Patients with metabolic syndrome have prolonged corrected QT interval (QTc)

The assessment of adolescent obesity's effects on ventricular repolarization

BACKGROUND

Currently, there is a lack of research on the Tp-Te interval and Tp-e/QT ratio in obese adolescents who have metabolic syndrome.

AIM

Our study aims to compare established ventricular repolarization parameters with these intervals and ratios in obese adolescents with or without metabolic syndrome, alongside a healthy control group, while exploring the association of these repolarization parameters with cardiovascular risk factors and echocardiographic variables.

METHODS

The study included 100 obese adolescents and 50 lean subjects, with the obese participants categorized into two subgroups. The Tp-Te interval was identified as the duration from the peak to the end of the T wave.

RESULTS

The metabolic and non-metabolic syndrome obese groups exhibited significantly elevated QTc and TpTe values compared to the control group, with no statistically significant differences observed in minimum QT, maximum QT, QT dispersion, QTc dispersion, TpTe dispersion, and TpTe/QT ratio values among obese subjects with metabolic or non-metabolic syndrome and controls. Specifically, TpTe values were significantly elevated in the non-metabolic syndrome obese groups compared to controls, while minimum TpTe values were significantly elevated in the metabolic syndrome obese groups compared to controls, and the prolongation of the QTc interval was notably elevated in the obese groups than in controls.

CONCLUSIONS

Obese adolescents demonstrated an elevated TpTe interval compared to healthy controls, without any significant differences observed in TpTe dispersion, and TpTe/QT ratio values between the two groups. Results of our study showed that a negative correlation between TpTe and HDL-cholesterol and a positive correlation between the TpTe/QT ratio and insulin sensitivity indices in adolescents with metabolic syndrome.

Assessment of Corrected QT Interval and QT Dispersion in Patients with Uncomplicated Metabolic Syndrome

Aim

Metabolic syndrome (MS) itself has become a new entity being a constellation of physiological, biochemical, metabolic, and clinical factors that have been related to an increased risk of cardiovascular diseases, type 2 diabetes mellitus (T2DM), and morbidity and mortality. The burden of MS is increasing all over the world with the current prevalence being 30%. The QT interval and QT dispersion (QTd) have been long associated with ventricular arrhythmia and sudden cardiac deaths. The association between QT and diabetes and healthy subjects has been clearly studied, but the association between QT and uncomplicated MS has not been very well defined.

Methods

A total of 400 patients visiting the medicine clinics were assessed for blood pressure, anthropometric measurements, fasting serum lipid profile, FBS, and electrocardiogram (ECG). The patients diagnosed with uncomplicated MS as per the International Diabetic Federation (IDF) criteria were included in the study. QT interval in the ECG was recorded, and the relationship between various parameters of an uncomplicated MetS and the QT interval was recorded.

Results

Our study revealed more females with uncomplicated MS as compared to males and increasing burden as age progressed. Body mass index (BMI), waist circumference (WC), hip circumference (HC), WHP, systolic blood pressure (SBP), Diastolic blood pressure (DBP), Fasting blood sugar (FBS), serum cholesterol, triglyceride (TG), and low-density lipoprotein (LDL) levels were positively correlated with QT values.

Conclusion

QT interval, a strong predictor of malignant ventricular arrhythmias and sudden cardiac deaths, is associated with uncomplicated MS.

Risk Assessment for Arrhythmia in Pediatric Renal Transplant Recipients

OBJECTIVES

Renal transplant recipients are at risk for ventricular arrhythmia and sudden death. To assess that risk, we compared the ventricular repolarization markers of pediatric renal transplant recipients with those of healthy children.

MATERIALS AND METHODS

We included 30 children and adolescents who were followed for at least 6 months after renal transplant; 30 age- and sex-matched children were included for the control group. Demographic features, medications, and laboratory findings were recorded. Blood pressure measurements, ventricular repolarization indexes including QT dispersion, corrected QT dispersion, T-wave peak-to-end interval dispersion, the T-wave peak-to-end interval∕QT ratio, the T-wave peak-to-end interval∕corrected QT ratio, left ventricular mass index, and relative wall thickness were compared between groups. In addition, the correlations of ventricular repolarization indexes with other variables were evaluated.

RESULTS

Blood pressure standard deviation scores, the mean heart rate, QT dispersion, corrected QT dispersion, the T-wave peak-to-end interval∕QT ratio, the T-wave peak-to-end interval/corrected QT ratio, left ventricular mass index, and relative wall thickness values were significantly higher in renal transplant patients, whereas T-wave peak-to-end interval dispersion, ejection fraction, and fractional shortening were similar between groups. Although ventricular repolarization indexes were similar in patients with and without left ventricular hypertrophy, only corrected QT dispersion was significantly higher in patients with hypertension (P = .006). The only variable that significantly predicted prolonged corrected QT dispersion was the systolic blood pressure standard deviation score (P = .005, β = .403).

