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George SA, Trampel KA, Brunner K, Efimov IR. Moderate Endurance Exercise Increases Arrhythmia Susceptibility and Modulates Cardiac Structure and Function in a Sexually Dimorphic Manner. J Am Heart Assoc 2024; 13:e033317. [PMID: 38686869 PMCID: PMC11179941 DOI: 10.1161/jaha.123.033317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 02/05/2024] [Indexed: 05/02/2024]
Abstract
BACKGROUND Although moderate endurance exercise has been reported to improve cardiovascular health, its effects on cardiac structure and function are not fully characterized, especially with respect to sexual dimorphism. We aimed to assess the effects of moderate endurance exercise on cardiac physiology in male versus female mice. METHODS AND RESULTS C57BL/6J mice of both sexes were run on a treadmill for 6 weeks. ECG and echocardiography were performed every 2 weeks. After 6 weeks of exercise, mice were euthanized, and triple parametric optical mapping was performed on Langendorff perfused hearts to assess cardiac electrophysiology. Arrhythmia inducibility was tested by programmed electrical stimulation. Left ventricular tissue was fixed, and RNA sequencing was performed to determine exercise-induced transcriptional changes. Exercise-induced left ventricular dilatation was observed in female mice alone, as evidenced by increased left ventricular diameter and reduced left ventricular wall thickness. Increased cardiac output was also observed in female exercised mice but not males. Optical mapping revealed further sexual dimorphism in exercise-induced modulation of cardiac electrophysiology. In female mice, exercise prolonged action potential duration and reduced voltage-calcium influx delay. In male mice, exercise reduced the calcium decay constant, suggesting faster calcium reuptake. Exercise increased arrhythmia inducibility in both male and female mice; however, arrhythmia duration was increased only in females. Lastly, exercise-induced transcriptional changes were sex dependent: females and males exhibited the most significant changes in contractile versus metabolism-related genes, respectively. CONCLUSIONS Our data suggest that moderate endurance exercise can significantly alter multiple aspects of cardiac physiology in a sex-dependent manner. Although some of these effects are beneficial, like improved cardiac mechanical function, others are potentially proarrhythmic.
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Affiliation(s)
- Sharon A George
- Department of Biomedical Engineering George Washington University Washington DC
- Department of Biomedical Engineering Northwestern University Chicago IL
| | - Katy Anne Trampel
- Department of Biomedical Engineering George Washington University Washington DC
- Department of Biomedical Engineering Northwestern University Chicago IL
| | - Kelsey Brunner
- Department of Biomedical Engineering George Washington University Washington DC
| | - Igor R Efimov
- Department of Biomedical Engineering George Washington University Washington DC
- Department of Biomedical Engineering Northwestern University Chicago IL
- Department of Medicine Northwestern University Chicago IL
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2
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Mercik J, Radziejewska J, Pach K, Zawadzki G, Zyśko D, Gajek J. ST-segment depression in atrioventricular nodal reentrant tachycardia: Important finding or just an artifact? Medicine (Baltimore) 2022; 101:e31806. [PMID: 36626431 PMCID: PMC9750532 DOI: 10.1097/md.0000000000031806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND The ST segment is component of the QRS-T complex located between the QRS and the T wave. ST segment changes during tachycardia with narrow QRS mainly takes the form of ST segment depression. This phenomenon is often observed in young healthy people for whom an ischemic background is unlikely. MATERIALS AND METHODS The study included 104 patients (71 women and 33 men) with paroxysmal narrow QRS complex tachycardia. In all patients electrophysiological study was performed and the diagnosis of atrioventricular nodal reentrant tachycardia was established. The arrhythmogenic substrate was then eliminated successfully by subsequent ablation using radiofrequency energy which confirmed the diagnosis, all patients had measured QRS components - QR, RS and RJ during the tachycardia and during the sinusrhythm. All of the measurements were done in lead V5. RESULTS The difference RJ-QR during tachycardia and sinus rhythm correlated negatively with tachycardia cycle length (R = 0.356, P = .001), first slowly, then rapidly reaching the cycle value of about 300 ms, then it decreases, stabilizing at the cycle level of about 270. By separating the RJ-QR in tachycardia and in the sinus rhythm from the tachycardia cycle, we can see that the correlation described in this point is largely due to the correlation between the heart rate and RJ-QR length in tachycardia. CONCLUSIONS In patients with atrioventricular nodal reentrant tachycardia, there is a significant ST-segment depression during tachycardia episodes and the degree of this change is related to tachycardia cycle length. The most probable explanation of the ST-segment depression is the overlap of the QRS complex on the preceded T wave. This phenomenon is also influenced by some intrinsic properties of the individual electrocardiogram. It is possible to rule out ischemic origin of the presented ST segment change.
