Variability of QT dispersion measurements in the surface electrocardiogram in patients with acute myocardial infarction and in normal subjects

Acute Mesenteric Ischemia: The Diagnostic Value of QT Parameters and their Relationship with CT Findings

BACKGROUND

One of the greatest challenges in the diagnosis of acute mesenteric ischemia (AMI) is the lack of specific laboratory tests that support multidetector computed tomography (CT). Our aim is to investigate the diagnostic value of electrocardiographic QT parameters in AMI and their relationship with CT findings.

MATERIALS AND METHODS

Patients who were admitted to the emergency department with abdominal pain were recruited retrospectively from the hospital information system. Grouping was carried out on the basis of AMI (n=78) and non-AMI (n=78). In both groups, the corrected QT (QTc) and QT dispersion (QTD) were measured on electrocardiographs, and the qualitative and quantitative CT findings were evaluated on CT examinations.

RESULTS

The QTc and QTD values were higher in the AMI group. The median QTc values were 456.16 (IQR: 422.88-483.16) for the AMI group and 388.83 (IQR: 359.74-415.83) for the control group (p<0.001), and the median QTD values were 58 (IQR: 50.3-68.25) for the AMI group and 46 (IQR: 42-50) for the control group (p<0.001). In the CT analysis, the QTc values were significantly higher among AMI patients, with images of paper-thin bowel walls and the absence of bowel wall enhancement (p=0.042 and p=0.042, respectively). Meanwhile, the QTD values were significantly higher among patients with venous pneumatosis findings on CT (p=0.005). In the regression analysis, a significant relationship was found between the QT parameters and AMI (p<0.001). For QTc, an AUC of 0.903 (95% CI: 0.857-0.950, p<0.001), a sensitivity of 80.8%, and a specificity of 82.3% were found. For QTD, an AUC of 0.821 (95% CI: 0.753-0.889, p<0.001), a sensitivity of 73.1%, and a specificity of 82.3% were found.

CONCLUSION

We found the QTc and QTD values to be significantly higher among AMI patients. Furthermore, we found a significant relationship between the CT findings and QTc and QTD and a significant relationship between survival and QTc in the AMI group.

Comparison of Machine Learning Algorithms Using Manual/Automated Features on 12-Lead Signal Electrocardiogram Classification: A Large Cohort Study on Students Aged Between 6 to 18 Years Old

PROPOSE

An electrocardiogram (ECG) has been extensively used to detect rhythm disturbances. We sought to determine the accuracy of different machine learning in distinguishing abnormal ECGs from normal ones in children who were examined using a resting 12-Lead ECG machine, and we also compared the manual and automated measurement using the modular ECG Analysis System (MEANS) algorithm of ECG features.

METHODS

Altogether, 10745 ECGs were recorded for students aged 6 to 18. Manual and automatic ECG features were extracted for each participant. Features were normalized using Z-score normalization and went through the student's t-test and chi-squared test to measure their relevance. We applied the Boruta algorithm for feature selection and then implemented eight classifier algorithms. The dataset was split into training (80%) and test (20%) partitions. The performance of the classifiers was evaluated on the test data (unseen data) by 1000 bootstrap, and sensitivity (SEN), specificity (SPE), AUC, and accuracy (ACC) were reported.

RESULTS

In univariate analysis, the highest performance was heart rate and RR interval in the manual dataset and heart rate in an automated dataset with AUC of 0.72 and 0.71, respectively. The best classifiers in the manual dataset were random forest (RF) and quadratic-discriminant-analysis (QDA) with AUC, ACC, SEN, and SPE equal to 0.93, 0.98, 0.69, 0.99, and 0.90, 0.95, 0.75, 0.96, respectively. In the automated dataset, QDA (AUC: 0.89, ACC:0.92, SEN:0.71, SPE:0.93) and stack learning (SL) (AUC:0.89, ACC:0.96, SEN:0.61, SPE:0.99) reached best performances.

CONCLUSION

This study demonstrated that the manual measurement of 12-Lead ECG features had better performance than the automated measurement (MEANS algorithm), but some classifiers had promising results in discriminating between normal and abnormal cases. Further studies can help us evaluate the applicability and efficacy of machine-learning approaches for distinguishing abnormal ECGs in community-based investigations in both adults and children.

Evaluation of the relationship between the level of addiction and exhaled carbon monoxide levels with QT dispersion in smokers

INTRODUCTION

Smoking increases the risk of arrhythmia. QT dispersion (QTd) is an important indicator for the determination of ventricular arrhythmia. In this study, we aimed to determine the arrhythmia risk by evaluating QTd in smokers and to assess the relationship between the level of nicotine addiction and carbon monoxide (CO) level in the expiratory air.

METHODS

This study was designed as a single-center, cross-sectional study. Among the chronic smokers referred to the Smoking Cessation Clinic of a tertiary hospital between October 2019 and January 2020, all those who had no risk factors for cardiac arrhythmias, except smoking, were included in the study. Sociodemographic data and smoking characteristics of the participants were collected and exhaled CO levels were measured. QT intervals were measured in all leads by using a 12-lead standard electrocardiogram (ECG), and heart rate corrected QT (QTc) intervals, QT dispersion (QTd), and corrected QT dispersion (QTcd) were calculated.

RESULTS

The mean age of the 250 patients was 37.2±9.3 years and the majority of patients (65%) were male. The mean amount of smoking was 25.74±16.03 packs/year and the mean value of CO was 12.36±7.06 ppm. The mean QTd was 23.83±13.12 ms, and the mean QTcd was 26.63±15.02 ms. A statistically significant relationship was found between QTd and QTcd and level of addiction, consumption of sticks/day and packs/year, and exhaled CO values (all p<0.001).

CONCLUSIONS

It was found that as the level of addiction, cigarette use amount, exhaled CO levels, and BMI increased in smokers, QT dispersion and arrhythmia risk increased.

Predictive factors of poor blood collecting flow during leukocyte apheresis for cellular therapy

Leukocyte apheresis is necessary in various cellular therapies. However, maintenance of a stable flow rate during leukocyte apheresis is often difficult, even in patients or donors without major problems. Despite this, predictive methods and evidence regarding the reality of the situation are limited. We conducted a retrospective analysis involving adult patients who required leukocyte apheresis for the treatment of neoplasms using WT1-pulsed dendritic cell vaccine. Monocytes were separated from apheresis products to obtain dendritic cells. All the patients were pre-evaluated based on laboratory and chest X-ray findings and subjected to an identical apheresis procedure. The occurrence of poor blood collecting flow during leukocyte apheresis was monitored, and the frequency, clinical information, and associated risk factors were analyzed. Among 160 cases, poor blood collecting flow was observed in 53 cases (33.1%) in a median time of 54 min (range, 2-127 min) post-initiation of leukocyte apheresis. Owing to difficulty in obtaining higher collecting flow, a longer procedure time was required, and in some cases, the scheduled apheresis cycles could not be completed. Consequently, the number of harvested monocytes was low. Multivariable analysis indicated that female patients have an increased risk of poor inlet flow rate. Furthermore, prolonged QT dispersion (QTD) calculated using Bazett's formula was found to be a risk factor. Although the patients did not present any major problems during leukocyte apheresis, poor blood collecting flow was observed in some cases. Sex and pre-evaluated QTD might be useful predictors for these cases; however, further prospective evaluation is necessary.

Assessment of Cardiac Arrhythmic Risk in Children With Covid-19 Infection

Coronavirus disease of 2019 (COVID-19) is a cause of significant morbidity and mortality worldwide. Although COVID-19 clinical manifestations are mainly respiratory, major cardiac complications are being reported. The mechanism of cardiac injury and arrhythmias is unclear. Also, drugs currently used to treat the COVID-19 may prolong the QT interval and may have a proarrhythmic propensity. The study aims to investigate the effects of COVID-19 infection with asymptomatic and mild symptoms on trans-myocardial repolarization parameters in children without treatment. A total of 105 COVID-19 patients were compared with 40 healthy children. The patient and control group data were compared by calculating the QT interval, corrected QT (QTc), QT dispersion (QTd), QTc dispersion (QTcd), Tp-e, Tp-e dispersion, Tp-e/QT ratio, and Tp-e/QTc ratio on the 12-lead surface electrocardiogram. The mean age was determined as 11.2 ± 0.3 years in the patient group, and 10.8 ± 2.1 years in the control group. In the COVID-19 group, QTd, QTcd, Tp-e, Tp-e dispersion, Tp-e/QT ratio and Tp-e/QTc ratio were statistically higher than the control group. The ventricular repolarization was impaired even in asymptomatic children with COVID-19 infection. These results suggest the need to further assess the long terms risks of prolonged QT dispersion in the setting of COVID-19 infection.

