1
|
Friedman A, Miles J, Liebelt J, Christia P, Engstrom K, Thachil R, Grushko M, Faillace RT. QT Dispersion and Drug-Induced Torsade de Pointes. Cureus 2021; 13:e12895. [PMID: 33643739 PMCID: PMC7903857 DOI: 10.7759/cureus.12895] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Background Amiodarone causes less drug-induced torsade de pointes (TdP) compared to other class III antiarrhythmics. Two theories proposed for this finding include that amiodarone has less repolarization heterogeneity, and/or decreases early after depolarization (EADs). Corrected QT (QTc) dispersion as measured on a surface electrocardiogram (ECG) represents spatial heterogeneity of ventricular repolarization. Objective The purpose of this study was to analyze the difference in QT dispersion between amiodarone and other class III antiarrhythmics and to determine the etiology of TdP. Methods This was a retrospective, observational study at Montefiore Medical Center between January 2005 and January 2015. Inclusion criteria were adults >18 years on amiodarone, dofetilide, or sotalol with prolonged QT interval on 12-lead ECG. ECGs were reviewed by three blinded observers. QTc was calculated using the Bazett and Framingham formulas. QTc dispersion was calculated by subtracting the shortest from the longest QTc. Analysis of variance (ANOVA) was applied for comparison between antiarrhythmic groups with Bonferroni correction for multiple comparisons. Results A total of 447 ECGs were reviewed and 77 ECGs met inclusion criteria. The average QT dispersion for amiodarone, dofetilide, and sotalol was 0.050, 0.037, and 0.034, respectively (p=0.006) and the average QTc dispersion by Bazett was 0.053, 0.038, and 0.037 (p=0.008) and by Framingham was 0.049, 0.036, and 0.035 (p=0.009), respectively. Conclusion Our results show that given the increase in QT dispersion seen with amiodarone, heterogeneous ventricular repolarization as measured by QTc dispersion likely does not account for the lower incidence of drug-induced TdP seen with amiodarone. The ability of amiodarone to decrease EADs via sodium-channel blockade is more likely the explanation for its lower incidence of drug-induced TdP.
Collapse
Affiliation(s)
- Ari Friedman
- Medicine, Jacobi Medical Center/Albert Einstein College of Medicine, Bronx, USA
| | - Jeremy Miles
- Cardiology, Montefiore Medical Center, Bronx, USA
| | - Jared Liebelt
- Cardiology, North Shore University Health Systems-Metro Chicago, Chicago, USA
| | | | | | - Rosy Thachil
- Cardiology, Albert Einstein College of Medicine/Jacobi Medical Center, Bronx, USA
| | - Michael Grushko
- Cardiology, Albert Einstein College of Medicine/Jacobi Medical Center, Bronx, USA
| | - Robert T Faillace
- Medicine, Albert Einstein College of Medicine/Jacobi Medical Center, Bronx, USA
| |
Collapse
|
2
|
Mozos I, Hancu M, Jost N, Cristescu A. Multipolar QRST isointegral maps and QT dispersion in old myocardial infarction. ACTA ACUST UNITED AC 2010; 97:11-21. [PMID: 20233686 DOI: 10.1556/aphysiol.97.2010.1.2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
UNLABELLED Chronic myocardial infarction (CMI) may create, due to structural heterogeneity, abnormal electrophysiological substrates which trigger re-entrant life-threatening ventricular arrhythmias. METHODS Electrical instability is assessed using body surface mapping (BSM) [multipolar isointegral QRST maps (mp I(QRST))] and 12-lead ECG (QT dispersion: QTd: the difference between maximal and minimal QT interval). The aim was to find the relation between mp I(QRST) and QTd in CMI patients. RESULTS The 32 CMI patients, underwent 12-lead ECG and 64-lead BSM. The 80% (25) of the patients had mp I(QRST) maps. QTd was larger in patients with mp than those with dipolar maps (dp): 170 +/- 20 ms in mp vs 94 +/- 19 ms in dp, respectively. The latter, mp I(QRST) was associated with a decrease of maximum and a stronger minimum. CONCLUSIONS Multipolar I(QRST) is associated with a loss of maximum values and increased absolute values of the minimum in CMI patients. I(QRST) and QTd provide similar information in predicting postinfarction arrhythmia risk.
