Long QT syndrome. New electrocardiographic characteristics.

摘要: The long QT syndrome is electrocardiographically characterized by a prolonged interval and several other, more subtle, ST-T-U wave abnormalities, most of which have not been quantified. To determine the possible usefulness new electrocardiographic characteristics in identifying patients with known syndrome, logistic regression models were applied to data base seven new, relatively independent, repolarization variables. These measured on digitized 12-lead electrocardiograms 315 normal subjects 37 (members well-identified families, QTc greater than 0.44 second, 27% symptomatic), who ranged age from 17 60 years. Electrocardiographic variables that independently differentiated (p less 0.001) included quantitative measures repolarization: early duration, rate, T symmetry, late phenomena, heterogeneity. All selected except duration variable essentially independent (r2 0.15), all contributed significantly identification syndrome. A classification model five predictor resulted an estimated sensitivity (95% confidence interval) 92.6% (81.6-100%) specificity 95.8% (93.6-98.1%). This performed better alternative was based as single variable. symptomatic status could be predicted any combination investigated model.