Comparison of QT dispersion in patients with ST elevation acute myocardial infarction (STEMI) before and after treatment by streptokinase versus primary percutaneous coronary intervention (PCI)

Background

QT dispersion (QTD) represents inhomogeneous ventricular repolarization such that an increased QTD may predispose the heart to malignant ventricular arrhythmias (VAs). This study was conducted to compare QTD in patients with ST-elevation myocardial infarction (STEMI) before and after treatment by streptokinase (SK) versus primary percutaneous coronary intervention (PCI).

Methods

The present case–control study was conducted on 185 STEMI patients who received SK (115 cases) or underwent primary PCI (70 cases). QTD and QT corrected dispersion before and 24 h after treatment. Likewise, they were also found to correct fatal arrhythmias (VT and VF) during the first 24 h after admission, and ejection fraction (EF) 24 h after treatment was evaluated.

Results

QTD decreased in the primary PCI group, though no significant difference was seen between the two studied groups (P > 0.05). A significant increase was detected in the EF mean values for the primary PCI-treated patients (P = 0.022). Moreover, there was a significant reduction in QTD of patients with fatal arrhythmias in the primary PCI group (P = 0.022).

Conclusion

An overall QTD reduction in the primary PCI group and a significant decrease in QTD of patients with fatal arrhythmias in the primary PCI group show that this treatment strategy is more efficient than thrombolytic therapy. As an important indicator of proper myocardial function, EF can independently predict improved myocardial function in the primary PCI group.

Age- and sex-based reference ranges for non-invasive ventricular repolarisation parameters

BACKGROUND

Some electrocardiographic parameters are able to assess indirectly ventricular repolarisation homogeneity. It is consequently essential to discriminate between normal and abnormal values in clinical decision-making. Considering there is still not a consensus about normal cut-off values, the aim of this study was to document reference intervals in all age groups of a healthy population, providing for age- and sex-percentile tables, which can be used easily and quickly in clinical practice.

METHODS

We evaluated repolarisation markers in 606 sex-matched participants aged 1 day-94 years. Each subject underwent a 12-lead electrocardiogram at rest, and the following parameters were measured: QT, corrected QT, QTpeak, Tpeak-Tend, Tpeak-Tend dispersion, Tpeak-Tend/QT and QTpeak/QT ratio.

RESULTS

A relationship was demonstrated between age and QTpeak, Tpeak-Tend, QT and QTc. In children, QTpeak, Tpeak-Tend and QT intervals increased linearly with age. In adolescents, all the three parameters remained stable. In adults, QTpeak and QT showed a further significant increase. On the contrary, Tpeak-Tend interval was longer in adults aged between 20 and 64 years than in participants aged 65 years or over, but the difference was not statistically significant. Male vs female participants showed longer Tpeak-Tend intervals; this sex difference was not statistically significant at birth and during childhood, whereas it was in adolescents and in adults.

CONCLUSIONS

Repolarisation parameters showed age- and sex-based variations, which are important to know to differentiate normal from pathological values.

The Effect of Glucose Variability on QTc Duration and Dispersion in Patients with Type 2 Diabetes Mellitus

Objective:

Glycemic variability (GV) is a new term with the episodes of hyper and hypoglycemia in diabetic patients. Both prolonged QT interval and QTd are potential risk factors for malignant ventricular arrhythmias affecting the mortality of different groups of patients including diabetes mellitus. In this study, we aimed to evaluate if the glucose variability increasing the QTc interval and QTc dispersion in type 2 diabetes mellitus.

Methods:

We included 275 consecutive patients with type 2 diabetes. We quantified the GV with standard deviation (SD) and coefficient of variation (CV) from 7 point glucose measures. We investigated the relationship of GV parameters with QT parameters.

Results:

The prevalence of prolonged QTc duration was 21%, no patients have prolonged QTc dispersion (> 80 ms). SD of the patients with prolonged QTc duration was significantly higher than the others (45.14 ±24.45 vs. 37.78 ±9.03 p<0.05). There was also a significant relationship between SD and QTc dispersion (r: 0.164; p: 0.007). There were no relationship between the QT parameters and microvascular diabetic complications. SD and HbA1c levels were significantly higher on the patients having peripheral neuropathy (p<0.005).

Conclusion:

The result of this study demonstratess that increased glycemic variability is associated with prolonged QTc duration and QTc dispersion. It is important to focus on targeting optimal glycemic control with GV as an additional goal point along with the traditional following parameters such as fasting-postprandial blood glucose and HbA1c.

Effect of Direct Stent Implantation on QTc Dispersion

The aim of this study was to evaluate whether direct stenting is superior to conventional stent implantation technique with respect to QTc dispersion in prospectively selected patients with simple lesion morphology and class II stable angina undergoing elective coronary stenting. One hundred thirty-four consecutive patients were divided into 2 groups based on the stenting technique used: the direct stenting without predilation group, group I (n=64), and the stenting with predilation group, group II (n=70). All patients had single-vessel disease. The primary end point of the study was the QTc dispersion at the 24th hour and at the first month after the procedure and the secondary end point of the study was the major clinical events (MCEs) rate in the hospital period and up to 1 month. Baseline maximum QTc, minimum QTc, and QTc dispersion were not different between the 2 groups. QTc dispersion decreased from 47 ±8 msec before stent implantation to 41 ±11 msec at 24 hours and 37 ±7 msec 1 month after angioplasty in group I (p<0.006 and p<0.01, respectively), whereas QTc dispersion decreased from 49 ±9 msec before stent implantation to 46 ±8 msec at 24 hours and 42 ±10 msec 1 month after angioplasty in group II (p<0.03 and p<0.01, respectively). Compared with group II, the decrease in QTc dispersion was significantly greater at the 24th hour and at the first month after the procedure in group I (p<0.003 and p<0.001, respectively). There was a decreased trend toward MCE rate in group I in relation to that of group II, but the statistical difference was not significant. Direct stenting is a feasible and safe technique. It is superior to conventional stenting technique in decreasing the QTc dispersion at the 24th hour and at the first month after the procedure, whereas it is equivalent to single-vessel conventional stent implantation technique with respect to MCEs rate in the short-term period.

Changes of QT Dispersion in Hemodialysis Patients after Administrating Zhigancao Decoction ()

OBJECTIVE

To observe the alteration of QT dispersion (QTd) and QTc dispersion (QTcd) in hemodialysis patients after oral administration of Zhigancao Decoction (, Roasted Licorice Decoction, RLD).

METHODS

To investigate the alteration of QTd and QTcd in 68 routine hemodialysis patients before and after hemodialysis with 12-lead electrocardiogram (ECG) after orally administrated RLD for 4 weeks. Blood was also taken for measurement of plasma electrolytes, liver function, renal function, hemoglobin (Hgb) and hematocrit (HCT).

RESULTS

After hemodialysis, QTd and QTcd were prolonged evidently; the difference was significant between before and after hemodialysis (P<0.05). After RLD orally administrated for 4 weeks, QTd and QTcd only slightly increased after dialysis compared with pre-dialysis (P>0.05). The QTd and QTcd of the post-therapy-post-dialysis decreased significantly compared with the pre-therapy-post-dialysis (P<0.05). There were no other significant changes in other variables (post-therapy-pre-dialysis vs. pre-therapy-pre-dialysis, or post-therapy-post-dialysis vs. pre-therapy-post-dialysis;P>0.05). After therapy, the number of patients with supraventricular arrhythmia, occasional ventricular premature beat and multiple ventricular premature beat were decreased from 15 to 4, 10 to 2 and 7 to 1, respectively.

CONCLUSION

RLD therapy not only lowered the increased QTd and QTcd after hemodialysis, but also displayed a safety profile.

Electrocardiographic Changes in Diabetes Mellitus

Diabetes mellitus (DM) has been known for many years to be associated with poor cardiovascular prognosis. Due to the sensitive neuropathy, the coronary artery disease in diabetic patients is frequently asymptomatic. Also twelve leads resting ECG can be within normal limits even in an advanced stage of coronary artery disease. Therefore in addition to the standard ECG other electrocardiographic procedures started to be studied in order to find some typical signs of myocardial damages caused by DM. Repeatedly reported results showed in DM patients without cardiovascular complications the tachycardia, shortening of the QRS and QT intervals, increase of the dispersion of QT interval, decreased amplitudes of depolarization waves, shortened activation time of ventricular myocardium and a flattening of T waves confirmed by the lower value of maximum and minimum in repolarization body surface isopotential maps. Most of these changes are even more pronounced in patients with cardiac autonomic neuropathy. Comparison with similar ECG changes in other diseases suggests that the electrocardiographic changes in DM patients are not specific and that they are particularly caused by an increased tone of the sympathetic nervous system what was indirectly confirmed by the heart rate variability findings in these patients.

