Relation between Beat‐to‐Beat QT Interval Variability and T‐Wave Amplitude in Healthy Subjects

Abstract

Objectives: Elevated beat-to-beat QT interval variability (QTV) has been associated with increased cardiovascular morbidity and mortality.The aim of this study was to investigate interlead differences in beat-to-beat QTV of 12-lead ECG and its relationship with the T wave amplitude.Methods: Short-term 12-lead ECGs of 72 healthy subjects (17 f, 38 ± 14 years; 55 m, 39 ± 13 years) were studied. Beat-to-beat QT intervals were extracted separately for each lead using a template matching algorithm. We calculated the standard deviation of beat-to-beat QT intervals as a marker of QTV as well as interlead correlation coefficients. In addition, we measured the median T-wave amplitude in each lead.Results: There was a significant difference in the standard deviation of beat-to-beat QT intervals between leads (minimum: lead V 3 (2.58 ± 1.36 ms), maximum: lead III (7.2 ± 6.4 ms), ANOVA: P < 0.0001). Single measure intraclass correlation coefficients of beat-to-beat QT intervals were 0.27 ± 0.18. Interlead correlation coefficients varied between 0.08 ± 0.33 for lead III and lead V 1 and 0.88 ± 0.09 for lead II and lead aVR. QTV was negatively correlated with the T-wave amplitude (r = -0.62, P < 0.0001). There was no significant affect of mean heart rate, age or gender on QT variability (ANOVA: P > 0.05).

Autonomic modulation of repolarization instability in patients with heart failure prone to ventricular tachycardia

“…Subjects with normal hearts were significantly younger and predominant women compared with the other study groups, which is in accordance with the general demographic profile of patients with supraventricular tachycardia without other cardiovascular diseases (38). However, QTV has been found to be relatively insensitive to age and does not differ between healthy younger and older adults (25,30). Although sex differences in QTV have been insufficiently investigated, as with the rate corrected QT interval (36), QTV (25) and QTV/HRV (30) have been shown to be higher in women than in men.…”

“…However, QTV has been found to be relatively insensitive to age and does not differ between healthy younger and older adults (25,30). Although sex differences in QTV have been insufficiently investigated, as with the rate corrected QT interval (36), QTV (25) and QTV/HRV (30) have been shown to be higher in women than in men. The higher proportion of women in the H Norm group may therefore have diminished the observed differences in QTV and QTV/HRV between the H Norm and HF groups.…”

Entropy Analysis of RR and QT Interval Variability during Orthostatic and Mental Stress in Healthy Subjects

“…Thirdly, we recorded only a single horizontal bipolar thoracic lead ECG. The QTV differs among leads [23] and lead II is typically used due to large T waves.…”

Reduced QT Variability and increased QT/RR slope in ECG signals of Depressed Patients with Suicidal Ideation

“…Moreover, we have also measured the amplitude of the T-waves for each beat by following the same procedure that has been described earlier articles [14,15]. Here, the T-wave for each beat was obtained by considering the peak of the voltage deflection within the ST segment of ECG signal.…”