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Affiliation(s)
- Jakub Mercik
- Department of Emergency Medicine, Wroclaw Medical University, Poland
| | | | - Katarzyna Pach
- Students’ Scientific Association, Department of Emergency Medical Service, Wroclaw Medical University, Poland
| | - Grzegorz Zawadzki
- Students’ Scientific Association, Department of Emergency Medical Service, Wroclaw Medical University, Poland
| | - Dorota Zyśko
- Department of Emergency Medicine, Wroclaw Medical University, Poland
| | - Jacek Gajek
- Department of Emergency Medical Service, Wroclaw Medical University, Poland
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Ritt LE, Milani M, Stein R. Long QT Syndrome: To Exercise Safely or Not To Exercise, That's the Question!!! Eur J Prev Cardiol 2022; 29:1630-1632. [PMID: 35708716 DOI: 10.1093/eurjpc/zwac109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Luiz Eduardo Ritt
- Bahiana School of Medicine and Public Health, Salvador, BA, Brazil.,D'or Research Institute (IDOR), Hospital Cardio Pulmonar, Salvador, BA, Brazil
| | - Mauricio Milani
- Health Sciences and Technologies Graduate Program, Unisversity of Brasilia (UnB), Brasilia, DF, Brazil.,Fitcordis Exercise Medicine Clinic, Brasilia, DF, Brazil
| | - Ricardo Stein
- Exercise Cardiology Research Group (CardioEx), Hospital de Clínicas, Rio Grade do Sul Federal University, Porto Alegre, RS, Brazil.,Post Graduate Studies Program in Cardiology, Medicine School, Rio Grande do Sul Federal University, Porto Alegre, RS, Brazil
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4
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Atanasovska T, Smith R, Graff C, Tran CT, Melgaard J, Kanters JK, Petersen AC, Tobin A, Kjeldsen KP, McKenna MJ. Protection against severe hypokalemia but impaired cardiac repolarization after intense rowing exercise in healthy humans receiving salbutamol. J Appl Physiol (1985) 2018; 125:624-633. [PMID: 29745804 DOI: 10.1152/japplphysiol.00680.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Intense exercise induces pronounced hyperkalemia, followed by transient hypokalemia in recovery. We investigated whether the β2 agonist salbutamol attenuated the exercise hyperkalemia and exacerbated the postexercise hypokalemia, and whether hypokalemia was associated with impaired cardiac repolarization (QT hysteresis). Eleven healthy adults participated in a randomized, counterbalanced, double-blind trial receiving either 1,000 µg salbutamol (SAL) or placebo (PLAC) by inhalation. Arterial plasma potassium concentration ([K+]a) was measured at rest, during 3 min of intense rowing exercise, and during 60 min of recovery. QT hysteresis was calculated from ECG ( n = 8). [K+]a increased above baseline during exercise (rest, 3.72 ± 0.7 vs. end-exercise, 6.81 ± 1.4 mM, P < 0.001, mean ± SD) and decreased rapidly during early recovery to below baseline; restoration was incomplete at 60 min postexercise ( P < 0.05). [K+]a was less during SAL than PLAC (4.39 ± 0.13 vs. 4.73 ± 0.19 mM, pooled across all times, P = 0.001, treatment main effect). [K+]a was lower after SAL than PLAC, from 2 min preexercise until 2.5 min during exercise, and at 50 and 60 min postexercise ( P < 0.05). The postexercise decline in [K+]a was correlated with QT hysteresis ( r = 0.343, n = 112, pooled data, P = 0.001). Therefore, the decrease in [K+]a from end-exercise by ~4 mM was associated with reduced QT hysteresis by ~75 ms. Although salbutamol lowered [K+]a during exercise, no additive hypokalemic effects occurred in early recovery, suggesting there may be a protective mechanism against severe or prolonged hypokalemia after exercise when treated by salbutamol. This is important because postexercise hypokalemia impaired cardiac repolarization, which could potentially trigger arrhythmias and sudden cardiac death in susceptible individuals with preexisting hypokalemia and/or heart disease. NEW & NOTEWORTHY Intense rowing exercise induced a marked increase in arterial potassium, followed by a pronounced decline to hypokalemic levels. The β2 agonist salbutamol lowered potassium during exercise and late recovery but not during early postexercise, suggesting a protective effect against severe hypokalemia. The decreased potassium in recovery was associated with impaired cardiac QT hysteresis, suggesting a link between postexercise potassium and the heart, with implications for increased risk of cardiac arrhythmias and, potentially, sudden cardiac death.