QT interval dispersion in the patients with central serous chorioretinopathy

AIM

To evaluate QT dispersion (QTD) in patients with central serous chorioretinopathy (CSC).

METHODS

This clinical, comperative, case-control study included 30 patients with CSC at acute phase (Group 1) and 30 age- and sex-matched healthy subjects (Group 2, the control group). From all subjects, a 12-lead surface electrocardiography was obtained. The heart rate (HR), QT maximum (QTmax), QT minimum (QTmin), QT corrected (QTc), QTD and Tmean were manually measured and analyzed. Student's t-test and Pearson's method of correlation were used for statistical analysis.

RESULTS

The patient and control groups were matched for age, smoking status (rate and duration) and gender. There were no significant differences with regard to these among the groups (P>0.05). The participants included 19 men (63.3%) and 11 women (36.7%) in Group 1, 20 men (66.7%) and 10 women (33.3%) in Group 2. QTmax, QTD and QTc were significantly higher than those of healthy controls (P<0.001 for QTmax, P=0.01 for QTD and P=0.001 for QTc). QTmin, Tmean and HR did not differ significantly between the study groups (P=0.28 for QTmin, P=0.56 for Tmean and P>0.05 for HR). No significant correlation was found between duration of the disorder and QTD values (r=0.13, P>0.05).

CONCLUSION

These findings suggest that CSC may be associated with an increase in QTD and that the patients might be at risk for ventricular arrhythmia.

Predictive value of myocardial delayed enhancement in Duchenne muscular dystrophy

In other cardiomyopathies, cardiac magnetic resonance imaging (CMR)-derived myocardial delayed enhancement (MDE), a marker of myocardial fibrosis, is a risk factor for sudden cardiac death (SCD). In Duchenne muscular dystrophy (DMD), the prognostic value of MDE for ventricular arrhythmias and death is unknown. This study aimed to evaluate associations between MDE and electrocardiographic (ECG) changes, ventricular remodeling, risk of arrhythmias, and death in DMD. This retrospective study included all subjects with DMD who had undergone a CMR between January 2006 and December 2011 and had available ECG and 24-h Holter records from the same period. Left ventricular (LV) MDE was semiquantitatively graded from 0 to 4. Comparisons of demographic and clinical characteristics between MDE and no-MDE groups were made. Cox regression analysis was performed to assess factors associated with death. This study investigated 32 boys with a median age of 13.8 years (range, 7.2-17.4 years) and found MDE present in 25 (78 %) of the boys. Compared with the no-MDE subjects, the MDE subjects were older (15.7 ± 3.3 vs 12.1 ± 4.8 years) and had a wider QT dispersion (QTd: 74 ± 30 vs 55 ± 33 ms), a higher incidence of ventricular tachycardia (40 vs 0 %), a lower LV ejection fraction (46 ± 12 vs 56 ± 9 %), a larger LV end-diastolic volume (124 ± 58 vs 68 ± 14 ml/m(2)), and a larger end-systolic volume (57 ± 29 vs 28 ± 10 ml/m(2)) (p < 0.05 for all). During the study period, six of the subjects (19 %) died. The factors associated with mortality were increased age, advanced grade of MDE, higher LV end-systolic volume, lower LV ejection fraction, use of beta-blockers, and ventricular tachycardia. Myocardial fibrosis detected by CMR is an independent predictor of adverse cardiac remodeling, ventricular arrhythmias, and death in DMD. Cardiac MRI using MDE can be applied as a screening tool to detect patients at risk for ventricular arrhythmias, more advanced disease, adverse LV remodeling, and death.

Influence of the left ventricular types on QT intervals in hypertensive patients

Objective:

To investigate the possible electrophysiological background of the greater excitability of concentric and eccentric left ventricular hypertrophy types in relation to the asymmetric type.

Methods:

187 patients with essential hypertension, without ishaemic heart disease were divided into three groups with regard to left ventricule type: concentric (relative wall thickness >0.42, interventricular septum/left ventricular posterior wall ≤1.3), eccentric (left ventricular diameter in systoles >32, relative wall thickness <0.42), asymmetric left ventricular hypertrophy (interventricular septum/left ventricular posterior wall >1.3), and three subgroups: mild (interventricular septum or left ventricular posterior wall 11-12 mm), moderate (interventricular septum or left ventricular posterior wall 13-14 mm) and severe left ventricular hypertrophy (interventricular septum or left ventricular posterior wall ≥15 mm). In all patients QT intervals, QT dispersion, left ventricular mass index and ventricular arrhythmias were measured. An upper normal limit for QT corrected interval: 450/460 ms for men/women; for QT dispersion: 70 ms.

Results:

The QT corrected interval and QT dispersion were increased in severe concentric and eccentric left ventricular hypertrophy (443 and 480 ms for QT corrected; 53 and 45 ms for QT dispersion, respectively), not significantly. QT dispersion in men with severe left ventricular hypertrophy was significantly enlarged (67.5 vs. 30 ms, p=0.047). QT interval was significantly longer in patients with complex ventricular arrhythmias (p=0.037).

Conclusion:

No significant association of QT intervals or QT dispersion with the degree/type of left ventricular hypertrophy was found. QT corrected interval and QT dispersion tend to increase proportionally to the left ventricular mass only in the concentric and eccentric type.

QT dispersion predicts mortality and correlates with both coronary artery calcification and atherosclerosis in hemodialysis patients

PURPOSE

QT dispersion (QTd) was shown to be an independent predictor of mortality in hemodialysis (HD) patients. It may be hypothesized that coronary artery calcification is related to QTd in HD patients because widespread calcification may also involve the cardiac conducting system in these patients. In this study, we aimed to investigate the relationships of corrected QTd (QTcd) with coronary artery calcification score (CACS), carotid plaque score (CPS) and possible influence of these parameters on survival of HD patients.

METHODS

Seventy-two HD patients (33 male, 39 female) were enrolled into the study. Mean age of the patients was 44 ± 12 years. Mean follow-up duration was 77 ± 24 months. CACS was determined by computed tomography. QTcd values were calculated as the difference of maximum and minimum QT intervals. Left ventricular mass index (LVMI) and CPS were measured by echocardiography.

RESULTS

QTcd was significantly correlated with CACS (r = 0.233, p = 0.049), CPS (r = 0.354, p = 0.003) and LVMI (p = 0.011, r = 0.299). CPS was found to be significantly higher in the group with high QTcd (>60 ms) [2 (1-4) versus 0 (0-1), p = 0.02]. CACS was significantly correlated with age (r = 0.44, p < 0.001), LVMI (r = 0.52, p < 0.001) and CPS (r = 0.32, p = 0.003). In Kaplan-Meier analysis, survival of patients with high QTcd was significantly lower than the patients with low QTcd. In Cox regression analysis for predicting mortality, age, serum albumin and QTcd were found to be the independent predictors of mortality.

CONCLUSIONS

QTcd independently predicted mortality, and it was significantly associated with coronary artery calcification, left ventricular hypertrophy and atherosclerosis in HD patients.

Prolonged QT dispersion in inflammatory bowel disease

AIM: To investigate the frequency and factors of prolonged QT dispersion that may lead to severe ventricular arrhythmias in patients with inflammatory bowel disease (IBD).

METHODS: This study included 63 ulcerative colitis (UC) and 41 Crohn’s disease (CD) patients. Forty-seven healthy patients were included as the control group. Heart rate was calculated using electrocardiography, corrected QT dispersion (QTcd) and the Bazett’s formula. Homeostasis model assessment (HOMA) was used to determine insulin resistance (IR). HOMA values < 1 were considered normal and values > 2.5 indicated a high probability of IR.

RESULTS: Prolonged QTcd was found in 12.2% of UC patients, and in 14.5% of CD patients compared with the control group (P < 0.05). A significant difference was found between the insulin values (CD: 10.95 ± 6.10 vs 6.44 ± 3.28, P < 0.05; UC: 10.88 ± 7.19 vs 7.20 ± 4.54, P < 0.05) and HOMA (CD: 2.56 ± 1.43 vs 1.42 ± 0.75, P < 0.05; UC: 2.94 ± 1.88 vs 1.90 ± 1.09, P < 0.05) in UC and CD patients with and without prolonged QTcd. Disease behavior types were determined in CD patients with prolonged QTcd. Increased systolic arterial pressure (125 ± 13.81 vs 114.09 ± 8.73, P < 0.01) and age (48.67 ± 13.93 vs 39.57 ± 11.58, P < 0.05) in UC patients were significantly associated with prolonged QTcd.

