Search

AimsDiagnosis of Long QT syndrome (LQTS) is based on prolongation of the QT interval corrected for heart rate (QTc) on surface ECG and genotyping. However, up to 25% of genotype positive patients have a normal QTc interval. We recently showed that individualized QT interval (QTi) derived from 24 h holter data and defined as the QT value at the intersection of an RR interval of 1,000 ms with the linear regression line fitted through QT-RR data points of each individual patient was superior over QTc to predict mutation status in LQTS families. This study aimed to confirm the diagnostic value of QTi, fine-tune its cut-off value and evaluate intra-individual variability in patients with LQTS.MethodsFrom the Telemetric and Holter ECG Warehouse, 201 recordings from control individuals and 393 recordings from 254 LQTS patients were analysed. Cut-off values were obtained from ROC curves and validated against an in house LQTS and control cohort.ResultsROC curves indicated very good discrimination between controls and LQTS patients with QTi, both in females (AUC 0.96) and males (AUC 0.97). Using a gender dependent cut-off of 445 ms in females and 430 ms in males, a sensitivity of 88% and specificity of 96% were achieved, which was confirmed in the validation cohort. No significant intra-individual variability in QTi was observed in 76 LQTS patients for whom at least two holter recordings were available (483 ± 36 ms vs. 489 ± 42 ms, p = 0.11).ConclusionsThis study confirms our initial findings and supports the use of QTi in the evaluation of LQTS families. Using the novel gender dependent cut-off values, a high diagnostic accuracy was achieved.

Perioperative Torsade de Pointes (TdP) is a potentially fatal arrhythmia. The association between the prolongation of corrected QT (QTc) interval and TdP has been well described, but prolonged QTc interval is likely not to be a sole determinant. The transmural dispersion of repolarization (TDR) represents regional heterogeneities in repolarization. Prolonged TDR is also considered responsible for TdP. Here we reviewed the current knowledge of perioperative TdP and their known mechanism along with risk factors including drugs. A number of perioperative drugs were reviewed for their effect on QT prolongation and TDR.

SUMMARY OBJECTIVE: With the coronavirus disease 2019 (COVID-19) continuing to spread all over the world, although there is no specific treatment until now, hydroxychloroquine and azithromycin have been reported to be effective in recent studies. Although long-term use of hydroxychloroquine and azithromycin has been reported to cause QT prolongation and malign arrhythmia, there is not enough data about the effect of short-term use on arrhythmia. Therefore, this study aims to assess the effect of hydroxychloroquine alone and hydroxychloroquine + azithromycin on corrected QT (QTc). METHODS: A baseline electrocardiogram and on-treatment baseline electrocardiogram were retrospectively collected in COVID-19 patients who received hydroxychloroquine and/or azithromycin. The QTc interval was calculated, and the baseline and peak QTc intervals were compared. In addition, the peak QTc intervals of monotherapy and combination therapy were compared. RESULTS: Of the 155 patients included, 102 (65.8%) patients were using hydroxychloroquine, and 53 (34.2%) patients were using hydroxychloroquine + azithromycin combination. The use of both hydroxychloroquine alone and hydroxychloroquine + azithromycin combined therapy significantly prolonged the QTc, and the QTc interval was significantly longer in patients receiving combination therapy. QTc prolongation caused early termination in both groups, 5 (4.9%) patients in the monotherapy group and 6 (11.3%) patients in the combination therapy group. CONCLUSION: In this study, patients who received hydroxychloroquine for the treatment of COVID-19 were at high risk of QTc prolongation, and concurrent treatment with azithromycin was associated with greater changes in QTc.

Background: Coronary heart disease is a major cause of mortality and this health problem is reaching pandemic in both developed, and developing countries. ACS carries significant morbidity and mortality and the prompt diagnosis, and appropriate treatment is essential. HR was identified as a risk predictor of ACS. Both continuous increase in high baseline heart rate and decrease in low baseline heart rate are associated with higher risk of CVD. Decreased heart rate could also cause dispersion of atrial repolarization which, in turn, initiate cardiovascular events. Aim: The aim of this study was to assess the correlation between heart rate and severity of coronary artery disease in patient with acute coronary syndrome. Patients and Methods: The retrospective study was conducted on 120 patients that fulfilled the inclusion criteria were recruited from Cardiology department in Tanta university hospitals presented with acute coronary syndrome. Results: There was highly significant difference between both groups regarding admission heart rate & QTc interval. Both groups of low AHR< 60 bpm & high AHR >90bpm were significantly associated with severe CAD &.Mainly those patients with higher admission heart rate were more likely to have higher Syntax scores (severe coronary lesion). Also, patients with prolonged QTc had severe coronary artery diseases, higher SS & high probability to suffer adverse cardiac events more than patients without prolonged QTc interval. Conclusion: The current study showed that QTc interval prolongation and admission HR are independent predictors of the severity of coronary artery disease in patients with acute coronary syndrome.

Background and aims An electrocardiogram (ECG) is a mandatory test for anyone presenting with loss of consciousness. Many referrals to the first seizure clinic (FSC) are caused by syncope. We assessed the sensitivity of neurologists’ ECG reporting in detecting rhythm abnormalities including some potentially life-threatening cardiac conditions. Methods We audited patients referred to a FSC in Glasgow over 4 years. All ECGs were interpreted by the attending neurologist as standard practice. Subsequently, two cardiologists reviewed the ECGs independently. Results Of 160 consecutive patients, 92 patients (58%) were diagnosed as having seizures, 43 (27%) as syncope, and 25 (16%) were unclassified. Twenty eight ECGs thought to be normal by the neurologist were considered abnormal by the cardiologist, including three with long corrected QT interval. The proportion of abnormal ECGs and disparity in reporting between neurologists and cardiologists persisted independent of the underlying diagnosis. Conclusion Reporting of ECGs by non-cardiologists may not be adequately sensitive in picking up potentially life threatening cardiac conditions. Cardiologist input into FSCs is recommended to enhance the diagnostic yield.

