Mean QT Interval Research Articles

Corrected QT interval and QT dispersion in temporal lobe epilepsy in children and adolescent

<b>Aim</b>: The purpose of this research was to contrast (heart-rate corrected QT interval) QTc, and (QT dispersion) QTd intervals in individuals with (temporal lobe epilepsy) TLE and those without TLE using a standard 12-lead electrocardiogram.<br /> <b>Patients & methods</b>: This cross-sectional research was undertaken on 100 cases aged 10 to 20 diagnosed with epilepsy in accordance with 2017 ILAE criteria. The patients’ informed written permission was acquired. In our study, we included 100 cases: 50 with TLE and 50 with non-TLE verified by seizure semiology. All patients were subjected to a comprehensive history, clinical examination (heart rate, pulse, and blood pressure), and clinical evaluation, which included a comprehensive epilepsy history. On the basis of neurology service documents or the initial publication of the international classification of diseases, 9<sup>th</sup> revision (ICD9) diagnostic or 10<sup>th</sup> revision (ICD10) codes for epilepsy, diagnostic age for epilepsy was calculated.<br /> <b>Results: </b>The mean QT interval in group I was 418.30±25.48 ms while that of group II was 406.20±27.63 ms, the mean QTc of group I was 513.60±61.94 ms and was 488.70±50.65 in group II. The calculated QTd was with a mean of 57.60±25.05 ms while that of group II was 43.60±31.89 ms. It means that the QT interval, QTc, and QTd values were considerably greater in the group I (temporal epilepsy) contrasted with group II (non-temporal epilepsy); (p=0.025, 0.030, and 0.016, respectively). The mean QT, QTc, and QTd values for FE were 409.20±20.80, 500.70±55.60, and 52.60±29.70 ms, respectively. QT, QTc, and QTd mean values for patients with widespread epilepsy were 412.00±25.60, 505.00±68.60, and 46.20±28.70 ms. QT, QTc, and QTd interval were insignificantly different between focal and generalized epilepsy. The longer an illness progresses, the longer the QT and QTc intervals, as there was a substantial positive correlation among illness’s course and QT interval (r=0.391, p<0.001) and QTc interval (r=0.289, p=0.011), but there was no noticeable impact on QTd due to the illness’s duration, as we found an insignificant correlation among duration of illness and QTC and QTd.<br /> <b>Conclusions: </b>Our findings indicate that; QTc interval and QTd are longer in epilepsy cases more among TLE cases contrasted with non-TLE. Since there was no distinction among different epilepsy types (focal and generalized).

Relationship between corrected QT prolongation and new-onset atrial fibrillation in the general Japanese population

Abstract Background The QT interval, an electrocardiogram (ECG) parameter, can be corrected for heart rate, giving the QTc. The QTc is an indicator of ventricular repolarisation and is widely used as a predictor of ventricular arrhythmia. Recent studies have reported a relationship between prolonged QTc and atrial fibrillation (AF) development. Purpose We investigated whether a relationship between QTc prolongation and new-onset AF could be identified in the general Japanese population. Methods This retrospective study evaluated the annual health check-up data of 103,304 adults (50,438 males; age, 54±15 years) that did not have AF at baseline, from April 2005 to October 2018. Most participants underwent annual health examinations as recommended by the Japanese health welfare policy. The QTc times were calculated with the Bazett formula (QTc=QT/√RR), using the mean QT and RR intervals. Participants were grouped according to QTc time: long-QTc group (males, >440 ms; females, >460 ms) and normal-QTc group. AF was diagnosed using a 12-lead surface ECG. Logistic regression analyses were performed to determine the strength of the association between prolonged QTc and new-onset AF. Multivariate analyses were adjusted for clinical variables (age, sex, obesity, hypertension, dyslipidaemia, diabetes, estimated glomerular filtration rate, and habitual drinking). Results The median follow-up time for the total study population was 6 years. During follow-up, 341 (0.3%) new cases of AF were recorded. Univariate analysis revealed a significant increase in new-onset AF in the long-QTc group (odds ratio [OR], 2.80; 95% confidence interval [CI], 1.85–4.25; p<0.001). After adjusting for clinical variables, multivariate analysis revealed that a long QTc was significantly associated with new-onset AF (OR, 1.71; 95% CI, 1.12–2.61; p=0.013). In the multivariate analysis, age (OR, 1.06; 95% CI, 1.05–1.07; p<0.001), sex (OR, 2.55; 95% CI, 1.95–3.33; p<0.001), obesity (OR, 1.46; 95% CI, 1.16–1.84; p=0.001), and habitual drinking (OR, 1.90; 95% CI, 1.50–2.41; p<0.001) were also significant predictors of new-onset AF. Conclusions Prolonged QTc is associated with an increased risk of new-onset AF in the general Japanese population. The mechanism of this causal relationship requires further investigation.

