Analysis of T-Wave Morphology From the 12-Lead Electrocardiogram for Prediction of Long-Term Prognosis in Male US Veterans

Abstract

Background-The aim of the present study was to assess the prognostic value of novel repolarization descriptors from the 12-lead ECG in a large cohort of US veterans. Methods and Results-Male US veterans (nϭ813) with cardiovascular disease had digital 12-lead ECGs recorded at the VA Medical Center, Washington, DC, between 1984 and 1991. The patient series was retrospectively compiled in 1991; follow-up was prospectively assessed until 2000. Novel ECG variables characterizing repolarization and the T-wave loop were automatically analyzed. Of 772 patients with technically analyzable data, 252 patients (32.6%) died after a mean follow-up of 10.4Ϯ3.8 years. Direct comparison between dead and alive patients showed that the so-called T-wave residua (the absolute and relative amount of nondipolar contents within the T wave) predicted mortality (111 900Ϯ164 700 versus 85 600Ϯ144 800 between dead and alive patients, PϽ0.0002; and 0.43Ϯ0.62% versus 0.33Ϯ0.56%, PϽ0.0005 for the absolute and relative T-wave residuum, respectively). On Cox regression analysis entering age, left ventricular ejection fraction, echocardiographic left ventricular hypertrophy, and either of the T-wave residua, risk prediction was independent for the absolute (Pϭ0.022) and for the relative (Pϭ0.006) T-wave residuum, respectively, with age (PϽ0.0001), presence of left ventricular hypertrophy (Pϭ0.002), and left ventricular ejection fraction (Pϭ0.004) also being predictors of survival. Conclusions-The heterogeneity of myocardial repolarization, measured by the so-called T-wave residuum in the ECG, confers long-term independent prognostic information in US veterans with cardiovascular disease.

Usefulness of QT-interval parameters for cardiovascular risk stratification in type 2 diabetic patients with arterial hypertension

“…Future efforts should focus on new, more reliable and precise methods of assessing ventricular repolarization complexity and abnormalities, such as spatial T-wave axis deviation, 35 descriptors of T-wave morphology 36 or principal component analysis of T-wave vector, 37 as well as on intervention studies to verify whether these repolarization abnormalities could be modified to decrease cardiovascular risk.…”

Effects of controlled hypoglycaemia on cardiac repolarisation in patients with type 1 diabetes

“…Therefore, novel repolarisation analyses have been developed to evaluate the characteristics of cardiac repolarisation with greater accuracy. New descriptors of T-wave morphology and the spatial QRS-T angle have already been shown to have better prognostic values than QT interval or QT dispersion with regard to cardiac events in several populations [12][13][14][15][16] and increased complexity of ventricular repolarisation measured by principal component analysis of T-wave morphology has been found to distinguish patients with congenital long QT syndrome from unaffected participants [17,18]. Therefore, we decided to study the effects of controlled insulininduced hypoglycaemia on the T-wave loop and the QRS complex loop in type 1 diabetic patients and age-matched non-diabetic control participants.…”

Detection of hypertrophic cardiomyopathy is improved when using advanced rather than strictly conventional 12-lead electrocardiogram

“…Advanced ECG parameters derived from signal averaging. Signal averaging was performed using software developed by the authors 20,21,25,28 to generate results for parameters of: 1) 12-lead HF QRS ECG; 20 2) derived 3-dimensional ECG, using the Frank-lead reconstruction technique of Kors et al 29 to derive several vectocardiographic parameters previously described by Draper et al, 30 including for example the spatial mean QRS-T angle 17,28,31 and the magnitude, 30 azimuth /elevation 30 and beat-to-beat variation 16 of the spatial ventricular gradient and its components; and 3) QRS and Twaveform complexity via SVD, for example to derive parameters such as the principal component analysis (PCA) ratio, 21,22,32 the "relative residuum" 21,23 and the dipolar and nondipolar voltages 19,25 of the QRS and T waveforms. The majority of the parameters studied and their related detailed methods have been described in other recent publications.…”

“…These techniques include beat-to-beat QT variability (QTV) 8-10, 12, 13 and R-wave to R-wave variability (RRV); 14, 15 "3-dimensional" (spatial and spatiotemporal) ECG; [16][17][18][19] highfrequency (HF) QRS ECG; 20 and detailed studies of waveform complexity by singular value decomposition (SVD). 7,19,[21][22][23] A theoretical advantage of computerized ECG systems is that they allow for multiple conventional and advanced ECG techniques to be performed in software during a single digital recording. Related results can then be integrated (scored) automatically by using statistical or pattern recognition techniques to maximize diagnostic or predictive accuracy.…”