In August 2020, the International Council on Harmonisation (ICH) released a new draft document, which for the first time combined nonclinical (S7B) and clinical (E14) Questions and Answers (QAs) into 1 document. FDA describes the revision as a "value proposition": if the human ether-à-go-go assay and the in vivo study are performed in a standardized way, the number of dedicated thorough QT (TQT) studies can be reduced. In this article, we describe and discuss the QAs that relate to clinical ECG evaluation. If supported by negative standardized nonclinical assays, QA 5.1 will obviate the need for a TQT study in the case that a2-fold exposure margin vs high clinical scenario cannot be obtained. QA 6.1 addresses drugs that are poorly tolerated in healthy subjects and cannot be studied at high doses or in placebo-controlled studies; it therefore mainly applies to oncology drugs. It will enable sponsors to claim that a new drug has a "low likelihood of proarrhythmic effects" in the case that the mean corrected QT effect is10 milliseconds at the time of market application. The E14 2015 revision allowed application of concentration-corrected QT analysis on data from routinely performed clinical pharmacology studies, for example, the first-in-human study and the proportion of dedicated TQT studies has since steadily decreased. It can be foreseen that the proposed new revision will further reduce the number of TQT studies. To achieve harmonization across regulatory regions, it seems important to reach consensus within the International Council on Harmonisation group on the new threshold proposed in 6.1. For this purpose, the Implementation Working Group has asked for public comments.

Objectives: To determine the frequency of altered cardiac repolarization by measuring the heart rate corrected QT interval in COPD patients. Setting: Department of Medicine at LUMHS hospital Hyderabad/Jamshoro. Study Design: Descriptive Cross sectional study. Duration of Study: 6 months from 01-03-2019 to 31-08-2019. Methods: A total of 232 patients with severe acute exacerbation of COPD were included in this study. A 12 lead ECG was performed. QT intervals were measured on a resting ECG tracing in lead II. The QT interval was measured manually from the starting point of the QRS complex to the terminal point of the down slope of the T wave. Results: A total of 232 patients with COPD were included in this study. Most of the cases were above 50 years of age. The average age of the patients was 53.74±4.35 years. There were 92.67% (215/232) male and 7.33% (17/232) female. Out of 232 patients, 21.14% were current smoker and 75.86% were ex-smoker. A QTc interval >0.44 seconds was considered abnormally prolonged. Frequency of altered cardiac repolarization by measuring the heart rate corrected QT interval in COPD patients was 31.47% (73/232). Rate of altered cardiac repolarization was not significant among different age groups (p=0.641). Rate of altered cardiac repolarization was significantly high in male as compare to female (33.5% vs. 5.9%; p=0.018). This was not significant between obese and non-obese groups (p=0.100). Rate of altered cardiac repolarization was significantly high in former smoker (p=0.0005) and those patients whose duration of COPD was above 15 years (p=0.0005). Conclusion: Patients with hypoxic chronic obstructive pulmonary disease (COPD) have evidence of a subclinical parasympathetic autonomic neuropathy, with apparent preservation of sympathetic function. Measuring heart rate corrected QT interval (QTc) test is repeatable, easy to perform and a sensitive indicator for autonomic dysfunction in breathlessness individuals with COPD.

Introduction: Childhood intoxications are among the most common reasons for admission to the emergency department. The aim of this study is to evaluate whether there is a primary marker that can determine the risk of arrhythmia by comparison of QT, QTc, QT/QTc, Tp-e/QT, Tp-e/QTc intervals in drug intoxications with prolonging QTc which can be fatal by causing arrhythmia in children. Materials and Methods: In this study, 55 patients who were admitted to Pediatric Emergency Department of Training and Research Hospital between January 2018 and August 2019 within the first 6 hours due to intoxication with QTc prolongation and followed up in our pediatric emergency department were retrospectively reviewed. In patients hospital records, age, sex, medication, time of application, clinical and physical examination findings, vital signs, treatments and results, laboratory findings, electrocardiogram findings at the time of admission hospital and in the 6. hour control, QT, QTc, Tp-e, Tp-e/QT and Tp-e/QTc times were recorded. Results: The median age of the patients in study was 155±77.2 months. The number of female patients was 33 (60%) and the number of male patients was 22. There was a statistically significant difference between leukocyte count, hemoglobin, platelet,bun, creatinine, SGPT and calcium values at the time of admission and control at the 6th hour. There was no statistically significant difference between CK-MB and troponin levels. Also, there was no statistically significant difference between QT, QTc, QT/QTc, Tp-e/QT and Tp-e/QTc intervals. But there was a statistically significant difference between Tp-e/QTc ratio and gender. Conclusions: Although QTc interval continues to be used to determine the risk of arrhythmia in children with drugs prolonging QTc, it may be significant to compare Tp-e and Tp-e/QTc ratio. However, studies involving a larger number of patients are needed to determine whether Tp-e interval and Tp-e/QTc ratio are a priority marker. Giriş: Çocukluk çağı zehirlenmeleri sık görülen acile başvuru nedenleri arasındadır. Bu çalışmada amacımız aritmiye neden olarak ölümcül olabilecek QTc uzaması yapan ilaçlarla zehirlenmelerde QT, QTc, QT/QTc, Tp-e/QT, Tp-e/ QTc oranlarını karşılaştırarak çocuklarda aritmi riskini belirleyebilecek öncelikli bir belirteç olup olmadığını değerlendirmektir. Gereç ve Yöntem: Çalışmamızda Ocak 2018 ve Ağustos 2019 tarihleri arasında Eğitim ve Araştırma Hastanesi Çocuk Acil servisine QTc uzaması yapan ilaçlarla zehirlenme nedeniyle ilk 6 saat içerisinde başvuran ve çocuk acilimizde takip edilen 55 hastanın dosyası retrospektif olarak incelenmiştir. Hasta dosyalarından yaş, cinsiyet, aldığı ilaç, müracaat süresi, klinik bulgu ve fizik muayene bulgusu,vital bulgular, yapılan tedavi ve sonuçları laboratuar bulguları ve başvuru anı ve kontrol bakılan 6. saat EKG (elektrokardiyografi) bulguları, QT, QTc, Tp-e, Tp-e/QT ve Tp-e/QTc süreleri kaydedilmiştir. Bulgular: Çalışmaya alınan hastaların yaş ortancası 155±77,2 ay idi. Kız hasta sayısı 33(%60), erkek hasta sayısı 22 (%40) idi. Çalışmamızda hastaların başvuru anı ve 6. saatte bakılan lökosit sayısı, hemoglobin, platelet, bun, kreatinin, SGPT ve kalsiyum değerleri arasında istatistiksel olarak anlamlı farklılık saptandı (p0,05).EKG’lerinde QT, QTc, QT/QTc, Tp-e/QT ve Tp-e/QTc süreleri arasında istatistiksel olarak anlamlı fark saptanmadı (p>0,05). Tp-e/QTc süreleri ve cinsiyet arasında istatistiksel olarak anlamlı bir farklılık mevcuttu (p