CONCLUSION: Our data show that IBD patients have prolonged QTcd in relation to controls. The routine follow-up of IBD patients should include determination of HOMA, insulin values and electrocardiogram examination.

QT Dispersion and Electrocardiographic Changes in Women With Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) represents additional risks to both mother and infant. Moreover it increases a woman's risk of cardiovascular disease in the postpartum. The aim of our study was therefore to detect changes of both the QT dispersion and the electrical heart field that could be typical for GDM. Body surface potential maps were obtained using the Cardiac 112.2 device from 26 young women with GDM and 54 young healthy pregnant women in the 36th week of pregnancy. The same recordings were obtained from 18 healthy women in the same age (19-36 years). The average QT dispersion (±SD) in women suffering from GDM was significantly higher (107±25 ms) both than in those with physiological pregnancy (73±18 ms) and than in the normal subjects (34±12 ms) (P<0.001). Moreover we have found in GDM patients shorter QRS complex 82.0±6.8 ms vs. 89.5±8.2 ms in healthy pregnant women and 90.8±7.9 ms in the control group (p=0.011), more horizontal electrical heart axis [16.4±20.1° vs. 42.4±28.7° and 74.6±39.2° respectively (P<0.05)] and lower some depolarization and repolarization amplitudes on isopotential and isointegral maps. According to these results we suppose that described electrocardiographic changes reflect a deterioration of the complete process of ventricular depolarization and repolarization in GDM.

Prognostic value of QT dispersion change following primary percutaneous coronary intervention in acute ST elevation myocardial infarction

This study analyzed the corrected QT dispersion (cQTd) before and at 24 hours after successful primary percutaneous coronary intervention (PCI) in 81 patients with single coronary artery disease and acute ST elevation myocardial infarction. Major cardiovascular events (MACE) at 1 year were defined as death, nonfatal myocardial infarction, life-threatening arrhythmias, and heart failure hospitalization. The cQTd before primary PCI was significantly longer in patients without MACE than in patients with MACE (73.1 ± 29.3 versus 56.3 ± 25.2 msec, P = 0.026). The cQTd at 24 hours after primary PCI was significantly shorter in patients without MACE than in patients with MACE (38.4 ± 20.8 versus 50.8 ± 28.7 msec, P = 0.045). Thus, the absolute cQTd change was significantly higher in patients without MACE compared to patients with MACE (P = 0.001). By multivariate analysis, absolute cQTd change was an independent predictor for the development of MACE, with an odds ratio of 1.498 for each 10-msec decrement in absolute cQTd change (95 percent confidence interval, 1.157 to 1.939, P = 0.002). In conclusion, the absolute cQTd change after primary PCI was an independent predictor of the development of MACE in patients with single vessel disease and acute ST elevation myocardial infarction.

Increased pretransplant QT dispersion as a risk factor for the development of cardiac complications during and after preparative conditioning for pediatric allogeneic hematopoietic stem cell transplantation

Although cardiac complications are some of the most serious complications of HSCT for leukemia, it is difficult to predict them. QTD has been reported as a predictor of heart failure and fatal arrhythmia in adults. The purpose of this study is to examine whether QTD predicts cardiac complications in pediatric HSCT. Eighteen patients (mean age, 6.9 yr; 11 ALL and seven AML) underwent high-dose cyclophosphamide treatment and total body irradiation as preparative conditioning for HSCT. QTD, QTcD, echocardiographic functional parameters, and cumulative anthracycline dose were evaluated. We compared these values between patients with and without cardiac complications. Among 18 patients, seven patients experienced cardiac complications (heart failure in four, arrhythmia in three). There were significant differences in QTD (43.7 ms in patients with cardiac complications vs. 30.2 ms in patients without the complications, p = 0.019) and QTcD (55.3 vs. 36.9 ms, p = 0.003) between the two groups. On the other hand, the cumulative dose of anthracycline and echocardiographic parameters were not significantly different between the two groups. Increases in QTD and QTcD during the pretreatment period may be risk factors for the development of cardiac complications during and after conditioning for pediatric HSCT.

Alterations in QT dispersion in the surface electrocardiogram of female adolescent inpatients diagnosed with bulimia nervosa

Increased QT dispersion (QTd) reflects cardiac autonomic imbalance and indicates elevated risk for cardiac arrhythmias. In the present study, we assessed heart rate, QT and corrected QT intervals, and QTd in 20 acutely ill bulimia nervosa adolescent inpatients on admission and discharge. A significant decrease in QTd was found between admission and discharge (67 +/- 13 milliseconds vs 55 +/- 12 milliseconds, respectively; P = .0005). The decrease in QTd values correlated significantly with the decrease in the frequency of bingeing/purging behaviors (r = 0.51, P = .022). No significant correlations were found between the electrocardiographic indices and other clinical and laboratory measures. The elevated QTd in malnourished bulimia nervosa patients might indicate a cardiac autonomic imbalance that is most likely corrected after symptomatic improvement.

Angioplasty decreases prolonged QT dispersion in patients with angina pectoris but not in patients with prior myocardial infarction

BACKGROUND AND HYPOTHESIS

Prolonged QT dispersion (QTd) is shortened by successful percutaneous transluminal coronary angioplasty (PTCA) in patients with ischemic heart disease. Particularly, QTd plays an important role in the prognostication in patients with prior myocardial infarction (MI). However, whether the effect of PTCA on QTd differs in patients with and without prior MI is not clear, and this study sought to clarify this question.

METHODS

In 41 consecutive patients with ischemic heart disease, we measured QTd from a routine 12-lead electrocardiogram taken at 72 h before and after successful PTCA. Patients were divided into two groups based on the presence or absence of prior MI: Group 1 consisted of 24 patients with angina (61 +/- 11 years old) without prior MI and Group 2 was comprised of 17 patients (69 +/- 10 years old) with prior MI. QTd was calculated as the difference between the maximum and minimum QT and QT corrected for heart rate (QTc), using Bazett's formula for calculating QTcd. All measurements were obtained manually and blindly.

RESULTS

In Group 1, 15 of 24 patients (63%) demonstrated multivessel disease and 16 of 24 (67%) patients had high QTd > 60 ms. Percutaneous transluminal coronary angioplasty decreased QTd and QTcd in Group 1 (QTd, from 83 +/- 35 to 57 +/- 19 ms, p < 0.05 ; QTcd, from 89 +/- 37 to 63 +/- 33 ms, p < 0.05), whereas no changes were observed in Group 2 (QTd, from 73 +/- 25 to 69 +/- 22 ms, NS; QTcd, from 80 +/- 30 to 79 +/- 28 ms, NS). QTd is more sensitive to decrease by successful PTCA in patients with angina than in patients with prior MI.

CONCLUSIONS

The effect of successful PTCA on inhomogeneity of ventricular repolarization reflected by QTd in patients with prior MI is different from that in patients without prior MI.

Effect of balloon inflation-induced acute ischemia on QT dispersion during percutaneous transluminal coronary angioplasty

BACKGROUND

QT dispersion (QTd = QTmax-QTmin) measured as interlead variability of QT interval reflects the spatial inhomogeneity of ventricular repolarization times, and increased QTd may provide a substrate for malignant ventricular arrhythmias. Ischemia is associated with regional abnormalities of conduction and repolarization.

HYPOTHESIS

This study aimed to investigate the effect of acute ischemia on QTd during successful percutaneous transluminal coronary angioplasty (PTCA).

METHODS

Forty-three patients (10 women, 33 men, mean age 56 years) were enrolled in the study. Electrocardiogram (ECG) recordings were taken before PTCA and during balloon inflation period. QT maximum (QTmax), QT minimum (QTmin), and QTd (QTmax-QTmin) values were calculated from the surface ECG.

RESULTS

There was no difference among QTmax values (p = 0.6). Mean QTmin during balloon inflation was lower than before PTCA (368 +/- 45 vs. 380 +/- 41 ms, p = 0.002). The difference between QTd values before and during balloon inflation was statistically important (65 +/- 9 vs. 76 +/- 10 ms, p = 0.001). This difference is caused by a decrease in QTmin during balloon inflation.

CONCLUSION

Acute reversible myocardial ischemia induced by balloon inflation causes an increase in QTd value, and this increment is the result of a decrease in QTmin interval. Therefore, QTd may be a marker of reversible myocardial ischemia.