Collapse
Affiliation(s)
- Ioana Mozos
- Department of Pathophysiology, University of Medicine and Pharmacy "Victor Babes", Timisoara, Romania.
| | | | | | | |
Collapse
|
3
|
Krantz MJ, Lowery CM, Martell BA, Gourevitch MN, Arnsten JH. Effects of Methadone on QT-Interval Dispersion. Pharmacotherapy 2005; 25:1523-9. [PMID: 16232014 DOI: 10.1592/phco.2005.25.11.1523] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
STUDY OBJECTIVE To evaluate the effects of methadone on QT-interval dispersion. DESIGN Single-center, prospective, cohort study. SETTING Methadone maintenance treatment facility. PATIENTS One hundred eighteen patients who were newly admitted to the facility. Intervention. Twelve-lead electrocardiograms (ECGs) were performed in patients at both baseline and 6 months after the start of methadone therapy. MEASUREMENTS AND MAIN RESULTS The ECGs were manually interpreted, and investigators were blinded to time interval and methadone dose. At least eight discernible ECG leads were required for study inclusion. Mean differences between baseline and follow-up rate-corrected QT (QTc) interval and QT dispersion were compared. Multivariate associations between clinical characteristics and magnitude of change in QT dispersion were assessed using linear regression. Mean +/- SD baseline QT dispersion was 32.9 +/- 12 msec, which increased to 42.4 +/- 15 msec (+9.5 +/- 18.6 msec, p<0.0001) after 6 months of therapy. The QTc increased by a similar magnitude (+14.1 msec, p<0.0001). No QT dispersion value exceeded 100 msec. The only variable associated with a greater increase in QT dispersion was antidepressant therapy (20 vs 8.5 msec, p=0.04). CONCLUSION Methadone modestly increased both QTc interval and QT dispersion. Increased QT dispersion reflects heterogeneous cardiac repolarization and occurs with nonantiarrhythmic agents, such as synthetic opioids. However, the magnitude of this effect appears to be substantially less with methadone than with antiarrhythmic drugs.
Collapse
Affiliation(s)
- Mori J Krantz
- Department of Medicine, Denver Health Medical Center, Denver, Colorado 80204, USA.
| | | | | | | | | |
Collapse
|
4
|
Aiba T, Shimizu W, Inagaki M, Satomi K, Taguchi A, Kurita T, Suyama K, Aihara N, Sunagawa K, Kamakura S. Excessive Increase in QT Interval and Dispersion of Repolarization Predict Recurrent Ventricular Tachyarrhythmia after Amiodarone. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2004; 27:901-9. [PMID: 15271008 DOI: 10.1111/j.1540-8159.2004.00557.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Although chronic amiodarone has been proven to be effective to suppress ventricular tachycardia (VT) and ventricular fibrillation (VF), how we predict the recurrence of VT/VF after chronic amiodarone remains unknown. This study evaluated the predictive value of the QT interval, spatial, and transmural dispersions of repolarization (SDR and TDR) for further arrhythmic events after chronic amiodarone. Eighty-seven leads body surface ECGs were recorded before (pre) and one month after (post) chronic oral amiodarone in 50 patients with sustained monomorphic VT associated with organic heart disease. The Q-Tend (QTe), the Q-Tpeak (QTp), and the interval between Tpeak and Tend (Tp-e) as an index of TDR were measured automatically from 87-lead ECG, corrected Bazett's method (QTce, QTcp, Tcp-e), and averaged among all 87 leads. As an index of SDR, the maximum (max) minus minimum (min) QTce (max-min QTce) and standard deviation of QTce (SD-QTce) was obtained among 87 leads. All patients were prospectively followed (15 +/- 10 months) after starting amiodarone, and 20 patients had arrhythmic events. The univariate analysis revealed that post max QTce, post SD-QTce, post max-min QTce, and post mean Tcp-e from 87-lead but not from 12-lead ECG were the significant predictors for further arrhythmic events. ROC analysis indicated the post max-min QTce > or = 106 ms as the best predictor of events (hazard ratio = 10.4, 95%, CI 2.7 to 40.5, P = 0.0008). Excessive QT prolongation associated with increased spatial and transmural dispersions of repolarization predict the recurrence of VT/VF after amiodarone treatment.