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Affiliation(s)
- Tania Atanasovska
- Institute for Health and Sport, Victoria University , Melbourne, Victoria , Australia
| | - Robert Smith
- Institute for Health and Sport, Victoria University , Melbourne, Victoria , Australia.,Department of Anaesthesia, Western Hospital , Melbourne, Victoria , Australia
| | - Claus Graff
- Department of Health Science and Technology, Faculty of Medicine, Aalborg University , Aalborg , Denmark
| | - Cao T Tran
- Division of Cardiology, John Hopkins University School of Medicine , Baltimore, Maryland
| | - Jacob Melgaard
- Department of Health Science and Technology, Faculty of Medicine, Aalborg University , Aalborg , Denmark
| | - Jørgen K Kanters
- Laboratory of Experimental Cardiology, Department of Biomedical Sciences, Copenhagen University , Copenhagen , Denmark
| | - Aaron C Petersen
- Institute for Health and Sport, Victoria University , Melbourne, Victoria , Australia
| | - Antony Tobin
- Intensive Care Unit, St. Vincent Hospital , Melbourne, Victoria , Australia
| | - Keld P Kjeldsen
- Department of Health Science and Technology, Faculty of Medicine, Aalborg University , Aalborg , Denmark.,Medical Department, Copenhagen University Hospital (Holbæk Hospital), Holbæk, Denmark.,Institute of Clinical Medicine, Faculty of Medicine, Copenhagen University , Copenhagen , Denmark
| | - Michael J McKenna
- Institute for Health and Sport, Victoria University , Melbourne, Victoria , Australia
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5
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Bika Lele EC, Pepouomi MN, Temfemo A, Mekoulou J, Assomo Ndemba P, Mandengue SH. [Effect of intermittent variable intensity exercise on QT variation and risk of sudden cardiac death among Cameroonian school adolescents]. Ann Cardiol Angeiol (Paris) 2017; 67:48-53. [PMID: 28705431 DOI: 10.1016/j.ancard.2017.03.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 03/22/2017] [Indexed: 10/19/2022]
Abstract
INTRODUCTION Several cases of sudden deaths are observed among students practicing sport and physical activity (SPA). Just few studies have been carried out on the variation of the QT (interval) and risk of sudden death during sporting exercises. AIM To determine the effect of variable intermittent stress intensity on the variation of QT and the risk of sudden cardiac death. PATIENTS AND METHODS Form 4, lower sixth and upper sixth students were recruited from a high school in Douala (Cameroon). Each subject was tested; starting with a 2-km walk followed by a sprint race or an endurance race, protocol I (P1) or the reverse; protocol II (P2). Two electrocardiograms were recorded; prior to the beginning of the SPA and 5minutes after the last race. QT was corrected using four formulas. RESULTS Forty-one subjects (21 women and 20 men), mean age 18±2 years were recruited. At the end of the exercise, corrected QT increased with Bazzet's formula and decreased with Frahmingam's formula. The difference was not significant with Fridericia and Hodges formulas. The frequency of long QT was higher at the end of the exercise with Bazzet's formula (12.2% vs. 24.4%, P=0.009) while the difference was not significant for the other formulas. CONCLUSION The risk of sudden cardiac death increases significantly after SPA. More studies on large samples are needed.
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Affiliation(s)
- E C Bika Lele
- Unité de physiologie des APS, faculté des sciences, université de Douala, 7064 Bassa Douala, Cameroun; Institut de recherches médicales et d'études des plantes médicinales (IMPM), BP 13033, Yaoundé, Cameroun
| | - M N Pepouomi
- Service de cardiologie, hôpital de Bonassama-Douala, Douala, Cameroun
| | - A Temfemo
- Unité de physiologie des APS, faculté des sciences, université de Douala, 7064 Bassa Douala, Cameroun
| | - J Mekoulou
- Unité de physiologie des APS, faculté des sciences, université de Douala, 7064 Bassa Douala, Cameroun
| | - P Assomo Ndemba
- Unité de physiologie des APS, faculté des sciences, université de Douala, 7064 Bassa Douala, Cameroun
| | - S H Mandengue
- Unité de physiologie des APS, faculté des sciences, université de Douala, 7064 Bassa Douala, Cameroun.