Changes in the QT intervals, QT dispersion, and amplitude of T waves after hemodialysis

BACKGROUND

Increased QT dispersion (QTd) has been associated with an increased risk for ventricular arrhythmias and sudden death in the general population and in various clinical states.

METHODS

We investigated the impact of hemodialysis (HD) on QT, QTd, and T-wave amplitude in subjects with end-stage renal failure. Data on 49 patients on chronic HD were studied. The QT, QTd, and the sum of amplitude of T waves (SigmaT) in millimetre in the 12 ECG leads, along with a host of other ECG parameters, body weight, blood pressure, heart rate, electrolytes, and hemoglobin/hematocrit were measured before and immediately after HD.

RESULTS

QT decreased (380.9 +/- 38.4-363.5 +/- 36.8 ms, P = 0.001), the QTc did not change (406.2 +/- 30.8-405.4 +/- 32.2 ms, P = 0.8), the QTd increased (31.3 +/- 14.6-43.9 +/- 18.6 ms, P = 0.003), and the SigmaT decreased (32.3 +/- 15.7-25.9 +/- 12.6 mm, P = 0.0001) after HD. There was no correlation between the change in QTd and the changes in serum cations, heart rate, the subjects' weight, T-wave duration, and SigmaT. However, the change in QTc correlated inversely with the change in serum Ca(++) (r =-0.339, P = 0.021).

CONCLUSION

QTd increased, the SigmaT decreased, and the QTc and T-wave duration remained stable, after HD. The QTd increase, although may be real, could also reflect measurement errors stemming from the decrease in the amplitude of T waves (as shown recently), imparted by HD; this requires clarification, to use QTd in patient on HD.

QT interval analysis in patients with chronic liver disease: a prospective study

In previous studies, it has been shown that QT interval prolongation is related to an increased mortality rate in chronic liver disease (CLD). But QT dispersion (QTd) and its clinical significance in CLD has not been well studied. The objectives of this study were to investigate the relation between QTd and severity of the disease and determine its prognostic value in cirrhotic patients. Thirty-three consecutive patients with cirrhosis and 35 sex- and age-matched healthy subjects were studied. QT intervals and QT dispersions were measured on admission, and all intervals were corrected for heart rate according to Bazett's formula. The authors analyzed the potential relationship between QT parameters and the disease severity according to Child-Pugh classification and compared these values between survivors and nonsurvivors after a 3-year follow-up. Child-Pugh classification is used to assess liver function in cirrhosis. Corrected QT (QTc) prolongations were found in 32% of patients with cirrhosis and 5.7% of the healthy controls (p <0.001). The prevalence of increased (>70 ms) corrected QT dispersion (QTcd) was 45% in patients with cirrhosis. According to Child-Pugh criteria: QTd, maximum QT interval (QTmax), corrected QTmax (QTcmax), and QTcd in class C were significantly higher than those of class A and B (p <0.05, for all comparison). But there was no significant difference between class A and B in QTmax, QTcmax, QTd, and QTcd. There were 10 (30%) deaths from all causes during 3-year follow-up in the study group. Cox regression analysis showed that QTd and QTcd were better mortality indicators than QTmax and QTcmax, and Child's classification was the best predictor for mortality among all variables. In conclusion, QT dispersion and corrected QT dispersion parameters were better mortality indicators than other QT interval parameters and also may give additional prognostic information in patients with chronic liver disease.

Alterations in QT dispersion in the surface electrocardiogram of female adolescents diagnosed with restricting-type anorexia nervosa

OBJECTIVE

QT dispersion (QTd), defined as the difference between the longest interval and the shortest interval in the 12-lead electrocardiogram (ECG), is a measure of myocardial repolarization inhomogeneity. We assessed QTd in malnourished anorexia nervosa (AN) inpatients and following weight restoration.

METHODS

QTd analysis, anthropometric evaluations, and laboratory tests were carried out in 30 malnourished female adolescent AN restricting-type (AN-R) inpatients and following weight restoration.

RESULTS

A significant increase was found in weight/height ratio and body mass index from malnourished stage to weight restoration, paralleled by a significant decrease in QTd (70+/-16 vs. 47+/-16 ms; P<.0001). No correlations were found between ECG indices and anthropometric and laboratory measures.

CONCLUSION

Elevated QTd in malnourished AN-R inpatients may indicate possible cardiac autonomic imbalance and/or myocardial damage, likely corrected following weight restoration.

QT interval and dispersion in very young children treated with antipsychotic drugs: a retrospective chart review

OBJECTIVES AND BACKGROUND

QT dispersion (QTd) is a measure of interlead variations of the surface 12-lead electrocardiogram (ECG). Increased QTd, found in various cardiac diseases, reflects cardiac instability and risk for lethal cardiac arrhythmias. Research suggests a link between psychotropic treatment, ECG abnormalities (QT prolongation), and increased sudden cardiac mortality rates. Reports of sudden death in children treated with psychotropic drugs have raised concerns about cardiovascular monitoring and risk stratification. QTd analysis has not been investigated in very young children treated with antipsychotic drugs. In the present retrospective chart review study, we calculated QT interval, QTd, and their rate-corrected values in very young children treated with antipsychotics.

METHODS

The charts of 12 children (ages 5.8 +/- 0.98 yr; 4 girls, 8 boys) were examined before initiation of antipsychotic treatment [risperidone (n = 7), clotinapine (n = 1), and propericiazine (n = 4)] and during the maintenance period after achieving a positive clinical response. Three children were concomitantly maintained on methylphenidate. QT interval, QTd, and their rate-corrected values were calculated.

RESULTS

QT interval, QTd, and their rate-corrected values were all within normal values both before and after successful drug treatment.

CONCLUSIONS

This preliminary, naturalistic, small-scale study suggests that antipsychotic treatment, with or without methylphenidate, in very young children is not commonly associated with significant alterations of QT interval and dispersion, suggesting the relative safety of these agents in this unique age group.

P-wave dispersion is increased in pregnancy due to shortening of minimum duration of P: does this have clinical significance?

Most pregnant women complain of palpitation, and various kinds of arrhythmias can be observed during pregnancy. We investigated P-wave and QT dispersion during pregnancy. Healthy pregnant women (n=162) and healthy age-matched, non-pregnant women (n=150) were included. We performed electrocardiography and transthoracic echocardiography and determined serum oestradiol levels in both groups, and performed Holter monitoring in the pregnant group only. Resting heart rate, P-wave dispersion, left ventricular diastolic diameter, left atrial diameter and serum oestradiol levels in the pregnant group were significantly higher than in the control group. Minimum P-wave duration was shorter in the control group than in the pregnant group; however, there was no statistically significant difference in maximum P wavelength and corrected QT dispersion between the groups. No atrial fibrillation was detected in the pregnant group during Holter monitoring. Shortening of the minimum P-wave duration leads to increased P-wave dispersion during pregnancy. In contrast to other pathologies with increased P-wave dispersion, paroxysmal atrial fibrillation is absent in pregnant women; this may be a result of the stable maximum P wavelength that is present during pregnancy.

QTc-interval abnormalities in a forensic population

BACKGROUND

Antipsychotic drugs have been linked to sudden death among psychiatric patients, with a suggestion that prolongation of the QT-interval detectable on a standard electrocardiogram may be linked to fatal cardiac arrhythmias in these circumstances. Patients in secure forensic psychiatric facilities may be particularly likely to be on high-dose antipsychotic medication, and yet, as far as the authors are aware, no study of QT-intervals among such patients has been reported.

AIM

To investigate the prevalence of QT-interval abnormalities and associated known risk factors for fatal cardiac arrhythmias in a sample of forensic patients.

METHOD

Participants had a 12-lead electrocardiogram taken at 50 mm/s. Information was collected on their age, gender, psychiatric diagnosis, history of cardiovascular, liver and kidney diseases, and smoking, on all medications and on history of seclusion over the previous 12 months. Analysis was carried out using binary logistic regression.

RESULTS

Lower rates of QT-interval abnormalities than might be expected for this population were found. It was also found that a high dose of antipsychotics was associated with QTc prolongation (Adjusted OR = 9.5, 95% CI 2.6-34.2), a result consistent with previous literature.

CONCLUSION

Forensic patients need not be at increased risk of QTc abnormality provided risk factors are properly managed. A high dose of antipsychotic medication increases the risk of QTc prolongation.

