Ventricular Repolarization Parameters Research Articles

Hafif Akut Miyokarditli Genç Hastalarda İnteratriyal Blok ve Ventriküler Repolarizasyon Parametreleri

Objective: To evaluate ECG findings regarding interatrial block and ventricular repolarization and certain biochemical parameters in young patients diagnosed as acute myocarditis with normal ventricular functions. Materials and Methods: 405 patients under the age of 35 who underwent diagnostic coronary angiography between January 2014 and January 2020 were retrospectively analyzed. Patients whose ECG records could not be accessed or quality were not suitable for evaluation, with sudden cardiac death, cardiomyopathy, ejection fraction <50%, diabetes mellitus, hypertension, chronic kidney and liver failure were excluded. Patients who underwent diagnostic angiography for the differential diagnosis of acute myocarditis were assigned to myocarditis group (n: 35), and age– and sex–matched subjects with normal coronary circulation and underwent coronary angiography for any other reason were assigned to control group (n: 35). Results: Heart rate, P wave duration, P wave peak time, PR interval, QRS, QT, and Tp–e interval, QTc, Tp–e/QT and Tp–e/QTc ratios did not differ from each other. Whereas troponin (p<0.001), glucose (p=0.004), LDL (p=0.015), AST (p<0.001), ALT (p<0.026), CRP (p<0.001) levels and neutrophil count (p=0.003) were markedly higher in myocarditis group, HDL was lower (p<0.001). Conclusions: Although biochemical parameters display differences in myocarditis group, ECG findings did not differ.

The effect of coronary slow flow on ventricular repolarization parameters

IntroductionIschemia due to microvascular dysfunction may be responsible for the heterogeneity of ventricular repolarization in coronary slow flow. To our knowledge, there is no study in which QT interval, Tp-Te interval, index of cardiac-electrophysiological balance (iCEB), and frontal QRS-T angle were evaluated together in patients with CSF. In this study, we examined for the first time the relationship between all these myocardial repolarization parameters and CSF. Materials and methodsThe study group included 178 patients (99 female, mean age: 50.6 ± 8.6 years) with isolated CSF without stenotic lesions and with angiographically proven normal coronary arteries. The control group included 120 patients (71 female, mean age: 49.3 ± 9.4 years) with normal coronary angiography. QRS duration, QT interval, QTc interval, Tp-Te interval, Tp-Te/QT, Tp- Te/QTc, iCEB score, and frontal QRS-T angle were calculated from 12‑lead ECGs. ResultsThere was no significant difference in demographic parameters between the two groups. Compared with the control group, patients with CSF had significantly longer QTmax duration, QT dispersion, Tp-Te interval, and higher iCEB score, wider frontal QRS-T angle. ConclusionIn our study, we found that many of the ventricular repolarization parameters were adversely affected in patients with CSF. Impaired parameters may be associated with the risk of malignant ventricular arrhythmias.

High risk of ventricular repolarization abnormalities among hemodialytic end-stage renal disease patients.

Patients with chronic renal disease (CKD) are at a significantly elevated risk for ventricular arrhythmia. Several electrocardiographic (ECG) methods can be used to assess the ventricular arrhythmia risk on the standard 12-lead ECG.

Association between ventricular premature contraction burden and ventricular repolarization duration.

Premature ventricular contraction is generally known as benign in the absence of structural heart disease; however, premature ventricular contraction-induced left ventricular systolic dysfunction or ventricular arrhythmias are defined in some cases. Ventricular repolarization duration differs between myocardial cells, which causes myocardial electrical heterogeneity and is thought to be responsible for ventricular arrhythmias. In our study, we aimed to evaluate the association of ventricular repolarization parameters including Tp-Te interval, Tp-Te/QT ratio, and QRS-T angle with premature ventricular contraction frequency in patients with premature ventricular contraction burden. A total of 80 subjects who were admitted to our cardiology department and underwent 24-h electrocardiography Holter monitoring were included. Patients were divided into two groups: group 1 is defined as premature ventricular contraction burden that had frequent premature ventricular contraction ≥1% in 24-h Holter monitoring, and group 2 is defined as rare premature ventricular contraction <1% in 24-h Holter monitoring. Tp-Te interval and Tp-Te/QT ratio are statistically significantly prolonged in the premature ventricular contraction burden group than in the control group (85.3±13.9 vs. 65.7±11.9, p<0.001; 0.19±0.03 vs. 0.15±0.02, p<0.001, respectively). QRS-T angle was statistically significantly abnormal in the premature ventricular contraction burden group (p=0.024). Increased Tp-Te interval and widened QRS-T angle are associated with ventricular arrhythmias and might be used for the prediction of premature ventricular contraction burden in patients with premature ventricular contraction in electrocardiography in the absence of 24-h Holter monitoring.