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Gravel H, Curnier D, Dahdah N, Jacquemet V. Categorization and theoretical comparison of quantitative methods for assessing QT/RR hysteresis. Ann Noninvasive Electrocardiol 2017; 22. [PMID: 28510313 DOI: 10.1111/anec.12463] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 03/27/2017] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND In the human electrocardiogram, there is a lag of adaptation of the QT interval to heart rate changes, usually termed QT/RR hysteresis (QT-hys). Subject-specific quantifiers of QT-hys have been proposed as potential biomarkers, but there is no consensus on the choice of the quantifier. METHODS A comprehensive literature search was conducted to identify original articles reporting quantifiers of repolarization hysteresis from the surface ECG in humans. RESULTS Sixty articles fulfilled our inclusion criteria. Reported biomarkers were grouped under four categories. A simple mathematical model of QT/RR loop was used to illustrate differences between the methods. Category I quantifiers use direct measurement of QT time course of adaptation. They are limited to conditions where RR intervals are under strict control. Category IIa and IIb quantifiers compare QT responses during consecutive heart rate acceleration and deceleration. They are relevant when a QT/RR loop is observed, typically during exercise and recovery, but are not robust to protocol variations. Category III quantifiers evaluate the optimum RR memory in dynamic QT/RR relationship modeling. They estimate an intrinsic memory parameter independent from the nature of RR changes, but their reliability remains to be confirmed when multiple memory parameters are estimated. Promising approaches include the differentiation of short-term and long-term memory and adaptive estimation of memory parameters. CONCLUSION Model-based approaches to QT-hys assessment appear to be the most versatile, as they allow separate quantification of QT/RR dependency and QT-hys, and can be applied to a wide range of experimental settings.
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Affiliation(s)
- Hugo Gravel
- Department of Kinesiology, University of Montreal, Montréal, QC, Canada
| | - Daniel Curnier
- Department of Kinesiology, University of Montreal, Montréal, QC, Canada
| | - Nagib Dahdah
- Division of Pediatric Cardiology and CHU Ste-Justine Research Center, CHU Ste-Justine, Montréal, QC, Canada
| | - Vincent Jacquemet
- Department of Pharmacology and Physiology, Faculty of Medicine, University of Montreal, Montréal, QC, Canada
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7
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Microvolt T-wave alternans amplifies spatial dispersion of repolarization in human subjects with ischemic cardiomyopathy. J Electrocardiol 2016; 49:733-9. [PMID: 27344495 DOI: 10.1016/j.jelectrocard.2016.06.002] [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: 10/22/2015] [Indexed: 11/23/2022]
Abstract
INTRODUCTION In experimental models, spatial dispersion of repolarization (DOR) due to discordant cellular alternans predisposes to ventricular fibrillation. To test the hypothesis that microvolt T-wave alternans (MTWA) in humans causes spatial DOR, we measured Tpeak-Tend interval (Tpe) and Tpe/QT ratio, electrocardiographic indices of spatial DOR. METHODS Mean Tpe and Tpe/QT were compared in ischemic cardiomyopathy patients with positive and negative MTWA studies. RESULTS MTWA was positive in 12 and negative in 24 patients. Tpe and Tpe/QT were higher in MTWA+ subjects compared to MTWA- subjects during exercise (64.5±6.8 vs. 54.9±8.7ms, p=0.001 and 0.218±0.03 vs. 0.177±0.02, p=0.001) but not at rest. CONCLUSION Ischemic cardiomyopathy patients have increased Tpe and Tpe/QT when MTWA is induced during exercise, suggesting that MTWA causes increased spatial DOR in humans. Future studies are needed to determine if Tpe and Tpe/QT during exercise might predict increased risk of SCD alone or in combination with measurement of MTWA.
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8
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Schilling JM, Horikawa YT, Zemljic-Harpf AE, Vincent KP, Tyan L, Yu JK, McCulloch AD, Balijepalli RC, Patel HH, Roth DM. Electrophysiology and metabolism of caveolin-3-overexpressing mice. Basic Res Cardiol 2016; 111:28. [PMID: 27023865 DOI: 10.1007/s00395-016-0542-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 02/17/2016] [Indexed: 10/22/2022]
Abstract
Caveolin-3 (Cav-3) plays a critical role in organizing signaling molecules and ion channels involved in cardiac conduction and metabolism. Mutations in Cav-3 are implicated in cardiac conduction abnormalities and myopathies. Additionally, cardiac-specific overexpression of Cav-3 (Cav-3 OE) is protective against ischemic and hypertensive injury, suggesting a potential role for Cav-3 in basal cardiac electrophysiology and metabolism involved in stress adaptation. We hypothesized that overexpression of Cav-3 may alter baseline cardiac conduction and metabolism. We examined: (1) ECG telemetry recordings at baseline and during pharmacological interventions, (2) ion channels involved in cardiac conduction with immunoblotting and computational modeling, and (3) baseline metabolism in Cav-3 OE and transgene-negative littermate control mice. Cav-3 OE mice had decreased heart rates, prolonged PR intervals, and shortened QTc intervals with no difference in activity compared to control mice. Dobutamine or propranolol did not cause significant changes between experimental groups in maximal (dobutamine) or minimal (propranolol) heart rate. Cav-3 OE mice had an overall lower chronotropic response to atropine. The expression of Kv1.4 and Kv4.3 channels, Nav1.5 channels, and connexin 43 were increased in Cav-3 OE mice. A computational model integrating the immunoblotting results indicated shortened action potential duration in Cav-3 OE mice linking the change in channel expression to the observed electrophysiology phenotype. Metabolic profiling showed no gross differences in VO2, VCO2, respiratory exchange ratio, heat generation, and feeding or drinking. In conclusion, Cav-3 OE mice have changes in ECG intervals, heart rates, and cardiac ion channel expression. These findings give novel mechanistic insights into previously reported Cav-3 dependent cardioprotection.
