Minimum QT Research Articles

Is the development of arrhythmia predictable in rheumatoid arthritis?

Objectives: This study aimed to determine whether there is a difference in the electrocardiography (ECG) measurements of healthy controls and rheumatoid arthritis (RA) patients and to predict whether they can be used to determine the risk of arrhythmia in patients. Patients and methods: The prospective study included 50 cardiac asymptomatic RA patients (38 males, 12 females; mean age: 46.8±9.1 years; range, 18 to 60 years) who met the 2010 American College of Rheumatology/European Alliance of Associations for Rheumatology RA criteria and 50 healthy volunteers (34 males, 16 females; mean age: 43.4±10.4 years; range, 18 to 60 years) as a control group between June 1, 2022, and August 31, 2022. Disease activity of the patients was calculated with the Disase Activity Score (DAS28). Heart rate, minimum and maximum QT intervals, QT dispersion, minimum and maximum P waves, P wave dispersion (Pd), minimum and maximum Tp-e intervals, Tp-e dispersion, minimum and maximum corrected QT (QTc) intervals, QTc dispersion, and the Tp-e/QTc ratio in ECGs were calculated. Results: The mean disease duration of the RA group was 9.09±5.74 years. The mean C-reactive protein level was 9.83±8.29, the mean erythrocyte sedimentation rate was 26.12±16.28 mm/h, and the mean DAS28 was 3.03±0.37. There was a statistically significant increase in the maximum P wave, Pd, maximum QT, QT dispersion, maximum QTc, QTc dispersion, maximum Tp-e, Tp-e dispersion, and Tp-e/QTc dispersion parameters in the RA group compared to the control group, while there was a significant decrease in the minimum P wave, minimum QT, and minimum QTc parameters. Conclusion: In our study, the Pd, QTc dispersion, Tp-e dispersion, and Tp-e/QTc dispersion values of our patients, which indicate the risk of atrial and ventricular arrhythmia, were found to be significantly higher. This finding suggests that our patients had an increased risk of cardiac morbidity and mortality. Arrhythmias are the likely source of the increase in sudden cardiac death in RA, and these new indicators measured on ECG can be used as standardized cardiovascular morbidity and mortality indicators in the future.

The assessment of adolescent obesity's effects on ventricular repolarization

BackgroundCurrently, there is a lack of research on the Tp-Te interval and Tp-e/QT ratio in obese adolescents who have metabolic syndrome. AimOur study aims to compare established ventricular repolarization parameters with these intervals and ratios in obese adolescents with or without metabolic syndrome, alongside a healthy control group, while exploring the association of these repolarization parameters with cardiovascular risk factors and echocardiographic variables. MethodsThe study included 100 obese adolescents and 50 lean subjects, with the obese participants categorized into two subgroups. The Tp-Te interval was identified as the duration from the peak to the end of the T wave. ResultsThe metabolic and non-metabolic syndrome obese groups exhibited significantly elevated QTc and TpTe values compared to the control group, with no statistically significant differences observed in minimum QT, maximum QT, QT dispersion, QTc dispersion, TpTe dispersion, and TpTe/QT ratio values among obese subjects with metabolic or non-metabolic syndrome and controls. Specifically, TpTe values were significantly elevated in the non-metabolic syndrome obese groups compared to controls, while minimum TpTe values were significantly elevated in the metabolic syndrome obese groups compared to controls, and the prolongation of the QTc interval was notably elevated in the obese groups than in controls. ConclusionsObese adolescents demonstrated an elevated TpTe interval compared to healthy controls, without any significant differences observed in TpTe dispersion, and TpTe/QT ratio values between the two groups. Results of our study showed that a negative correlation between TpTe and HDL-cholesterol and a positive correlation between the TpTe/QT ratio and insulin sensitivity indices in adolescents with metabolic syndrome.