Effects of COVID-19 infection on ECG parameters in outpatients

Abstract Objective Covid-19 infection has been declared as a pandemic disease by the World Health Organization (WHO) and has been associated with increased morbidity and mortality. More than 400 million people diagnosed with the disease has been reported until February 2022 [1]. Covid-19 infection mostly progresses with lung involvement and pneumonia, however, its effects on the cardiovascular system are also well-known. Studies have reported that Covid 19 infection can trigger cardiac events such as acute myocardial damage, acute myocarditis, acute coronary syndrome (ACS), ventricular arrhythmias, cardiogenic shock, and cardiac arrest [2]. Electrocardiogram (ECG) is an important tool to diagnose cardiac involvement. QTc interval, QT dispersion, Tp-e interval, Tp-e/QTc ratio are defined as ventricular repolarization parameters and these parameters are associated with increased risk of ventricular arrhythmia [3,4]. In our study, we aimed to evaluate to predict ventricular arrhythmia by ECG in Covid-19 patients. Methods Our study is a single-center, cross-sectional study. Patients diagnosed with Covid-19 in our center between July and October 2020 were included. 408 patients with positive SARS-CoV2 PCR test were detected and the ECGs of the patients were recorded at admission and 15 days after symptomatic recovery. After the exclusion criteria, remained 91 patients were analyzed. Conduction parameters (PR and QRS durations) and repolarization parameters (QTc interval, QT dispersion, Tp-e interval and Tp-e/QTc ratio) were evaluated in 12-lead ECG recordings. Results Ninety-one patients with Covid-19 infection were included. The group were consisted of 47 male (52%) and 44 female (48%). The mean age was 50.4 years. As a result of the statistical analysis, no significant difference was observed between the groups in terms of PR interval (142.2±21.4 ms vs. 140.1±19.0 ms; p=0.312). QRS duration was found significantly higher during active infection (91.4±12.2 ms vs. 88.8±10.9 ms; p=0.022). The mean QTc duration was detected longer in the first ECG, but no statistically significant difference was observed between the two groups (426.1±23.6 ms vs. 422.5±26.2 ms; p=0.237). QT dispersion (35.2±7.3 ms vs. 27.7±7.8 ms; p&amp;lt;0.001), Tp-e interval (86.7±10.1 ms vs. 76.1±9.9 ms; p&amp;lt;0.001) and Tp-e/QTc ratio (0.204±0.026 vs 0.180±0.025; p&amp;lt;0.001) were found significantly higher during active infection Conclusion In our study, QRS complex, QT dispersion, Tp-e interval, Tp-e/QTc ratio were significantly higher during active infection. We considered these parameters as a contributor of the increased mortality by inducing ventricular arrhythmia and sudden death in Covid-19 patients during active infection. Funding Acknowledgement Type of funding sources: None.

The relationship between length of stay in intensive care unit and Tpeak-Tend and Tpeak-Tend/QTc ratio in COVID 19 patients with acute coronary syndrome.