Prolonged corrected QT (QTc) interval is a hallmark of cirrhotic cardiomyopathy (CCM) and has been ascertained to predict mortality in cirrhosis. However, some critical issues remain to be addressed including unanimous cut-off, calculation approach and applicable population. A total of 274 patients with cirrhosis were included. The prolonged QTc interval over 440 ms according to adjusted Fridericia’s formula was used to stratify enrolled subjects. Independent predictors of 3-year mortality were identified with Cox regression model. The Kaplan–Meier method was implemented to obtain survival curves. To reduce impact of selection bias and possible confounders, a propensity score matching (PSM) analysis was used. QTc > 440 ms was an independent risk factor in the entire cohort and PSM subset (HR 2.532, 95% CI 1.431–4.480, p=.001; HR 2.802, 95% CI 1.171–6.701, p=.021, respectively). Subgroup analysis showed that QTc > 440 ms was an independent predictor in cirrhotics with age ≤60 years (HR = 1.02, p=.035) and in the presence of ascites (HR = 1.01, p=.008). The prolonged QTc interval might help to identify patients with high-risk of all-cause mortality.

Background: Heart rate–corrected QT interval (QTc) prolongation, whether secondary to drugs, genetics including congenital long QT syndrome, and/or systemic diseases including SARS-CoV-2–mediated coronavirus disease 2019 (COVID-19), can predispose to ventricular arrhythmias and sudden cardiac death. Currently, QTc assessment and monitoring relies largely on 12-lead electrocardiography. As such, we sought to train and validate an artificial intelligence (AI)–enabled 12-lead ECG algorithm to determine the QTc, and then prospectively test this algorithm on tracings acquired from a mobile ECG (mECG) device in a population enriched for repolarization abnormalities. Methods: Using >1.6 million 12-lead ECGs from 538 200 patients, a deep neural network (DNN) was derived (patients for training, n = 250 767; patients for testing, n = 107 920) and validated (n = 179 513 patients) to predict the QTc using cardiologist-overread QTc values as the “gold standard”. The ability of this DNN to detect clinically-relevant QTc prolongation (eg, QTc ≥500 ms) was then tested prospectively on 686 patients with genetic heart disease (50% with long QT syndrome) with QTc values obtained from both a 12-lead ECG and a prototype mECG device equivalent to the commercially-available AliveCor KardiaMobile 6L. Results: In the validation sample, strong agreement was observed between human over-read and DNN-predicted QTc values (−1.76±23.14 ms). Similarly, within the prospective, genetic heart disease–enriched dataset, the difference between DNN-predicted QTc values derived from mECG tracings and those annotated from 12-lead ECGs by a QT expert (−0.45±24.73 ms) and a commercial core ECG laboratory [10.52±25.64 ms] was nominal. When applied to mECG tracings, the DNN’s ability to detect a QTc value ≥500 ms yielded an area under the curve, sensitivity, and specificity of 0.97, 80.0%, and 94.4%, respectively. Conclusions: Using smartphone-enabled electrodes, an AI DNN can predict accurately the QTc of a standard 12-lead ECG. QTc estimation from an AI-enabled mECG device may provide a cost-effective means of screening for both acquired and congenital long QT syndrome in a variety of clinical settings where standard 12-lead electrocardiography is not accessible or cost-effective.

The course of type 1 diabetes in children can be complicated by cardiovascular disorders in the form of life-threatening arrhythmias, especially in patients with congenital long QT syndrome (LQTS). It remains relevant to determine the risk groups for developing such complications, to search for convenient diagnostic algorithms and subsequent management tactics for children with type 1 diabetes mellitus (T1DM) who have acquired and congenital long LQTS. Study purpose is to determine the risk groups for the development of cardiovascular complications of type 1 diabetes mellitus in children, by the QT and corrected (QTc) interval ranges. Materials and methods. The examination involved 53 children with type 1 diabetes, who were divided into 2 groups depending on the duration of the disease. To determine the parameters relevant for the study, the bioelectrical activity of the heart was assessed by ECG and Holter ECG monitoring. For additional assessment of the patients' condition over a long period of time, they were offered to keep a diary with monitoring of parameters important for the study. Statistical processing of the research results was carried out with the SPSS 22.0 program. Results and conclusions. Changes in the duration of the QTc interval and its variance have been proved depending on the duration of the disease and influence of the glycemia level plus insulin therapy on the value of these indicators. For children with newly diagnosed type 1 diabetes, an algorithm has been developed to identify risk groups for the development of cardiovascular complications associated with LQTS, which makes it possible to determine three risk groups and the tactics of their further management. According to the authors, the main goal of reducing the risk of developing cardiovascular complications in the form of ventricular arrhythmias (which can lead to sudden death syndrome) is the timely diagnosis of long QT interval syndrome. Recognition of congenital LQTS is important, since unstable glycemic levels and the appointment of insulin therapy can significantly worsen the child's condition. For children with newly diagnosed type 1 diabetes mellitus before the appointment of insulin therapy, the authors propose their own algorithm for identifying risk groups for the development of cardiovascular complications associated with long QT interval syndrome and tactics for their further management. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of these Institutes. The informed consent of the patient was obtained for conducting the studies. No conflict of interest was declared by the authors. Key words: type 1 diabetes, long QT syndrome, patient management algorithm.