33. Association between QT Dispersion and Left Ventricular Hypertrophy in Hypertensive Heart Disease Patients

Background: The variation in QT length reflects regional repolarization differences in the heart. An Increased in QT dispersion is associated with an increased left ventricular mass index in hypertensive individuals. Objective: The aim of this study was to investigate association between QT dispersion and left ventricular hypertrophy (LVH) in hypertensive heart disease (HHD) individuals. Method: This study was a-single centre, retrospective study, included 47 patients with hypertension who had visited the cardiology clinic. Electrocardiography (EKG) and trans-thoracal echocardiography (TTE) were performed. Patients were divided into LVH group (27) and control group (20) based on TTE findings. Patients with valvular abnormalities, myocardial infarction, LV dysfunction, pericardial disease, arrhythmia related, and pulmonary disease were excluded from this study. Results: LVH was diagnosed in 31 (56%) of the patients by 2D echocardiography. The QT interval maximum was higher at 414.00 ± 59.87, than 396.19 ± 37.75 in the control group. Corrected QT (QTc) maximum in HHD group also higher at 448.08 ± 54.83 compared to control group in 421.67 ± 35.61. QT minimum and QTc minimum both are higher in HHD group at 350.40 ± 53.27 and 378.32 ± 43.00 respectively than in controlled group, at 339.05 ± 43.12 and 361.29 ± 45.26. There was no significant association in QT dispersion (p = 0.582) and QTc dispersion (p = 0.265) between HHD group and controlled group. Conclusion: The QT dispersion trend was narrowly higher in hypertensive patient with LVH in HHD group than the controlled group but it was statistically insignificant.

Increased QT dispersion and related factors in patients with systemic sclerosis

Introduction: Cardiac arrhythmias and sudden death may occur as a result of ventricular myocardial fibrosis or ischemia in patients with systemic sclerosis (SSc). QT prolongation and QT dispersion, which facilitate the development of ventricular fibrillation, are important cardiac problems associated with increased mortality. In this study, we aimed to investigate the prevalence of corrected QT dispersion (cQTD) and related factors in our patients with systemic sclerosis compared to healthy controls. Material and Method: The 12-lead electrocardiograms with a rate of 25 mm/s of patients with no previous history of cardiovascular disease and controls were analyzed. cQTD was defined as the difference between the maximum QT interval and the minimum QT interval. Nailfold capillaroscopy examination was performed. Disease activity was evaluated using revised European Scleroderma Study Group activity index. Results: Forty-nine SSc patients (45 females, mean age 53.26±10.63 years, and disease duration 8.0 (1-25) years) and 41 controls (37 females, mean age 49.29±8.02 years) were included. While the frequency of smoking was significantly higher in controls (p=0.025), erythrocyte sedimentation rate was higher in patients (p<0.001). cQTD was significantly higher in the patient group compared to the control group (65.14±17.57 ms and 42.73±10.03 ms, respectively, p<0.001). A significant positive correlation was found between erythrocyte sedimentation rate and cQTD in the patient group. We found no association between cQTD and disease activity, medications, anti-SSA/Ro positivity, capillaroscopy paterns, presence of interstitial lung disease and pulmonary arterial hypertension. Conclusion: In our study, cQTD, which indicates an increased risk for ventricular arrhythmia and cardiovascular mortality, was found to be significantly higher in the patients compared to the controls. Determining cardiac risks with an electrocardiogram, which is a non-invasive and easily available method, is important in the follow-up of SSc patients.

The association between electrocardiographic data and obesity in children and adolescents.

There are not enough studies investigating the relationship between obesity and ECG abnormalities in children and adolescents. This study aims to investigate the relationship between obesity and electrocardiographic data in children and adolescents for early diagnosis to prevent arrhythmia or sudden death in later stages of life. A total of 65 children and adolescents with obesity applied to our pediatric endocrinology outpatient clinic with nonspecific complaints and without any known chronic illnesses; 76 healthy children and adolescents were included in the study. Anthropometric and laboratory data, blood pressure measurements, and 12-lead electrocardiography data of all participants were collected. There was a statistically significant difference between the obese and the control group in terms of triglycerides, total cholesterol, high density lipoprotein, low density lipoprotein levels, and systolic blood pressure. According to electrocardiographic findings, there was a statistically significant difference between the two groups in terms of heart rate (p=0.008), PR duration (p<0.001), left ventricular hypertrophy (p=0.02), P maximum (p=0.04), P dispersion (p<0.001), QRS duration (p<0.001), QT minimum (p=0.007), QT maximum (p=0.03), QT dispersion (p=0.024), QTc minimum (p=0.002), QTc dispersion (p=0.003), Tp-e minimum (p=0.007), and Tpe maximum (p=0.003) variables. There were significant differences between the electrocardiographic evaluation of obese group compared to the control group in our study, which may be associated with risk of cardiac arrhythmia. These differences require monitorization in terms of cardiac arrhythmia and risk of sudden death. Further studies with longer follow-up time are needed to support the potential clinical outcomes of our findings.