Patients with coronavirus disease 2019 (COVID-19) can develop cardiac injury resulting in cardiac arrhythmias, myocarditis, and acute coronary syndrome (ACS). In this study, we aimed to investigate whether COVID-19 infection affects ventricular repolarization parameters such as Tpeak-Tend interval (Tp-e), QT interval, corrected QT (QTc), Tp-e/QT, and Tp-e/cQT in patients with ACS. The study consisted of two groups. The first group included patients with ACS and COVID-19 (Group 1) (n=50). Polymerase chain reaction test positive patients were enrolled. The second group included patients with only ACS (Group 2) (n=100). The risk of ventricular arrhythmias was evaluated on the basis of the measured electrocardiographic Tp-e and QT interval, and QTc, Tp-e/QT, and Tp-e/QTc values. Tp-e interval, QTc, and Tp-e/QTc were significantly higher in the group1 than group 2 (p < .001, p < .018, and p < .001, respectively). Significant positive correlations were found between Tp-e, D-dimer level, and C-reactive protein (CRP) level in the group1 (p=.002, p=0.03, and p=.021, respectively). Univariate and multivariate regression analyses revealed that Tp-e was one of the independent predictor of length of stay in the intensive care unit (ICU). (B=1.662, p=.006 and B=1.804, p=.021, respectively). In the patients with ACS, COVID-19 infection caused increases in QTc, Tp-e, and Tp-e/QTc ratio. In addition, age and prolonged Tp-e were found to be independent predictors of prolonged ICU stay.

ECG descriptors of ventricular repolarization are associated with cardiac events in a gene-specific manner in long QT syndrome patients

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): Assistance Publiques Hôpitaux de Paris (APHP) Background Congenital long QT syndrome (LQTS) is still associated with syncope and a risk of sudden cardiac death despite the dramatic reduction in mortality associated with beta-blocker therapy. Current risk stratification tools are imperfect. Objective To assess the contribution of automated scalar ECG descriptors of ventricular repolarization for arrrhythmic risk stratification in genotyped LQTS patients. Methods Patients with genotyped type 1, 2 or 3 LQTS with at least 1 digital ECG recording have been included in the study. History at diagnosis, and follow-up data were collected. Cardiac events included syncope, aborted cardiac arrest, appropriate implantable cardioverter-defibrillator therapy in VF zone, and sudden death. ECG were analyzed using the BRAVO algorithm embedded in the CalECG software, version 4.1.0. QT interval duration was manually checked but ECG descriptors of Ventricular Repolarization were fully automatic. Multivariate cox regression analysis were performed to identify parameters associated with cardiac events. Results 467 patients (58% female, median age at diagnosis=25, LQT1,2,3 54%, 39%, 7%) were followed-up during 15.2±9.2 years. Rate of cardiac event was 1.2/100 patients-year before diagnosis and 0.9/100 patients-year during follow-up. QTc duration was associated with the occurrence of cardiac events in the whole study population (HR=1.01 95%CI 1.0-1.01, p=0.03). Ventricular repolarization parameters associated with cardiac events were different according to LQTS type. Cardiac events were associated with increased time to accumulate 50% of T-wave energy (HR=1.53 95%CI 1.04-2.26, p=0.03) in LQT1 but with a decrease in T-wave slopes (ascending slope HR=0.63 95%CI 0.17-0.75, p&amp;lt;0.01) in type 2 LQTS patients. QTc duration was not independently associated with cardiac events in genotype specific multivariate models. Conclusions T-wave morphology parameters are associated with cardiac events in a gene-specific manner. Change in T-wave symmetry and T-wave flattening are associated with cardiac events in type 1 and type 2 LQTS respectively. The descriptors of ventricular repolarization are promising parameters or risk stratification beyond QTc duration in LQTS patients.

QT interval instability and variability in dogs with naturally-occurring hypercortisolism.

Hypercortisolism is one of the most common endocrine diseases in dogs. In humans, it is clearly associated with a higher risk of cardiovascular events, but studies in dogs are scarce. To investigate the arrhythmogenic risk of dogs with naturally-occurring hypercortisolism (NOHC), indices of variability and instability of the QT interval were retrospectively studied in 38 dogs with NOHC and prospectively studied in 12 healthy dogs: variance (QTv), total instability (TI), short-term (STI) and long-term (LTI), and mean (QTm). Except for QTm, all parameters studied were higher in the NOHC group than in the control group. In addition, STI and QTv showed moderate positive correlation with left ventricle wall thickness. The NOHC group was subdivided according to cortisol suppression pattern in the low-dose dexamethasone suppression test. All electrocardiographic indices of partial and absent suppression patterns were numerically higher than healthy dogs. QTv and TI were lower in the control group than in both NOHC subgroups. LTI and STI were lower in the CG than in the group with the partial suppression pattern. There was no statistical difference between sex groups in any of the electrocardiographic parameters studied. This result might indicate that the etiology of NOHC, and its consequent influence on hypothalamus-pituitary-adrenal axis could interfere on the heterogeneity of ventricular repolarization parameters in different ways, especially in the short-term and the long-term stability; however further studies are necessary to understand the role of cortisol on electrical instability in dogs.

