30721839 DOI: 10.1016/j.jelectrocard.2018.12.003] [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: 06/27/2018] [Revised: 11/10/2018] [Accepted: 12/05/2018] [Indexed: 10/27/2022]
Abstract
BACKGROUND AND OBJECTIVES The risk of sudden death and cardiac arrhythmia increases in morbidly obese patients. We aimed to evaluate the marker of arrhythmias such as Tp-e/QT, Tp-e/QTc, Tp-e/JT and Tp-e/JTc ratios in extreme obesity. METHODS The study included 41 extremely obese patients and 41 control subjects. QTmax, QTmin, QRS, JT and Tp-e intervals were measured od 12‑lead electrocardiographies. In addition, Tp-e/QT, Tp-e/QTc, Tp-e/JT and Tp-e/JTc rates and QTc, cQTd and JTc intervals were calculated. RESULTS Tp-e interval (79.2 ± 9.7 ms (milisecond) vs. 68.6 ± 8.1, p < 0.001), QTc interval (395.9 ± 18.8 vs. 377.9 ± 19.3 ms, p < 0.001), JTc interval (317.1 ± 27.0 vs. 297.4 ± 23.2 ms, p = 0.001), Tp-e/QT ratio (0.22 ± 0.03vs. 0.19 ± 0.02, p < 0.001), Tp-e/QTc ratio (0.20 ± 0.26vs. 0.18 ± 0.02, p = 0.001), Tp-e/JT ratio (0.29 ± 0.04 vs. 0.25 ± 0.03, p < 0.001), TPe/JTc ratio (0.25 ± 0.04 vs. 0.23 ± 0.03, p = 0.018), QTd (32.8 ± 10 vs.15 ± 6.4 ms, p < 0.001) and cQTd (70.0 ± 30.1 vs. 31.3 ± 22.4 ms, p < 0.001) were significantly higher in obese patients. CONCLUSION Compared to healthy subjects potential ECG repolarization predictors were significantly increased in extremely obese patients.
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Affiliation(s)
- M Inanir
- Abant Izzet Baysal University, Medical Faculty, Cardiology Department, Bolu, Turkey.
| | - I Sincer
- Abant Izzet Baysal University, Medical Faculty, Cardiology Department, Bolu, Turkey
| | - E Erdal
- Abant Izzet Baysal University, Medical Faculty, Cardiology Department, Bolu, Turkey
| | - Y Gunes
- Abant Izzet Baysal University, Medical Faculty, Cardiology Department, Bolu, Turkey
| | - M Cosgun
- Abant Izzet Baysal University, Medical Faculty, Cardiology Department, Bolu, Turkey
| | - A K Mansiroglu
- Abant Izzet Baysal University, Medical Faculty, Cardiology Department, Bolu, Turkey
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9
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Duan J, Tao J, Zhai M, Li C, Zhou N, Lv J, Wang L, Lin L, Bai R. Anticancer drugs-related QTc prolongation, torsade de pointes and sudden death: current evidence and future research perspectives. Oncotarget 2018; 9:25738-25749. [PMID: 29876021 PMCID: PMC5986642 DOI: 10.18632/oncotarget.25008] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 03/13/2018] [Indexed: 01/08/2023] Open
Abstract
Anticancer drugs may have proarrhythmic effects including drug-induced QT interval prolongation, which is of particular importance because it can lead to a fatal polymorphic ventricular tachycardia termed torsade de pointes (TdP). QT interval prolongation and TdP are rare life-threatening untoward effects of anticancer therapy, particularly with arsenic trioxides and anthracyclines, and even some novel molecular targeted drugs touted as 'tumor specific'. Several factors that affect myocardial repolarization can further increase the risk of TdP. This article reviews the mechanism of QT interval prolongation, risk factors for TdP and the QT toxicity of anticancer drugs as well as its management. Specific attention should be paid to high-risk populations such as patients with underlying heart diseases, electrolyte imbalance and bradycardia. To minimize the occurrence of QT interval prolongation and TdP, it is advisable to conduct a careful risk factor assessment before antitumor therapy. To this end, several new biomarkers have been introduced to predict TdP triggering and recent studies have pointed out the potential clinical relevance of genetic testing.