CONCLUSIONS

Ventricular repolarization anomalies, hypertension, left ventricular hypertrophy, and cardiac geometry irregularity may be observed after renal transplant in pediatric recipients despite acceptable allograft functions and normal serum electrolyte levels. Control of systolic blood pressure would decrease the risk of ventricular repolarization abnormalities, namely, the corrected QT dispersion. Follow-up of cardiovascular risks with noninvasive methods is recommended in all pediatric renal transplant recipients.

Prediction of sudden cardiac arrest in the general population: Review of traditional and emerging risk factors

Sudden cardiac death (SCD) is the most common and devastating outcome of sudden cardiac arrest (SCA), defined as an abrupt and unexpected cessation of cardiovascular function leading to circulatory collapse. The incidence of SCD is relatively infrequent for individuals in the general population, in the range of 0.03-0.10% per year. Yet, the absolute number of cases around the world is high due to the sheer size of the population at risk, making SCA/SCD a major global health issue. Based on conservative estimates, there are at least 2 million cases of SCA occurring worldwide on a yearly basis. As such, identification of risk factors associated with SCA in the general population is an important objective from a clinical and public health standpoint. This review will provide an in-depth discussion of established and emerging factors predictive of SCA/SCD in the general population beyond coronary artery disease and impaired left ventricular ejection fraction. Contemporary studies evaluating the association between age, sex, race, socioeconomic status and the emerging contribution of diabetes and obesity to SCD risk beyond their role as atherosclerotic risk factors will be reviewed. In addition, the role of biomarkers, particularly electrocardiographic ones, on SCA/SCD risk prediction in the general population will be discussed. Finally, the use of machine learning as a tool to facilitate SCA/SCD risk prediction will be examined.

TdP Incidence in Methoxamine-Sensitized Rabbit Model Is Reduced With Age but Not Influenced by Hypercholesterolemia

Metabolic syndrome is associated with hypercholesterolemia, cardiac remodeling, and increased susceptibility to ventricular arrhythmias. Effects of diet-induced hypercholesterolemia on susceptibility to torsades de pointes arrhythmias (TdP) together with potential indicators of arrhythmic risk were investigated in three experimental groups of Carlsson's rabbit model: (1) young rabbits (YC, young control, age 12-16 weeks), older rabbits (AC, adult control, age 20-24 weeks), and older age-matched cholesterol-fed rabbits (CH, cholesterol, age 20-24 weeks). TdP was induced by α-adrenergic stimulation by methoxamine and I_Kr block in 83% of YC rabbits, 18% of AC rabbits, and 21% of CH rabbits. High incidence of TdP was associated with high incidence of single (SEB) and multiple ectopic beats (MEB), but the QTc prolongation and short-term variability (STV) were similar in all three groups. In TdP-susceptible rabbits, STV was significantly higher compared with arrhythmia-free rabbits but not with rabbits with other than TdP arrhythmias (SEB, MEB). Amplitude-aware permutation entropy analysis of baseline ECG could identify arrhythmia-resistant animals with high sensitivity and specificity. The data indicate that the TdP susceptibility in methoxamine-sensitized rabbits is affected by the age of rabbits but probably not by hypercholesterolemia. Entropy analysis could potentially stratify the arrhythmic risk and identify the low-risk individuals.

Characteristics of Ventricular Electrophysiological Substrates in Metabolic Mice Treated with Empagliflozin