The role of baseline and post-treatment frontal QRS-T angle for detecting arterial blood pressure control

ABSTRACT Objectives: In this study, we aimed to investigate the value of the frontal QRS-T angle (f(QRS-T)) in determining blood pressure control among newly diagnosed hypertensive patients with no left ventricular hypertrophy. Methods: Fifty patients with newly diagnosed hypertension were included in this single-center study. The patients were examined with 12-lead ECGs and 24-hour ambulatory blood pressure monitoring (24 h-ABPM) before and 1 month after antihypertensive treatment. Results: Baseline and post-treatment f(QRS-T) angle values were observed to be similar (38.0 [0.0–174.0] and 37.0 [1.0–139.0], respectively; p = .827). The values of QT minimum (p = .006), QTc mean (p = .030), Tp-e (p = .027), and JTc (p = .010) significantly decreased after control of blood pressure. Conclusions: The f(QRS-T) angle, which can be easily calculated on the ECG, is not a useful tool to determine hypertension control at early stage in newly diagnosed hypertensive patients.

The diagnostic value of QT dispersion for acute coronary syndrome in patients with nondiagnostic initial electrocardiograms

Introduction: Chest pain is a frequent cause for admission to the emergency department (ED). It can be a sign of various conditions, from a minor disorder to a life-threatening disease such as acute myocardial infarction (AMI). Despite the availability of modern-day tools for the diagnosis of AMI, about 5% of patients with AMI are missed in the ED, with subsequent associated morbidity and mortality. QT dispersion as a marker for arrhythmic potential being a marker of in-homogeneity of ventricular repolarization. The QT dispersion is increased in myocardial ischemia. Aims: This study we hypothesized that QTD could accurately identify patients with the acute coronary syndrome (ACS) who presented with chest pain and nondiagnostic initial electrocardiograms (ECGs). Subjects and Methods: The study population included (50) patients (37 males, 13 females) and (10) chronic stable ischemic patients as a control group, they were all in sinus rhythm on admission. All the studied patients were subjected to: History taking; complete physical examination was performed to rule out any other medical problems, standard 12-lead ECG, cardiac markers, echocardiographic examination. QT interval was calculated. The difference between the maximum and minimum QT intervals, occurring in any of the 12 leads, was measured as QTD. A corrected QT interval (QTc) of >440 ms is defined as abnormal, and the difference between QTc max and QTc min was calculated as QTcD. QT dispersion ≤40 ms was considered normal. Results: In the present study, we found that 26 patients (52%) have prolonged QTD (mean 78.800 ms, standard deviation [SD] ±49.555) and 44 patients (88%) have prolonged cQTD (mean 83.322 ms, SD ± 48.491) For patients who were admitted to the ED with chest pain and nondiagnostic initial ECG but later diagnosed as having ACS. Furthermore, we found that only 6 (12%) of patients have a significant prolongation QTD than normal in initial nondiagnostic ECG with elevated cardiac biomarkers (creatine kinase myocardial band at 0 h 48, mean creatine kinase myocardial band (CK MP) at 12 h was 145.833 ± SD 52.660, creatine phosphokinase (CPK) at 0 h: 635.33, mean CPK at 12 h 2448.66 ± SD 538.744). It has been suggested that the initial QTD level has a low predictive power for new cardiac events but that QTD can be more helpful for low-risk patients. Conclusion: Hence, in this study, we found that QTD and QTcD values are higher for ACS patients than for patients without ACS with nondiagnostic initial ECG.