Does the use of proton pump inhibitors in children affect ventricular repolarisation parameters?

Proton pump inhibitors are widely used agents in the treatment of dyspepsia, and their effects on ventricular repolarisation through ion channels are well-known. Our aim is to evaluate the change in ventricular repolarisation parameters on electrocardiogram before and after proton pump inhibitor treatment. This study included 69 patients who had symptoms such as burning stomach pain, bloating, nausea, and heartburn for at least 3 months. Electrolyte levels of the patients were measured before and after treatment, and 12-lead electrocardiograms were taken at the initial and 1st month follow-up visit. Heart rate, QT interval, corrected QT (QTc), QT dispersion (QTd), QTc dispersion (QTcd), Tp-e measurements, and Tp-e/QT ratio were calculated and compared. Thirty-nine of the patients were girls, 30 were boys, and the mean age was 13.16 ± 3.02 years. Electrolyte levels of the patients before and after treatment were within the normal range. There was no statistically significant difference in the QTc, the Tp-e duration, or the Tp-e/QT ratio of the patients before and after treatment. We did not find a significant prolongation in the QTc duration or any other ventricular repolarisation parameters after proton pump inhibitor treatment in children with dyspepsia. We did not observe ventricular arrhythmia in our patients during follow-up. However, different results might be obtained with a larger sample and a longer follow-up period. These patients may have an increased risk of developing ventricular arrhythmias. Therefore, precaution should be taken when using drugs that prolong the QT period, and follow-up with serial electrocardiograms should be planned.

Examination of New Electrocardiographic Repolarization Markers in Diabetic Patients with Noncritical Coronary Artery Disease.

Background Diabetes mellitus (DM) is a multisystemic, chronic disease that affects many organs. Coronary artery disease (CAD) is the leading cause of death in patients with DM. The electrocardiogram's new ventricular repolarization parameters can predict mortality and morbidity. The ventricular repolarization indices were examined in diabetic patients with a CAD diagnosis in this study. Methods The study group consisted of 84 DM patients (51 males; mean age 58.8 ± 6.6) with noncritical CAD. The control group consisted of 84 DM patients (47 males; mean age 58.7 ± 8.8) with a normal coronary artery. The intervals of QT, QRS, JT, and Tp-e were all measured. Tp-e/QT, Tp-e/QTc, Tp-e/JT, and Tp-e/JTc ratios were determined with QTc, QTd, QTdc, and JTc intervals. Results Heart rate (74.4 ± 13.1 vs. 70.0 ± 13.6 bpm, p: 0.036), QT (381.0 ± 30.3 vs. 368.6 ± 29.1 ms, p: 0.008), QTc (407.5 (359–450) vs. 389 (339–430) ms, p < 0.001), QTd (25.1 ± 6.2 vs. 21.9 ± 9.9 ms, p: 0.013), QTdc (26.7 ± 6.1 vs. 23.1 ± 10.8 ms, p: 0.010), Tp-e (95.7 ± 12.2 vs. 73.6 ± 9.8 ms, p < 0.001), JT (293.8 ± 22.0 vs. 283.5 ± 30.9 ms, p: 0.014), and JTc (313.6 ± 12.3 vs. 302.4 ± 33.7 ms, p=0.005) intervals, and Tp-e/QT (0.25 ± 0.03 vs. 0.20 ± 0.03 ms, p < 0.001), Tp-e/QTc [0.23 (0.19–2.33) vs. 0.19 (0.14–0.25) ms, p=0.007], Tp-e/JT (0.33 ± 0.04 vs. 0.26 ± 0.04 ms, p < 0.001), and Tp-e/JTc (0.30 ± 0.03 vs. 0.24 ± 0.03 ms, p < 0.001) ratios were all found to be significantly higher in diabetic patients with noncritical CAD. Conclusion In this study, ventricular repolarization markers on the surface ECG were found to be elevated in diabetic CAD patients. These variables may be related to fatal arrhythmic events. To be sure, large-scale, randomized controlled trials are required.

