Evidence regarding clinical use of microvolt T-wave alternans

Background: Microvolt T-wave alternans (MTWA) testing in many studies has proven to be a highly accurate predictor of ventricular tachyarrhythmic events (VTEs) in patients with risk factors for sudden cardiac death (SCD)
Background: Microvolt T-wave alternans (MTWA) testing in many studies has proven to be a highly accurate predictor of ventricular tachyarrhythmic events (VTEs) in patients with risk factors for sudden cardiac death (SCD) but without a prior history of sustained VTEs (primary prevention patients). In some recent studies involving primary prevention patients with prophylactically implanted cardioverter-defibrillators (ICDs), MTWA has not performed as well. Objective: This study examined the hypothesis that MTWA is an accurate predictor of VTEs in primary prevention patients without implanted ICDs, but not of appropriate ICD therapy in such patients with implanted ICDs. Methods: This study identified prospective clinical trials evaluating MTWA measured using the spectral analytic method in primary prevention populations and analyzed studies in which: (1) few patients had implanted ICDs and as a result none or a small fraction (≤15%) of the reported end point VTEs were appropriate ICD therapies (low ICD group), or (2) many of the patients had implanted ICDs and the majority of the reported end point VTEs were appropriate ICD therapies (high ICD group). Results: In the low ICD group comprising 3,682 patients, the hazard ratio associated with a nonnegative versus negative MTWA test was 13.6 (95% confidence interval [CI] 8.5 to 30.4) and the annual event rate among the MTWA-negative patients was 0.3% (95% CI: 0.1% to 0.5%). In contrast, in the high ICD group comprising 2,234 patients, the hazard ratio was only 1.6 (95% CI: 1.2 to 2.1) and the annual event rate among the MTWA-negative patients was elevated to 5.4% (95% CI: 4.1% to 6.7%). In support of these findings, we analyzed published data from the Multicenter Automatic Defibrillator Trial II (MADIT II) and Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) trials and determined that in those trials only 32% of patients who received appropriate ICD therapy averted an SCD. Conclusion: This study found that MTWA testing using the spectral analytic method provides an accurate means of predicting VTEs in primary prevention patients without implanted ICDs; in particular, the event rate is very low among such patients with a negative MTWA test. In prospective trials of ICD therapy, the number of patients receiving appropriate ICD therapy greatly exceeds the number of patients who avert SCD as a result of ICD therapy. In trials involving patients with implanted ICDs, these excess appropriate ICD therapies seem to distribute randomly between MTWA-negative and MTWA-nonnegative patients, obscuring the predictive accuracy of MTWA for SCD. Appropriate ICD therapy is an unreliable surrogate end point for SCD. Key words: Arrhythmia; Sudden cardiac death; Cardiac arrest; ICD; T-wave alternans; Surrogate endpoint; Ventricular tachyarrhythmic event; Primary prevention
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Metadaten
Author:Stefan H. Hohnloser, Takanori Ikeda, Richard J. Cohen
URN:urn:nbn:de:hebis:30-112917
URL:http://hdl.handle.net/1721.1/61763
DOI:http://dx.doi.org/http://dx.doi.org/10.1016/j.hrthm.2008.10.011
Parent Title (English):Heart Rhythm
Document Type:Preprint
Language:English
Date of Publication (online):2011/08/24
Year of first Publication:2011
Publishing Institution:Univ.-Bibliothek Frankfurt am Main
Release Date:2011/08/24
Tag:Arrhythmia ; Cardiac arrest ; ICD ; Sudden cardiac death ; Surrogate endpoint ; T-wave alternans ; Ventricular tachyarrhythmic event
Volume:2009
Issue:Supplement 1 (2009) 6.3
Pagenumber:9
First Page:36
Last Page:44
Note:
Creative Commons Attribution-Noncommercial-Share Alike 3.0 http://creativecommons.org/licenses/by-nc-sa/3.0/
Source:Author's final manuscript ; http://hdl.handle.net/1721.1/61763 ; Published as: http://dx.doi.org/10.1016/j.hrthm.2008.10.011 ; Heart Rhythm 6.3, Supplement 1 (2009): S36-S44
HeBIS PPN:274499908
Institutes:Medizin
Dewey Decimal Classification:610 Medizin und Gesundheit
Sammlungen:Universitätspublikationen
Licence (German):License LogoCreative Commons - Namensnennung-Keine kommerzielle Nutzung-Weitergabe unter gleichen Bedingungen

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