Higher QTc Dispersion Research Articles

MİTRAL KAPAK PROLAPSUSU OLAN ÇOCUKLARDA KARDİYAK OTONOMİK DİSFONKSİYONUN VE ARİTMİ RİSKİNİN DEĞERLENDİRİLMESİ

Objective: The occurrence of symptoms in patients with mitral valve prolapse (MVP) is linked to autonomic dysfunction and neuroendocrine causes rather than progressive mitral valve insufficiency. The goal was to assess the risk of autonomic dysfunction and arrhythmia in patients with MVP.
 Methods: The study included 63 patients with primary MVP and a control group of 64 children of similar age and gender. Following a physical examination, all patients' histories were taken, and 12-lead ECGs, autonomic function tests, echocardiography, and 24-hour Holter rhythm studies were performed.
 Results: The patient group had a higher mean resting heart rate than the control group. Orthostatic hypotension was found in 8 patients (12.6%) and 4 children (6.2%) in the control group. When compared to the control group, patients with MVP had higher QTc dispersion, frontal QRS-T angle, Tp-e interval, and Tp-e/QTc ratio. There was no significant difference between the two groups in terms of conventional measurements of heart rate variability in the Holter ECG, as well as no significant difference in HRDC.
 Conclusion: Although cases with pathological findings in the initial ECG were excluded from our study, we believe that the high frontal QRS-T angle observed in MVP patients is a novel and significant finding. Furthermore, it has been discovered that HRDC, a new and understudied parameter in children, does not show a significant difference in patients with MVP.

QTc dispersion as a novel marker in identifying patients requiring an epicardial approach for ablation of scar mediated ventricular tachycardia

IntroductionEpicardial exit sites of ventricular tachycardia (VT) are frequently encountered during VT ablation requiring an epicardial ablation approach for successful elimination of VT. We sought to assess the utility of repolarization markers in identifying individuals requiring an epicardial ablation approach in addition to an endocardial approach. Methods32 patients who underwent successful ablation for scar mediated VT were included in the study. Fourteen patients who required a combined endocardial and epicardial VT ablation were defined as epicardial VT group (Epi) whereas 18 patients who were successfully ablated from the endocardium alone constituted the endocardial VT group (Endo). Repolarization markers during sinus rhythm were compared between the two groups. ResultsA higher QTc max and QTc dispersion were seen in the Epi group compared to Endo group (479 ± 34 vs 449 ± 20, p = 0.008 and 63 ± 13 vs 38 ± 8, p = 0.001, respectively). Ts-p and Ts-p/Tp-e were higher in the Epi group (166 ± 23 vs 143 ± 23, p = 0.008 and 1.55 ± 0.26 vs 1.3 ± 0.21, p < 0.005). On multivariate regression, QTc dispersion was an independent predictor of the need for an epicardial approach to ablation. A QTc dispersion more than 51.5 msec identified individuals requiring a combined epicardial and endocardial approach to ablation with a sensitivity of 92.9% and a specificity of 100%. ConclusionsPatients requiring an epicardial ablation have a higher QTc dispersion. A value greater than 51.5 msec reliably differentiates between the two groups with high sensitivity and specificity.

QT interval dispersion in North Indian children with Kawasaki disease without overt coronary artery abnormalities

Increased QT interval dispersion has been associated with an increased risk for ventricular arrhythmias and sudden cardiac events. We examined the QT interval dispersion in 20 North Indian children with Kawasaki disease (KD) with no coronary artery abnormalities on echocardiography compared the same with matched controls. The study population consisted of 20 children in convalescent phase of KD and 20 age and sex-matched healthy controls. Intervals were measured with the use of a digital caliper with least count of 0.01mm by a single blinded observer. The QTc dispersion was calculated as the difference between the maximum and minimum corrected QT intervals in 12 and 8 leads (i.e. the 6 precordial leads, the shortest extremity lead, and the median of the 5 other extremity leads). Of the 480 leads obtained (12 per subject), 36 were excluded from analysis (15 because of poor T wave formation and 11 because of presence of U waves). Children with KD had significantly higher QTc dispersion in 12 lead (67.08±17.72 ms compared to 47.63±16.48 ms in controls P≤0.001) as well as 8 lead (60.51±18.54 ms compared to 42.92±18.03 ms in controls P≤0.001) analysis. There was no correlation between delay in IVIG therapy and QT interval dispersion. In conclusion, QT interval dispersion is significantly increased in North Indian children with KD. The dispersion is indicative of inhomogenous ventricular repolarization and may represent increased risk for developing ventricular arrhythmia in this population.