Reduction of QTc Dispersion by the Angiotensin II Receptor Blocker Valsartan May Be Related to Its Anti-Oxidative Stress Effect in Patients with Essential Hypertension

QT dispersion has been reported to increase in patients with essential hypertension, and abnormal QT dispersion is associated with arrythmias and sudden cardiac death. However, whether change in QT dispersion is related to oxidative stress is unclear. We examined the effect of the angiotensin II receptor blocker valsartan on QT dispersion and the relationship between oxidative stress and QT dispersion in patients with essential hypertension. Hypertensive patients whose systolic blood pressure (SBP) was more than 140 mmHg and/or diastolic blood pressure (DBP) was more than 90 mmHg were treated with valsartan. Blood pressure was measured once a month for 6 months. The difference between the maximal and minimal QT intervals within a 12-lead surface ECG was measured and QT dispersion and QTc dispersion corrected by heart rate were obtained before and 6 months after treatment. Left ventricular mass (LVM) assessed by echocardiography was obtained at baseline and 6 months after treatment. Venous blood samples were obtained at baseline and 6 months after treatment to measure serum levels of lipoperoxidation (LPO) and type I and III procollagen. Treatment with valsartan significantly decreased SBP and DBP. QTc dispersion decreased significantly 6 months after treatment with valsartan as compared to the baseline values. Valsartan treatment did not affect the LVM. Valsartan significantly decreased the abnormally high LPO levels. The changes in QTc dispersion were positively correlated with changes in the serum levels of LPO and with changes in DBP. The correlation between changes in LPO and QTc dispersion was more close than that between changes in DBP and QTc dispersion. In conclusion, antihypertensive therapy with valsartan reduces QTc dispersion and this may be related to the ability of valsartan to reduce oxidative stress in patients with essential hypertension.

QT-interval dispersion in acute myocardial infarction is only shortened by thrombolysis in myocardial infarction grade 2/3 reperfusion

BACKGROUND

Increased QT interval dispersion (QTd) has been found in patients with acute myocardial infarction (AMI). In previous studies this has been shown to decrease with thrombolysis.

HYPOTHESIS

The aim of this study was to compare the effects of reperfusion by primary percutaneous transluminal coronary angioplasty (PTCA) and by thrombolysis on QTd and correlate these results with the degree of reperfusion.

METHODS

We studied 60 patients with a first AMI. The study cohort included 40 consecutive patients who had received thrombolysis (streptokinase or rt-PA); 20 additional consecutive patients with successful primary PTCA, all with preselected Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow by predefined selection criteria (12 stents); and 20 controls. A 12-lead ECG for QTd calculation was recorded before thrombolysis or PTCA and immediately after the procedure. All values were corrected according to Bazett's formula (QTcd). QTd and QTcd values before and after each procedure in three groups and the respective percent changes of deltaQTd and deltaQTcd were compared separately.

RESULTS

QTd and QTcd were significantly increased before thrombolysis/PTCA versus normals. An angiogram performed after thrombolysis showed adequate reperfusion (TIMI grade 2/3) in 20 patients, while in the other 20 only TIMI 0/1 reperfusion was achieved. Thrombolysis-TIMI flow 2/3 and PTCA significantly reduced QTd (from 68 +/- 10 to 35 +/- 8 ms, p < 0.001, deltaQTd = 48 +/- 11%, in the Thr-TIMI flow 2/3 group,and from 79 +/- 11 to 38 +/- 9 ms, p < 0.001, deltaQTd = 52 +/- 9%, in the PTCA group), while in the Thr-TIMI flow 0/1 group no significant changes were recorded. A percent QTd decrease > 30 s had 96% sensitivity, 85% specificity, and 93% positive and 94% negative predictive value, respectively, for TIMI 2/3 flow.

CONCLUSIONS

A significant decrease in QT dispersion may provide an additional electrocardiographic index for successful (TIMI 2/3) reperfusion.

QT dispersion in comparison to Tl-201-SPECT for detection of myocardial ischaemia

OBJECTIVE

There is controversy whether the measurement of QT dispersion might provide information about the presence and extent of ischaemic myocardium. It was the aim to analyse the diagnostic value of QT dispersion for the detection of myocardial ischaemia in comparison to Tl-201-SPECT.

PATIENTS AND METHODS

100 patients were randomly selected from patients referred for Tl-201-SPECT. QT duration was measured in all 12 leads in the resting ECG and in the ECG either at maximal bicycle exercise or during peak dipyridamole stress. QT dispersion was calculated and correlated with parameters of ischaemia for all patients and for the bicycle exercise and the dipyridamole group separately.

RESULTS

25 patients had to be excluded from the analysis because QT dispersion could not be measured. Regression analysis did not show significant correlation neither for all 75 patients nor for the bicycle exercise nor for the dipyridamole group correlating grade of myocardial ischaemia, number of ischaemic segments and summed ischaemic stress score with QT dispersion in the resting or the stress ECG and QTd and there was no significant difference between groups.

CONCLUSION

QT dispersion could not be measured in 25/100 patients (25%). In the remaining patients QT dispersion did not correlate with the extent or grade of myocardial ischaemia.

The Alteration of QT Dispersion in Hemodialysis Subjects

OBJECTIVE

We attempted to observe the alterations in QTd and QTcd in chronic renal failure (CRF) patients before and after hemodialysis (HD) to determine the relevant determinants of QTc duration in HD.

METHODS

The HD was carried out 2 or 3 times/week in a standard setting for 4-4.5 h. No drug therapy was applied during HD, except for isotonic NaCl infusions and sodium heparin. Maintenance drug therapy, including digitalis, antihypertensive, anti-anginal, and beta-blocking agents, was not changed. In the study, we investigated the alterations in QTd and QTcd in 68 CRF patients before and after HD with 12-lead ECG. Plasma Na(+), K(+), ionized Ca, creatinine, urea nitrogen, and hemoglobin were also controlled before and after HD.

RESULTS

In our study QTd and QTcd significantly increased at the end of HD (p < 0.01). Plasma Na(+) and K(+) decreased, and ionized Ca increased after HD (p < 0.05, 0.01). Plasma Na(+), K(+), ionized Ca levels, ultrafiltration volume and myocardial ischemia appear to be the main determinants of QTc duration in HD, not hypertension, gender, patient age, or duration of chronic HD.

CONCLUSION

Changes in plasma Na(+), K(+) and ionized Ca, the ultrafiltration volume and presence of ischemic heart disease in HD have significant effects on QTcd. ECG data demonstrate that the risk of arrhythmia could be higher with decreased plasma Na(+) and K(+), increased ionized Ca, the presence of ischemic heart disease and an increased ultrafiltration rate during HD. These results might provide some valuable references for proper HD programs.

QT dispersion and viable myocardium in patients with prior myocardial infarction and severe left ventricular dysfunction

BACKGROUND

QT dispersion (QTd) has been found to correlate to the amount of viable myocardium in patients with Q-wave myocardial infarction and well-preserved LV function. However, this relationship is unknown in patients with severe left ventricular dysfunction.

METHODS

Thirty-four patients with prior large myocardial infarction and severe left ventricular dysfunction underwent Tc-99m sestamibi single photon emission cardiac tomography (SPECT) and F-18 fluorodeoxyglucose (FDG) SPECT. Viability was defined as a defect relative count density (DCD) of at least 20% greater on FDG SPECT. QTd, corrected QT dispersion (QTcd), and QT coefficient of variation (cv) in patients with viable myocardium was compared to those without viable myocardium in the infarct area.

RESULTS

Thirteen patients were excluded from analysis for poor FDG images or inadequate ECG tracings. Of the remaining patients, 10 (48%) were found to have viability on FDG SPECT. QTd, QTcd, and QTcv in patients with viability were: 58 +/- 22 ms, 61 +/- 23 ms, and 4.81 +/- 1.76%, respectively, which did not differ significantly from those in patients without viability (QTd = 56 +/- 14 ms, QTcd = 70 +/- 16 ms and Qtcv = 5.06 +/- 1.20% [P = NS]). Moreover, neither FDG defect size, nor LVEF correlated with QTd.

CONCLUSIONS

This study indicates no relationship between QTd and viability in patients with myocardial infarction and severe left ventricular dysfunction.

Is QT dispersion associated with sudden cardiac death in patients with hypertrophic cardiomyopathy?

