T-wave alternans and dispersion of the QT interval as risk stratification markers in patients susceptible to sustained ventricular arrhythmias

Armoundas, Antonis A.; Osaka, Motohisa; Mela, Theofanie; Rosenbaum, David S.; Ruskin, Jeremy N.; Garan, Hasan; Cohen, Richard J.

doi:10.1016/s0002-9149(98)00570-0

Cited by 39 publications

(20 citation statements)

References 17 publications

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“…ϭ sudden cardiac death VF ϭ ventricular fibrillation VT ϭ ventricular tachycardia from the meta-analysis: five studies were not prospective (12,16,19,35,38), five studies did not use primary data (21,22,27,29,34), two studies assessed pacing-induced T-wave alternans (5,25), one study had less than six months of follow-up (18), and one study did not provide enough primary data (31). An attempt was made to contact the author of the study that did not provide enough data (31).…”

Section: Abbreviations and Acronymsmentioning

confidence: 99%

Microvolt T-Wave Alternans for the Risk Stratification of Ventricular Tachyarrhythmic Events

Gehi

Stein

Metz

et al. 2005

Journal of the American College of Cardiology

218

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Microvolt T-wave alternans testing has significant value for the prediction of ventricular tachyarrhythmic events; however, there are significant limitations to its use. The predictive value of MTWA varies significantly depending on the population studied. Careful standardization is needed for what constitutes abnormal MTWA. The incremental prognostic value of MTWA when used with other methods of risk stratification is unclear.

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Section: Abbreviations and Acronymsmentioning

confidence: 99%

Microvolt T-Wave Alternans for the Risk Stratification of Ventricular Tachyarrhythmic Events

Gehi

Stein

Metz

et al. 2005

Journal of the American College of Cardiology

218

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“…[1][2][3][4][5] The transition from concordant to discordant action potential duration (APD) alternans is also a harbinger of vulnerability to ventricular fibrillation. 6 -10 Recent optical mapping studies by Pastore et al 9 linked these 2 findings by demonstrating that with increasing pacing rate, APD first alternates concordantly throughout the tissue (causing T-wave alternans) and then becomes spatially discordant, with areas of long-short APD alternation adjacent to areas with short-long APD alternation (causing both QRS and T-wave alternans).…”

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confidence: 99%

Mechanisms of Discordant Alternans and Induction of Reentry in Simulated Cardiac Tissue

Qu¹,

et al. 2000

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Background-T-wave alternans, which is associated with the genesis of cardiac fibrillation, has recently been related to discordant action potential duration (APD) alternans. However, the cellular electrophysiological mechanisms responsible for discordant alternans are poorly understood. Methods and Results-We simulated a 2D sheet of cardiac tissue using phase 1 of the Luo-Rudy cardiac action potential model. A steep (slope Ͼ1) APD restitution curve promoted concordant APD alternans and T-wave alternans without QRS alternans. When pacing was from a single site, discordant APD alternans occurred only when the pacing rate was fast enough to engage conduction velocity (CV) restitution, producing both QRS and T-wave alternans. Tissue heterogeneity was not required for this effect. Discordant alternans markedly increases dispersion of refractoriness and increases the ability of a premature stimulus to cause localized wavebreak and induce reentry. In the absence of steep APD restitution and of CV restitution, sustained discordant alternans did not occur, but reentry could be induced if there was marked electrophysiological heterogeneity. Both discordant APD alternans and preexisting APD heterogeneity facilitate reentry by causing the waveback to propagate slowly. Conclusion-Discordant alternans arises dynamically from APD and CV restitution properties and markedly increases dispersion of refractoriness. Preexisting and dynamically induced (via restitution) dispersion of refractoriness independently increase vulnerability to reentrant arrhythmias. Reduction of dynamically induced dispersion by appropriate alteration of electrical restitution has promise as an antiarrhythmic strategy. (Circulation.