Abstract 13785: QT Prolongation and QT Variability Predict New-Onset Atrial Fibrillation in the General Japanese Population

Background: The QT interval, an electrocardiogram (ECG) parameter, can be corrected for heart rate to obtain the QTc, an indicator of ventricular repolarization widely used as a predictor of ventricular arrhythmia. Although prolonged QTc and atrial fibrillation (AF) development are linked, there are few reports of QTc variability and AF development. Purpose: To identify a relationship between QTc prolongation and variability and new-onset AF in the general Japanese population. Methods: This retrospective study evaluated the annual health check-up data of 103,304 adults (50,438 males; age, 54±15 years) without AF at baseline, between April 2005 and October 2018. Most participants underwent annual health examinations as recommended by the Japanese health welfare policy. The QTc times were calculated with the Bazett formula (QTc=QT/√RR), using the mean QT and RR intervals. QTc variability was evaluated as the difference between the maximum and minimum QTc values at multiple checkups. AF was diagnosed using a 12-lead surface ECG. The strength of the association between QTc prolongation and variability and new-onset AF was determined using logistic regression analyses. Multivariate analyses were adjusted for clinical variables (age, sex, obesity, hypertension, dyslipidemia, diabetes, estimated glomerular filtration rate, and habitual drinking). Results: The median follow-up time was 6 years. During follow-up, 341 (0.3%) new AF cases were recorded. Univariate analysis revealed a significant increase in new-onset AF in the QTc prolongation (odds ratio [OR] per 10 ms, 1.08; 95% confidence interval [CI], 1.03-1.13; p<0.001) and the QTc variability (OR per 10 ms, 1.15; 95% CI, 1.07-1.23; p<0.001). After adjusting for clinical variables, multivariate analysis revealed that QTc prolongation and variability were significantly associated with new-onset AF (OR per 10 ms, 1.09; 95% CI, 1.04-1.14; p<0.001) (OR per 10 ms, 1.16; 95% CI, 1.09-1.24; p<0.001). Conclusions: QTc prolongation and variability are associated with an increased risk of new-onset AF in the general Japanese population. Although they have been reported to be involved with the autonomic nervous system, the mechanism of this causal relationship requires further investigation.

Bedaquiline Effect Towards QT Interval in Drug Resistant Tuberculosis (DR-TB): A Systematic Review

Objective: Bedaquiline is recommended by World Health Organization (WHO) to treat Drug-Resistant Tuberculosis (DR-TB). Bedaquiline is chosen due to its efficacy and safety in numerous studies. One adverse event that could happen is QT interval prolongation, which increases the risk of Torsade de Pointes (TdP) and leads to death. This study aimed to discuss the knowledge on the effect of bedaquiline on before-after and changes of QT interval. Materials and Methods: This systematic review based on PRISMA guidelines through PubMed, Cochrane, Science Direct, ProQuest, Google Scholar, and Epistemonikos until April 10, 2023. The keywords used was (“Bedaquiline” AND “QT Interval”). We implemented inclusion and exclusion criteria by PICOS framework then assessed the studies by Joanna Briggs Institute (JBI) critical appraisal checklist tools. Results: From 1.170 articles, eleven articles met the criteria. In total 2449 patients assessed in this study. Most of the studies carried out treatment duration of 6 months. There was a change in the mean QT interval between 11ms to 52.5ms in patients using bedaquiline from the beginning to the end of treatment. The mean QT interval after treatment ranges from 409.7ms – 464.5ms. Conclusion: The use of bedaquiline requires attention to the ECG before and during therapy. Regular monitoring is necessary to prevent QT prolongation.

#3282 ASSOCIATION OF PROLONGED QT INTERVALS WITH MORTALITY IN HEMODIALYSIS PATIENTS: A NATIONWIDE RETROSPECTIVE COHORT STUDY

