Microvolt-level T-wave alternans determination using the spectral method in patients with QT prolongation: value of adjusting the T-wave window.
J Electrocardiol
; 45(6): 758-63, 2012.
Article
em En
| MEDLINE
| ID: mdl-22960166
ABSTRACT
BACKGROUND:
Microvolt-level T-wave alternans (MTWA) measured by the spectral method is a useful risk predictor for sudden cardiac death because of its high negative predictive value. MTWA analysis software selects a segment of the ECG that encompasses the T-wave in most individuals, but may miss the T-wave end in patients with QT prolongation. HYPOTHESES (1) In patients with QT prolongation, adjustment of the T-wave window will increase the sensitivity of MTWA detection. (2) The extent of T-wave window adjustment needed will correspond to the degree of QT prolongation.METHODS:
Using data from long-QT syndrome patients, including QTc <0.45 s (normal), 0.45-0.49 s (moderate prolongation), and ≥ 0.50s (severe prolongation), MTWA analysis was performed before and after T-wave window adjustment.RESULTS:
Of 119 patients, 74% required T-wave window adjustment. There was a stronger association between the magnitude of the T-wave offset and the unadjusted QT than between the magnitude of the T-wave offset and QTc (Spearman correlation coefficient 0.690 vs. 0.485 respectively, P<.05). Of 99 initially negative MTWA results, 4 became non-negative after adjustment of the T-wave window (P<.05). All 8 initially positive studies and 12 initially indeterminate studies remained positive and indeterminate, respectively.CONCLUSIONS:
T-wave window adjustment can enable detection of abnormal MTWA that otherwise would be classified as "negative" or "normal." Newly developed T-wave window adjustment software may further improve the negative predictive value of MTWA testing and should be validated in a structural heart disease population.
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Algoritmos
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Síndrome do QT Longo
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Reconhecimento Automatizado de Padrão
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Diagnóstico por Computador
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Eletrocardiografia
Tipo de estudo:
Diagnostic_studies
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Prognostic_studies
Limite:
Adult
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Female
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Humans
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Male
Idioma:
En
Revista:
J Electrocardiol
Ano de publicação:
2012
Tipo de documento:
Article
País de afiliação:
Estados Unidos