Empagliflozin (EMPA) is a sodium–glucose transporter 2 (SGLT2) inhibitor that functions as a new-generation glucose-lowering agent and has been proven to be beneficial for patients with cardiovascular diseases. However, the possible benefits and mechanisms of its antiarrhythmic effects in cardiac tissue have not yet been reported. In this study, we elucidated the possible antiarrhythmic effects and mechanisms of EMPA treatment in cardiac tissues of metabolic syndrome (MS) mice. A total of 20 C57BL/6J mice (age: 8 weeks) were divided into four groups: (1) control group, mice fed a standard chow for 16 weeks; (2) MS group, mice fed a high-fat diet for 16 weeks; (3) EMPA group, mice fed a high-fat diet for 12 weeks and administered EMPA at 10 mg/kg daily for the following 4 weeks; and (4) glibenclamide (GLI) group, mice fed a high-fat diet for 12 weeks and administered GLI at 0.6 mg/kg daily for the following 4 weeks. All mice were sacrificed after 16 weeks of feeding. The parameters of electrocardiography (ECG), echocardiography, and the effective refractory period (ERP) of the left ventricle were recorded. The histological characteristics of cardiac tissue, including connexin (Cx) expression and fibrotic areas, were also evaluated. Compared with the MS group, the ECG QT interval in the EMPA group was significantly shorter (57.06 ± 3.43 ms vs. 50.00 ± 2.62 ms, p = 0.011). The ERP of the left ventricle was also significantly shorter in the EMPA group than that in the GLI group (20.00 ± 10.00 ms vs. 60.00 ± 10.00 ms, p = 0.001). The expression of Cx40 and Cx43 in ventricular tissue was significantly lower in the MS group than in the control group. However, the downregulation of Cx40 and Cx43 was significantly attenuated in the EMPA group compared with the MS and GLI groups. The fibrotic areas of ventricular tissue were also fewer in the EMPA group than that in the MS group. In this study, the ECG QT interval in the EMPA group was shorter than that in the MS group. Compared with the MS group, the EMPA group exhibited significant attenuation of downregulated connexin expression and significantly fewer fibrotic areas in ventricles. These results may provide evidence of possible antiarrhythmic effects of EMPA.

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

BACKGROUND

Weight loss after bariatric surgery has been associated with reduced cardiovascular mortality and overall mortality in obese patients. In this study, we aimed to analyze the changes between pre-operation and post-operation ventricular arrhythmia predictors in patients who underwent bariatric surgery.

MATERIALS AND METHODS

The study included 58 patients who underwent bariatric surgery. We measured QT max, QT min, QRS, JT, and Tp-e intervals, and we estimated Tp-e/QT max, Tp-e/QTc max, Tp-e/JT, Tp-e/JTc rates, QTc max, QTc min, cQTd, and JTc intervals both pre-op and 6 months post-op.

RESULTS

Heart rate, PR, QT max, QTc max, QTc min, cQTd, JTc, Tp-e, Tp-e/QT max, Tp-e/QTc max, Tp-e/JT, and Tp-e/JTc values, which were close to the upper limit in the pre-op period, showed statistically significant decreases at 6 months post-op.

CONCLUSION

The results of our study showed that bariatric surgery had positive effects on the regression of ventricular repolarization parameters and the possible development of ventricular arrhythmia.

The relevance between graft preservation solutions and QTc interval during living donor kidney transplantation and rat cardiomyocytes sampling

BACKGROUND

The purpose of the retrospective study was to identify the impacts of different solutions on the electrocardiogram and cardiovascular changes. Moreover, the differences between these solutions were analyzed by examining their impacts on rat ventricular cardiomyocytes.

METHODS

Eighty renal transplant patients were evaluated retrospectively. The patients were divided into two groups: Group UW (n =40) used the University of Wisconsin solution, and Group HTK (n =40) used the Histidine-Tryptophan-Ketoglutarate solution. Electrocardiograms of the subjects were obtained three times at different periods; during the pre-perfusion, intraoperative kidney reperfusion, and postperfusion phase at the end of the surgery. Any Electrocardiogram or cardiovascular alterations were noted and analyzed. Adult male Wistar rats were used for in vitro experiments. Myocyte contractility, action potentials, and membrane current were recorded in enzymatically isolated ventricular myocytes.

RESULTS

Sinus bradycardia was detected in 19 patients of Group UW, while there was short-term asystole in eight patients. However, no cardiac changes were observed in Group HTK patients. In both Groups, reperfusion and postperfusion corrected QT (QTc) intervals were different from pre-perfusion QTc intervals. Group UW patients' reperfusion and postperfusion QTc's values were higher than those of the Group HTK patients. In rat myocytes, prominent asystole episodes were observed at specific concentrations of the UW solution compared to the HTK solution. The UW solution depolarized the resting membrane potential significantly and decreased the peak value of action potential, whereas the HTK solution did not elicit a significant change in those parameters. Accordingly, the UW solution elicited a significant inward current at -70 mV, while the HTK solution activated only a modest current, which may not change the membrane potential.

CONCLUSION

Prolongation of QTc intervals was detected with reperfusion in both groups according to electrocardiography analysis. However, the QTc interval was observed to be longer in cases using the UW solution and required intervention intraoperatively. HIPPOKRATIA 2021, 25 (1):22-30.

Caloric restriction in heart failure: A systematic review

BACKGROUND AND AIMS

Nutrition exerts a determinant role in maintaining cardiac function, regulating insulin and mitochondrial efficiency, that are essential to support energy production for contractility. In patients with heart failure (HF), myocardial tissue efficiency is reduced because of decreased mitochondrial oxidative capacity. In HF conditions, cardiomyocytes shift toward glucose and a reduction in fatty acid utilization. Calorie restriction induces weight loss in obese patients and can be beneficial in some HF patients, although this has generated some controversy. This study aims to evaluate the impact of the CR diet on myocardial efficiency in HF patients.

