Effects of the Ventricular Activation Sequence on the JT Interval

Banker, Jeffrey; Dizon, José; Reiffel, James A.

doi:10.1016/s0002-9149(97)89276-4

Cited by 23 publications

(15 citation statements)

References 8 publications

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“…This suggestion seems to be important for the calculation of QT dispersion in VPBs, because the QT interval encompasses the duration of ventricular depolarization and repolarization together and the widened QRS complexes of VPBs can contribute to the risk of cardiac death. On the other hand, it was shown that the JT interval, similar to the QT interval, depends on the duration of ventricular depolarization and is markedly shorter for some ventricular conduction abnormalities [18]. Using univariate analysis, we observed a greater prognostic importance of QT dispersion in comparison with JT dispersion.…”

Section: Discussionmentioning

confidence: 66%

Dispersion of QT Interval following Ventricular Premature Beats and Mortality after Myocardial Infarction

Dabrowski

Kramarz²,

Piotrowicz³

1999

Cardiology

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In a group of 193 postinfarction patients with ventricular premature beats on a resting 12-lead ECG, the dispersion of QT and JT intervals was calculated as a difference between maximum and minimum QT and JT intervals in ventricular premature beats. During a follow-up of 38 ± 17 months, death from all causes was noted in 56 patients. Univariate predictors of mortality included QT dispersion ≥100 ms, JT dispersion ≥100 ms, left ventricular ejection fraction <40%, complete bundle branch block, ‘R-on-T’ index of ventricular premature beats <1 and age of patients >60 years. At multivariate Cox proportional hazards survival analysis, only QT dispersion ≥100 ms, left ventricular ejection fraction <40% and complete bundle branch block had an independent relation to postinfarction mortality. The final model selected increased QT dispersion as the prognostic factor which was the most strongly related to mortality (χ² = 23.60, p = 0.0000).

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Section: Discussionmentioning

confidence: 66%

Dispersion of QT Interval following Ventricular Premature Beats and Mortality after Myocardial Infarction

Dabrowski

Kramarz²,

Piotrowicz³

1999

Cardiology

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“…The Bazett formula is commonly applied to adjust QT interval for heart rate, considering the interval is underestimated at low heart rate and overestimated at fast heart rate with the Bazett formula, we also adopted the Fridericia formula. 16 The JTc has been proposed as a more appropriate measure of ventricular repolarization than QTc when QRS duration is ≥120 ms. 17 The JTc was derived simply by subtracting the QRS duration from QTcB. The cut off value of QTcB is 430 ms for men and 450 ms for women.…”

Section: Methodsmentioning

confidence: 99%

Patients with Metabolic Syndrome Have Prolonged Corrected QT Interval (QTc)

Bai

Sun

et al. 2009

Clinical Cardiology

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Background: Prolongation of corrected QT interval (QTc) increases morbidity and mortality and QTc has been found to be longer in patients with diabetes mellitus than in healthy controls. It is still inconclusive whether the metabolic syndrome results in QTc prolongation. Hypothesis: We hypothesized that metabolic syndrome might contribute to risk of QTc prolongation. The hypothesis was tested in a large population. Methods: A total of 5,815 individuals (men: 1,950, women: 3,865 aged 20-80 years) were enrolled. Metabolic syndrome was defined according to the revised third NationalCholesterol Education Program Adult Treatment Panel (NCEP-ATP III). QTc was calculated by using Bazett and Fridericia equations and the corrected JT interval (JTc) was derived by subtracting the QRS duration from the QTcB. All individuals had physical examinations, electrocardiograms, echocardiography, and blood tests. Results: Individuals with metabolic syndrome had longer QTcs and JTc than those without metabolic syndrome (439.84 ms versus 430.90 ms in men, 456.37 ms versus 445.12 ms in women, respectively, p < 0.001 using Bazett formula). The more the number of abnormal metabolic parameters they had, the longer the QTcs and JTc they had. Trend analysis indicated that QTcB, QTcF , and JTc were significantly correlated to the number of abnormal metabolic parameters both in men and in women. After being adjusted for conventional risk factors, QTcB, QTcF , and JTc remained negatively associated with serum potassium concentration and positively associated with interventricular septal thickness. Conclusions: Metabolic syndrome is a risk factor for prolonged QTc, which may further increase cardiovascular morbidity and mortality in the subjects with metabolic syndrome.

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“…6,7 Other researchers have found that the JT interval is not independent of the QRS duration, with the relationship varying according to the conduction abnormality. 8 In view of the practical importance of these issues, we examined the prognostic value of QT and JT in normal conduction and in wide QRS complex. Our primary goal was to derive a simple, clinically useful tool for determining abnormally long repolarization in the face of ventricular conduction delay and to validate it against future coronary heart disease (CHD).…”

mentioning

confidence: 99%

Prognostic Significance of Corrected QT and Corrected JT Interval for Incident Coronary Heart Disease in a General Population Sample Stratified by Presence or Absence of Wide QRS Complex

2003

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Background-Heart rate-corrected QT interval (QTc) is the traditional method of assessing the duration of repolarization.Prolonged heart rate-corrected QT interval is associated with higher risk of mortality in patients with coronary heart disease (CHD) and in the general population. However, the QTc is typically not evaluated when QRS duration is Ն120 ms, because increased QRS duration (QRSd) contributes to QT interval prolongation. In these circumstances, the JT interval has been proposed as a more valid way to assess ventricular repolarization. Methods and Results-To allow for variation in heart rate, corrected JT interval (JTc) was defined as QTcϪQRSd. Using data from the Atherosclerosis Risk in Communities Study, JTc and QTc were compared for their prognostic associations with incident CHD events among 14 696 men and women who were CHD-free at baseline, having either normal conduction or wide QRS complex. Among individuals with normal QRS duration, logistic regression adjusted for age, hypertensive status, diabetes, race, systolic blood pressure, smoking, HDL and LDL cholesterol, R-R interval, and menopausal status in women showed QTc and JTc were nonpredictive of future coronary events in men but significant in women. In individuals with wide QRS complex (QRSd Ն120 ms), similar analyses showed JTc had a significant prognostic advantage compared with QTc in men but not in women, among whom only 11 events occurred. Conclusions-The JTc is a simple measurement that is a significant independent predictor of incident CHD events in men with wide QRS complex.

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Effects of the Ventricular Activation Sequence on the JT Interval

Cited by 23 publications

References 8 publications

Dispersion of QT Interval following Ventricular Premature Beats and Mortality after Myocardial Infarction

Dispersion of QT Interval following Ventricular Premature Beats and Mortality after Myocardial Infarction

Patients with Metabolic Syndrome Have Prolonged Corrected QT Interval (QTc)

Prognostic Significance of Corrected QT and Corrected JT Interval for Incident Coronary Heart Disease in a General Population Sample Stratified by Presence or Absence of Wide QRS Complex

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