Collapse
Affiliation(s)
- Takeshi Aiba
- Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, Suita, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
5
|
Yoshiga Y, Shimizu A, Yamagata T, Hayano T, Ueyama T, Ohmura M, Itagaki K, Kimura M, Matsuzaki M. Beta-blocker decreases the increase in QT dispersion and transmural dispersion of repolarization induced by bepridil. Circ J 2002; 66:1024-8. [PMID: 12419934 DOI: 10.1253/circj.66.1024] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Bepridil is effective for intractable cardiac arrhythmia, but in rare cases will induce torsades de pointes (TdP) associated with QT interval prolongation. Beta-blockers will effectively prevent TdP in some clinical settings, so the effect of beta-blocker on the change in QT interval, QT dispersion and transmural dispersion of repolarization (TDR) induced by bepridil was investigated in 10 patients (7 male, 3 female; 62+/-6 years old) with intractable paroxysmal atrial fibrillation. The QTc interval, QTc dispersion and TDR were measured before and after 1 month of administration of bepridil, and then a beta-blocker was added and the QTc interval, QTc dispersion and TDR re-measured 1 month later. Bepridil significantly prolonged the QTc interval (0.42+/-0.05 to 0.50+/-0.08; p<0.01), and increased both the QT dispersion (0.07+/-0.05 to 0.14+/-0.08; p<0.01) and TDR (0.10+/-0.04 to 0.16+/-0.05; p<0.01). The addition of a beta-blocker decreased the QTc interval (0.50+/-0.08 to 0.47+/-0.04; p=0.09) and significantly decreased both the QTc dispersion (0.14 +/-0.08 to 0.06+/-0.02; p<0.01) and TDR (0.16+/-0.05 to 0.11+/-0.04; p<0.001). Compared with the control, the combination therapy significantly prolonged the QTc interval, but did not increase either QTc dispersion or TDR, and so was effective in all patients with intractable AF. The findings suggest that beta-blocker reduces the increase in QT dispersion and TDR induced by bepridil, and combined therapy with bepridil and beta-blocker might thus be useful for intractable atrial fibrillation.
Collapse
Affiliation(s)
- Yasuhiro Yoshiga
- Division of Cardiovascular Medicine, Department of Medical Bioregulation, Yamaguchi University School of Medicine, Ube, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Passman R, Kadish A. Polymorphic ventricular tachycardia, long Q-T syndrome, and torsades de pointes. Med Clin North Am 2001; 85:321-41. [PMID: 11233951 DOI: 10.1016/s0025-7125(05)70318-7] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
PMVT is an uncommon arrhythmia with multiple causes. Classification and management are based on the Q-T interval. Torsades de pointes denotes PMVT in the setting of a prolonged Q-T interval and usually is iatrogenic in origin, although congenital LQTS is being recognized more frequently. Therapy of PMVT focuses on the establishment of hemodynamic stability, the removal or correction of precipitants, and the acute and long-term inhibition of subsequent episodes. Evaluation of these patients should include a thorough history and physical examination and an assessment for underlying heart disease and known [figure: see text] eliciting factors. Long-term management must be tailored to the individual and the underlying cause and should be conducted by an experienced cardiac electrophysiologist.