Effects of azithromycin on ventricular repolarization in children with COVID-19

IntroductionAzithromycin is used to treat pediatric COVID-19 patients. It can also prolong the QT interval in adults. This study assessed the effects of azithromycin on ventricular repolarization in children with COVID-19. MethodThe study prospectively enrolled children with COVID-19 who received azithromycin between July and August 2020. An electrocardiogram was performed before, one, three, and five days post-treatment. Using ImageJ®, the following parameters were measured: QT max, QT min, Tp-e max, and Tp-e min. The parameters QTc max, QTc min, Tp-ec max, Tp-ec min, QTcd, Tp-ecd, and the QTc/Tp-ec ratio were calculated using Bazett's formula. ResultsThe study included 105 pediatric patients (mean age 9.8±5.3 years). The pretreatment heart rate was higher than after treatment (before 92 [79–108]/min vs. Day 1 82 [69–108)]/min vs. Day 3 80 [68–92.2]/min vs. Day 5 81 [70–92]/min; p=0.05). ConclusionAzithromycin does not affect the ventricular repolarization parameters on ECG in pediatric COVID-19 cases.

Epicardial adipose tissue and risk of arrhythmia in nephrotic syndrome.

Patients with nephrotic syndrome (NS) are at a high risk of cardiovascular disease, obesity, and dyslipidemia. The aim of this study was to evaluate the formation of epicardial adipose tissue (EAT) and investigate electrocardiographic (ECG) parameters in patients. Thirty-two patients aged 0-18 years and 15 control patients were compared. In the patient group, physical examination and laboratory parameters were recorded. Atrial depolarization and ventricular repolarization parameters in ECG were compared between the groups. EAT was evaluated with M-mode measurements on echocardiography. There was no difference between the groups in terms of sex, age, body mass index, systolic and diastolic BP. EAT was found to be significantly higher in the patient group. In ECG evaluations it was determined that atrial depolarization and ventricular repolarization parameters increased in the patient group. Cardiovascular morbidity and mortality are high in kidney diseases. Measurement and follow-up of EAT and ECG findings as a noninvasive parameter can provide information in NS.

Relationship between ventricular repolarization parameters and the inducibility of ventricular arrhythmias during electrophysiological study in patients with coronary artery disease.

Risk stratification of sudden cardiac death in patients with coronary artery disease is of great importance. We evaluated the association between ventricular repolarization and induction of malignant ventricular arrhythmias on electrophysiological study of patients with coronary artery disease. A total of 177 patients (65±10.1 years, 83.6% male, mean left ventricular ejection fraction [LVEF] 37.5±13.6%) were analyzed. For each 10 ms increment in the QT interval, there was a 7% increase in malignant ventricular arrhythmias inducibility; QT cutoff point of 452 ms had an accuracy of 0.611 for predicting malignant ventricular arrhythmias (p=0.011). Male gender (odds ratio [OR]=4.18, p=0.012), LVEF <35% (OR=2.32, p=0.013), amiodarone use (OR=2.01, p=0.038), and prolonged QT (OR=1.07, p=0.023) were associated with malignant ventricular arrhythmias. In patients with ventricular dysfunction, QT >452 ms was associated with significantly increased risk of malignant ventricular arrhythmias (OR=5.44, p=0.0004). In those with LVEF ³35%, QT dispersion (QTd) was significantly higher in patients with inducible malignant ventricular arrhythmias. QTd >20 ms had 0.638 accuracy and 81.3% negative predictive value in predicting malignant ventricular arrhythmias. QT interval is an independent factor associated with malignant ventricular arrhythmias in patients with coronary artery disease. The combination of ventricular dysfunction and prolonged QT interval is associated with a 5.44-fold increase of malignant ventricular arrhythmias induction. Male gender, amiodarone use, and decreased left ventricular ejection fraction are also associated with increased risk of inducibility of malignant ventricular arrhythmias on the electrophysiological study.

Conduction system pacing versus biventricular pacing: Reduced repolarization heterogeneity in addition to improved depolarization.