Introduction Patients undergoing evaluation for an inherited arrhythmia syndrome undertake a series of ambulatory investigations including 24-h Holter monitor, exercise treadmill testing (ETT), and others. Patch monitors may simplify the evaluation, providing accurate arrhythmia evaluation and QT assessment. Methods and results Patients referred for evaluation of an inherited arrhythmia syndrome underwent standard investigations, including 12-lead electrocardiography (ECG), 24-h Holter monitoring, ETT, along with supplemental monitoring using a 7-day ECG patch monitor. Heart rates (HR), corrected QT intervals (QTc), and ectopic burden were compared across monitoring modalities. Among 35 patients that wore the patch monitor, the median age was 39 years (54% male). There was intermediate correlation between resting HR across modalities (r = .58-.66) and poor correlation of peak HR (r = .27-.39). There was intermediate correlation between resting QTc intervals across modalities (r = .72-.77) but negligible correlation between QTc intervals at peak HR across modalities (r = -.01 to -.06). There was good correlation in PAC and PVC ectopic burden across the Holter and patch monitor. Conclusion Patch monitors may simplify the evaluation of patients for an inherited arrhythmia syndrome and provide resting QT assessment over time. However, QTc interval comparison at peak HRs remains variable, and may be limited by the single-lead ECG vector when using the patch monitor. Apart from QTc intervals at peak HR, patch monitors demonstrated good correlation with the ECG and Holter monitor for other parameters.

Background/Aim: In recent years, prolonged corrected QT (QTc) interval is thought to be an independent risk factor in patients with Acute Coronary Syndrome (ACS). Our aim in this study is to determine whether there is a relationship between the Neutrophil/Lymphocyte Ratio (NLR), which is a new inflammatory parameter, and prolonged QTc corrected (QTc) interval in patients with ACS. Methods: In a retrospective cohort study, 649 patients with ACS were enrolled from January 2017 to July 2019, out of which ninety-two patients died during follow-up. Patients were divided into two groups according to the prolonged QTc interval (QTc ≥450 msec). The relationship between QTc interval prolongation and NLR was evaluated. The primary endpoint was early all-cause death. Results: Thirty-one of 135 patients (22.9% P=0.002) with QTc interval prolongation and 61 of 514 patients without QTc prolongation (11.8% P=0.002) died. Prolonged QTc interval was positively correlated with NLR (r=0.20, P=0.001). Both NLR (OR: 1,016; 95% CI: 1.004–1.028; P=0.01) and QTc interval (OR: 1.016; 95% CI: 1.004–1.028; P=0.006) independently predicted early mortality. In the ROC curve analysis, the AUC value of QTc interval to predict in-hospital mortality was 0.680 (95% CI: 0.597-0.763; P=0.001), with a sensitivity of 35%, a specificity of 82% and an optimum cut-off value of ≥450 msec. The AUC value of NLR to predict in-hospital mortality was 0.711 (95% CI: 0.653-0.769; P

Aims Our study adds to the sparse literature on the effect of multiple fine particulate matter (PM2.5) components on QT interval length, an outcome with high clinical relevance in vulnerable populations. To our knowledge, this is the first study to examine the association between spatiotemporally resolved exposures to PM2.5 components and QT interval length. Methods and results Among 578 men living in Eastern Massachusetts between 2000 and 2011, we utilized time-varying linear mixed-effects regressions with a random intercept to examine associations between acute (0–3 days), intermediate (4–28 days), and long-term (1 year) exposure to PM2.5 components, temperature, and heart-rate corrected QT interval (QTc). Each of the PM2.5 components and temperature was geocoded to the participant’s residential address using validated ensemble and hybrid exposure models and gridMET predictions. We also evaluated whether diabetic status modified the association between PM2.5 components and QTc interval. We found consistent results that higher sulfate levels and colder temperatures were associated with significant longer QTc across all moving averages except the day of exposure. The greatest effect of sulfate and temperature was detected for the 28-day moving average. In the multi-pollutant model, each 1.5 µg/m3 IQR increase in daily sulfate was associated with a 15.1 ms [95% confidence interval (CI): 10.2–20.0] increase in QTc interval and in the single-pollutant models a 15.3 ms (95% CI: 11.6–19.1) increase in QTc interval. Other secondary particles, such as nitrate and organic carbon, also prolonged QT interval, while elemental carbon decreased QT interval. We found that diabetic status did not modify the association between PM2.5 components and QTc interval. Conclusion Acute and long-term exposure to PM2.5 components and temperature are associated with changes in ventricular repolarization as measured by QT interval.

Acute cardiovascular poisoning is a major cause of adverse outcomes in poisoning emergencies. The prognostic validity of corrected QT (QTc) and dispersed QT (QTd) in these outcomes is still limited. The present study aimed to determine the risk factors of mortality, adverse cardiovascular events (ACVE), and intensive care unit (ICU) admission in patients with acute cardiovascular toxicities and assess the validity of QTc and QTd intervals in predicting these outcomes. This study was conducted on adult patients admitted to Tanta University Poison Control Center with a history of acute cardiotoxic drugs or toxins exposure. The demographic and toxicological data of patients were recorded. Clinical examination, routine laboratory investigations, ECG grading, and measurement of QTc and QTd were performed. The patients were grouped according to their adverse outcomes. Among the included patients, 51 (31.48%) patients died, 61 (37.65%) patients had ACVE, and 68 (41.98%) patients required ICU admission. The most common cause of poisoning is aluminum phosphide, followed by cholinesterase inhibitors. QTd and QTdc showed no significant difference among outcome groups. The best cut-off values of QTc to predict mortality, ACVE, and ICU admission were > 491.1 ms, > 497.9 ms, and ≥ 491.9 ms, respectively. The derived cut-off QTc values were independent predictors for all adverse outcomes after adjusting for poison type, serum HCO3, and pulse. The highest odds ratios for all adverse outcomes were observed in aluminum phosphide poisoning and low HCO3