Collapse
Affiliation(s)
- R Passman
- Departments of Medicine and Preventive Medicine, Cardiac Electrophysiology, Northwestern University Medical School, Chicago, Illinois, USA.
| | | |
Collapse
|
7
|
DiGregorio RV. Pharmacotherapeutic Advances in Cardiac Resuscitation: A Review of the Advanced Cardiac Life Support (ACLS) 2000 Guidelines and Their Impact on Pharmacy Practice. J Pharm Pract 2001. [DOI: 10.1106/khk1-tlwk-65tv-mjqt] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The treatment of sudden cardiac death is a challenging area of pharmacotherapy. Despite decades of medication use, outcomes from the treatment of cardiac arrest remain poor. Recent advances in the treatment of cardiac arrest have been incorporated into the American Heart Association’s Advanced Cardiac Life Support 2000 guidelines. A summary and review of these guidelines are presented. Included in the changes to the cardiac arrest treatment guidelines are new medications (amiodarone and vasopressin), new approaches to using medications and the evidence to support these changes. The implications of instituting these new guidelines and strategies for the implementation of the new paradigm are discussed.
Collapse
Affiliation(s)
- Robert V. DiGregorio
- Division of Pharmacy Practice, Arnold & Marie Schwartz College of Pharmacy & Health Sciences, Long Island University, 75 Dekalb Avenue, Brooklyn, NY 11201, Pharmacy & Emergency Services, The Brookdale University Hospital & Medical Center, 1 Brookdale Plaza, Brooklyn, NY 11212
| |
Collapse
|
8
|
Abstract
QT dispersion was originally proposed to measure spatial dispersion of ventricular recovery times. Later, it was shown that QT dispersion does not directly reflect the dispersion of recovery times and that it results mainly from variations in the T loop morphology and the error of QT measurement. The reliability of both automatic and manual measurement of QT dispersion is low and significantly lower than that of the QT interval. The measurement error is of the order of the differences between different patient groups. The agreement between automatic and manual measurement is poor. There is little to choose between various QT dispersion indices, as well as between different lead systems for their measurement. Reported values of QT dispersion vary widely, e.g., normal values from 10 to 71 ms. Although QT dispersion is increased in cardiac patients compared with healthy subjects and prognostic value of QT dispersion has been reported, values are largely overlapping, both between healthy subjects and cardiac patients and between patients with and without adverse outcome. In reality, QT dispersion is a crude and approximate measure of abnormality of the complete course of repolarization. Probably only grossly abnormal values (e.g. > or =100 ms), outside the range of measurement error may potentially have practical value by pointing to a grossly abnormal repolarization. Efforts should be directed toward established as well as new methods for assessment and quantification of repolarization abnormalities, such as principal component analysis of the T wave, T loop descriptors, and T wave morphology and wavefront direction descriptors.
Collapse
Affiliation(s)
- M Malik
- Department of Cardiological Sciences, St. George's Hospital Medical School, London, United Kingdom.
| | | |
Collapse
|
9
|
Boriani G, Biffi M, De Simone N, Bacchi L, Martignani C, Bitonti F, Zannoli R, Butrous G, Branzi A. Repolarization changes in a double-blind crossover study of dofetilide versus sotalol in the treatment of ventricular tachycardia. Pacing Clin Electrophysiol 2000; 23:1935-8. [PMID: 11139961 DOI: 10.1111/j.1540-8159.2000.tb07056.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
UNLABELLED The aim of this study was to determine whether a therapeutic response to Class III antiarrhythmic drugs is related to predictable changes in repolarization on the electrocardiogram (ECG). A group of 57 patients with ischemic heart disease and inducible ventricular tachycardia (VT) at electrophysiological study (EPS) were selected from a population enrolled in a randomized double-blind crossover study of dofetilide (500 micrograms bid) versus sotalol (160 mg bid). ECGs were analyzed blindly, and RR, QT (maximum value/12 leads), QTc (Bazett's formula), QT dispersion (QTmax-QTmin over 12 leads) and QTc dispersion, were calculated at baseline and on the third day of treatment (4 hours after dosing), when patients underwent EPS to test the effects of study drugs on VT inducibility. RESULTS At EPS 21 patients were responders to dofetilide and 22 to sotalol. On day 3, a significant increase in QT and QTc and decrease in QT and QTc dispersion, compared to baseline, was measured in responders and nonresponders, with both dofetilide and sotalol. No significant difference in QTc or QT dispersion between responders and nonresponders was observed in either treatment group. In conclusion, treatment with dofetilide and sotalol was associated with an increase in QT and QTc, and a decrease in QT and QTc dispersion. In contrast with previous reports, a differential effect on QT or QTc dispersion was not observed in drug responders versus nonresponders.