METHODS

On Pubmed and Embase, articles related to the keywords: "chronic heart failure" with "diet," "nutrition," "insulin resistance," and "caloric restriction" have been searched, Studies, including exercise or food supplementation, were excluded.

RESULTS

The retrieved articles showed that weight loss, through the activation of insulin and various kinase pathways, regulates the efficiency of myocardial tissue. In contrast, insulin resistance represents a strong cardiovascular risk factor that reduces myocardial function.

CONCLUSION

CR diet represents the first therapy in overweight HF patients, both with preserved ejection fraction (HFpEF) and with reduced ejection fraction (HFrHF) because reducing body fat, the myocardial function increased. Insulin activity is the critical hormone that regulates mitochondrial function and cardiac efficiency. However, a severely restricted diet may represent a severe risk factor correlated with all-cause mortality, particularly in underweight HF patients. Long-term studies conducted on large populations are necessary to evaluate the effects of CR on myocardial function in HF patients.

Myo-inositol and d-chiro-inositol oral supplementation ameliorate cardiac dysfunction and remodeling in a mouse model of diet-induced obesity

Obesity is an independent risk factor to develop cardiac functional and structural impairments. Here, we investigated the effects of supplementation of inositols on the electrical, structural, and functional cardiac alterations in the mouse model of high fat diet (HFD) induced obesity. Three groups of C57BL6 mice (n = 16 each) were studied: j) HFD feeding; jj) HFD feeding + inositols from week 9 to 13; jjj) standard diet feeding. Study observation period was 13 weeks. Inositols were administered as mixture of myo-inositol and d-chiro-inositol in the drinking water. Effects of inositols were evaluated based on electrical, structural, and functional cardiac features, autonomic sympatho-vagal balance and arrhythmogenic susceptibility to adrenergic challenge. Heart samples were collected for histological evaluations and transcriptional analyses of genes involved in defining the shape and propagation of the action potential, fatty acid metabolism and oxidative stress. Inositol supplementation significantly restored control values of heart rate and QTc interval on ECG and of sympatho-vagal balance. Moreover, it blunted the increase in left ventricular mass and cardiomyocyte hypertrophy, reversed diastolic dysfunction, reduced the susceptibility to arrhythmic events and restored the expression level of cardiac genes altered by HFD. The present study shows, for the first time, how a short period of supplementation with inositols is able to ameliorate the HFD-induced electrical, structural and functional heart alterations including ventricular remodeling. Results provide a new insight into the cardioprotective effect of inositols, which could pave the way for a novel therapeutic approach to the treatment of HFD obesity-induced heart dysfunction.

The effect of venlafaxine on blood pressure and ECG in rats fed with high-fat-fructose diet

Metabolic syndrome represents one of the major health, social and economic issues nowadays, and affects more than 25% people worldwide. Being a multifactorial health problem, metabolic syndrome clusters various features, such as obesity, dyslipidemia, hyperglycemia and hypertension. Each of these disturbances represents a risk factor for developing cardiovascular disease. Moreover, patients with metabolic syndrome are more likely to suffer from depression, thus treatment with antidepressants (e.g. venlafaxine) is often neccessary. However, many of the antidepressants themselves may contribute to worsening or even development of the metabolic syndrome, thus creating a “vicious circle”. The aim of this work was to investigate on the animal model of metabolic syndrome, i.e. on hypertriacylglycerolemic rats fed high-fat-fructose diet (HFFD): 1) the effect of a change in diet from HFFD to a standard diet (SD) and the effect of venlafaxine treatment, 2) during HFFD, 3) as well as during a changed diet to SD. We focused on biometric parameters, blood pressure and selected ECG parameters. We observed the reversibility of the present metabolic and cardiovascular changes by switching the HFFD to SD in the last 3 weeks of the experiment. Switch to the standard diet led to decrease of body weight, even in the presence of venlafaxine. Administration of venlafaxine caused the decrease of heart weight/body weight index in rats fed with HFFD compared to the untreated group fed with HFFD for 8 weeks. Blood pressure, which was increased in the HFFD group showed a tendency to decrease to control values after switching to the standard diet . Administration of venlafaxine led to significant increase in all parameters of blood pressure when rats were fed with HFFD throughout the whole experiment. In untreated rats fed with HFFD for 8 weeks, we observed a shorter PQ interval and prolonged QRS complex as well as QTc interval compared to untreated rats with diet switched to SD. This effect was potentiated by venlafaxine administered not only during HFFD but even after switch to SD. Our results point to the fact that metabolic syndrome is clearly affecting the function of the cardiovascular system by modifying blood pressure and electrical activity of the heart. Moreover, administration of venlafaxine may lead to worsening of the observed changes, especially in the presence of high-fat-fructose diet.