The relationship between QT interval indices with cardiac autonomic neuropathy in diabetic patients: a case control study

BackgroundLong QT interval (QT) and abnormal QT dispersion (QTd) are associated with sudden death. The relationship between cardiac autonomic neuropathy (CAN) and QT indices in type 2 diabetic patients were investigated.MethodsTotally 130 diabetic subjects (mean age 50.87 ± 13.9 years) were included (70 individuals with and 60 individuals without CAN). All participants had sinus cardiac rhythm. The patients who had diseases or take drugs that cause orthostatic hypotension (OH), cardiac arrhythmia and QT prolongation were excluded. After interview and examination, standard and continuous ECG was taken in supine position with deep breathing and standing up position. CAN diagnosis was based on Ewing’s tests. QT, QT corrected (QTc), minimum QT (QT min), maximum QT (QT max) and mean ± SD of QT (QT mean) and QTd were assessed from standard ECG. QTc was calculated by Bazett’s formula from V2 lead. QTc > 440 ms in men and QTc > 460 ms in women and QTd > 80 ms were considered abnormal.ResultsIn patients with CAN, 21.5% were symptomatic. The prevalence of abnormal QTc and QTd was 11.3% and 28.7%, respectively. There was no significant difference between the patients with or without CAN in terms of long QTc and abnormal QTd. However, the mean ± SD of QT max, QT mean and QTd was higher in the patients with CAN (P value < 0.03). The used cut points for QTc and QTd have high specificity (79% for both) and low sensitivity (30% and 37%, respectively). To use QTc and QTd as screening test for CAN in T2DM patients, the cutoff points 380 and 550 ms are suggested, respectively.ConclusionThe prevalence of asymptomatic CAN was 3.7 times that of symptomatic CAN. In patients with CAN the QT max, QT mean and QTd were higher than those without CAN. There was no association between CAN and long QTc and abnormal QTd.

Electrocardiographic Evaluation of the Ventricular Arrhythmia Risk in Patients Diagnosed With Schizophrenia.

The purpose of this study was to examine electrocardiographic ventricular arrhythmia predictors in patients with schizophrenia by comparing with healthy controls. The study included 100 patients with schizophrenia and 100 healthy controls. Electrocardiography (ECG) was performed on all participants in resting position. T-wave peak to end (Tp-e), QT ranges, P-wave dispersion (Pd), and R-R range were measured. Then, the Schizophrenia Positive and Negative Syndrome Scale (PANSS) and the Calgary Depression Scale for Schizophrenia (CDSS) were applied to the schizophrenia group. The PANSS positive symptom subscale was calculated as 10.41 (SD = 2.27), the negative symptom subscale was calculated as 14.44 (SD = 5.42), and the overall functionality level was calculated as 27.04 (SD = 5.43). The mean CDSS score was determined to be 3.74 (SD = 2.15). No differences were detected in the heart rate measurements of the patient and control groups in ECG results (P = .427). The minimum QT interval and minimum Tp-e wave times were found to be low in the patient group (P < .001 for both intervals). Corrected QTc dispersion, Pd, Tp-e dispersion, and QT dispersion were found to be higher in the patient group than in healthy controls (P < .001 for all intervals). Based on our results, it is possible to speculate that patients with schizophrenia are at a risk of developing cardiac arrhythmia and cardiac dysfunction if they do not receive treatment. For this reason, clinicians should pay attention to cardiac transmission problems when organizing the treatment of patients. Further studies should be conducted to determine cardiac problems in patients with schizophrenia.

Diurnal Corrected QT Interval and QT Dispersion Variation in Non-alcoholic Cirrhotic Patients and Healthy Control: A Case-Control Study, Iran

Background: Cirrhosis could lead to a long corrected QT (QTc) interval in a subgroup of patients, but there are spare data on its diurnal variation. Objectives: The present study aimed to determine the diurnal variation of QTc interval and its relationship to heart rate and blood pressure variation during 24-hour Holter-monitoring in non-alcoholic cirrhosis in comparison with the healthy controls. Methods: The study population comprised 15 patients with non-alcoholic cirrhosis and 15 healthy subjects, undergoing 24-hour electrocardiogram (ECG), heart rate, and blood pressure monitoring. The mean QT interval, mean QTc, maximum and minimum QT, QT dispersion (QT disp), heart rate, and mean arterial blood pressure were measured for each person for 24 hours. Liver stiffness measurement (LSM) was performed by FibroScan® 502 machine (EchoSense, Paris, France, 5 MHz). The results were demonstrated as percentages and mean ± SD. P value ≤ 0.05 was considered significant. Results: Mean QTc was significantly higher in cirrhosis (438 ms) than healthy controls (401.7 ms) (P = 0.03). The mean heart rate was significantly different in cirrhotic patients (79.6 ± 2.9/bpm) compared to healthy controls (72.47 ± 2.0/bpm) (P = 0.05). Conclusions: In this study, QTc was prolonged and increased with the severity of cirrhosis, and its diurnal variation in cirrhosis was different from healthy subjects.