Collapse
Affiliation(s)
- G Boriani
- Institute of Cardiology, University of Bologna, Via Massarenti 9, 40138 Bologna, Italy.
| | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Gillis AM. Effects of antiarrhythmic drugs on QT interval dispersion--relationship to antiarrhythmic action and proarrhythmia. Prog Cardiovasc Dis 2000; 42:385-96. [PMID: 10768315 DOI: 10.1053/pcad.2000.0420385] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Class IA, IC, and III antiarrhythmic drugs prolong ventricular repolarization (VR) which is manifest as QT interval prolongation on the surface electrocardiogram. These drugs may prolong VR in a spatially heterogeneous manner which results in increased dispersion of VR. This may be manifest as increased QT interval dispersion. Antiarrhythmic drug-induced decreases in QT interval dispersion are associated with antiarrhythmic efficacy in patients with the long QT syndrome and in patients with sustained ventricular tachycardia. Antiarrhythmic drug-induced increases in QT interval dispersion are associated with ventricular proarrhythmia secondary to torsades de points ventricular tachycardia. A number of factors may modulate the effects of antiarrhythmic drugs on dispersion of VR, including the disease state, transient ischemia, electrolyte abnormalities, changes in autonomic tone, and hemodynamic stress.
Collapse
Affiliation(s)
- A M Gillis
- Division of Cardiology, Foothills Hospital, Calgary, Alberta, Canada
| |
Collapse
|
11
|
Abstract
Abnormalities in the QT interval can be divided into 3 types, prolongation of the QT interval, increases in the dispersion of the QT interval, and abnormalities in the heart rate dependent behavior of the QT interval. Abnormalities may be found in short or long-term recordings. Prolongation of the QT interval may reflect factors associated with an adverse prognosis in coronary disease and may in itself be arrhythmogenic. The data to date suggest that there is an association between adverse prognosis and QT interval prolongation in coronary disease, both before and after acute myocardial infarctions. This relationship is weak, however, and is not clinically useful. The data as to whether increased QT dispersion postmyocardial infarction relates to adverse prognosis is weak because there is no convincing evidence yet. If there is a relationship it is weak. Abnormalities in the rate dependent behavior of the QT interval are widely found, but as no large scale prospective study with mortality as an endpoint has yet been undertaken the significance of rate dependent abnormalities is uncertain. The widespread introduction of beat-to-beat QT analysis of 24 hour Holter tapes may take QT intervalology into the realm of clinical practice.
Collapse
Affiliation(s)
- P Davey
- Nuffield Department of Medicine, John Radcliffe Hospital, Oxford, United Kingdom
| |
Collapse
|
12
|
Houltz B, Darpö B, Swedberg K, Blomström P, Crijns HJ, Jensen SM, Svernhage E, Edvardsson N. Comparison of QT dispersion during atrial fibrillation and sinus rhythm in the same patients, at normal and prolonged ventricular repolarization. Europace 2000; 2:20-31. [PMID: 11225593 DOI: 10.1053/eupc.1999.0068] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
AIMS Drug-induced increase in QT dispersion has been associated with increased risk of ventricular proarrhythmia. The aim of the present study was to compare QT dispersion during atrial fibrillation and sinus rhythm in the same patients at normal and prolonged ventricular repolarization. METHODS AND RESULTS Sixty-one patients who had had chronic atrial fibrillation for 8 +/- 14 months received a 6 h infusion of the Ikr-blocker almokalant, the first 90 min of which are used for this analysis. The following day, after conversion to sinus rhythm, by almokalant (n = 19) or direct current cardioversion (n=42), an identical 90 min infusion was administered. Prior to infusion, there was no difference in precordial QT dispersion between atrial fibrillation and sinus rhythm (29 +/- 12 vs 36 +/- 17 ms, P=ns). During infusion, at prolonged repolarization, the increase in QT dispersion was greater during sinus rhythm than during atrial fibrillation (58 +/- 49 vs 30 +/- 15 ms, P=0.0011, after 30 min infusion). No correlation was found between QT dispersion and the QT or RR interval. CONCLUSION QT dispersion during atrial fibrillation does not differ from QT dispersion during sinus rhythm during normal repolarization. while measurement of QT dispersion during prolonged repolarization, induced by an Ikr-blocker, yielded larger values during sinus rhythm than during atrial fibrillation.