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Affiliation(s)
- Jialin Duan
- Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Jingwen Tao
- Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Maocai Zhai
- Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Chengpeng Li
- Department of Cardiology, Wuhan Hospital of Integrated Traditional Chinese and Western Medicine, Wuhan, P.R. China
| | - Ning Zhou
- Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Jiagao Lv
- Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Lin Wang
- Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Li Lin
- Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Rong Bai
- Department of Cardiology, An Zhen Hospital, Capital Medical University, Beijing, P.R. China.,Texas Cardiac Arrhythmia Institute at St. David's Medical Center, Austin, TX, USA
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Nouraei H, Bennett M, Rabkin S. Value of the New Spline QTc Formula in Adjusting for Pacing-Induced Changes in Heart Rate. Cardiol Res Pract 2018; 2018:2052601. [PMID: 29805797 PMCID: PMC5902062 DOI: 10.1155/2018/2052601] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Revised: 12/15/2017] [Accepted: 01/14/2018] [Indexed: 01/08/2023] Open
Abstract
AIMS To determine whether a new QTc calculation based on a Spline fit model derived and validated from a large population remained stable in the same individual across a range of heart rates (HRs). Second, to determine whether this formula incorporating QRS duration can be of value in QT measurement, compared to direct measurement of the JT interval, during ventricular pacing. METHODS Individuals (N=30; 14 males) aged 51.9 ± 14.3 years were paced with decremental atrial followed by decremental ventricular pacing. RESULTS The new QTc changed minimally with shorter RR intervals, poorly fit even a linear relationship, and did not fit a second-order polynomial. In contrast, the Bazett formula (QTcBZT) showed a steep and marked increase in QTc with shorter RR intervals. For atrial pacing data, QTcBZT was fit best by a second-order polynomial and demonstrated a dramatic increase in QTc with progressively shorter RR intervals. For ventricular pacing, the new QTc minus QRS duration did not meaningfully change with HR in contrast to the HR dependency of QTcBZT and JT interval. CONCLUSION The new QT correction formula is minimally impacted by HR acceleration induced by atrial or ventricular pacing. The Spline QTc minus QRS duration is an excellent method to estimate QTc in ventricular paced complexes.
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Affiliation(s)
- Hirmand Nouraei
- Department of Medicine (Cardiology), University of British Columbia, Vancouver, BC, Canada
| | - Matthew Bennett
- Department of Medicine (Cardiology), University of British Columbia, Vancouver, BC, Canada
| | - Simon Rabkin
- Department of Medicine (Cardiology), University of British Columbia, Vancouver, BC, Canada
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11
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Yankelson L, Hochstadt A, Sadeh B, Pick B, Finkelstein A, Rosso R, Viskin S. New formula for defining "normal" and "prolonged" QT in patients with bundle branch block. J Electrocardiol 2018; 51:481-486. [PMID: 29395105 DOI: 10.1016/j.jelectrocard.2017.12.039] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 12/12/2017] [Indexed: 11/18/2022]
Abstract
OBJECTIVES To predict the QT interval in the presence of normal QRS for patients with left bundle branch block (LBBB). BACKGROUND There is no acceptable method for simple and reliable QT correction for patients with bundle branch block (BBB). METHODS We measured the QT interval in patients with new onset LBBB who had a recent electrocardiogram with narrow QRS for comparison. 48 patients who developed in-hospital LBBB were studied. Patients who had similar heart rate before and after LBBB were included. We used linear regression, the Bogossian method, and our new fixed QRS replacement method to evaluate the most reliable correction method. RESULTS JTc (QTc-QRS) interval was preserved before and after LBBB (328.9 ± 25.4 ms before LBBB vs. 327.3 ms post LBBB (p = 0.550). Mean predicted preLBBB QTc difference was 1.3 ms, -21.3 ms and 1.6 ms for the three methods respectively (p < 0.001 for Bogossian comparison with the other methods). Coefficients of correlation (R) between actual preLBBB QTc with predicted preLBBB QTc were 0.707, 0.683 and 0.665 respectively (p > 0.3 for R comparisons between all methods). The average absolute difference in preLBBB QTc was 15.5 ms and 16.7 ms for the regression and fixed-gender methods (p value between the two = 0.321) and 25.5 ms for the Bogossian method, which was found to be significantly underperforming. CONCLUSIONS In patients with LBBB, replacing of the QRS duration after deriving the QTc interval with a fixed value of 88 ms for female and 95 ms for male provides a simple and reliable method for predicting the QTc before the development of LBBB.