QT Dispersion and Left Ventricular Hypertrophy in Elderly Hypertensive and Normotensive Patients

Inhomogeneity of ventricular repolarization as detected by QT dispersion may be a potential leading mechanism of sudden death in hypertensive and normotensive (age related) left ventricular hypertrophy. Aim of this study was to investigate QT dispersion, ventricular arrhythmias, and left ventricular mass index in elderly hypertensive and normotensive patients. Study population consisted of 60 consecutive patients (sex: 34 men/26 women; age: 63 +/- 11 years) with essential arterial hypertension and 48 age and sex-matched control subjects (24 men/24 women; 64 +/- 16 years). Measurements included QTc dispersion, ventricular arrhythmias, and left ventricular hypertrophy. Hypertensive patients had greater left ventricular mass index (P = .006) and higher QTc dispersion (P = .004) than controls. Left ventricular hypertrophy was diagnosed in 57 (31 men/26 women) of all subjects. These patients had higher blood pressure (P < .05), Lown's score (P < .001), and QTc dispersion (P < .001). QTc dispersion and Lown's score were independent predictors of left ventricular mass index (P < .001). Conclusively, QTc dispersion is a strong indicator of left ventricular mass index and might be used in risk stratification of hypertensive and normotensive elderly patients.

Dispersion of the Corrected QT and JT Interval in the Electrocardiogram of Alcoholic Patients

The aim of this study was to analyze the corrected QT interval (QTc), its dispersion (QTcd), and the QT interval index (QTcI) and to compare it with the corrected JT interval (JTc), its dispersion (JTcd), and the JT interval index (JTcI) in long-term alcoholic users, by investigating the ventricular activation until the completion of repolarization. The study of ECGs was performed on a selected group of 49 male white alcoholic patients, mean age 53.51+/-4.78 years. The control group was pair-matched. The analysis of ECGs was performed according to the Minnesota Code, and Bazett's formula gave the values of the corrected QT interval and JT interval. The results of the descriptive statistics in the group of alcoholics showed a range of the QTcd of 12.0 to 103.0 milliseconds, mean 44.2+/-18.6 milliseconds, compared with 5.0 to 68.0 milliseconds, mean 23.8+/-11.1 milliseconds, in the control group (p < 0.0001). The range of JTcd in the alcoholic patients was 11.0 to 88.0 milliseconds, mean 43.0+/-18.3 milliseconds, compared with 5.0 to 66.0 milliseconds, mean 22.8+/-12.1 milliseconds, in the control group (p < 0.0001). The QTc from 422.0 to 480.0 milliseconds was obtained in 69.4% of the alcoholic patients and 32.6% of the controls. The QTc over 480.0 milliseconds was found in 24.5% of the alcoholic patients, but was not recorded among the controls at all (p < 0.0001). The QTcd over 50.0 milliseconds was registered in 34.7% of the alcoholic patients, while in the controls a QTcd above 50 milliseconds was found in 2.0% (p < 0.0001). The mean values of QT were markedly higher in the alcoholic patients (p < 0.01) than in the controls. The same was the case with the values of QTd, QT(I), QTcd, and QTcI (p < 0.0001). Also, the mean values of JTd, JT(I), JTc, JTcd, and JTcI were significantly higher in the alcoholic patients than in the controls (p < 0.0001). The mean value of JT, although higher in the alcoholic patients, did not significantly differ between the examined groups (p=0.1002). The odds ratio estimated for prolonged QTc and for enlarged QTcd in the alcoholics versus the controls was 31.625 and 25.500 (p < 0.0001), respectively. Persons who consume various alcoholic beverages excessively and for a long time have significantly higher dispersions of the QTc and JTc, intervals and they have a significantly higher estimation of relative risk for the prolonged QTc interval and higher QTc dispersion than the control group, i.e., higher risk of arrhythmias.