Investigation of the effect of epicardial adipose tissue thickness on cardiac conduction system in children with type 1 diabetes mellitus

Objectives Investigation of the association between epicardial adipose tissue thickness (EATT) and P-wave dispersion (Pd), QT dispersion (QTd), corrected QT dispersion (QTcd) and Tp-e interval in children with Type 1 Diabetes Mellitus (T1DM) was aimed. Methods Forty-one children with T1DM and 41 age- and gender-matched healthy children were included in the study. Demographical characteristics of all cases were examined. In echocardiography; in addition to conventional echocardiographic measurements, end-systolic EATT was measured from right ventricular free wall. In electrocardiogram; Pd, QTd, QTcd and Tp-e interval durations, as well as Tp-e/QT and Tp-e/QTc ratios were calculated. Correlation values between EATT and electrocardiographic parameters were also noted. Results Mean age of the patient group was determined to be 12.43 ± 3.04 years and that of the control group was determined to be 12.08 ± 2.56 years. There was no significant difference between the groups in regard to age, gender, body weight, height and body mass index. In the patient group; EATT, Pd, QTd, QTcd and Tp-e interval were determined to be significantly higher compared to the control group. In the patient group, no significant correlation was determined between EATT and Pd, QTd, QTcd and Tp-e. However, when both patient and control groups were evaluated together, a statistically significant positive correlation was determined between EATT and Pd, QTd, QTcd and Tp-e. Conclusions In children with T1DM, an increase in epicardial adipose tissue thickness and in risk of cardiac arrhythmias has been demonstrated. To reveal the possible unfavorable effects of EATT on cardiac conduction system in T1DM patients needs further studies.

Murine model of left ventricular diastolic dysfunction and electro-mechanical uncoupling following high-fat diet

BACKGROUND/OBJECTIVES

It is well established that obesity is an independent risk factor for cardiac death. In particular various cardiac alterations have been described in obese patients such as long QT on ECG, impaired diastolic filling of the left ventricle (LV), and all-type arrhythmias. In the present study, the above alterations were all reproduced in a mouse model of fat diet-induced obesity.

ANIMALS/METHODS

In C57BL6 mice fed on a high fat (n = 20, HF-group) or standard diet (n = 20, C-group) for 13 weeks, balanced by sex and age, we examined heart morphology and function by high-frequency ultrasounds and electric activity by surface ECG. Besides, the autonomic sympathovagal balance (heart-rate variability) and the arrhythmogenic susceptibility to adrenergic challenge (i.p. isoproterenol) were compared in the two groups, as well as glucose tolerance (i.p. glucose test) and liver steatosis (ultrasounds).

RESULTS

Body weight in HF-group exceeded C-group at the end of the experiment (+28% p < 0.01). An abnormal ventricular repolarization (long QTc on ECG) together with impaired LV filling rate and increased LV mass was found in HF-group as compared to C. Moreover, HF-group showed higher heart rate, unbalanced autonomic control with adrenergic prevalence and a greater susceptibility to develop rhythm disturbances under adrenergic challenge (i.p. isoprenaline). Impaired glucose tolerance and higher liver fat accumulation were also found in HF mice compared to C.

CONCLUSIONS

The described murine model of 13 weeks on HF diet, well reproduced the cardiovascular and metabolic disorders reported in clinical obesity, suggesting its potential utility as translational mean suitable for testing new pharmaco-therapeutic approaches to the treatment of obesity and its comorbidity.

Metabolic syndrome and its components as risk factors for prolonged corrected QT interval in apparently healthy Korean men and women

BACKGROUND

Metabolic syndrome (MetS) is clinically important because of its association with increased risk of sudden cardiac death, as well as cardiovascular disease-related mortality. Data between MetS and prolonged corrected QT (QTc) intervals, a useful predictor of sudden cardiac death, are limited in apparently healthy adults.

OBJECTIVE

This study determined the association between MetS and QTc interval in apparently healthy Korean men and women.

METHODS

We examined the association between MetS and QTc interval in 2157 Korean adults (1317 men and 840 women) in a health examination program but excluded participants with a history of ischemic heart disease, stroke, cardiac arrhythmia, cancer, thyroid, respiratory, renal, hepatobiliary, or rheumatologic disease. The QTc interval was calculated using Bazett's formula (QTc = QT/√RR). Multivariate-adjusted mean QTc values by the number of MetS components were calculated after sex stratification and compared using analysis of covariance test.