His-bundle pacing (HBP) and left-bundle-area pacing (LBAP) are conduction system pacing (CSP) modalities increasingly used as alternatives to conventional biventricular pacing (BiVP). While effects of CSP on ventricular depolarization have been reported, effects on ventricular repolarization have not. QRS duration (QRSd) and validated ECG parameters of ventricular repolarization associated with arrhythmic risk (T-peak-to-T-endTransmural , T-peak-to-T-endTotal , T-peak dispersion, QTc, QTc dispersion) were analyzed post-implant in 107 patients: 60 with CSP (HBP: n = 35, LBAP: n = 25) and 47 with BiVP. T-wave memory resolution and QTc shortening were analyzed on ECGs obtained ≥25 days post-implant. Twenty blinded measurements were obtained by both authors to assess Interobserver variability. Although QRSd was shorter with HBP versus LBAP (119 ± 7 ms vs. 132 ± 9 ms, p = .02), there were no significant differences in any repolarization parameters between these methods of CSP. However, when comparing CSP (HBP + LBAP) to BiVP, both QRSd (125 ± 5 ms vs. 147 ± 7 ms, p < .0001) and repolarization parameters (T-peak-to-T-endTransmural : 83 ± 5 ms vs. 107 ± 8 ms; T-peak-to-T-endTotal : 110 ± 7 ms vs. 137 ± 10 ms; QTc: 470 ± 12 ms vs. 506 ± 12 ms; all p ≤ .0001) were significantly shorter with CSP. Improved T-peak-to-T-end values were unrelated to pre-implant QRSd or LV function. Interobserver variability was 4.6 ± 1.9 ms. Frontal QRS-T angle narrowing (132° to 104°, p = .001) and QTc shortening (483 ± 13 ms to 464 ± 12 ms, p = .008) were seen only with CSP. In addition to improved depolarization, CSP reduced repolarization heterogeneity and provided greater T-wave memory resolution as compared to BiVP. Both modalities of CSP (HBP + LBAP) resulted in comparably reduced repolarization heterogeneity regardless of baseline QRSd and LV function. These observations may confer lower arrhythmogenic risk and warrant further study.

OR46. Increased of Ventricular Repolarization Abnormalities in Hemodialytic End-Stage Renal Disease

Abstract Background and Aims Cardiac or ventricular arrhythmia risks, including sudden cardiac death, are highly increased in patients with CKD, especially when reaching end-stage renal disease (ESRD). Several electrocardiographic (ECG) methods can be used to assess ventricular arrhythmia risk on the standard 12-lead ECG. This study aimed to evaluate ventricular repolarization abnormalities in patients with hemodialytic ESRD. Methods and Results Fifty-three patients with hemodialytic ESRD and thirty-two pre-dialytic CKD as controls were enrolled in the study. ECG parameters: QT, QTc, Tp-e, Tp-e/QT, and Tp-e/QTc were measured manually using callipers on ECG recordings from all participants. The normality of the data was analyzed with the Shapiro-Wilk test. The independent-samples T-test for normal distribution and the Mann-Whitney U test for abnormal distribution were used for analysis. Mean age in hemodialytic and pre-dialytic groups were 46.6±11.5 and 56.1±10.6 years old, respectively. Mean creatinine serum in hemodialytic and pre-dialytic groups were 9.9±4.7 and 2.4±0.7 mg/dL. Ventricular repolarization abnormalities in hemodialytic compared to pre-dialytic group: QTc (448.2±33.9 vs. 427.9±31.3 msec, p = 0.007), Tp-e (80[40:130] vs. 70[40:120] msec, p = 0.022), Tp-e/QT (0.23±0.06 vs. 0.20±0.05, p = 0.043) were found to be significantly different. While QT (360.4±47.8 vs. 355.9±36.6 msec, p = 0.646) and Tp-e/QTc (0.18[0.08:0.33] vs. 0.16[0.09:0.25], p = 0.196) were increased in hemodialytic group but not significantly different. Conclusion Ventricular repolarization abnormalities were found to be increased in patients with hemodialytic end-stage renal disease. Measuring ECG parameters of ventricular repolarization may help to identify risk for arrhythmogenesis and sudden cardiac death.

Exercise-induced electrocardiographic changes after treadmill exercise testing in healthy children: A comprehensive study.