To investigate differences in heart rate variability (HRV) during oral glucose tolerance tests (OGTTs) in response to the rate of change in glucose and to different glycaemic ranges in individuals with type 1 diabetes. This was a single‐centre, prospective, secondary outcome analysis in 17 individuals with type 1 diabetes (glycated haemoglobin 53 ± 6.3 mmol/L), who underwent two OGTTs (after 12 and 36 hours of fasting) investigating differences in HRV in response to rapid glucose increases/decreases and different glycaemic ranges during OGTT. Based on the rate of change in glucose level, the variables heart rate (P 50 ms difference (P

Objective: The Coronavirus disease-2019 (COVID-19) pandemic has caused the death of many people worldwide. Treatment protocol had to be developed as soon as possible so drug combinations, whose reliability has not been fully disclosed, have started to be used. In this study, we aimed to evaluate the effect of azithromycin (AZT), hydroxychloroquine (HCQ), and favipiravir (FVR) combination on the corrected QT (QTc) interval. Material and Methods: Eighty-four consecutive COVID 19 patients were enrolled in the study. All patients received AZT and HCQ, however, FVR was added to the combination in 32 patients with severe pneumonia at the beginning. ECG characteristics of all patients before treatment and on the fifth day of treatment were compared. Results: There was no significant difference between the HCQ+AZT group (n=52) and HCQ+AZT+FVR groups (n=32) in terms of baseline clinical characteristics. QTc interval significantly prolonged on the fifth day of treatment in the HCQ+AZT group (413,75±30,13;440,27±36,11 p 500 ms was detected after the treatment, four patients in the HCQ+AZT+FVR group and three patients in the HCQ+AZT group. Conclusion: We observed that FVR caused more prolongation in the QTc interval when used with the combination of HCQ+AZT. We recommend that patients who receive this treatment be monitored more closely for QTc.

QTc stands for heart-rate corrected QT interval on the electrocardiogram and is a measure of the efficiency of repolarization of the left ventricle. Excessive prolongation, generally considered to be >500 ms, can result in a potentially fatal ventricular arrhythmia known as torsade de pointes. Some psychiatric medications can cause this arrhythmia and, therefore, this issue is important to all prescribers of psychiatric medications. It is also important to keep in mind that there are multiple algorithms used to calculate the QTc. The Bazett's algorithm, one of the most commonly used algorithms on electrocardiogram machines, can produce an artificially prolonged QTc; however, the use of this algorithm is not generally identified on the printout from the electrocardiogram machine, which can cause unnecessary concern and delay treatment of patients. For these reasons, this article explains the basic concepts of the QT interval and QTc interval and discusses why it is important for psychiatrists and other prescribers to know this information. A case report is then used to illustrate the clinical application of this knowledge so that effective treatment is not unnecessarily delayed.

OBJECTIVE Bepridil prolongs the QT interval and can induce torsade de pointes. Although increased bepridil concentration may be a primary cause of prolonged QT, the relationship between serum bepridil concentration and prolonged QT remains unclear. We investigated the relationship between serum bepridil concentration and the corrected QT (QTc) interval in patients treated with bepridil. MATERIALS AND METHODS A retrospective study was performed at the National Cerebral and Cardiovascular Center in Japan. Patients with atrial fibrillation who were treated with bepridil from January 2014 to December 2015 were enrolled in the study. Serum bepridil concentrations and electrocardiogram data collected more than 21 days after the initiation of bepridil were used for analysis. RESULTS A total of 60 patients were included in this study. There was a significant difference in mean QTc interval before and after initiation of bepridil (p < 0.0001). A significant relationship was observed between bepridil dose (p = 0.014) or serum bepridil concentration (p

It has been reported in the literature that the increase in body temperature shortens QT interval on electrocardiogram through heart rate modulation. However, the effects of fever on ventricular repolarization are not clearly known. This study elaborates on QT interval of isolated fever, corrected QT (cQT), Tp-e interval, the ratio of corrected Tp-e (cTp-e) and Tp-e/QT, and their impacts on arrhythmia potential.This prospective study was performed on 74 patients without any active and chronic diseases other than fever and upper respiratory tract infection. The study included patients at the age of 18-50 years suffering from fever above 38.2 °C. QT and Tp-e intervals of the patients were measured from their ECGs taken in febrile and afebrile periods. cQT and cTp-e values were calculated according to Bazett, Fridericia, and Framingham formulations.QT and Tp-e intervals were observed to be shorter in the febrile period (p 0.001 and p = 0.006 respectively). cTp-e was found to be longer in the febrile period according to Bazett, Fridericia, and Framingham formulations (p 0.001, p = 0.002, p 0.001, respectively). Tp-e/QT ratio was found to be higher in the febrile period than in the afebrile period (p 0.001).Although QT, cQT, and Tpe intervals were shorter, cTpe interval and Tpe/QT ratio were longer and higher in the febrile period, respectively. These findings may indicate that fever may create a proarrhythmic effect by causing variability in the transmural distribution of myocardial repolarization.