RESULTS

The overall prevalence of MetS was 30.5% in men and 19.8% in women. The QTc interval positively correlated with age, body mass index, blood pressure, fasting plasma glucose, triglycerides, and potassium level in both men and women and negatively correlated with calcium and potassium levels and smoking status in men. The multivariate-adjusted mean QTc value increased proportionally with increasing number of MetS components (P values < 0.001 for both men and women).

CONCLUSION

We confirmed the arrhythmogenic potential of MetS in apparently healthy Korean men and women. These findings suggest that careful monitoring of electrocardiography is necessary to evaluate possible arrhythmic risk in individuals with MetS.

Subclinical ventricular repolarization abnormality in uncontrolled compared with controlled treated hypertension

Background

Antihypertensive medications have variable effects on the duration of the QT interval. This study aims to demonstrate the subclinical ventricular conduction defect in treating hypertensive patients taking in consideration the status of the blood pressure control with the antihypertensive agents.

Methods

This cross-section study was performed at the Departments of Physiology and Pharmacology, College of Medicine, Al-Mustansiriya University, Baghdad, Iraq. A total number of 97 hypertensive patients (30 males and 67 females) were eligible to enroll in the study. The patients were grouped into controlled hypertension (Group I) and uncontrolled hypertension (Group II). Each participant is subjected to the electrocardiograph (ECG) investigation. A QT nomogram plot used to identify the patients who are vulnerable or at risk of developing cardiac arrhythmias.

Results

There were no significant differences in the values of the electrocardiogram determinants between Group I and Group II. Abnormal prolonged QTcB interval observed in 18 out of 80 (22.5%) patients of Group II compared with 4 out of 17. The JT index value of ≥112 was observed in 20 out of 80 (25%) patients of Group II compared with 6 out of 17 (35.3%) patients of Group I. A significant correlation between the QTcB duration with JT index observed in both Groups I and II.

Conclusion

Patients with hypertension have variability in ventricular repolarization (QTcB and JT) irrespective of their blood pressure control putting them at higher risk of cardiac arrhythmias.

Randomized Controlled Trial of High-Volume Energy Drink Versus Caffeine Consumption on ECG and Hemodynamic Parameters

Background

Caffeine in doses <400 mg is typically not considered arrhythmogenic, but little is known about the additional ingredients in energy drinks. We evaluated the ECG and blood pressure (BP) effects of high‐volume energy drink consumption compared with caffeine alone.

Methods and Results

This was a randomized, double‐blind, controlled, crossover study in 18 young, healthy volunteers. Participants consumed either 946 mL (32 ounces) of energy drink or caffeinated control drink, both of which contained 320 mg of caffeine, separated by a 6‐day washout period. ECG, peripheral BP, and central BP measurements were obtained at baseline and 1, 2, 4, 6, and 24 hours post study drink consumption. The time‐matched, baseline‐adjusted changes were compared. The change in corrected QT interval from baseline in the energy drink arm was significantly higher than the caffeine arm at 2 hours (0.44±18.4 ms versus −10.4±14.8 ms, respectively; P=0.02). The QTc changes were not different at other time points. While both the energy drink and caffeine arms raised systolic BP in a similar fashion initially, the systolic BP was significantly higher at 6 hours when compared with the caffeine arm (4.72±4.67 mm Hg versus 0.83±6.09 mm Hg, respectively; P=0.01). Heart rate, diastolic BP, central systolic BP, and central diastolic BP showed no evidence of a difference between groups at any time point. Post energy drink, augmentation index was lower at 6 hours.

Conclusions

The corrected QT interval and systolic BP were significantly higher post high‐volume energy drink consumption when compared with caffeine alone. Larger clinical trials validating these findings and evaluation of noncaffeine ingredients within energy drinks are warranted.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02023723.

Effects of Metabolically Healthy and Unhealthy Obesity on Prolongation of Corrected QT Interval

Although obesity and the metabolic syndrome (MS) often co-occur, many obese (OB) subjects have a favorable metabolic profile. It is unclear whether these factors independently influence cardiac electrophysiology including prolongation of the QT interval. We examined associations among obesity, MS, and prolonged corrected QT (QTc) interval in a large sample of Chinese research participants aged ≥35 years recruited from rural areas of Liaoning Province during 2012 to 2013. Of the 11,209 participants, 6,364 (56.8%) were nonobese and metabolically healthy (OB-/MS-), 2,853 (25.5%) were OB-/MS+, 493 (4.4%) were OB+/MS-, and 1,499 (13.4%) were OB+/MS+. Mean (±SD) QTc intervals were higher in OB-/MS+ (436.3 ± 24.3) and OB+/MS+ (436.6 ± 25.9) participants but not OB+/MS- participants (425.4 ± 24.0) than in OB-/MS- participants (426.8 ± 21.5, p <0.001), and the prevalence of QTc prolongation was higher in OB-/MS+ and OB+/MS+ participants (adjusted odds ratios [aOR] 1.68, 95% confidence interval [CI] 1.52 to 1.85; aOR 1.92, 95% CI 1.69 to 2.17, respectively) compared with OB-/MS- group but not in OB+/MS- participants (aOR 0.92, 95% CI 0.73 to 1.15). Prevalence increased with each MS component (aOR 1.27, 95% CI 1.22 to 1.32) but not with body mass index (aOR 1.01, 95% CI 0.99 to 1.02). In conclusion, prolonged QTc interval is associated with the MS and not independently associated with obesity.