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Affiliation(s)
- Jan M Schilling
- Veterans Affairs San Diego Healthcare System, San Diego, CA, USA.,Department of Anesthesiology, University of California San Diego, La Jolla, CA, USA
| | - Yousuke T Horikawa
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA.,Department of Pediatrics, Sharp Rees-Stealy Medical Group, San Diego, CA, USA
| | - Alice E Zemljic-Harpf
- Veterans Affairs San Diego Healthcare System, San Diego, CA, USA.,Department of Anesthesiology, University of California San Diego, La Jolla, CA, USA
| | - Kevin P Vincent
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA
| | - Leonid Tyan
- Department of Medicine, Cellular and Molecular Arrhythmia Research Program, University of Wisconsin, Madison, WI, USA
| | - Judith K Yu
- Department of Anesthesiology, University of California San Diego, La Jolla, CA, USA
| | - Andrew D McCulloch
- Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.,Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Ravi C Balijepalli
- Department of Medicine, Cellular and Molecular Arrhythmia Research Program, University of Wisconsin, Madison, WI, USA
| | - Hemal H Patel
- Veterans Affairs San Diego Healthcare System, San Diego, CA, USA.,Department of Anesthesiology, University of California San Diego, La Jolla, CA, USA
| | - David M Roth
- Veterans Affairs San Diego Healthcare System, San Diego, CA, USA. .,Department of Anesthesiology, University of California San Diego, La Jolla, CA, USA.
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9
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Jukić A, Carević V, Zekanović D, Stojanović-Stipić S, Runjić F, Ljubković M, Fabijanić D. Impact of Percutaneous Coronary Intervention on Exercise-Induced Repolarization Changes in Patients With Stable Coronary Artery Disease. Am J Cardiol 2015; 116:853-7. [PMID: 26174604 DOI: 10.1016/j.amjcard.2015.06.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 06/06/2015] [Accepted: 06/06/2015] [Indexed: 11/17/2022]
Abstract
Recent reports suggest T peak to T end (Tpe) interval and Tpe/QT ratio as valuable indicators of increased arrhythmogenic risk in patients with coronary artery disease (CAD). We aimed to examine the exercise-induced changes in these indexes in patients with stable CAD, before and after percutaneous coronary intervention (PCI). Forty patients were consecutively included in the interventional group (n = 20), with significant lesions (≥75% luminal narrowing) suitable for PCI and in the control group (n = 20), with no significant coronary artery lesions (<50% luminal narrowing). One day before and 30 days after the coronarography, all patients performed treadmill exercise stress testing, and the electrocardiographic (ECG) indexes of repolarization were assessed during baseline and at peak exercise intensity. In the control group, the QT interval, QTc (QT-corrected) interval, Tpe interval, and Tpe/QT ratio measured at peak exercise significantly decreased from baseline values (p = 0.001, p = 0.004, p <0.001, and p = 0.017, respectively). Conversely, in interventional patients before the PCI, an increase in the Tpe interval and the Tpe/QT ratio was observed at exercise (p = 0.009, and p <0.001, respectively), with only the QT interval exhibiting a significant decrease from baseline (p <0.001). Thirty days after the PCI, all the ECG arrhythmogenic indexes measured at peak exercise significantly decreased from baseline values, thus assuming the same trend as detected in controls. In conclusion, restoration of blood supply normalized exercise-induced repolarization changes, suggesting that revascularization of previously ischemic myocardium lowers the cardiac arrhythmogenic potential in patients with stable CAD.
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Affiliation(s)
- Anita Jukić
- Department of Cardiology, University Hospital Centre Split, Split, Croatia
| | - Vedran Carević
- Department of Cardiology, University Hospital Centre Split, Split, Croatia
| | | | - Sanda Stojanović-Stipić
- Department of Anestesiology, Reanimatology and Intensive Care, University Hospital Centre Split, Split, Croatia
| | - Frane Runjić
- Department of Cardiology, University Hospital Centre Split, Split, Croatia
| | - Marko Ljubković
- Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
| | - Damir Fabijanić
- Department of Cardiology, University Hospital Centre Split, Split, Croatia.