QT dispersion is significantly greater in patients with hypertrophic cardiomyopathy (HCM) than that in healthy subjects. Few data exist regarding the prognostic value of QT dispersion in HCM. In this study, we retrospectively investigated the association between QT dispersion and sudden cardiac death in 46 patients with HCM (mean 33.1 +/- 15.5 years, 32 men). The case group consisted of 23 HCM patients who died suddenly, and the control group consisted of 23 HCM patients who survived uneventfully during follow-up. Study patients were pair-matched for age, gender, and maximum left ventricular wall thickness. QT dispersion (maximum minus minimum QT interval) was manually measured on early 12-lead ECGs using a digitizing board. An in-house program was used for calculating QT interval, QT dispersion, JT interval, and JT dispersion (maximum minus minimum J point to T end interval). Patients in the case group tended to have shorter RR intervals than those in the control group (777 +/- 171 vs 856 +/- 192 ms, P = 0.08). Maximum corrected QT and JT intervals did not discriminate the case group from controls (489 +/- 29 vs 479 +/- 27 ms, P = NS; 375 +/- 36 vs 366 +/- 22 ms, P = NS, respectively). Greater QT dispersion and JT dispersion were found in the case group compared with controls (74 +/- 28 vs 59 +/- 21 ms, P = 0.02 and 76 +/- 32 vs 59 +/- 26 ms, P = 0.03, respectively). The measurements of maximum QT, JT, and T peak to T end intervals, precordial QT and JT dispersion, and T peak and T end dispersion were all comparable between the two groups (P = NS for all). No systematic changes in ECG measurements were found from late ECGs of the case group compared to those from early ECGs (P = NS). No correlation between maximum left ventricular wall thickness and QT dispersion, JT dispersion, maximum QTc or JTc intervals was observed (r < 0.29, P > 0.05 for all). Our results show that increased QT dispersion and JT dispersion is weakly associated with sudden cardiac death in the selected patients with HCM.

QT dispersion and left ventricular function after stent placement in acute myocardial infarction

BACKGROUND

QT dispersion is increased in acute myocardial infarction (AMI), but the relation of QT dispersion to left ventricular (LV) function has not yet been fully elucidated. The purpose of this study was to evaluate the relationship between QT dispersion and LV function in patients with successful coronary stenting in AMI.

METHODS

Seventy five patients with AMI who underwent percutaneous transluminal coronary angioplasty (PTCA) were enrolled in this study. Corrected QT dispersion was measured before, immediately after, 24 h after, 48 h after, and 6 months after PTCA. Left ventricular ejection fraction (LVEF) was evaluated by left ventriculography at 6 months after PTCA.

RESULTS

Corrected QT dispersion at 24 h after and 48 h after PTCA were significantly related to LVEF by univariate analysis (r=-0.282, p<0.05 and r=-0.326, p<0.01, respectively). In multiple regression model, corrected QT dispersion at 24 h after and 48 h after PTCA revealed significant associations with LVEF (R(2)=0.441, coefficient=-0.283, p=0.006 and R(2)=0.411, coefficient=-0.225, p=0.039, respectively), but corrected QT dispersion before, immediately after, and 6 months after PTCA were not associated with LVEF.

CONCLUSIONS

Corrected QT dispersion at 24 h after and 48 h after PTCA in AMI correlate with LVEF at 6 months after PTCA.

QT dispersion in non-apneic simple snoring patients and the effect of surgical therapy on QT dispersion

AIM

Increased QT dispersion in cases of obstructive sleep apnea, which may induce serious arrhythmias, is a well-known process. However, there is little information about the QT dispersion in patients with simple snoring without apnea. We investigated QT dispersion in snoring and the effect of surgical therapy on QT dispersion.

METHODS

One hundred and sixty two patients with simple snoring without apnea were included in this study. Patients had polysomnography and surface electrocardiography (ECG) on the pre-operative 1st week and post-operative 4th week. The patients underwent one of the three surgical procedures, which include uvulopalatopharyngoplasty, laser assisted uvulopalatoplasty, and cautery assisted uvulopalatoplasty. QT dispersion was calculated in each patient from pre-operative and post-operative surface ECG. Pre-operative and post-operative values were compared using the student's t test. P<0.05 was considered statistically significant.

RESULTS

One hundred and fourteen of the patients were male, 48 were female, and the mean age was 35.2+/-14.1 years (range: 21-51). No improvements were observed in 9 of the patients. Surgical interventions were successful in 153 patients (94%). Post-operative QTc max and QTc dispersion values were significantly shortened, and QTc min was increased compared to the pre-operative values (449.6+/-6.2 vs. 440.9+/-20.8, and 68.2+/-8.4 vs. 43.8+/-6.2, and 381.3+/-7.8 vs. 397.0+/-5.9 respectively; P=0.001).

CONCLUSION

This study shows that QT dispersion is increased in simple snoring patients without apnea and that QT dispersion decreases after surgical interventions.

Diurnal variation in QT dispersion in patients with chronic heart failure

QT dispersion is defined as the difference in QT interval among the different leads of the standard 12-lead electrocardiogram and reflects inhomogeneity of myocardial repolarization. Dispersion of repolarization is an important electrophysiologic feature that is considered fundamental for the initiation of ventricular fibrillation. However, no data exist regarding the diurnal variation of QT dispersion measured from simultaneous 12-lead recording in chronic heart failure patients. The aim of this study was to identify diurnal variation in QT dispersion in patients with chronic heart failure. QT dispersion was measured in the 12-lead standard electrocardiogram in 11 patients with chronic heart failure. QT dispersion in these patients was increased in the afternoon compared to the morning. It is concluded that QT dispersion has a clear diurnal variation in patients with chronic heart failure. These findings have potentially significant implications for therapy and prevention of sudden cardiac death in patients with chronic heart failure.

The association of QT dispersion and QT dispersion ratio with extent and severity of coronary artery disease

BACKGROUND

Although prolongation of the QT intervals in acute ischemic conditions, such as acute myocardial infarction, intracoronary balloon inflation, and exercise induced ischemia, has been shown, association of rest QT intervals with extent and severity of stable coronary artery disease (CAD) has not been assessed so far. The effects of extent and severity of stable CAD on rest QT interval were analyzed in this study.

METHODS

Rest 12-lead electrocardiograms (ECG) were recorded in 162 clinically stable subjects undergoing coronary angiography before the angiography for measurement of corrected QT dispersion (cQTd) and the QT dispersion ratio (QTdR) defined as QT dispersion divided by cycle length and expressed as a percentage. Angiographic "vessel score,""diffuse score," and "Gensini score" were used to evaluate the extent and severity of coronary atherosclerosis. Subjects were grouped as follows: those with normal angiogram (Group 1), those with insignificant (<50%) coronary stenosis (Group 2), and those with 1- (Group 3), 2- (Group 4), or 3-vessel disease (Group 5).

RESULTS

cQTd and QTdR were higher in Group 3 compared with Group 1 (P < 0.001 and P = 0.001, respectively), in Group 4 compared with Group 1 (P < 0.001 for both) and Group 2 (P = 0.001 and P = 0.003, respectively), and in Group 5 compared with Group 1 (P < 0.001 for both) and Group 2 (P < 0.001 and P = 0.003, respectively). cQTd and QTdR were positively correlated with the vessel score (r = 0.422, P < 0.001; r = 0.358, P < 0.001, respectively), diffuse score (r = 0.401, P < 0.001; r = 0.357, P < 0.001, respectively) and Gensini score (r = 0.378, P < 0.001; r = 0.373, P < 0.001, respectively). In multiple linear regression analyses, cQTd was found to be independently associated only with diffuse score (beta= 0.325, P = 0.038). Also, QTdR was independently associated with diffuse score (beta= 0.416, P = 0.006) and Gensini score (beta= 0.374, P = 0.011).

CONCLUSIONS

Rest cQTd and QTdR are increased, and related to the extent and severity of coronary atherosclerosis in patients with stable CAD.

QT peak dispersion, not QT dispersion, is a more useful diagnostic marker for detecting exercise-induced myocardial ischemia

BACKGROUND

The electrocardiographic indices of QT dispersion (QTd), QT peak dispersion (QTpd), and the principal component analysis ratio (PCAr) are related to the occurrence of fatal arrhythmia and are influenced by physical exercise.

OBJECTIVE

The purpose of this study was to investigate whether or not the QT parameters can be used as markers for exercise-induced myocardial ischemia.

METHODS

We measured these QT parameters at rest and at 3 minutes after exercise using exercise-stress thallium-201 scintigraphy (SPECT), compared with conventional ST segment changes in 161 patients with suspected or known coronary artery disease. The patients were classified into four groups (normal, redistribution, fixed defect, and redistribution with fixed defect) according to SPECT.