Relationship between QT Interval Dispersion and Degree of Coronary Artery Disease

Background: It has been shown that QT dispersion (QTD) increases during episodes. Currentstudyhas been done in order to determine QTD in patients with stable angina, assess myocardial ischemia and infarction. Aims of Study: This study aiming to determine the relationship between severity of coronary artery disease (CAD) and degree of QTD. Patients and Method: A 214 patients (177 men and 37 women) underwent diagnostic coronary angiography because of suspected CAD. Standard resting 12 lead electrocardiogram (ECG) were recorded within 24hrs before coronary angiography. QT intervals were measured manually by ruler method and QTD were gauged as (QT maximum – QT minimum). A 184 patients had CAD and control group (30 persons) had a normal coronary angiogram Interestingly, QTD has increased significantly as there was sever increment of CAD. QTD was in 1 vessel disease, 2 vessel disease, in 3 vessel disease, and in left main stem disease. Left ventricular dysfunction has raised QTD significantly in patients with 1,2 vessels, as well as left main stem disease. QTD clearly elevated as Gensini score increased. Involvement of proximal left anterior descending artery did not increase QTD significantly in patients with CAD. Multiple regression analysis demonstrated that severity of CAD, left ventricular dysfunction and previous myocardial infarction were independently associated with increased QTD. QTD increased significantly in patients with stable angina compared to the controls.Severity increase of CAD resulted in significant increase in QTD, and presence of LV dysfunction has caused further increase.

Dependence of QT (QTc) interval duration on the blood pressure level in patients with arterial hypertension

Introduction. Arterial hypertension is associated with electric instability of the myocardium and the development of fatal ventricular arrhythmias. One of the main causes for the electric instability of the myocardium is the in homogeneity of the ventricular repolarization processes, which can be estimated by studying QT interval duration and dispersion. Objectives.To study the dependence of QT interval (QTc) duration on the level of blood pressure in patients with arterial hypertension using a standard ECG recording and an ambulatory ECG monitoring. Materials and methods. Were examined147 patients, 124 of which with arterial hypertension and 23 without arterial hypertension. Patients were divided into 5 groups according to their blood pressure level: group 1 – normal or elevated blood pressure on a background of antihypertensive therapy: 56 patients (38.1 %), group 2 –grade 1 hypertension; 39 patients (26, 5 %), group 3 –grade 2 hypertension: 22 patients (15 %), group 4 –grade 3 hypertension: 7 patients (4.8 %), the fifth group – normal or elevated pressure: 23 patients, which is 15.6 % (comparison group, without arterial hypertension). The study of the dependence of QT interval (QTc) duration on the level of BP was carried out according to the analysis of the data of standard ECG, ECG Holter monitoring and 24-hour blood pressure monitoring. Results. A statistically significant regression dependence of the duration of minimal nocturnal QT intervals and corrected QTc on the stage of arterial hypertension in groups 1 and 4 with p &lt; 0.05 was establishedon the basis of Student’s t-test for independent samples. Conclusions. There was a statistically significant regression dependence of the minimum QT interval at night and the minimum corrected interval QTc at night on the daily level of variability 1 of systolic blood pressure, which indicates a direct dependence of the QT interval and QTc on blood pressure.

Evaluation of cardiac arrhythmia incidence in patients treated with oral moxifloxacin