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10
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Zhang Y, Bao M, Dai M, Zhong H, Li Y, Tan T. QT hysteresis index improves the power of treadmill exercise test in the screening of coronary artery disease. Circ J 2014; 78:2942-9. [PMID: 25311775 DOI: 10.1253/circj.cj-14-0697] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND QT hysteresis phenomenon exists in healthy subjects, and is more exaggerated in patients with coronary artery disease (CAD) and long QT syndrome. The purpose of this study was to establish an appropriate method to evaluate the magnitude of QT hysteresis, and assess the value of QT hysteresis index in the treadmill exercise test (TET) in predicting CAD. METHODS AND RESULTS: A total of 138 subjects with suspected CAD and referred for TET and selective coronary angiography (SCA) were divided into positive (n=77) and negative (n=61) SCA groups. Dynamic ECG were recorded during TET. QT/RR curves were constructed and QTp (Q-Tpeak) and QTe (Q-Tend) hysteresis indices were calculated for each subject. SYNTAX score in the positive SCA group was determined. The QTp and QTe hysteresis indices in the positive SCA group were significantly higher than in the negative SCA group. The combination of QTe hysteresis index and conventional TET criteria had the highest sensitivity and negative predictive value according to receiver operating characteristic curve, and was an independent predictor on multivariate logistic regression. QT hysteresis indices significantly correlated with SYNTAX score in the positive SCA group. CONCLUSIONS QTe hysteresis index enhances the specificity of predicting CAD in TET. It improves the diagnostic value of TET for CAD significantly when combined with conventional criteria and is associated with the severity of CAD.
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Affiliation(s)
- Yijie Zhang
- Department of Cardiology, Wuhan University, Renmin Hospital
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11
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Tran CT, Bundgaard H, Ladefoged SD, Haunsø S, Kjeldsen K. Potassium dynamics are attenuated in hyperkalemia and a determinant of QT adaptation in exercising hemodialysis patients. J Appl Physiol (1985) 2013; 115:498-504. [PMID: 23722704 DOI: 10.1152/japplphysiol.01019.2012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Disturbances in plasma potassium concentration (pK) are well known risk factors for the development of cardiac arrhythmia. The aims of the present study were to evaluate the effect of hemodialysis on exercise pK dynamics and QT hysteresis, and whether QT hysteresis is associated with the pK decrease following exercise. Twenty-two end-stage renal disease patients exercised on a cycle ergometer with incremental work load before and after hemodialysis. ECG was recorded and pK was measured during exercise and recovery. During exercise, pK increased from 5.1 ± 0.2 to 6.1 ± 0.2 mM (mean ± SE; P < 0.0001) before hemodialysis and from 3.8 ± 0.1 to 5.1 ± 0.1 mM (P < 0.0001) after hemodialysis. After 2 min of recovery, pK had decreased to 5.0 ± 0.2 mM and 4.1 ± 0.1 mM (P < 0.0001) before and after hemodialysis, respectively. pK increase during exercise was accentuated after hemodialysis. The pK increase was negatively linearly correlated with pK before exercise (β = -0.21, R(2) = 0.23, P = 0.001). QT hysteresis was negatively linearly correlated with the decrease in pK during recovery (β = -28 ms/mM, R(2) = 0.36, P = 0.006). Thus, during recovery, low pK was associated with relatively longer QT interval. In conclusion, new major findings are an accentuated increase in pK during exercise after hemodialysis, an attenuated increase in pK in hyperkalemia, and an association between pK and QT interval adaptation during recovery. The acute pK shift after exercise may modulate QT interval adaptation and trigger cardiac arrhythmias.
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Affiliation(s)
- Cao Thach Tran
- Laboratory for Molecular Cardiology, The Heart Centre, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
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12
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Krahn AD, Healey JS, Chauhan VS, Birnie DH, Champagne J, Sanatani S, Ahmad K, Ballantyne E, Gerull B, Yee R, Skanes AC, Gula LJ, Leong-Sit P, Klein GJ, Gollob MH, Simpson CS, Talajic M, Gardner M. Epinephrine Infusion in the Evaluation of Unexplained Cardiac Arrest and Familial Sudden Death. Circ Arrhythm Electrophysiol 2012; 5:933-40. [DOI: 10.1161/circep.112.973230] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Epinephrine infusion may unmask latent genetic conditions associated with cardiac arrest, including long-QT syndrome and catecholaminergic polymorphic ventricular tachycardia (VT).