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Affiliation(s)
- Lior Yankelson
- Cardiac Electrophysiology, Division of Cardiology, NYU Langone Health, New York University School of Medicine, New York, USA.
| | - Aviram Hochstadt
- Department of Cardiology, Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Ben Sadeh
- Department of Cardiology, Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Benley Pick
- Department of Cardiology, Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Ariel Finkelstein
- Department of Cardiology, Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Raphael Rosso
- Department of Cardiology, Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Sami Viskin
- Department of Cardiology, Tel Aviv Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
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12
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Arrhythmogenic drugs can amplify spatial heterogeneities in the electrical restitution in perfused guinea-pig heart: An evidence from assessments of monophasic action potential durations and JT intervals. PLoS One 2018; 13:e0191514. [PMID: 29352276 PMCID: PMC5774816 DOI: 10.1371/journal.pone.0191514] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 01/06/2018] [Indexed: 01/01/2023] Open
Abstract
Non-uniform shortening of the action potential duration (APD90) in different myocardial regions upon heart rate acceleration can set abnormal repolarization gradients and promote arrhythmia. This study examined whether spatial heterogeneities in APD90 restitution can be amplified by drugs with clinically proved proarrhythmic potential (dofetilide, quinidine, procainamide, and flecainide) and, if so, whether these effects can translate to the appropriate changes of the ECG metrics of ventricular repolarization, such as JT intervals. In isolated, perfused guinea-pig heart preparations, monophasic action potentials and volume-conducted ECG were recorded at progressively increased pacing rates. The APD90 measured at distinct ventricular sites, as well as the JTpeak and JTend values were plotted as a function of preceding diastolic interval, and the maximum slopes of the restitution curves were determined at baseline and upon drug administration. Dofetilide, quinidine, and procainamide reverse rate-dependently prolonged APD90 and steepened the restitution curve, with effects being greater at the endocardium than epicardium, and in the right ventricular (RV) vs. the left ventricular (LV) chamber. The restitution slope was increased to a greater extent for the JTend vs. the JTpeak interval. In contrast, flecainide reduced the APD90 restitution slope at LV epicardium without producing effect at LV endocardium and RV epicardium, and reduced the JTpeak restitution slope without changing the JTend restitution. Nevertheless, with all agents, these effects translated to the amplified epicardial-to-endocardial and the LV-to-RV non-uniformities in APD90 restitution, paralleled by the increased JTend vs. JTpeak difference in the restitution slope. In summary, these findings suggest that arrhythmic drug profiles are partly attributable to the accentuated regional heterogeneities in APD90 restitution, which can be indirectly determined through ECG assessments of the JTend vs. JTpeak dynamics at variable pacing rates.