QT Prolongation and Malignant Arrhythmia: How Serious a Problem?

QT prolongation constitutes one of the most frequently encountered electrical disorders of the myocardium. This is due not only to the presence of several associated congenital syndrome but also, and mainly, due to the QT-prolonging effects of several acquired conditions, such as ischaemia and heart failure, as well as multiple medications from widely different categories. Propensity of repolarization disturbances to arrhythmia appears to be inherent in the function of and electrophysiology of the myocardium. In the present review the issue of QT prolongation will be addressed in terms of pathophysiology, arrhythmogenesis, treatment and risk stratification approaches. Although already discussed in literature, it is hoped that the mechanistic approach of the present review will assist in improved understanding of the underlying changes in electrophysiology, as well as the rationale for current diagnostic and therapeutic approaches.

Effect of obesity and weight loss on ventricular repolarization: a systematic review and meta-analysis

We performed a systematic review and meta-analysis of the effects of obesity ± overweight and weight loss on the corrected QT interval (QTc) and QT or QTc dispersion (indices of ventricular repolarization). Mean difference for both QTc and QT or QTc dispersion with 95% confidence intervals (CIs) was calculated comparing obese ± overweight subjects and normal weight controls and QTc and QT or QTc dispersion before and after weight loss from diet ± exercise or bariatric surgery. A total of 22 studies fulfilled the selection criteria. Compared with normal weight controls, there was a significantly longer QTc in obese ± overweight subjects (mean difference of 21.74 msec, 95% CI: 18.76 to 22.32) and significantly longer QT or QTc dispersion (mean difference of 15.17 msec, 95% CI: 13.59 to 16.74). Weight loss was associated with a significant decrease in QTc (mean difference -25.77 msec, 95% CI: -28.33-23.21) and QT or QTc dispersion (mean difference of -13.46 msec, 95% CI: -15.60 to -11.32 in obese ± overweight subjects. Thus, obesity ± overweight is associated with significant prolongation of QTc and QT or QTC dispersion. Weight loss in obese ± overweight subjects produces significant decreases in these variables. © 2016 World Obesity.

Metabolomic patterns associated to QTc interval in shiftworkers: an explorative analysis

OBJECTIVES

(1)H NMR-metabolomic approach was used to investigate QTc interval correlation with plasma metabolic profiles in shiftworkers.

METHODS

Socio-demographic data, electrocardiographic QTc interval and plasma metabolic profiles from 32 male shiftworkers, were correlated by multivariate regression analysis.

RESULTS

We found a positive correlation between QTc interval values, body mass index, glycemia and lactate level and a negative correlation between QTc interval and both pyroglutamate and 3-hydroxybutyrate plasma level.

CONCLUSIONS

Our analysis provides evidence of the association between clinical, metabolic profiles and QTc interval values. This could be used to identify markers of early effects and/or susceptibility in shiftworkers.

Risk of Mortality Associated With QT and JT Intervals at Different Levels of QRS Duration (from the Third National Health and Nutrition Examination Survey)

QT prolongation in the setting of QRS >120 ms is believed to be triggered by prolonged depolarization rather than repolarization. Hence, JT interval is suggested as an alternative to QT interval when QRS duration is prolonged. It is unclear, however, if JT and QT intervals portend similar risk of mortality for different durations of QRS. We examined the association between QT and JT, separately, with all-cause mortality across different levels of QRS duration in 8,025 participants (60 ± 13 years, 41% white and 54% women) from the Third National Health and Nutrition Examination Survey. At baseline (1986 to 1994), 486 participants (6%) had QRS duration ≥120 ms. During a follow-up of up to 18 years, 3,045 deaths (38%) occurred. There were significant nonlinear relations of QT and JT intervals with mortality (p <0.001). Hence, QT and JT were categorized as prolonged (>95th percentile), shortened (<5th percentile), and normal (reference group). In multivariate-adjusted Cox regression models, prolonged JT (hazard ratio [HR] 4.75, 95% confidence interval [CI] 1.86 to 12.11) was associated with increased risk of mortality more than prolonged QT (HR 1.50, 95% CI 1.03 to 2.17) in participants with QRS ≥120 ms (interaction p = 0.02). In participants with QRS duration <120 ms, prolonged QT and JT were equally predictive of all-cause mortality (HR 1.27, 95% CI 1.06 to 1.54, and HR 1.31, 95% CI 1.10 to 1.55, respectively). Similar patterns were observed with shortened QT and JT intervals. In conclusion, although both QT and JT intervals are predictive of mortality, JT is more predictive in the setting of QRS duration >120 ms supporting the use of JT interval in patients with prolonged QRS.