RESULTS

At rest, QTd and PCAr were greater in the fixed defect and redistribution with fixed defect groups. PCAr, however, increased after exercise in the redistribution and redistribution with fixed defect groups. Although QTpd at rest was not significantly different among the four groups, it increased in the redistribution and redistribution with fixed defect groups after exercise (QTpd after exercise: normal, 36 +/- 16 ms vs. redistribution, 51 +/- 23 ms, redistribution with fixed defect, 53 +/- 19 ms; P<.05). For myocardial infarction reflected by fixed defect, QTd at rest was the most useful indicator, while QTpd after exercise was the most useful indicator for exercise-induced myocardial ischemia according to multiple logistic regression analysis with receiver operating characteristic curves. In addition, the change in PCAr by exercise was an independent predictor for exercise-induced ischemia.

CONCLUSIONS

QTpd and PCAr could be useful indices for exercise-induced myocardial ischemia. Determining the QTpd of a patient after exercising can improve the diagnostic accuracy of ischemia in a routine clinical setting.

Effects of coronary revascularization and concomitant aneurysmectomy on QT interval duration and dispersion

A reduction in QT dispersion (QTd) has been previously shown in patients receiving thrombolytics and undergoing coronary artery bypass grafting (CABG). The purpose of the present study was to investigate changes occurring in corrected QT intervals or QT dispersion after CABG and concomitant aneurysmectomy in the same session. The study population included 43 patients with coronary artery disease with left ventricular aneurysm (LVA). The control group included 32 patients with coronary artery disease without LVA. The study patients underwent CABG and aneurysmectomy in the same surgical session. Corrected maximum and minimum QT interval duration (QTcmax and QTcmin) and corrected QT dispersion (QTcd) were measured in the study patients before and after surgery. QTcmax and QTcd in the patients with LVA were significantly higher than in the patients without LVA (P < .001 and P < .001, respectively). QTcmax and QTcd in the patients with LVA were significantly shortened after surgery (P < .001 and P < .001, respectively). This study showed that QTcmax and QTcd values are significantly reduced after CABG and concomitant aneurysmectomy. We have suggested that coronary revascularization and left ventricular reconstruction in the same session have beneficial effects on QT interval duration and dispersion.

Pacing-induced electrophysiological remodeling in hypertrophic obstructive cardiomyopathy--observations on cardiac memory

BACKGROUND

Hypertrophic cardiomyopathy carries an increased risk for sudden cardiac death. While pacing therapy reduces the left ventricular outflow tract gradient and improves symptoms in a subgroup of hypertrophic obstructive cardiomyopathy (HOCM) patients, its electrophysiological consequences are unknown and were therefore assessed in this prospective study.

METHODS AND RESULTS

Fifteen consecutive HOCM patients were studied and compared with 14 patients without HOCM paced because of sinus bradycardia. ECG intervals were measured before pacemaker implantation and after > or =3 months of DDD pacing in HOCM patients and > or =5 weeks in controls. Both groups showed similar ECG signs of cardiac memory development. In HOCM patients, with baseline QTc 447 +/- 33 ms, cardiac memory development was not associated with any significant changes in ECG intervals. In contrast, baseline repolarization in control patients was significantly prolonged by 6% (QTc 429 +/- 33 vs 454 +/- 46 ms; P < 0.05). Furthermore, in HOCM patients repolarization was 7% shorter during DDD pacing compared to sinus rhythm (JTc 329 +/- 25 vs 353 +/- 21 ms; P < 0.05), despite a significantly prolonged ventricular activation time (QRS duration 155 +/- 16 vs 91 +/- 9 ms; P < 0.01).

CONCLUSIONS

Importantly, the development of cardiac memory-induced different repolarization responses depending on baseline structure and electrophysiology. In HOCM patients repolarization was shorter during right ventricular apical pacing than during normal activation despite prolonged activation time.

QT dispersion in sarcoidosis

STUDY OBJECTIVES

QT dispersion (QTd) is the maximal interlead difference in QT interval on surface 12-lead ECG. An increase in QTd is found in various cardiac diseases. Sarcoidosis augments inhomogeneity in ventricular repolarization by sarcoid granuloma, which significantly correlates with ventricular fibrillation. Changes in QTd in the course of sarcoidosis have not been investigated previously.

DESIGN

The study included 35 patients with systemic sarcoidosis. The diagnosis of systemic sarcoidosis was made by biopsy. Thallium scintigraphy was performed in all patients with systemic sarcoidosis. Cardiac sarcoidosis was diagnosed in 16 patients based on abnormal thallium scintigraphy and normal coronary arteriography results. QTd, corrected QTd (cQTd), maximum QT (QTmax), maximum corrected QT (cQTmax), minimum QT, and minimum corrected QT intervals were measured. Twenty-four healthy subjects represented the control group for QT interval analysis.

MEASUREMENTS AND RESULTS

In the cardiac sarcoidosis group, mean QTd (+/- SD) was significantly greater than in the noncardiac sarcoidosis group and control group (49.50 +/- 10.86 ms, 28.14 +/- 11.02 ms, and 27.08 +/- 10.41 ms, respectively; p < 0.001). cQTd was significantly greater in the cardiac sarcoidosis group than in the noncardiac sarcoidosis group and control group (53.17 +/- 10.44 ms, 30.61 +/- 10.94 ms, and 29.01 +/- 10.52 ms, respectively; p < 0.001). QTmax (440 +/- 15.01 ms, 409 +/- 14.86 ms, and 410 +/- 13.21 ms; p < 0.001) and cQTmax (449 +/- 16.31 ms, 417 +/- 12.51 ms, and 418 +/- 11.76, respectively; p < 0.001) were also significantly greater in patients with cardiac sarcoidosis. In a limited follow-up group (11 cardiac and 9 noncardiac sarcoidosis patients), the incidence of premature ventricular contraction (PVC) on ECG was greater in the cardiac sarcoidosis group than in the noncardiac sarcoidosis group (36% and 0%, respectively; p < 0.05). A medium correlation existed between QTd and PVC (r = 0.331, p < 0.05).

CONCLUSIONS

QTd, cQTd, QTmax, and cQTmax are prolonged in patients with cardiac sarcoidosis compared to the patients with noncardiac sarcoidosis and control subjects. The incidence of PVC on ECG was greater in the cardiac sarcoidosis group than in the noncardiac sarcoidosis group.

QT interval dispersion in dialysis patients

The leading cause of mortality in dialysis patients is cardiovascular complications, including ventricular arrhythmias and sudden cardiac death. A reliable non-invasive predictive test of sudden death is therefore important. The interlead variation in duration of the QT interval on the surface electrocardiogram corrected with heart rate (QTc dispersion) might serve as a surrogate for ventricular arrhythmia. Prolonged QTc dispersion is commonly encountered in dialysis patients and possesses an increased risk of all mortality, including cardiovascular mortality. QT dispersion might be affected by shifts of the intracellular electrolytes during dialysis and increasing deposition of iron in cardiac muscles in these patients who have underlying heart diseases. Although no well-designed study has been done, the factors contributing to prolongation of QTc dispersion should be avoided. We summarize the results of the currently available clinical studies that examined QTc dispersion in dialysis patients.

Notable effects of angiotensin II receptor blocker, valsartan, on acute cardiotoxic changes after standard chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisolone

BACKGROUND

There are three distinct types of doxorubicin-induced cardiotoxicity (acute, chronic, and late-onset). Although previous studies with animal models suggest that angiotensin II plays a key role in the process of the doxorubicin-induced cardiotoxicity, there has been no such observation in humans. This randomized study investigated whether valsartan, a new class of angiotensin II receptor blocker (ARB), can inhibit acute cardiotoxicity after doxorubicin-based chemotherapy.

METHODS

Forty consecutive patients with untreated non-Hodgkin lymphoma who were scheduled to undergo standard chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP) (mean age, 56 yrs; range, 24-70 yrs) were randomized with minimization methods to receive CHOP with or without 80 mg/day of valsartan. Acute cardiotoxicity was comprehensively evaluated with neurohumoral, echocardiographic, and electrocardiographic markers before and on Days 3, 5, and 7 after the initiation of CHOP.

RESULTS

CHOP induced transient increases in the left ventricular end-diastolic diameter in an echocardiogram, the QTc interval and QTc dispersion in an electrocardiogram, and in the plasma brain and atrial natriuretic peptides. All these changes returned to nearly normal levels within a week after CHOP (P < 0.001). Notably, valsartan significantly prevented all these changes except for the elevation in atrial natriuretic peptide (P < 0.05). No significant change was observed in blood pressure or heart rate between the valsartan and control groups.

CONCLUSIONS

The results indicate that angiotensin II may play an essential role in acute CHOP-induced cardiotoxicity in humans. Future long-term studies are necessary to judge whether ARBs have a potential to prevent the chronic or late-onset types of doxorubicin-induced cardiotoxicity.