Background Cardiac arrhythmias are expected among patients with epilepsy due to the effect of anti-epileptic drugs. Temporal lobe epilepsy also causes autonomic seizures that may affect heart rhythm. Prolongation of the corrected QT interval and QT dispersion is a risk factor for cardiac arrhythmia. Objectives We aimed to assess corrected QT interval and QT dispersion in patients with epilepsy and if there is a difference between patients with temporal epilepsy versus non-temporal epilepsy. Methods This study was conducted on 100 patients (50 patients with temporal epilepsy and 50 patients with non-temporal epilepsy) and 50 age- and sex-matched healthy controls. They underwent a prolonged (6 to 24 h) 22 channel computerized electroencephalogram monitor with a 10–20 system. QT dispersion, QT interval, and corrected QT interval (using Bazett’s formula) were calculated. Results This study showed significantly higher QT dispersion and corrected QT interval in patients with epilepsy when compared to the age- and sex-matched control group (P < 0.001, P < 0.001). Also, the corrected QT interval and QT dispersion were significantly higher in temporal epilepsy patients when compared to the non-temporal group (P < 0.001, P < 0.001). Conclusion Corrected QT interval and QT dispersion are higher in epileptic patients and more among temporal epilepsy patients in comparison to non-temporal epilepsy patients.

Introduction Previous studies have observed that hypo- and hyperthermia are associated with several atrial and ventricular electrocardiographical parameters, including the corrected QT interval. Preclinical studies have shown that drugs that exert an effect on body temperature also exert an effect on the corrected QT interval. Therefore, increased characterization in healthy humans of the association between the corrected QT interval and body temperature within the normal body temperature range aids in understanding the mechanism behind drug induced corrected QT interval effects. The objective of this analysis was to evaluate the association between body temperature and electrocardiographical parameters in normothermic healthy volunteers. Methods Data from 3023 volunteers collected at our center were analyzed. Only subjects considered healthy after review of collected data by a physician, including a normal tympanic body temperature (35.5–37.5 °C) and in sinus rhythm, were included in the analysis. Subjects were divided into body temperature quartiles for analysis and a linear multivariate model with body temperature as a continuous was performed. Another multivariate analysis was performed with only the QT subintervals as independent variables and body temperature as dependent variable. Results Mean age was 33.8±17.5 years and mean body temperature was 36.6±0.4 °C. Body temperature was independently associated with age (standardized coefficient (SC)=−0.252, P Conclusion Body temperature in normothermic healthy volunteers was associated with heart rate, J-point amplitude in lead V4 and ventricular conductivity, primarily through a prolongation of the QRS duration. In contrast, atrial and AV nodal ECG parameters were not independently associated with body temperature. Funding Acknowledgement Type of funding source: None

Objective. This study determined the relationship between plasma adiponectin level and corrected QT interval (QTc) in smokers and non-smokers. Methodology. This cross-sectional analytical study was undertaken in 30 smokers and 30 non-smokers. Plasma adiponectin level was determined by enzyme-linked immunosorbent assay (ELISA). The QT interval was measured by routine 12-lead ECG with Lead II rhythm and QTc was calculated. Results. Mean plasma adiponectin level was significantly lower in smokers (27.89±15 μg/ml) than that of non-smokers (52.13±21.57μg/ml) (p

Background/Aims This study investigated the prognostic power of corrected QT (QTc) interval in patients with acute heart failure (AHF) according to sex. Methods We analyzed multicenter Korean Acute Heart Failure registry with patients with AHF admitted from 2011 to 2014. Among them, we analyzed 4,990 patients who were followed up to 5 years. Regarding QTc interval based on 12 lead electrocardiogram, patients were classified into quartiles according to sex. Results During follow-up with median 43.7 months, 2,243 (44.9%) patients died. The relationship between corrected QT interval and all-cause mortality followed a J-curve relationship. In Kaplan-Meier analysis, both sex had lowest mortality in the second QTc quartile. There were significant prognostic differences between the second and the fourth quartiles in male (log-rank p = 0.002), but not in female (log-rank p = 0.338). After adjusting covariates, the third (hazard ratio [HR], 1.185; 95% confidence interval [CI], 1.001 to 1.404; p = 0.049) and the fourth (HR, 1.404; 95% CI, 1.091 to 1.535; p = 0.003) quartiles demonstrated increased risk of mortality compared to the second quartile in male. In female, however, there was no significant difference across quartiles. QTc interval was associated with 5-year all-cause mortality in J-shape with nadir of 440 to 450 ms in male and 470 to 480 ms in female. Conclusions QTc interval was an independent predictor of overall death in male, but its significance decreased in female. The relationship between QTc interval and all-cause mortality was J-shaped in both sex.

Electrocardiographic markers have been used in people to classify arrhythmogenic risk. The aims of this study were to investigate electrocardiographic markers of conduction and repolarization in Boxers and non-Boxer dogs, and compare such findings between groups. Ten-lead standard electrocardiograms of Boxer dogs and non-Boxers recorded from 2015 to 2018 were retrospectively reviewed. Dogs ≥4 years of age and weighing >20kg were included. Animals with valvular insufficiencies, congenital cardiopathies, cardiac dilation, suspected systolic dysfunction, biphasic T-wave, bundle branch blocks, and those receiving antiarrhythmics were excluded. Electrocardiographic markers of conduction, QRS duration (QRSd) and dispersion (QRSD), and repolarization (corrected QT interval, Tpeak-Tend, JT and JTpeak), as well as derived indices, were measured. Two hundred dogs met the inclusion/exclusion requirements, including 97 Boxers (8.1±2.5 years old; 30±7kg) and 103 non-Boxer (8.8±2.5 years old, 30±8kg). QRSd and QRSD, and repolarization markers in lead II and left precordial lead V4 were considered similar between groups. Dispersion of late repolarization on lead rV2, Tpeak-Tend interval, was considered longer in Boxers (45±8ms vs 38±10ms, P=0.01). The Tpeak-Tend/JTpeak and the JTpeak/JT also differed between groups. Our results indicate that the dispersion of myocardial late repolarization in lead rV2 is slower in Boxers than other dog breeds. RESUMO: Marcadores eletrocardiográficos têm sido estudados em seres humanos para estratificação do risco arritmogênico. Os objetivos deste estudo foram investigar os marcadores eletrocardiográficos de condução e repolarização miocárdica em Boxers e em cães de outras raças, e comparar tais resultados entre os grupos. Para tal, a eletrocardiografia convencional de 10 derivações registradas de 2015 a 2018 foram avaliadas de maneira retrospectiva. Cães com idade igual ou superior a 4 anos e pesando >20kg foram incluídos. Animais com insuficiência valvar, cardiopatias congênitas, dilatação cardíaca, suspeita de disfunção sistólica, onda T bifásica, bloqueio(s) de ramo(s), ou aqueles que recebiam antiarrítmicos foram excluídos. Variáveis eletrocardiográficas de condução, como a duração e dispersão do complexo QRS (QRSd e QRSD, respectivamente), e repolarização (intervalo QT corrigido, Tpico-Tfinal, JT e JTpico), bem como índices derivados, foram mensurados. Duzentos cães que se adequaram aos critérios de inclusão/exclusão foram incluídos, 97 Boxers (8,1±2,5 anos; 30±7kg) e 103 não Boxers (8,8±2,5 anos; 30±8kg). O QRSd e o QRSD, e os marcadores de repolarização nas derivações II e V4 foram similares entre os grupos. O marcador de dispersão da repolarização tardia na derivação rV2, Tpico-Tfinal, foi considerado mais longo no Boxers (45±8ms vs 38±10ms, P=0.01). O Tpico-Tfinal/JTpico e o JTpico/JT também diferiram entre os grupos. Nossos resultados indicam que a dispersão da repolarização miocárdica tardia na derivação precordial direita, rV2, é mais lenta no Boxer do que nas outras raças.