Methods and Results—
Patients with unexplained cardiac arrest (normal left ventricular function and QT interval) and selected family members from the Cardiac Arrest Survivors with Preserved Ejection Fraction Registry (CASPER) registry underwent epinephrine challenge at doses of 0.05, 0.10, and 0.20 μg/kg per minute. A test was considered positive for long-QT syndrome if the absolute QT interval prolonged by ≥30 ms at 0.10 μg/kg per minute and borderline if QT prolongation was 1 to 29 ms. Catecholaminergic polymorphic VT was diagnosed if epinephrine provoked ≥3 beats of polymorphic or bidirectional VT and borderline if polymorphic couplets, premature ventricular contractions, or nonsustained monomorphic VT was induced. Epinephrine infusion was performed in 170 patients (age, 42±16 years; 49% men), including 98 patients with unexplained cardiac arrest. Testing was positive for long-QT syndrome in 31 patients (18%) and borderline in 24 patients (14%). Exercise testing provoked an abnormal QT response in 42% of tested patients with a positive epinephrine response. Testing for catecholaminergic polymorphic VT was positive in 7% and borderline in 5%. Targeted genetic testing of abnormal patients was positive in 17% of long-QT syndrome patients and 13% of catecholaminergic polymorphic VT patients.
Conclusions—
Epinephrine challenge provoked abnormalities in a substantial proportion of patients, most commonly a prolonged QT interval. Exercise and genetic testing replicated the diagnosis suggested by the epinephrine response in a small proportion of patients. Epinephrine infusion combined with exercise testing and targeted genetic testing is recommended in the workup of suspected familial sudden death syndromes.
Clinical Trial Registration—
URL:
http://www.clinicaltrials.gov
. Unique identifier: NCT00292032.
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Affiliation(s)
- Andrew D. Krahn
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Jeffrey S. Healey
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Vijay S. Chauhan
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - David H. Birnie
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Jean Champagne
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Shubhayan Sanatani
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Kamran Ahmad
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Emily Ballantyne
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Brenda Gerull
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Raymond Yee
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Allan C. Skanes
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Lorne J. Gula
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Peter Leong-Sit
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - George J. Klein
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Michael H. Gollob
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Christopher S. Simpson
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Mario Talajic
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
| | - Martin Gardner
- From the University of British Columbia (A.D.K.), Vancouver, BC; Population Health Research Institute, McMaster University (J.S.H.), Hamilton, ON; University Health Network (V.S.C.), Toronto, Canada; University of Ottawa Heart Institute (D.H.B., M.H.G.), Ottawa, ON; Quebec Heart Institute (J.C.), Laval Hospital, Quebec City, PQ; BC Children’s Hospital (S.S.), Vancouver, British Columbia, Vancouver, BC; St Michael’s Hospital (K.A.), Toronto, Canada; University of Western Ontario (E.B., R.Y., A.C.S.,
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Pelchovitz DJ, Ng J, Chicos AB, Bergner DW, Goldberger JJ. QT-RR hysteresis is caused by differential autonomic states during exercise and recovery. Am J Physiol Heart Circ Physiol 2012; 302:H2567-73. [PMID: 22542617 DOI: 10.1152/ajpheart.00041.2012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
QT-RR hysteresis is characterized by longer QT intervals at a given RR interval while heart rates are increasing during exercise and shorter QT intervals at the same RR interval while heart rates are decreasing during recovery. It has been attributed to a lagging QT response to different directional changes in RR interval during exercise and recovery. Twenty control subjects (8 males, age 51 ± 6 yr), 16 subjects with type 2 diabetes (12 males, age 56 ± 8 yr), 71 subjects with coronary artery disease (CAD) and preserved left ventricular ejection fraction (LVEF) (≥50%) (51 males, age 59 ± 12 yr), and 17 CAD subjects with depressed LVEF (<50%) (13 males, age 57 ± 10 yr) underwent two 16-min exercise tests followed by recovery. In session 2, parasympathetic blockade with atropine (0.04 mg/kg) was achieved at end exercise. QT-RR hysteresis was quantified as: 1) the area bounded by the QT-RR relationships for exercise and recovery in the range of the minimum RR interval at peak exercise to the minimum RR interval + 100 ms and 2) the difference in QT interval duration between exercise and recovery at the minimum RR interval achieved during peak exercise plus 50 ms (ΔQT). The effect of parasympathetic blockade was assessed by substituting the QT-RR relationship after parasympathetic blockade. QT-RR hysteresis was positive in all groups at baseline and reversed by parasympathetic blockade (P < 0.01). We conclude that QT-RR hysteresis is not caused by different directional changes in RR interval during exercise and recovery. Instead, it is predominantly mediated by differential autonomic nervous system effects as the heart rate increases during exercise vs. as it decreases during recovery.