Background: The effect of moxifloxacin on QT interval is reversible and dose related, mainly provided by weakly but rapidly activated rectifying potassium channel blockade, IKr or human ether-a-go-go-related gene potassium channels. Retrospective data suggested an increase in cardiac event rates with moxifloxacin use. Nevertheless, except for case reports and experimental trials about QT/QTc, there are insufficient data in the literature on the incidence of cardiac arrhythmias detected by electrocardiography (ECG) and Holter monitoring. In this trial, we sought to determine the effects of newly administrated oral moxifloxacin on the incidence of cardiac arrhythmias. Methods: Forty-four patients (mean age 34.0 ± 10.4 years) treated with oral moxifloxacin with the indications of upper airway infections, community-acquired pneumonia, and acute exaggerated bronchitis were enrolled. All patients were screened for cardiac arrhythmia before therapy (BT) (0th day), on the 3rd day (during therapy [DT]), and on the 10th day (after therapy ORIGINAL ARTICLE) with ECG and on the 3rd and 10th day with Holter monitorization. Before starting of the therapy, structural heart diseases were excluded using echocardiography, and other exclusion criteria were based on the laboratory tests.Results: The mean heart rate (HR) assessed by Holter monitoring was not significantly different during and after antibiotic therapy, although the mean HR measured from surface ECG was significantly reduced during and after antibiotic therapy compared to baseline (BT: 80.3 ± 13.9 beats per minute [BPM] vs. DT: 76.3 ± 11.3 vs. BPM vs. AT: 75.9 ± 106.0 BPM; P = 0.007). The mean QT interval value was increased on the 3rd day when compared to 0th day and was similar with the value on the 10th day (BT: 353.1 ± 24.6 msn vs. DT: 363.3 ± 23.7 msn vs. AT: 361.8 ± 20.8 msn; P = 0.034). The mean QTc interval was significantly increased on the 3rd day; however, it was decreased to the baseline value AT (BT: 396.4 ± 20.2 msn vs. DT: 404.4 ± 19.3 msn vs. AT: 397.5 ± 21.0 msn; P = 0.011). When the Holter monitoring findings of our study were analyzed in terms of gender interaction, minimal and maximal HR and QT dispersion parameters as well as the frequencies of ventricular and supraventricular extrasystoles and other arrhythmia findings were not different between male and females. Conclusion: Oral moxifloxacin started on an outpatient basis with the indication of airway infections resulted in a temporary increase in QT interval DT. However, it does not affect QTc and is not related with serious cardiac arrhythmias during Holter monitoring.

Abstract P371: The Effects of Omega-3 Fatty Acid Ethyl Esters on QT Dispersion and Corrected QT Dispersion in Hypertensive Patients With Left Ventricular Hypertrophy

Background: Left ventricular hypertrophy (LVH) leads to arrhythmia such as atrial fibrillation, ventricular arrhythmias and known risk factor of sudden cardiac death. Recent study suggests that Omega-3 fatty acid ethyl esters have anti-arrhythmic effects and reduce sudden cardiac death among survivor of myocardial infarction. QT dispersion(QTD) reflects ventricular repolarization heterogeneity and prolonged QTD has been associated with the risk of arrhythmic death in coronary artery disease patients. However, no study has done to prove the effects of Omega-3 fatty acid ethyl esters on QTD and corrected QTD(cQTD) in hypertensive patients with LVH Objective: We tried to evaluate the effects of Omega-3 fatty acid ethyl esters on QTD and cQTD in hypertensive patients with LVH Design and Method: This study included 30 hypertensive patients who confirmed LVH by ECG voltage criteria. The patients were evaluated with 12-leads electrocardiography before and 3~6 months after treatment of Omega-3 fatty acid ethyl esters(1g/day). We measured QTD (maximal QT interval - minimal QT interval) and cQTD (maximal corrected QT interval - minimal corrected QT interval) by Bazett’s formula using electronic caliper before and after treatment. Results: QTD (before: 60.86±14, after: 51.84±13.95 P=0.003) and cQTD (before: 63.83±14.18, after: 51.83±13.94 P&lt;0.001) was significantly reduced after treatment of Omega-3 fatty acid ethyl esters Conclusions: The QTD and cQTD significantly reduced after treatment of Omega-3 fatty acid ethyl esters in hypertensive patients with LVH. It may partially explain the anti-arrhythmic effect of Omega-3 fatty acid ethyl esters.