The aim of this study was to assess the effect of volanesorsen on the corrected QT (QTc) interval. This thorough QT study enrolled 52 healthy male and female subjects who were randomized at a singl...

espanolIntroduccion: Se ha comunicado que algunos tratamientos utilizados para la infeccion por COVID-19 pueden ocasionar alteracionesdel intervalo QT y arritmias graves. La medicion por electrocardiograma (ECG) convencional requiere personaladicional y riesgo de contagio. Nuevas tecnologias para obtencion de un ECG conectados a telefonos inteligentes (smartphones)proporcionan una alternativa para evaluacion del QTc.Objetivo: El objetivo fue evaluar la factibilidad de un dispositivo para registro electrocardiografico de un canal, para la mediciondel intervalo QT en pacientes con sospecha o confirmacion de infeccion por COVID-19, antes de recibir drogas queprolongan el intervalo QT.Material y metodos: Se obtuvieron registros de ECG con un dispositivo Kardia Mobile (KM) con trasmision a un smarthphone.La seccion de electrofisiologia cardiaca centralizo la recepcion por medio electronico de los ECG en formato de archivo pdf yrealizo las mediciones de los intervalos QTm y QTc.Resultados: Se estudiaron 31 pacientes, edad promedio 61 anos (rango 20-95 anos), sospechosos de presentar infeccion porCOVID-19 enrolados para tratamiento con hidroxicloroquina, azitromicina, ritonavir y lopinavir. Los registros pudieron serleidos en todos los casos, y debieron repetirse en dos casos. Los valores del intervalo QTc promedio en varones y mujeres fue423 mseg (rango 380-457 mseg) y 439 mseg (rango 391-540 mseg), respectivamente. El tiempo de respuesta desde el enviodel ECG al grupo de analisis fue 11 min (rango 1-155).Conclusiones: Los registros ECG obtenidos con dispositivos KM, para trasmision a un smartphone a un grupo central delectura, permitieron la medicion del intervalo QTc en todos los pacientes. EnglishBackground: Some therapies used for COVID-19 can prolong the QT interval and produce severe arrhythmias. QT interval measuredfrom a standard electrocardiogram (ECG) requires additional personnel and risk of infection. Novel technologies to obtain anECG connected to smartphones provide an alternative for the evaluation of corrected QT interval (QTc).Objective: The aim of this study was to evaluate the feasibility of using a single-lead ECG device to measure the QT interval in patientswith suspected or confirmed COVID-19 before receiving treatment with drugs that can prolong the QT interval.Methods: The ECG was obtained with a KardiaMobile (KM) device and transmitted to a smartphone. The ECG recordings weresaved as pdf files and electronically submitted to the electrophysiology section which centralized the reception and assessed themeasured QT and QTc intervals.Results: A total of 31 patients (mean age 61 years, range 20-95 years) with suspected COVID-19 enrolled for treatment with hydroxychloroquine,azithromycin, ritonavir or lopinavir were analyzed. The recordings could be read in all the cases and had to be repeatedin two cases. The mean value of the QTc interval was 423 ms (range 380-457 ms) in men and 439 ms (range 391-540 ms) in women.The response time since the ECG recording was submitted for analysis was 11 min (range 1-155).Conclusions: The QTc interval could be measured from ECG recordings obtained with KM devices connected to a smartphone andtransmitted to a centralized reading center in all patients.

Introduction: It is highly crucial to develop novel strategies in order to further enhance the monitoring of sudden cardiac arrest in athletes and establish standard medical care procedures to control monitoring and treatment costs. Therefore, this study aimed to investigate the effects of a high-intensity competition on cardiac troponin T (cTnT) and its correlation with the corrected QT interval (QTc) in the trained athletes. Materials & Methods: In total, 32 male athletes (mean age: 26.9±4.7 years, body mass index: 25.6±1.6 kg/m2) competed in 8-min high intensity competitions. The competition items included running on skillmill for 400 meters; three-stage deadlifting, weight lifting (110kg) with 5 repetitions; (130kg) with 3 repetitions; and (150kg) with 1 repetition, bar pulling up with 30 repetition, 30-kg kettlebell swinging, and 20 sandbag throwing with different weights at a distance of 5m behind a 75-cm box. Moreover, lead II electrocardiogram was utilized in order to measure the resting QTc. The intravenous blood test was performed to determine the level of troponin T before and immediately after the competition. In addition, ANOVA with repeated measures was used to examine the differences between variables in resting position, post competition, and after correction for the volume of plasma lost. In addition, Bonferroni post hoc test was used to identify which mean differences were statistically significant. The Pearson Correlation Coefficient was calculated to assess the level of correlations between the variables and QTc. Ethics code: IR.SRTTU.SSF.2018.103 Findings: The results showed an immediate significant increase in the cardiac Troponin T after high-intensity competition, compared to the resting position (P