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“…26 TWA is considered to reflect the temporal dispersion of repolarization, but the correlation between QT dispersion and TWA has not been clarified. Armoundas et al reported a moderate correlation between QTc at rest and TWA, 30 but in their study, 62% of the study population had coronary artery disease, so the relationship between TWA and the QT indices in cardiomyopathy could not be inferred.…”

Section: Discussionmentioning

confidence: 72%

Relationship Between the QT Indices and the Microvolt-Level T Wave Alternans in Cardiomyopathy.

et al. 2001

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wave alternans (TWA) is an electrocardiographic abnormality of beat-to-beat changes in the morphology of ventricular repolarization, which was first described by Mines in 1913. 1 Experimental and clinical observations indicate that TWA can be associated with an increased propensity for serious ventricular arrhythmias, particularly ventricular fibrillation, 2-7 and TWA can occur in clinical conditions, such as long QT syndrome, 5,8 myocardial ischemia 6,7,9,10 and metabolic and electrolyte disturbances. 11,12 Visually apparent TWA on the electrocardiogram (ECG) has been a fairly uncommon finding in practice, but using the spectral method of Smith et al, 3 Rosenbaum et al found a strong correlation between the presence of TWA at the microvolt level and the electrophysiologic inducibility of ventricular arrhythmias. 13 TWA shows a temporal dispersion of repolarization and because QT dispersion, calculated as the range of QT intervals (QTmax-QTmin), is associated with the risk of ventricular tachyarrhythmia and of sudden cardiac death in a broad spectrum of clinical conditions including congenital and acquired long QT syndromes, 14 myocardial infarction [15][16][17] and cardiomyopathies, 18-21 it has been proposed as a simple noninvasive measurement of the spatial dispersion of repolarization available from the 12-lead body surface ECG. 14 Since Antzelevitch et al showed 'the transmural dispersion of repolarization', 22 several studies [23][24][25] have attempted to understand the abnormality of ventricular repolarization using not only the duration from the onset of the QRS complex to the end of the T wave (QT), but also the duration from the onset of the QRS complex to the peak of the T wave (QTp) and the duration from the peak of the T wave to the end of the T wave (TpE). Both TWA and QT dispersion have been proposed as useful noninvasive tools for risk assessment of ventricular tachyarrhythmias. QT dispersion and these QT indices are generally measured at rest, and TWA is evaluated during exercise. In this study, we clarified the relationship between TWA and the QT indices (including QTp and TpE), particularly that of the QT indices during exercise, in cardiomyopathy. We compared the results from patients with dilated cardiomyopathy (DCM), a disease of contraction disturbance, with those from patients with hypertrophic cardiomyopathy (HCM), a disease of impaired relaxation. Methods PatientsThe study group consisted of 47 patients with DCM (M:F = 37:10, 52±14 years old) and 39 patients with HCM (M:F = 36:3, 58±11 years old) who were referred to Kobe University Hospital. Informed consent was obtained from all participants. Beta-blockers and antiarrhythmic agents were discontinued for more than 5 times of their respective half-lives before examination. Measurement of the Microvolt-Level TWATWA was measured at rest and during controlled bicycle exercise testing (EXT) using a CH2000 system (Cambridge Heart Inc, Bedford, MA, USA), which used the spectral method described by Smith et al. 3 We performed TWA testing as d...

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T-wave alternans and dispersion of the QT interval as risk stratification markers in patients susceptible to sustained ventricular arrhythmias

Cited by 39 publications

References 17 publications

Microvolt T-Wave Alternans for the Risk Stratification of Ventricular Tachyarrhythmic Events

Microvolt T-Wave Alternans for the Risk Stratification of Ventricular Tachyarrhythmic Events

Mechanisms of Discordant Alternans and Induction of Reentry in Simulated Cardiac Tissue

Relationship Between the QT Indices and the Microvolt-Level T Wave Alternans in Cardiomyopathy.

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