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Vinet A, Dubé B, Nadeau R, Mahiddine O, Jacquemet V. Estimation of the QT-RR relation: trade-off between goodness-of-fit and extrapolation accuracy. Physiol Meas 2017; 38:397-419. [PMID: 28067212 DOI: 10.1088/1361-6579/aa57b4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Correction of the QT interval in the ECG for changes in heart rate (RR interval) is needed to compare groups of patients and assess the risk of sudden cardiac death. The QTc represents the QT interval at 60 bpm, although most patients typically have a faster heart rate, thus requiring extrapolation of the QT-RR relationship. OBJECTIVE This paper investigates the ability of QT-RR models with increasing number of parameters to fit beat-to-beat variations in the QT interval and provide a reliable estimate of the QTc. APPROACH One-, two- and three-parameter functions generalising the Bazett and Fridericia formulas were used in combination with hysteresis reduction (memory) obtained by time-averaging the history of RR intervals with exponentially-decaying weights. In normal men and women datasets of Holter recordings in normal subjects (24 h monitoring), two measures were computed for each model: the root mean square error (RMSE) of fitting and the difference between the estimated QTc and a reference QTc obtained by collecting data points around RR = 1000 ms. MAIN RESULTS The two- and three-parameter functions all gave similar low RMSE with uncorrelated residues. An optimal memory parameter was found that still minimized the RMSE and could be used for all functions and subjects. This reduction in RMSE resulted from changes in the parameters linked to the increased steepness of the QT-RR relation after hysteresis reduction. At optimal memory, the two and three-parameter models provided poorer prediction of the QTc as compared to the Fridericia's model in subjects with fast heart rates, since accurate representation of the steeper QT-RR relation worsened the extrapolation that was then needed to determine the QTc. SIGNIFICANCE As a result, among all models investigated, the Fridericia formulation offered the best trade-off for QTc prediction robust to memory and fast heart rates.
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Affiliation(s)
- Alain Vinet
- Faculty of Medicine, Department of pharmacology and physiology, Université de Montréal, Montréal, QC, Canada. Centre de Recherche, Hôpital du Sacré-Cœur, Montréal, QC, Canada. Institut de Génie Biomédical, Université de Montréal, Montréal, QC, Canada
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Sriwattanakomen R, Mukamal KJ, Shvilkin A. A novel algorithm to predict the QT interval during intrinsic atrioventricular conduction from an electrocardiogram obtained during ventricular pacing. Heart Rhythm 2016; 13:2076-82. [DOI: 10.1016/j.hrthm.2016.06.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Indexed: 01/08/2023]
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Tabatabaei P, Keikhavani A, Haghjoo M, Fazelifar A, Emkanjoo Z, Zeighami M, Bakhshandeh H, Ghadrdoost B, Alizadeh A. Assessment of QT and JT Intervals in Patients With Left Bundle Branch Block. Res Cardiovasc Med 2016; 5:e31528. [PMID: 26949694 PMCID: PMC4756254 DOI: 10.5812/cardiovascmed.31528] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 08/23/2015] [Accepted: 09/07/2015] [Indexed: 11/16/2022] Open
Abstract
Background Prolongation of the QT interval is considered a risk factor for cardiac adverse events and mortality. Left bundle branch block (LBBB) lengthens the QT interval. The corrected QT interval (QTc) is most likely overestimated because its prolongation is caused by increases in depolarization duration and not in repolarization. Objectives In this study, we aimed to apply corrected JT interval (JTc) as an appropriate measure of ventricular repolarization for predicting QTc in a formula. Patients and Methods The study population consisted of 101 patients with sinus rhythm (SR) and narrow QRS complexes (< 120 milliseconds). All patients underwent electrophysiology studies or ablation. A diagnostic catheter was positioned in the right ventricular apex (RVA) to induce LBBB at two different cycle lengths (CLs; 600 and 700 mv). The intrinsic QRS complex, QT time, and JT time were measured during SR and subsequent RVA pacing. The JTc was derived simply by subtracting the QRS duration from the QTc. Results Stimulation from the RVA increased the QTc from 456.20 ± 38.63 ms to 530.67 ± 47.73 ms at a CL of 600 (P < 0.0001) and to 502.32 ± 47.26 ms at 700 CL (P < 0.0001). JTc showed no significant changes with stimulation from the RVA (102.97 ± 11.35 ms vs. 103.59 ± 10.67 ms, P = 0.24). There was no significant correlation between JTc and QRS complex duration. A significant correlation was seen between QRS and QTc at both CLs. The ROC curve indicated that sensitivity of 80% and specificity of 67% were obtained with JTc duration of 92.6 ms. Conclusions Right ventricular pacing increases the QT interval without increasing the JT interval. Our results confirm that JTc, as an index of repolarization, is independent of ventricular depolarization. Therefore, it can be applied for predicting QTc in patients with LBBB.