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Affiliation(s)
- Daniel J Pelchovitz
- Division of Cardiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA
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14
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Gemma LW, Ward GM, Dettmer MM, Ball JL, Leo PJ, Doria DN, Kaufman ES. β-blockers protect against dispersion of repolarization during exercise in congenital long-QT syndrome type 1. J Cardiovasc Electrophysiol 2011; 22:1141-6. [PMID: 21635612 DOI: 10.1111/j.1540-8167.2011.02091.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
INTRODUCTION β-Blocker therapy reduces syncope and sudden death in long-QT syndrome type 1 (LQT1), but the mechanism of protection is incompletely understood. This study tested the hypothesis that β-blockade reduces QT prolongation and dispersion of repolarization, measured as the T peak-to-end interval (T(pe) ), during exercise and recovery in LQT1 patients. METHODS AND RESULTS QT and T(pe) were measured in 10 LQT1 patients (33 ± 13 years) and 35 normal subjects (32 ± 12 years) during exercise tests on and off β-blockade. In LQT1 patients, β-blockade reduced QT (391 ± 25 milliseconds vs 375 ± 26 milliseconds, P = 0.04 during exercise; 419 ± 41 milliseconds vs 391 ± 39 milliseconds, P = 0.02 during recovery) and markedly reduced T(pe) (91 ± 26 milliseconds vs 67 ± 19 milliseconds, P = 0.03 during exercise; 103 ± 26 milliseconds vs 78 ± 11 milliseconds, P = 0.02 during recovery). In contrast, in normal subjects, β-blockade had no effect on QT (320 ± 17 milliseconds vs 317 ± 16 milliseconds, P = 0.29 during exercise; 317 ± 13 milliseconds vs 315 ± 14 milliseconds, P = 0.15 during recovery) and mildly reduced T(pe) (69 ± 13 milliseconds vs 61 ± 11 milliseconds, P = 0.01 during exercise; 77 ± 19 milliseconds vs. 68 ± 14 milliseconds, P < 0.001 during recovery). CONCLUSION In LQT1 patients, β-blockers reduced QT and T(pe) during exercise and recovery, supporting the theory that β-blocker therapy protects LQT1 patients by reducing dispersion of repolarization during exercise and recovery.
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Affiliation(s)
- Lee W Gemma
- Heart and Vascular Research Center, MetroHealth Campus of Case Western Reserve University, Cleveland, Ohio, USA
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15
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Korantzopoulos P, Letsas KP, Christogiannis Z, Kalantzi K, Massis I, Milionis HJ, Pappas C, Goudevenos JA. Exercise-induced repolarization changes in patients with stable coronary artery disease. Am J Cardiol 2011; 107:37-40. [PMID: 21146683 DOI: 10.1016/j.amjcard.2010.08.038] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 08/21/2010] [Accepted: 08/21/2010] [Indexed: 02/02/2023]
Abstract
Exercise is a classic trigger of ventricular arrhythmias in the setting of coronary artery disease (CAD). The aim of this study was to examine the changes of novel indexes of repolarization in patients with stable CAD who underwent exercise stress testing. Sixty-seven consecutive patients (mean age 62 ± 9 years, 60 men) who underwent treadmill exercise stress testing according to the Bruce protocol and completed the test without evidence of ischemia were enrolled. Baseline clinical and demographic characteristics were recorded, and indexes of repolarization such as corrected QT (QTc) interval, T peak-to-end (Tpe) interval, and Tpe/QT ratio were assessed at baseline and at peak exercise. A similar group of control subjects without CAD (n = 68, mean age 60 ± 11 years, 52 men) were also studied. All participants successfully completed the test. In the patient group, the QTc interval significantly increased from baseline to peak exercise (median 385 ms [25th percentile 357 ms, 75th percentile 407 ms] vs 418 ms [381 ms, 447 ms], p <0.001). The Tpe interval and the Tpe/QT ratio were also significantly increased at peak exercise (42 ms [36 ms, 60 ms] vs 78 ms [60 ms, 84 ms], p <0.001; and 0.17 [0.14, 0.22] vs 0.21 [0.16, 0.25], p = 0.015). In the control group, the QTc interval did not change significantly, the Tpe interval decreased at peak exercise (62 ms [41 ms, 80 ms] vs 48 ms [40 ms, 78 ms], p = 0.05), and the Tpe/QT ratio did not show a significant change (0.18 [0.12, 0.22] vs 0.16 [1.14, 0.21], p = 0.39). In patients with stable CAD and normal treadmill exercise stress test results, the QTc interval, the Tpe interval, and the Tpe/QT ratio increased during exercise. In conclusion, it is reasonable to assume that despite the absence of inducible ischemia, the spatial dispersion of repolarization is increased during exercise, exposing these patients to increased arrhythmic risk.
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16
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GRAY CHRISTOPHER, GULA LORNEJ, KLEIN GEORGEJ, SKANES ALLANC, YEE RAYMOND, SY RAYMOND, SALISBURY BENJAMINA, WONG JORGE, CHATTHA ISHVINDER, SUBBIAH RAJESHN, KRAHN ANDREWD. Expression of a Common LQT1 Mutation in Five Apparently Unrelated Families in a Regional Inherited Arrhythmia Clinic. J Cardiovasc Electrophysiol 2010; 21:296-300. [DOI: 10.1111/j.1540-8167.2009.01626.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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