Abstract Background and Aims The prevalence of prolonged QT intervals is known to be prevalent among hemodialysis patients. In the general population, prolonged QT intervals are linked to increased mortality, however, the correlation between prolonged QT intervals and prognosis in hemodialysis patients remains uncertain. The objective of this study was to investigate the association between prolonged QT intervals and mortality and cardiac death among hemodialysis patients. Method We conducted a retrospective cohort study using the JSDR2019-2020, a nationwide registry of hemodialysis patients in Japan. We excluded from these subjects those younger than 18 years, with QT interval deficit, dialysis less than 3 times a week, atrial fibrillation, peritoneal dialysis, and home dialysis. In 2019, we collected data on various factors and basic patient information, and subsequently monitored outcomes in 2020. QT intervals were corrected using Bazett's formula. Our primary and secondary outcomes were death and cardiac death which we defined as a composite of heart failure, pulmonary edema, arrhythmia, ischemic heart disease, and acute myocardial infarction, respectively. We performed univariate and multivariate analyses of the relationship between QT interval categories and outcomes using logistic regression models, adjusting for age, gender, cause of end-stage renal failure, serum concentrations of iron, potassium, magnesium, calcium, and phosphorus, history of dialysis, and history of cardiovascular disease. We also created a restricted cubic spline to visualize the relationship between QT intervals and outcomes. We employed multivariate imputation by chained equations to complement missing values. We set the significance level at 5%. Results Of the 332,599 patients in the database, 198,624 were included in the analysis of this study. The mean (standard deviation: SD), median (quartiles), and actual number (%) of subjects were: age 69.8 (12.4), 130,735 (65.8) male, 101,988 (51.3) with diabetes, and 66.0 (29.0, 128.0) months of dialysis history. The mean QT interval (SD) was 450.7 msec (30.5). During the 1-year observation period, there were 29,705 deaths, 7,247 cardiac deaths, and 12,166 new cases of ischemic heart disease. The odds ratios (95% confidence intervals: 95%CI, p value) for death within 1 year in the three QT interval categories (<460 [reference], 460< = &<500, 500<) were 1(−), 1.58 (1.52-1.64, p<0.001), and 2.49 (2.35-2.62, p<0.001), respectively. In multivariate analysis, the adjusted odds ratios for death within 1 year in each QT interval category were 1(−), 1.44 (1.37-2.12, p<0.001), and 1.98 (1.87-2.09, P<0.001), respectively. Our analysis of cardiac death as an outcome also revealed a statistically significant increase in cardiac death with increasing QT intervals. Conclusion QT intervals were prolonged in hemodialysis patients, and prolonged QT intervals were significantly associated with increased mortality and cardiac death.

Stereotactic arrhythmia radiotherapy for ventricular tachycardia does not appear to alter QRS duration and QTc interval: a secondary analysis of the prospective STARNL-1 trial

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Dutch Heart Foundation grant to dr. P.G. Postema, MD PhD Background Stereotactic arrhythmia radiotherapy (STAR) has evolved as promising bail-out treatment in patients with therapy-refractory ventricular tachycardia (VT). The mechanism of action of STAR in preventing VT has yet to be elucidated and further understanding could improve this technique in the future. Preclinical studies reported an increase in conduction velocity and consequently a decrease in conduction intervals on electrocardiograms (ECGs) within the first months after STAR, although this has not yet been evaluated in detail in prospective studies. Purpose To evaluate the early effects of STAR on ventricular conduction as electrocardiographically assessed. Methods The STARNL-1 was a prospective, monocenter, pre-post intervention study. Six patients with VT recurrences despite optimal doses of anti-arrhythmic drugs (AADs), after one or more unsuccessful catheter ablation(s), were considered therapy-refractory. Patients were treated with a single fraction of 25 Gy. ECG evaluation included ECGs recorded pre-therapy, at 3 hours, 12 hours, 24 hours, 1 month, and 3 months after therapy. For an additional assessment, only patients in whom AADs remained unchanged up to 3 months after STAR were selected. QRS duration and QT interval were measured by a single observer using digital callipers. Four consecutive beats were used to measure and calculate a mean QRS duration and QT interval per ECG. This study was not powered to evaluate for significant changes in ECG parameters. Results All patients were male, all suffered from ischaemic cardiomyopathy, and all completed 3-month follow-up. One patient presented with atrial fibrillation on ECG recordings, and three patients with a paced rhythm. Four patients (66.7%) were selected for an additional assessment, two patients (P1 and P2, 33.3%) underwent changes in AAD dose and were therefore excluded. Figure 1 shows a line graph of the QRS duration and QTc interval of all STARNL-1 patients during 3-month follow-up. As can be appreciated from Figure 1, QRS duration and QTc interval did not appear to be altered between pre-therapy and 3 months after therapy. When excluding P1 and P2, QRS duration and QTc interval also did not appear to be altered between pre-therapy and 3 months after therapy. Conclusion(s) STAR for VT does not appear to alter QRS duration and QTc interval within the first 3 months after therapy.

Restoration of cardiac metabolic flexibility by glutathione in ecstasy-treated male Wistar rats is dependent of circulating testosterone and xanthine oxidase/uric acid/caspase 3 modulations