Introduction: Chagas’ disease lacks elements to predict which carriers will evolve into cardiac form and which will remain in undetermined form. Objective: To evaluate the relationship between electrocardiographic evolution and Tpeak–Tend and QT intervals, both corrected for heart rate, in chagasic patients with normal initial electrocardiogram. Method: Chagasic patients admitted to the institution until 2002 were retrospectively evaluated, and the electrocardiogram was normal at the first consultation. The Tpeak–Tend and QT intervals were measured in milliseconds at the V2 and V5 derivations, with the mean values corrected for heart rate (Bazett). The relationship of these values with the electrocardiographic evolution of the individuals was analyzed, considering the gender, time of evolution and whether they received benznidazole or not. Results: The corrected Tpeak–Tend interval showed no statistical significance among those who maintained or not normal electrocardiogram. The corrected QT interval, the treatment with benznidazole and the time of evolution showed significance for the maintenance of normal electrocardiogram. In the multivariate evaluation, treatment with benznidazole, the QTc interval and the time of evolution were independent variables for the maintenance of normal electrocardiogram. Conclusion: The Tpeak–Tend interval showed no predictor of electrocardiographic evolution. The increased QT interval favored changes.

Rationale: Acute pulmonary embolism is one of the most serious cardiovascular conditions. QT-interval prolongation represents a hallmark for torsades de pointes or polymorphic ventricular tachycardia and sudden cardiac death. So, identifying the QT-interval prolongation inducer considered very important. Patient concerns: A 55-year-old housewife woman presented with a thrombophilic acute pulmonary embolism-induced marked electrocardiographic QT-interval prolongation. Diagnosis: Acute pulmonary embolism-induced QT-interval prolongation. Interventions: Electrocardiography, computed tomography pulmonary angiogram, and echocardiography. Lessons: Bisoprolol may be helping in the reversal QT-interval prolongation. QT-interval prolongation that is a hallmark for torsades de pointes, and serious ventricular tachyarrhythmias with subsequent sudden cardiac death. Acute pulmonary embolism-induced QT-interval prolongation should be put among the acquired causes of the long QT syndrome. Outcomes: Dramatic response for both electrocardiographic and clinical signs of acute pulmonary embolism-induced QT-interval prolongation post-bisoprolol. Why don’t we use bisoprolol in the management of acute pulmonary embolism-induced electrocardiographic marked QT-interval prolongation?

Background: Sepsis is one of the most serious conditions where early diagnosis is important to decrease mortality. We assessed the use of corrected QT (QTc) interval, and procalcitonin level (PCT) ...

Background There are controversial reports on QT interval response to ganglionic plexi ablation that are selectively targeted during cardioneuroablation (CNA) or occurs as collateral lesion during left atrial ablation procedures. Both shortening or prolongation of the heart-rate corrected QT interval (QTc) with therapeutic or safety implications were described. Purpose In this retrospective study, we investigated longitudinal changes of QTc after CNA. Methods The study included 108 patients (age: 39±12 years, 60% males) who underwent biatrial cardioneuroablation (radiofrequency time: 15.5±6.7 min) for symptomatic functional bradyarrhythmias. Surface ECG examinations were performed on the day before the CNA (N=108), 1 hour after the CNA (N=106), on the 1st post-ablation day (N=50), at the 3-month (N=99), and 1-year (N=63) follow-up visits. Automated measurements of QT interval were employed for the analysis. Four formulas (Bazett, Framingham, Fridericia, and Hodges) were used for the correction of QT interval to instant heart rate. Results QTc significantly prolonged immediately after the CNA with rapid return to baseline values (Figure and Table). This was particularly valid for QT correction by Framingham formula (and similarly for Fridericia and Hodges formulas). The QTc by Bazett formula, which is known to overestimate QT at higher heart rates, returned to baseline more slowly and incompletely. Several mechanisms may contribute to observed QTc dynamics: (1) direct effect of autonomic denervation with recovery phenomenon; (2) QT hysteresis with an extremely long time constant; or (3) artifact due to suboptimum QT correction to a substantial change of heart rate. Conclusions The study suggests that CNA produces acute prolongation of QTc interval with rapid decay and virtual normalization in 3 months. CNA in otherwise healthy subjects is not likely associated with substantial long-term risk of long-QT-associated arrhythmias. In the same way, we cannot confirm earlier observations of clinically significant QTc shortening effect of ganglionated plexi ablation. Funding Acknowledgement Type of funding sources: None. Figure 1Table 1

Background The cases of Rifampicin-Resistant Tuberculosis (RR-TB) in our country have increased every year and RR-TB deaths are thought to be caused by prolongation of the QTc interval due to side effects of anti-tuberculosis drugs. Thus, cytokines are needed to be used as early markers of prolongation of the QTc interval in RR-TB patients. Objective This study aims to analyze the correlation of inflammatory cytokines on QTc interval in RR-TB patients who received shorter regimens. Methods This study uses a case-control study with a time series conducted in the period September 2019 to February 2020 in one of the referral hospitals for Tuberculosis in Indonesia. Cytokines levels from blood samples were measured using the ELISA method, while QTc intervals were automatically recorded using an electrocardiography machine. The statistical analysis used was the Chi-square test, Man Whitney test, Independence t-test, and Spearman-rank test with p, Highlights • QTc interval prolonging in RR-TB patients did not correlate with TNF-α, IL-1β, and IL-6 levels. • Potassium and calcium levels were significantly decreased in the continuation phase. • QTc interval prolongation has no significant association with potassium and calcium levels.