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Affiliation(s)
- Peyman Tabatabaei
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran
| | - Ala Keikhavani
- Department of Cardiology, Ziaeian General Hospital, International Campus Medical School, Tehran University of Medical Sciences, Tehran, IR Iran
| | - Majid Haghjoo
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran
| | - Amirfarjam Fazelifar
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran
| | - Zahra Emkanjoo
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran
| | - Mahbobeh Zeighami
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran
| | - Hooman Bakhshandeh
- Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran
| | - Behshid Ghadrdoost
- Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran
| | - Abolfath Alizadeh
- Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Tehran, IR Iran
- Corresponding author: Abolfath Alizadeh, Cardiac Electrophysiology Research Center, Rajaie Cardiovascular Medical and Research Center, Vali-E-Asr St., Niayesh Blvd., P. O. Box: 15745-1341, Tehran, IR Iran. Tel: +98-2123922164, Fax: +98-2122055594, E-mail:
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Vlachos K, Georgopoulos S, Efremidis M, Sideris A, Letsas KP. An update on risk factors for drug-induced arrhythmias. Expert Rev Clin Pharmacol 2015; 9:117-27. [DOI: 10.1586/17512433.2016.1100073] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Zulqarnain MA, Qureshi WT, O'Neal WT, Shah AJ, Soliman EZ. Risk of Mortality Associated With QT and JT Intervals at Different Levels of QRS Duration (from the Third National Health and Nutrition Examination Survey). Am J Cardiol 2015; 116:74-8. [PMID: 25929581 DOI: 10.1016/j.amjcard.2015.03.038] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/19/2015] [Accepted: 03/19/2015] [Indexed: 10/23/2022]
Abstract
QT prolongation in the setting of QRS >120 ms is believed to be triggered by prolonged depolarization rather than repolarization. Hence, JT interval is suggested as an alternative to QT interval when QRS duration is prolonged. It is unclear, however, if JT and QT intervals portend similar risk of mortality for different durations of QRS. We examined the association between QT and JT, separately, with all-cause mortality across different levels of QRS duration in 8,025 participants (60 ± 13 years, 41% white and 54% women) from the Third National Health and Nutrition Examination Survey. At baseline (1986 to 1994), 486 participants (6%) had QRS duration ≥120 ms. During a follow-up of up to 18 years, 3,045 deaths (38%) occurred. There were significant nonlinear relations of QT and JT intervals with mortality (p <0.001). Hence, QT and JT were categorized as prolonged (>95th percentile), shortened (<5th percentile), and normal (reference group). In multivariate-adjusted Cox regression models, prolonged JT (hazard ratio [HR] 4.75, 95% confidence interval [CI] 1.86 to 12.11) was associated with increased risk of mortality more than prolonged QT (HR 1.50, 95% CI 1.03 to 2.17) in participants with QRS ≥120 ms (interaction p = 0.02). In participants with QRS duration <120 ms, prolonged QT and JT were equally predictive of all-cause mortality (HR 1.27, 95% CI 1.06 to 1.54, and HR 1.31, 95% CI 1.10 to 1.55, respectively). Similar patterns were observed with shortened QT and JT intervals. In conclusion, although both QT and JT intervals are predictive of mortality, JT is more predictive in the setting of QRS duration >120 ms supporting the use of JT interval in patients with prolonged QRS.
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