Introduction and objectives: The abuse of ecstasy as a recreational drug is widespread, despite its complications such as cardiac injury and dyslipidaemia. Till date, the involvement of testosterone and xanthine oxidase (XO)/ uric acid (UA)/ caspase 3 signaling in ecstasy-induced cardiac injury and dysmetabolism is yet to be reported. The possible effect of glutathione in ecstasy-induced cardiac injury is also yet to be documented. Hence, this study was designed to evaluate the involvement of circulating testosterone and XO/UA/caspase 3 pathway in ecstasy-induced cardiac injury and dysmetabolism. Also, the effect of glutathione in ecstasy-induced cardiac injury was explored. Methods: Forty eight male Wistar rats were randomly distributed into six groups (n= 8). The control rats received distilled water, glutathione-treated rats received 15 mg/kg of glutathione, low dose ecstasy-treated (LDE) and high dose ecstasy-treated (HDE) rats received 5 mg/kg and 15 mg/kg of ecstasy respectively, LDE + glutathione-treated rats received 15 mg/kg of glutathione and 5 mg/kg of ecstasy, and HDE + glutathione-treated rats received 15 mg/kg of glutathione and 15 mg/kg of ecstasy via gavage for 8 weeks. Results: Ecstasy significantly increased the relative cardiac mass, but did not significantly alter the body weight gain and absolute cardiac mass. It also caused increased mean arterial pressure, diastolic pressure, heart rate, PR interval, and QT interval. In addition, it led to insulin resistance and improved β-cell function, increased fasting levels of insulin and plasma and cardiac lactate, lactate dehydrogenase, creatinine kinase, troponin I and T, C-reactive protein, total cholesterol, triglycerides, LDL-C, lipid peroxidation, TNF-α, IL-1β, IL-6, and NF-kB levels. These alterations were accompanied by increased plasma and cardiac levels of XO, UA, and caspase 3, reduced circulating testosterone, glutathione content, and glucose-6- phosphate dehydrogenase, and distortion of cardiac histo-architecture. However, glutathione administration averted ecstasy-driven cardiac injury and metabolic derangement. Conclusions: Taken together, these findings infer that ecstasy induces defective cardiac metabolic flexibility, which is associated with upregulation of XO/UA/caspase 3 signaling and downregulation of circulating testosterone and glutathione defense mechanisms. Also, these results indicate that glutathione alleviates ecstasy-induced cardiac metabolic inflexibility by suppressing XO/UA/caspase 3 signaling and enhancing circulating testosterone and glutathione defense mechanisms. Self funded This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Study to Determine the Safety and Efficacy of Teneligliptin (20 Mg) in Naive Type 2 Diabetes Mellitus

Background: Teneligliptin is a novel, highly selective DPP-4 inhibitor with long half-life, approved in Japan (2012) and in Korea (2014) to treat patients of type 2 DM. It is characterized by a considerably rigid structure formed by five consecutive rings. Teneligliptin, 20mg/day as monotherapy and combination therapy in type 2 DM was shown to be effective in reducing HbA1c and fasting plasma glucose levels without any significant adverse events. Present study was conducted to determine the safety and efficacy of Teneligliptin (20 mg) in naive type 2 diabetes mellitus. Materials and methods: The present study was a hospital based prospective study undertaken to study the safety and efficacy of teneligliptin (20 mg) in naïve type 2 diabetes mellitus. Newly diagnosed type 2 diabetes mellitus patients within age group 18-70 years were studied. All patients were assessed for Blood sugar levels (Fasting and Postprandial HbA1C, Serum urea, Serum Creatinine, Serum uric acid, Lipid profile and ECG. Results: The mean age of total patients was 52.86 ±9.24 years. The mean HbA1c among patients with DM was 7.76 ±1.61. The mean serum urea was 29.12±6.58mg/dl while Serum creatinine was 1.08±0.18 mg/dl. The mean fasting Blood sugar of the patients before treatment was 123.55 ±10.72 and 103.12 ±8.63 mg/dl after treatment with statistical significant difference (p<0.05). The mean blood urea of the patients before treatment was 29.12 ±6.58 and 20.86 ±5.04 mg/dl after treatment with no statistical significant difference. (p >0.05) The mean QT interval of the patients before treatment was 0.37±0.03 and 0.38±0.03 seconds after treatment with statistical non-significant difference (p <0.05). Conclusion: The present study concludes that, Teneligliptin, a novel DPP-4I, when prescribed as a monotherapy antidiabetic agent in a dose of 20 mg daily, significantly improved glycemic parameters. The results of this study suggest that teneligliptin can be considered to be an effective antidiabetic agent in the management of Indian patients with type naive 2 Diabetes Mellitus.

QT interval instability and QRS interval dispersion in healthy cats and cats with a hypertrophic cardiomyopathy phenotype.

Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats. Electrocardiographic (ECG) analysis can help with the diagnosis of HCM and also in the investigation of the secondary consequences of the disease. This study investigated ECG markers of QT interval variability (total instability [TI], short-term instability [STI], long-term instability [LTI], QT variance [QTv]), mean QT interval (QTa) and QT interval corrected for heart rate (QTac), as well as the duration (QRSd) and dispersion (QRSv) of the QRS interval in healthy cats and in those with HCM. Data were collected from 63 domestic cats: 40 in the control group and 23 in the HCM group. Fifty consecutive QT intervals were recorded for all cats and then QTa, QTac, QTv, TI, LTI and STI were calculated. QRSd and QRSv were also obtained for all animals. A Mann-Whitney U-test was used for group comparison. Receiver operating characteristic curves were plotted to evaluate the sensitivity and specificity of all markers for HCM. Logistic regression analysis was performed to assess the risks of cats having HCM, based on the studied indexes. QTa (P <0.01), QTac (P <0.01), QRSd (P <0.01) and STI (P = 0.02) were higher in the HCM group. QTa >158.8 ms, QTac >27.4 ms and QRSd >0.045 s had an accuracy of 77.4%, 68.2% and 80.9%, respectively, in detecting HCM. Logistic regression showed that cats with QTa >158 ms, QTac >27.4 ms and QRSd >0.045 s had a 1.58-, 1,23- and 6.5-fold higher risk, respectively, of developing HCM. Cats with HCM had higher ventricular instability as assessed by STI and showed a prolongation of the QT and QRS intervals via the QTa, QTac and QRSd markers. These markers show potential as ancillary screening tools for identifying the presence of HCM.

QTc interval measurement in patients with right bundle branch block: A practical method.

Prolonging the QT interval in the right bundle branch block (RBBB) can create challenges for electrophysiologists in estimating repolarization time and eliminating the effect of depolarization changes on QT interval. In this study, we aimed to develop a practice formula to eliminate the effect of depolarization changes on QT interval in patients with RBBB. This prospective study evaluated accidentally induced RBBB in patients undergoing electrophysiological study. Two expert electrophysiologists recorded the ECG parameters, including QRS duration, QT interval, and cycle length, in the patients. The formula was developed based on QT interval differences (with and without RBBB) and its proportion to QRS. Additionally, the Bazzet, Rautaharju, and Hodge formulas were used to evaluate QTc. We evaluated 96 patients in this study. The mean QT interval without RBBB was 369.39 ± 37.38, reaching 404.22 ± 39.23 after inducing RBBB. ΔQT was calculated as 34.83 ± 17.61, and the ratio of ΔQT/QRS with RBBB was almost 23%. Our formula is: (QTwith RBBB - 23% × QRS). Subtraction of 25% instead of 23% seems more straightforward and practical. Our formula could also predict the QTc interval in RBBB based on the Bazzet, Rautaharju, and Hodge formulas. Previous formulas for QT correction were hard to apply in the clinical setting or were not specified for RBBB. Our new formula allows a rapid and practical method for QT correction in RBBB in clinical practice.

Exploring the Clinical Characteristics of Patients with Implanted Cardioverter Defibrillator Shocks after Coronavirus Disease 2019 Infection: A Comprehensive Analysis

Abstract Background: The relationship between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and implantable cardioverter defibrillator (ICD) shock remains unclear. We analyzed the characteristics of patients receiving shocks after SARS-CoV-2 infection to explore the causes of these shocks and to provide information for subsequent treatment. Subjects and Methods: We retrospectively analyzed the data from seven patients hospitalized at First People’s Hospital of Yunnan Province between December 2022 and January 2023 after experiencing ICD shocks or ventricular arrhythmias following SARS-CoV-2 infection. We collected baseline information, data related to device parameters and events, and laboratory results to analyze the causes of electrical shocks. Results: All patients received ICD implantation at our hospital. The mean age of the patients was 67 ± 10 years. Four patients underwent implantation for primary prevention and three for secondary prevention. These patients received 80 ICD shocks after SARS-CoV-2 infection, 71 (89%), and 9 (11%) of which were the treatment for ventricular tachycardia and atrial fibrillation, respectively. There were 54 antitachycardia pacing treatments, of which 48 arrhythmic events were terminated through antitachycardia pacing, and 6 were not. Laboratory data revealed six patients had blood potassium levels below 4.0 mM. Five patients had blood calcium levels below 2.11 mmol/L. Four patients had elevated troponin concentrations (0.030–0.297 ng/mL). All patients had significantly elevated N-terminal pro-B-type natriuretic peptide levels (608.8–25,758 pg/mL). Six patients had a QT interval of &gt;440 ms and a mean QT interval of 460 ± 46 ms. Conclusion: SARS-CoV-2 infection may be associated with ICD shocks. Clinicians should pay close attention to patients with ICDs after SARS-CoV-2 infection and actively eliminate arrhythmogenic triggers to minimize the likelihood of ICD shock.

Protocol Development and Initial Experience With Intravenous Sotalol Loading for Atrial Arrhythmias.