Collapse
Affiliation(s)
- B Houltz
- Department of Medicine, Sahlgrenska University Hospital, Ostra, Göteborg, Sweden
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Groh WJ, Shinn TS, Engelstein EE, Zipes DP. Amiodarone reduces the prevalence of T wave alternans in a population with ventricular tachyarrhythmias. J Cardiovasc Electrophysiol 1999; 10:1335-9. [PMID: 10515557 DOI: 10.1111/j.1540-8167.1999.tb00188.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Testing for the presence of microvolt T wave alternans (TWA) is useful for arrhythmic risk stratification. Whether antiarrhythmic pharmacotherapy affects the presence of TWA is unknown. We tested whether patients with known ventricular tachyarrhythmias who were receiving amiodarone were less likely to manifest TWA as compared with those not receiving amiodarone. METHODS AND RESULTS Forty-four patients with a history of ventricular tachyarrhythmias and an implantable cardioverter defibrillator (ICD) implanted at least 1 month earlier underwent TWA testing. In this group, 14 patients were receiving amiodarone and 30 were not. Indeterminate test results occurred in 13 patients without a significant difference in those receiving or not receiving amiodarone. In the 31 patients with determinate TWA testing, a positive test was less likely in those receiving amiodarone (1 of 9 [11%]) as compared with those not receiving amiodarone (14 of 22 [64%]; P = 0.04). During a follow-up period averaging 0.9 +/- 0.2 years, the presence of TWA (P = 0.04) and decreased left ventricular ejection fraction (P = 0.05) predicted appropriate ICD therapy for ventricular tachyarrhythmias. CONCLUSION The prevalence of TWA was decreased in a chronic ventricular tachyarrhythmic population receiving amiodarone as compared with a population not receiving amiodarone.
Collapse
Affiliation(s)
- W J Groh
- Krannert Institute of Cardiology, Indiana University School of Medicine, Indianapolis 46202-4800, USA.
| | | | | | | |
Collapse
|
14
|
Hailer B, Leeuwen PV, Lange S, Wehr M. Spatial distribution of QT dispersion measured by magnetocardiography under stress in coronary artery disease. J Electrocardiol 1999. [DOI: 10.1016/s0022-0736(99)90103-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
15
|
Cuomo S, Mayer MC, Comoletti C, D'Onofrio A, Buffardi S, Russo V. Abnormal QT Dispersion Predicts Unexpected Sudden Death in Young Patients with Thalassemia Major. Ann Noninvasive Electrocardiol 1999. [DOI: 10.1111/j.1542-474x.1999.tb00214.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
|
16
|
Yi G, Elliott P, McKenna WJ, Prasad K, Sharma S, Guo XH, Camm AJ, Malik M. QT dispersion and risk factors for sudden cardiac death in patients with hypertrophic cardiomyopathy. Am J Cardiol 1998; 82:1514-9. [PMID: 9874057 DOI: 10.1016/s0002-9149(98)00696-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This study examines the relation of QT dispersion (QTd) on a surface electrocardiogram (ECG) to clinical features and established risk factors of sudden cardiac death (SCD) in patients with hypertrophic cardiomyopathy (HC). One hundred fifty-six consecutive patients with HC (91 men, mean age 41+/-15 years, range 7 to 79) and 72 normal subjects (41 men, mean age 39+/-9 years, range 20 to 60) were studied. Standard 12-lead ECGs were recorded from each subject using a MAC VU electrocardiograph. Patients with nonsinus rhythm, atrioventricular conduction block, QRS duration > 120 ms, age < 15 years, and low amplitude T waves were excluded from the analysis (n=51). Another 22 patients who were receiving amiodarone and/or sotalol therapy were also excluded. QT