Impact of cardiac rehabilitation on ventricular repolarization indexes in patients with rheumatid arthritis

ObjectiveAbnormalities in ventricular repolarization (VR) parameters have been associated with sudden cardiac death (SCD) in patients with rheumatoid arthritis (RA). The benefits of cardiac rehabilitation (CR) in patients with RA are well recognized. We aimed to assess its impact on VR indexes in patients with RA. MethodsThis study included 45 patients with RA (36 female, age 58 ± 5.5 years) and 50 age- and sex-matched otherwise healthy controls. Baseline electrocardiogram (ECG) recordings were used to compare VR parameters such as maximum and minimum QT intervals, and corrected, and dispersion (QTmax, QTmin, cQTmax, cQTmin, QTd, cQTd, respectively), JT and cJT intervals, Tp-e and cTp-e intervals, and Tp-e/QT and Tp-e/cQT ratios in patients with RA and healthy individuals. The effects of 6-week CR in patients with RA were also evaluated by comparing pre- and post-CR ECGs, exercise tolerance test (MET and VO2max) and RA characteristics (C-reactive protein (CRP), Disease Activity Score 28 (DAS28) and Health Assessment Questionnaire(HAQ)). ResultsIn comparison with the healthy individuals, the patients with RA had significantly higher cQTmax and QTmin intervals, QTd, cQTd, Tp-e and cTp-e intervals, and Tp-e/QT and Tp-e/cQT ratios. At the end of CR, all VR indexes (p < 005), except QTd, were significantly decreased as did the results for CRP, DAS28, and HAQ (all p < 0.05), and MET and VO2max (p < 0.05 for both) were significantly increased in patients with RA. ConclusionsCR may provide an improvement in the majority of VR indexes which are related with ventricular arrhythmia and SCD in patients with RA. Changes in ETT parameters and RA characteristics may contribute to improvement of several VR indexes such as cQTd, cJT and Tp-e intervals at the end of CR.

Does attention deficit hyperactivity disorder have cardiac arrhythmia potential?

Objective: Attention deficit hyperactivity disorder (ADHD) is quite common in the general pediatric population. In this population, sympathomimetic drugs, which are at risk of arrhythmia, are frequently used. In this study, ECG characteristics of drug naive ADHD patients were compared control group. Methods: This study was performed 43 drug naive ADHD patients and 36 healthy children who admitted to the child and adolescent psychiatry outpatient clinic between November 2017 and January 2018. A standard 12-lead ECG of the patient and control group were evaluated. The ADHD and control group data were compared by calculating the minimum and maximum QT inter-val, corrected QT (QTc), QT dispersion (QTd), the peak and the end of the T wave (Tp-e) and Tp-e dispersion (Tp-ed) on 12-lead surface ECG. Tp-e interval was measured tangent method. The Bazett formula was used for QT correction. Results: The mean age of the patients with ADHD was 10.6±3.2 and 62.8% of them were male and similar to the control group. There was no significant difference between ADHD and control groups in terms of heart rate, min QT, max QT and min Tp-e values. QTc, QTd, max Tp-e and Tp-ed intervals were statistically higher ADHD patients than control group. Conclusion: QT dispersion and Tp–e is a measure of transmural dispersion of repolari-zation and related to cardiac arrhythmias. High QTd, QTc, max Tp-e and Tp-ed intervals in ADHD patients may indicate a potential cardiac arrhythmia. Physicians should make careful assessments of ADHD patients before pre-scribing sympathomimetic drugs.

Antimicrobials and QT prolongation.

Solithromycin, a ketolide/macrolide antibiotic, has recently been reported to be free of the expected QT-prolonging effect of macrolides. It appears that its keto substitution provides a structural basis for this observation, as the other two tested ketolides also have minimal QT effect.Among non-cardiovascular therapies, antimicrobials probably carry the greatest potential to cause cardiac arrhythmias. This is a result of their propensity to bind to the delayed rectifier potassium channel, IKr, inducing QT prolongation and risk of torsades de pointes ventricular tachycardia, their frequent interference with the metabolism of other QT prolongers and their susceptibility to metabolic inhibition by numerous commonly used drugs.Unfortunately, there is evidence that medical practitioners do not take account of the QT/arrhythmia risk of antimicrobials in their prescribing practices. Education on this topic is sorely needed. When a macrolide is indicated, a ketolide should be considered in patients with a QT risk.