Oral sotalol is a class III antiarrhythmic commonly used for the maintenance of sinus rhythm in patients with atrial fibrillation (AF). Recently, the Food and Drug Administration (FDA) approved the use of IV sotalol loading, based primarily on modeling data for the infusion. We aimed to describe a protocol and experience with IV sotalol loading for elective treatment of adult patients with AF and atrial flutter (AFL). We present our institutional protocol and retrospective review of initial patients treated with IV sotalol for AF/AFL at the University of Utah Hospital between September 2020 and April 2021. Eleven patients received IV sotalol for initial loading or dose escalation. All patients were male, aged 56-88 years (median 69). Mean QT interval (QTc) intervals increased from baseline (mean 384 ms) immediately after infusion of IV sotalol (mean change 42ms), but no patient required discontinuation of the medication. Six patients were discharged after 1 night; 4 patients were discharged after 2 nights; and 1 patient was discharged after 4 nights. Nine patients underwent electrical cardioversion prior to discharge (2 prior to load; 7 post-load on the day of discharge). There were no adverse events during the infusion or within 6 months of discharge. Persistence of therapy was 73% (8 of 11) at mean 9.9 weeks to follow up, with no discontinuations for adverse effects. We employed a streamlined protocol that was successfully implemented to facilitate the use of IV sotalol loading for atrial arrhythmias. Our initial experience suggests feasibility, safety, and tolerability while reducing hospitalization duration. Additional data are needed to augment this experience as IV sotalol use is broadened across different patient populations.

Cardiovascular concentration-effect relationships of amodiaquine and its metabolite desethylamodiaquine: Clinical and preclinical studies.

Amodiaquine is a 4-aminoquinoline used extensively for the treatment and prevention of malaria. Orally administered amodiaquine is largely converted to the active metabolite desethylamodiaquine. Amodiaquine can cause bradycardia, hypotension, and electrocardiograph QT interval prolongation, but the relationship of these changes to drug concentrations is not well characterized. We conducted a secondary analysis of a pharmacokinetic study of the cardiac safety of amodiaquine (10mg base/kg/day over 3days) in 54 Kenyan adults (≥18 years) with uncomplicated malaria. Nonlinear mixed effects modelling was used to assess amodiaquine and desethylamodiaquine concentration-effect relationships for vital sign (pulse rate, blood pressure) and electrocardiograph interval (QT, QRS, PR) outcomes. We also measured the spontaneous beating heart rate after cumulative dosing of amodiaquine and desethylamodiaquine in isolated mouse atrial preparations. Amodiaquine and desethylamodiaquine caused concentration-dependent mean decreases in pulse rate (1.9 beats/min per 100 nmol/L; 95% confidence interval: 1.5-2.4), supine systolic blood pressure (1.7mmHg per 100 nmol/L; 1.2-2.1), erect systolic blood pressure (1.5mmHg per 100 nmol/L; 1.0-2.0) and erect diastolic blood pressure (1.4mmHg per 100 nmol/L; 1.0-1.7). The mean QT interval prolongation was 1.4 ms per 100 nmol/L irrespective of correction factor after adjustment for residual heart rate dependency. There was no significant effect of drug concentration on postural change in blood pressure or PR and QRS intervals. In mouse atria, the spontaneous beating rate was significantly reduced by amodiaquine (n= 6) and desethylamodiaquine (n= 8) at 3μmol/L (amodiaquine: 10±2%; desethylamodiaquine: 12 ±3%) and 10μmol/L (amodiaquine: 50 ±7%; desethylamodiaquine: 46 ±6%) concentrations with no significant difference in potency between the 2 compounds. Amodiaquine and desethylamodiaquine have concentration-dependent effects on heart rate, blood pressure, and ventricular repolarization.

Atrial Fibrillation Discrimination for Real-Time ECG Monitoring Based On QT Interval Variation

Background/Objectives: An occasional Atrial Fibrillation (AF) event in heart rhythm should be monitored regularly, in continuous intervals. Timely detection of these anomalies in heart rhythm is required to save patients from sudden cardiac arrest. Method: A long-duration ECG categorization algorithm named AFECOC is proposed. For this one-minute-long 71 signals are attained from the Physionet’s “MIT-BIH arrhythmia (MA)” and “AF” database. Two-stage filtering of noisy signals is employed before signal analysis. Four algorithms i.e. Error-Correcting Output Code (ECOC), Naïve Bayes, Decision Tree, and K-Nearest Neighbor(K-NN) are applied to reduce the feature set and then signals are classified with ECOC classifier. Findings: It was found that the ECOC algorithm gives the highest accuracy of 81.95% on the complete feature set. To exclude the irrelevant features, the highest performing algorithm ECOC was used that extracts the combination of the feature sets that get most affected during AF. The combination of ’heart-beat’ and ’mean QT-interval’ are found to be the most relevant features affected during AF events. The accuracy of these two features was evaluated with four classifiers namely ECOC, Naïve Bayes, Decision tree-based and K mean classifier and the accuracy obtained was 89.6%, 76.19%, 76.19%, and 61% respectively. It concludes that the proposed methodology achieved the highest accuracy of 89.6% with the ECOC classifier. Finally, all the AF rhythms have been checked using annotated labels for spontaneous change in QT-interval to verify the designed methodologies. Novelty: Instead of missing P-waves and RR-interval variation, recognition of mean QT interval variation-based AF event detection algorithm gives better accuracy for longer signals. Hence, it can be implemented in Real- Time continuous monitoring. Keywords: Atrial Fibrillation (AF); Classification; Error Correcting Output Code (ECOC); Feature extraction; QTinterval

Effect of spinal anesthesia on QT interval: Comparative study of severe pre-eclamptic and normotensive parturients undergoing cesarean section.