Background:Treadmill exercise testing is a crucial diagnostic tool for evaluating congenital and acquired heart disease in the pediatric population. This study aimed to perform a comprehensive evaluation of exercise-induced electrocardiographic (ECG) changes in children. Although there are numerous studies on exercise testing in various cardiac pathologies, studies on exercise-induced ECG changes in normal children with coverage of all ECG parameters of atrial and ventricular depolarization and repolarization are very scant, if any.Aims and Objectives:This study aimed to investigate the exercise-induced ECG changes in healthy children and evaluate the effects of gender and four different formulas of heart rate correction of Bazett, Fridericia, Framingham and Hodges on ventricular repolarization parameters pre-and post-exercise.Materials and Methods:Between April 2019 and April 2020, all children with normal electrocardiogram, echocardiogram and exercise test, high-quality ECG tracings and consent for participation were enrolled in this prospective study. Twenty electrocardiographic parameters were measured and 25 indices were calculated. P-value < 0.05 was considered significant.Results:Seventy-four healthy children were studied. Amplitudes of P, S, and T waves increased significantly after the exercise. All durations, except P wave time to peak and T peak -T end /QT (Tp-e/QT) interval decreased significantly with exercise. Generally, the parameters of ventricular repolarization were not statistically significant between males and females. There were significant differences among the heart-rate corrected values of intervals of QTc, QoTc, JTc, J point to peak T and Tp-e/QTc by various formulas. There was no U wave either at pre-exercise or post-exercise. QT interval was shortened by 24.6 % ± 12.1 % with exercise. The ECG-derived estimated duration of mechanical systole and diastole decreased with exercise. The percentage of decrease in diastole was more than systole (43.79 %± 13.31% versus 33.74% ±15.79 %, respectively, P-value < 0.001).Conclusion:Diastolic time decreased more than systolic time with exercise and systolic time to diastolic time increased with exercise. Hodges' and Fridericia's formulas resulted in the longest and shortest QT and QoT, JT, and JTP, respectively. Thus, using a single value as the cut-off for long QT syndrome can lead to under or over-diagnosis. Nomograms incorporating data on age, heart rate, and heart rate correction formula are indispensable for accurate long QT diagnosis. Furthermore, gender differences in ventricular repolarization parameters are not generally present in 5 to 14-year-old healthy children. The lack of U wave in this study may implicate the need for more careful investigation in the presence of U wave in the treadmill exercise testing of healthy children.

Evaluation of ventricular repolarization variables in pediatric COVID-19

INTRODUCTION: Although the childhood clinic of COVID-19 is more innocent than adults, its unknown aspects continue to cause concern among pediatricians. One of these unsettling aspects is the cardiovascular system effects. We investigate the role of ventricular repolarization parameters in predicting arrhythmia risk in pediatric COVID-19. METHODS: Twelve-channel surface electrocardiograms of a total of 166 participants, including children diagnosed with COVID-19 and healthy controls, were analyzed. The QT interval, corrected QT interval, QTc dispersion, Tpeak-Tend, Tp-e dispersion, Tp-e / QT and Tp-e / QTc ratio were calculated. The correlations between ventricular repolarization parameters and laboratory values were examined. RESULTS: In our study, the COVID-19 patients had a significantly longer Tpeak-Tend (64.51 ± 8.64 and 57.62 ± 7.96; p < 0.001), Tp-e dispersion (21.77 ± 6.4 and 18.01 ± 6.78; p < 0.001), and corrected QT interval (393.18 ± 20.06 and 380 ± 22.3; p < 0.001) duration than the control group. There was a significantly higher Tp-e / QT ratio (0.17 ± 0.02 and 0.15 ± 0.02; p < 0.001), Tp-e / QTc ratio (0.16 ± 0.02 and 0.15 ± 0.02; p < 0.001) in group with COVID-19 than the controls. In addition a positive correlation was found between Tpeak-Tend interval, Tp-e dispersion and white blood cells in the group with SARS CoV2 infection. DISCUSSION AND CONCLUSION: Evaluating these ventricular repolarization parameters in pediatric SARS CoV2 infection may be useful in predicting the risk of ventricular arrhythmia.