Evaluation of the Tp-e Interval and Tp-e/QT Ratio in Patients with Mitral Annular Calcification

Objective: Mitral annular calcification (MAC) is regarded as a manifestation of cardiovascular disease. Recent studies have shown that prolongation of the interval between the peak and end of the T wave on electrocardiogram (Tp-e), which is accepted as an index of transmural dispersion of ventricular repolarization, and the Tp-e/QT ratio are associated with ventricular arrhythmias. In the present study, we aimed to evaluate ventricular repolarization using the Tp-e interval and Tpe/ QT ratio in patients with MAC. Methods: Fifty patients with MAC (27 females and 23 males; mean age 71.6 ± 8.0 years) and 50 patients without MAC (26 females and 24 males; mean age 69.3 ± 6.2 years) were included in this study. Maximum and minimum QT and Tp-e intervals as well as corrected values according to heart rate were calculated using a 12- lead electrocardiogram. QT dispersion and Tp-e/QT ratios were calculated. All parameters were compared between the two groups. Results: Patients with MAC had significantly higher Tp-e (75.8 ± 11.6 vs. 62.1 ± 8.7; p<0.001) and cTp-e intervals (84.9 ± 14.3 vs. 67.5 ± 9.7; p<0.001), Tp-e/QT (0.19 ± 0.02 vs. 0.15 ± 0.02; p<0.001) and cTp-e/QT ratios (0.19 ± 0.03 vs. 0.15 ± 0.02; p<0.001), and cQT values (390.1 ± 31.5 vs. 373.8 ± 26.1; p=0.006) compared with the control subjects. There were positive correlations between E/Em ratio and cTp-e interval (r=0.396; p=0.004) and between the E/Em ratio and cTp-e/QT ratio (r=0.535; p<0.001) in the MAC group. Conclusion: Our findings indicate that the patients with MAC had higher Tp-e and cTp-e intervals and Tp-e/QT and cTp-e/QT ratios compared with the subjects without MAC.

The effects of zoledronic acid on ECG: a prospective study on patients with bone metastatic cancer.

There are controversial results in the risk of atrial fibrillation as well as arrhythmogenic potential of bis-phosphonates. 37 patients and 40 healthy controls were evaluated prospectively with regard to the cardiac side effects related to the use of zoledronic acid (ZA) and its effects on electrocardiography (ECG) parameters. As the basal ECG results of the patients diagnosed with cancer compared with the control group, it was determined that QT maximum was significantly lower, QT minimum was significantly higher. However; it was determined that QT disp, P max, P min, and P disp values were not significantly different. There was no statistically significant difference in P max, P min, P disp, QT max, QT min, QT disp values of the ECG parameters measured from cancer patients, before and 60 minutes after ZA therapy. There were no significant alterations in ECG in the acute period, indicated that ZA had no arrhythmia potential in the early period in patients with no underlying cardiac disease. However: patients receiving ZA should be monitored more closely because of the risk of arrhythmia which may ensue due to hypocalcemia, hypomagnesemia, or other chemotherapeutics.

Electrocardiography-Derived Predictors for Therapeutic Response to Treatment in Children with Postural Tachycardia Syndrome

To explore whether electrocardiography (ECG) variables could be used to predict responses to physical treatment in children with postural tachycardia syndrome (POTS). Forty children with POTS and 32 healthy controls were enrolled in this study. General information and hemodynamic and supine ECG variables, including QT interval dispersion (QTd), were collected. The children with POTS received physical treatment and 3months of follow-up. A receiver-operating characteristic curve was used to evaluate the value of ECG variables for predicting the effectiveness of physical treatment. Compared with the healthy children, the children with POTS had longer baseline QTd and heart rate (HR)-corrected QTd (QTcd), but shorter minimum QT intervals (QTmin) and minimum HR-corrected QT intervals (P<.05). In children with POTS, responders to physical treatment had a longer baseline time between QRS complexes (RR) interval of minimum QT interval and a longer QTcd compared with nonresponders. A longer QTcd was a significant risk factor for the presence of POTS (OR, 1.022; P=.02) and for undesirable responses to physical treatment in children with POTS (OR, 1.044; P=.03). Baseline QTcd was positively correlated with the HR elevation from supine to upright seen in children with POTS (r=0.348; P=.003). Receiver operating characteristic curve analysis demonstrated an area under the curve of 0.73, and using 43.0 msec as a cutoff of QTcd yielded a sensitivity of 90% and a specificity of 60%. QTcd might be useful for predicting the effectiveness of physical treatment for POTS in children.