interval and QTd were measured using automated analysis in the remaining 83 patients (46 men, age 40+/-14 years, range 16 to 76). QT interval (406+/-38 ms), QTc interval (432+/-27 ms), and QTd (43+/-25 ms) were significantly greater in patients with HC than in normal controls (386+/-31 ms, 404+/-16 ms, 26+/-16 ms, respectively) (p <0.0001). QTd was significantly greater in patients with HC with chest pain compared with asymptomatic or mildly symptomatic patients (50+/-28 ms vs 37+/-20 ms, p=0.02). Increased QTd was found in patients with dyspnea New York Heart Association functional classes II/III than in those with dyspnea New York Heart Association functional class I (50+/-27 ms vs 38+/-22 ms, p=0.04). QTd was weakly correlated with maximum left ventricular wall thickness (r=0.228, p=0.038). No significant association was found between QTd and any risk factors for SCD. Thus, patients with HC have increased QTd. The QTd correlates with symptomatic status. Assessment of QTd might provide complementary clinical characterization of patients with HC but its relation to SCD remains uncertain.
Collapse
Affiliation(s)
- G Yi
- Department of Cardiological Sciences, St. George's Hospital Medical School, London, United Kingdom
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Hailer B, Leeuwen P, Lange S, Gronemeyer D, Wehr M. Spatial Dispersion of the Magnetocardiographically Determined QT Interval and Its Components in the Identification of Patients at Risk for Arrhythmia after Myocardial Infarction. Ann Noninvasive Electrocardiol 1998. [DOI: 10.1111/j.1542-474x.1998.tb00039.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
|
18
|
Oikarinen L, Paavola M, Montonen J, Viitasalo M, Mäkijärvi M, Toivonen L, Katila T. Magnetocardiographic QT interval dispersion in postmyocardial infarction patients with sustained ventricular tachycardia: validation of automated QT measurements. Pacing Clin Electrophysiol 1998; 21:1934-42. [PMID: 9793090 DOI: 10.1111/j.1540-8159.1998.tb00013.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
QT dispersion is a measure of heterogeneity in ventricular repolarization. Increased ECG QT dispersion is associated with life-threatening ventricular arrhythmias. We studied if magnetocardiographic (MCG) measures of QT dispersion can separate postmyocardial infarction patients with and without susceptibility to sustained VT. Manual dispersion measurements were compared to a newly adapted automatic QT interval analysis method. Ten patients with a history of sustained VT (VT group) and eight patients without ventricular arrhythmias (Controls) were studied after a remote myocardial infarction. Single-channel MCGs were recorded from 42 locations over the frontal chest area and the signals were averaged. QT dispersion was defined as maximum-minimum or standard deviation of measured QT intervals. VT group showed significantly more QT and JT dispersion than Controls. QTapex dispersions were 127 +/- 26 versus 83 +/- 21 ms (P = 0.004) and QTend dispersions 130 +/- 37 versus 82 +/- 37 ms (P = 0.013), respectively. Automatic method gave comparable values. Their relative differences were 9% for QTapex and 27% for QTend dispersion on average. In conclusion, increased MCG QT interval dispersion seems to be associated with a susceptibility to VT in postmyocardial infarction patients. MCG mapping with automated QT interval analysis may provide a user independent method to detect nonhomogeneity in ventricular repolarization.
Collapse
Affiliation(s)
- L Oikarinen
- Department of Medicine, Helsinki University Central Hospital, Finland
| | | | | | | | | | | | | |
Collapse
|