Comparison of ventricular repolarization parameters of Covid-19 patients diagnosed with chest CT and RT-PCR

Background and objectives The aim of the comparison is to evaluate the marker of ventricular repolarization parameters such as QT, QTc, cQT, Tp-e, Tp-e/QT, Tp-e/QTc, Tp-e/JT and Tp-e/JTc ratios and the risk of ventricular arrhtythmias in patients with newly diagnosed Covid-19. Methods The study included 2 separate groups. The first one consisted of 96 positive reverse transcriptase polymerase chain reaction (RT-PCR) Covid-19 patients and the second one of 106 patients with negative PCR but positive chest computed tomography (CT) findings consistent with Covid-19. We measured QTmax, QTmin, QRS, JT and Tp-e intervals and estimated Tp-e/QT max, Tp- e/QTc max, Tp-e/JT and Tp-e/JTc rates and QTc max, QTc min, cQTd and JTc intervals. Results QT max, QT min, JT, cQTd, Tp-e, Tp-e/QT max, Tp-e/QTc max, Tp-e/JT, Tp-e/JTc values were significantly higher in RT-PCR Covid-19 patient group. Conclusion Positive RT-PCR Covid-19 patients should be followed more closely, in terms of high ventricular repolarization parameters and preventing ventricular arrhythmias that may develop due to this.

Ventricular Repolarization Parameters and Coronary Involvement in Kawasaki Disease

To evaluate electrocardiogram markers to predict coronary involvement in patients with Kawasaki disease by assessing measures of ventricular repolarization parameters on the 12-lead electrocardiogram. This cross-sectional study included 180 Spanish and Japanese patients ≤14years of age with Kawasaki disease, with or without coronary involvement, from 2011 to 2016. We manually measured the Tp-Te/QT ratio and QTc interval (with Bazett's formula) in 12-lead electrocardiogram in the acute and recovery period and explored their potential association with coronary involvement. No association was found between Tp-Te/QT ratio obtained manually in V5 and V6 leads and coronary involvement in the acute (V5:0.25 [IQR, 0.21-0.27] vs 0.25 [IQR, 0.20-0.27], P=.80; V6:0.24 [IQR, 0.21-0.27] vs 0.25 [IQR, 0.20-0.27], P=.86) or the recovery (V5: 0.23 [IQR, 0.20-0.25] vs 0.23 [IQR, 0.19-0.25], P=.68; V6: 0.23 [IQR, 0.20-0.25] vs 0.23 [IQR, 0.17-0.25], P=.50) period. By contrast, QTc in V5 and V6 was significantly lower in patients with Kawasaki disease and coronary involvement in the acute period (V5: 378ms [IQR, 364-395ms] vs 390ms [IQR, 371-411ms], P=.04; V6: 377ms [IQR, 364-392ms] vs 390ms [IQR, 371-410ms], P=.01). A QTc interval of <385ms in lead V6 was associated with a 2.5-fold increased risk of coronary involvement (OR, 2.5; 95% CI, 1.2-5.3; P=.02). Manually measured QTc interval may be a marker of coronary disease in the acute period of Kawasaki disease.

Evaluation of Changes in Ventricular Repolarization Parameters in Morbidly Obese Patients Undergoing Bariatric Surgery.

Weight loss after bariatric surgery has been associated with reduced cardiovascular mortality and overall mortality in obese patients. In this study, we aimed to analyze the changes between pre-operation and post-operation ventricular arrhythmia predictors in patients who underwent bariatric surgery. The study included 58 patients who underwent bariatric surgery. We measured QT max, QT min, QRS, JT, and Tp-e intervals, and we estimated Tp-e/QT max, Tp-e/QTc max, Tp-e/JT, Tp-e/JTc rates, QTc max, QTc min, cQTd, and JTc intervals both pre-op and 6 months post-op. Heart rate, PR, QT max, QTc max, QTc min, cQTd, JTc, Tp-e, Tp-e/QT max, Tp-e/QTc max, Tp-e/JT, and Tp-e/JTc values, which were close to the upper limit in the pre-op period, showed statistically significant decreases at 6 months post-op. The results of our study showed that bariatric surgery had positive effects on the regression of ventricular repolarization parameters and the possible development of ventricular arrhythmia.