This study aimed to compare the effect of spinal anesthesia on QT interval in severe pre-eclamptic and normotensive parturients who underwent cesarean section in a Nigerian tertiary hospital. Twelve-lead electrocardiogram (ECG) was obtained before, and at intervals after spinal anaesthesia on fifty severe pre-eclamptic (Group A) and fifty normotensive parturients (Group B) who underwent caesarean section. The effect of spinal anaesthesia on QT interval was compared. The preoperative (baseline) mean QT interval was longer in group A than in group B; 453.10 ± 34.11 ms versus 399 ± 18.79 ms, P < 0.001. The prevalence of prolonged QT interval in the severe pre-eclamptic group before spinal anesthesia was 80% while in the normotensive group it was 0%, P < 0.001. At 5, 30, 60, and 120 min after the establishment of spinal anesthesia, the mean QT interval in the severe pre-eclamptic group was shortened and maintained within normal limits; 414.74 ± 28.05, 418.28 ± 30.95, 411.18 ± 19.21 and 401.36 ± 17.52 ms with P < 0.001 throughout. In the normotensive group, there was no significant change in the mean QT interval. This study demonstrated that the QT interval was more prolonged among the severe pre-eclamptic parturients. Spinal anesthesia using 0.5% hyperbaric bupivacaine normalized the QT interval and maintained it within normal limits during the study period.

Left Cardiac Sympathetic Denervation for Long QT Syndrome: 50 Years' Experience Provides Guidance for Management.

This study sought to report our single-center experience with left cardiac sympathetic denervation (LCSD) for long QT syndrome (LQTS) since1973. LCSD is still underutilized because clinicians are often uncertain whether to use it versus an implantable cardioverter-defibrillator (ICD). We performed LCSD in 125 patients with LQTS (58% women, mean QT interval corrected for frequency [QTc] 527 ± 60ms, 90% on beta blockers) with a follow-up of 12.9 ± 10.3 years. They were retrospectively divided into 4 groups according to the clinical/genetic status: very high risk (n=18, symptomatic in the first year of life or with highly malignant genetics), with aborted cardiac arrest (ACA) (n=31), with syncope and/or ICD shocks on beta blockers (n=45), in primary prevention (n=31). After LCSD, 17% in the very high risk group remained asymptomatic, compared with 52%, 47%, and 97% in the other 3 groups (P< 0.0001), with an overall 86% decrease in the mean yearly cardiac event rate (P< 0.0001). Among 45 patients with only syncope/ICD shocks before LCSD, none had ACA/sudden death as first symptom after LCSD and a 6-month post-LCSD QTc<500ms predicted excellent outcome. Patients with a QTc≥500ms have a 50% chance of shortening it by an average of 60ms. LCSD results are not affected by common genotypes. We provide definitive evidence for the long-term efficacy of LCSD in LQTS. The degree of antiarrhythmic protection is influenced by patient's specificity and amount of QTc shortening. This novel approach to the analysis of the outcome allows cardiologists to rationally decide and tailor their management strategies to the individual features of their patients.

Tip 1 Diabetes Mellitusta Kardiyak Elektrofizyolojik Denge İndeksinin Değerlendirilmesi

Background: Type 1 diabetes mellitus (T1DM) has been suggested to carry the risk of developing cardiac arrhythmias. The risk of cardiovascular events and sudden death is higher in patients with T1DM. The index of cardiac electrophysiological balance (iCEB), which shows the balance between ventricular depolarization and repolarization, is a new electrocardiographic (ECG) parameter when compared to other ECG parameters. iCEB provides more information on ventricular arrhythmo-genesis than the other traditional ECG parameters such as QT and corrected QT (QTc) intervals. The aim of this study is to evaluate the relationship between T1DM and iCEB.Materials and Methods: This study was conducted retrospectively. The patient group consisted of 50 patients (58% male, mean age 32.9 ± 8.7 years) diagnosed with T1DM, while the control group consisted of 50 healthy individuals (58% male, mean age 33.9 ± 6.8 years). The clinical, demo-graphic and ECG records of the patients were obtained from our hospital's medical documentation system. iCEB and corrected iCEB (iCEBc) values of all participants were calculated by dividing the relevant QT and QTc intervals by the QRS duration.Results: Mean PR, QRS, and QT intervals were similar between groups, while mean heart rate and QTc interval were found to be higher in the T1DM group than in healthy subjects [(83.1 ± 9.8 vs 78.9 ± 13.3 bpm, respectively, p = 0.019) and (425 ± 20.4 vs 397.6 ± 10.6 ms, respectively, p &amp;lt; 0.001)]. The iCEBc of the patient group with T1DM was higher than the control group (5.1 ± 0.5 vs 4.7 ± 0.4 ms, p &amp;lt;0.001, respectively). However, there was no significant difference in iCEB be-tween the patient and control groups (4.3 ± 0.4 and 4.3 ± 0.4 ms, respectively, p = 0.402).Conclusions: In our study, iCEBc was found to be significantly increased in T1DM patients com-pared to healthy subjects. Consequently; it is important to evaluate the risk of ventricular ar-rhythmia with iCEBc in T1DM patients.Key Words: Electrocardiography, Index of cardiac electrophysiological balance, Type 1 diabetes mellitus, Ventricular arrhythmia

Investigation role of ondansetron on long QT interval among non-cardiac patients

BackgroundOndansetron is one of the commonly prescribed anti-emetic in emergency department however, high dose of the drug is associated with prolonged QT interval. This study was designed to evaluate the effect of ondansetron on prolongation of QT interval among patients referred to our emergency department. MethodsIn this cross-sectional study patients referred to the emergency department of Imam Reza hospital from June 2019 to December 2019 were included. Before the administration of ondansetron 12-lead electrocardiography was performed in all the patients. 4 mg of i.v. ondansetron was administered to these patients and ECG was obtained again. QT interval was calculated automatically from the system from these electrocardiographs. Demographic data of these patients along with QT interval findings was recorded in the questionnaire and analyzed statistically using SPSS software. ResultsA total of 55 patients were included with the mean age of 58 ± 13 years, where 36 were females (65.5%) and 19 were males (34.5%). The mean QT interval before and after injection of 4 mg intravenous ondansetron was not statistically significant, p-value = 0.073. Similarly, QT interval before and after the administration of the drugs was also not significantly different among females and males, p = 0.479 and p = 0.078, respectively. The age of the patients was also not associated with prolonged QT interval, p = 0.948. ConclusionsThe findings of our study indicated that 4 mg i.v. administration of ondansetron among non-cardiac patients referred to emergency department is not associated with QT interval prolongation.

B-PO03-159 INTERPRETATION OF PRONE-POSITION 12-LEAD SURFACE ELECTROCARDIOGRAM AND MAIN DIFFERENCES WHEN COMPARED TO SUPINE-POSITION ECGS: INSIGHTS FROM A CASE-CONTROL STUDY

Prone position is a valuable treatment strategy in acute respiratory distress syndrome (ARDS) and is frequently used in surgical scenarios. Nonetheless, prone position may hinder proper acquisition and interpretation of the 12-lead electrocardiogram (ECG) as there is a sparsity of data regarding standardization of lead position and interpretation. We aimed to analyze and compare ECGs in the supine and prone positions to provide guidance for adequate interpretation and clinical utility of the ECG in prone position. This was a multicenter prospective cohort study in which ECGs in the prone and supine position were compared, including patients with COVID-19 infection and healthy controls. The precordial leads for the prone ECGs were placed in the following fashion: V1 in the right paraspinal region at the level of the T7 vertebra, V2 in the left paraspinal region at the level of the T7 vertebra, V4 in the mid-scapular region at the level of the T8 vertebra (approximately bellow the tip of the scapula), V3 halfway between V3 and V4, V5 at the posterior axillary line at the level of the T8 vertebra, and V6 at the mid-axillary line at the level of T8 vertebra - same position as the V6 in the supine position. A total of 45 patients with COVID-19 infection were compared with 40 healthy volunteers (48% of the patients were female, the mean age in the entire cohort was 48.8 years, and the mean BMI was 27.9). The mean heart rate, PR interval, QRS duration, QT and QTc interval, and QRS axis in the frontal plane were found to positively correlate in supine and prone ECGs. The main difference found was no correlation of the QRS amplitude between supine and prone ECGs in leads V1, V2, V3, and V4; but there was positive correlation in leads V5 and V6. Prominent Q waves were present in the anteroseptal leads (V1-V3) in the prone posterior position. In addition, T-wave inversions or flattening were observed in leads V1 and V2 were present in a majority of patients in the prone posterior position. ECGs performed in the prone position are an acceptable alternative to supine ECGs. Special attention and review of prior supine ECGs may be necessary for precise interpretation of the anteroseptal precordial leads which may be misleading (i.e, septal infarct).

Electrocardiographic biomarkers to predict atrial fibrillation in sinus rhythm electrocardiograms

ObjectiveEarly prediction of atrial fibrillation (AF) development would improve patient outcomes. We propose a simple and cheap ECG based score to predict AF development.MethodsA cohort of 16 316 patients was...