Considerations for assessing the potential effects of antidiabetes drugs on cardiac ventricular repolarization: A report from the Cardiac Safety Research Consortium

Thorough QT studies conducted according to the International Council on Harmonisation E14 guideline are required for new nonantiarrhythmic drugs to assess the potential to prolong ventricular repolarization. Special considerations may be needed for conducting such studies with antidiabetes drugs as changes in blood glucose and other physiologic parameters affected by antidiabetes drugs may prolong the QT interval and thus confound QT/corrected QT assessments. This review discusses potential mechanisms for QT/corrected QT interval prolongation with antidiabetes drugs and offers practical considerations for assessing antidiabetes drugs in thorough QT studies. This article represents collaborative discussions among key stakeholders from academia, industry, and regulatory agencies participating in the Cardiac Safety Research Consortium. It does not represent regulatory policy.

Diet-induced obesity causes long QT and reduces transcription of voltage-gated potassium channels

In humans, obesity is associated with long QT, increased frequency of premature ventricular complexes, and sudden cardiac death. The mechanisms of the pro-arrhythmic electrophysiologic remodeling of obesity are poorly understood. We tested the hypothesis that there is decreased expression of voltage-gated potassium channels in the obese heart, leading to long QT. Using implanted telemeters, we found that diet-induced obese (DIO) wild-type mice have impaired cardiac repolarization, demonstrated by long QT, as well as more frequent ventricular ectopy, similar to obese humans. DIO mice have reduced protein and mRNA levels of the potassium channel Kv1.5 caused by a reduction of the transcription factor cyclic AMP response element binding protein (CREB) in DIO hearts. We found that CREB knock-down by siRNA reduces Kv1.5, CREB binds to the Kv1.5 promoter in the heart, and CREB increases transcription of mouse and human Kv1.5 promoters. The reduction in CREB protein during lipotoxicity can be rescued by inhibiting protein kinase D (PKD). Our results identify a mechanism for obesity-induced electrophysiologic remodeling in the heart, namely PKD-induced reduction of CREB, which in turn decreases expression of the potassium channel Kv1.5.

Patients transplanted for nonalcoholic steatohepatitis are at increased risk for postoperative cardiovascular events

Nonalcoholic steatohepatitis (NASH) is an independent predictor of coronary artery disease (CAD). Our aim was to compare the incidence of cardiovascular (CV) events between patients transplanted for NASH and alcohol (ETOH)-induced cirrhosis. This is a retrospective cohort study (August 1993 to March 2010) of 242 patients (115 NASH and 127 ETOH) with ≥12 months follow-up after liver transplantation (LT). Those with hepatocellular carcinoma or coexisting liver diseases were excluded. Kaplan-Meier's and Cox's proportional hazard analyses were conducted to compare survival. Logistic regression was used to calculate the likelihood of CV events, defined as death from any cardiac cause, myocardial infarction, acute heart failure, cardiac arrest, arrhythmia, complete heart block, and/or stroke requiring hospitalization <1 year after LT. Patients in the NASH group were older (58.4 versus 53.3 years) and were more likely to be female (45% versus 18%; P < 0.001). They were more likely to be morbidly obese (32% versus 9%), have dyslipidemia (25% versus 6%), or have hypertension (53% versus 38%; P < 0.01). On multivariate analysis, NASH patients were more likely to have a CV event <1 year after LT, compared to ETOH patients, even after controlling for recipient age, sex, smoking status, pretransplant diabetes, CV disease, and the presence of metabolic syndrome (26% versus 8%; odds ratio = 4.12; 95% confidence interval = 1.91-8.90). The majority (70%) of events occurred in the perioperative period, and the occurrence of a CV event was associated with a 50% overall mortality. However, there were no differences in patient, graft, or CV mortality between groups.

CONCLUSIONS

CV complications are common after LT, and NASH patients are at increased risk independent of traditional cardiac risk factors, though this did not affect overall mortality.

Anatomic, hematologic, and biochemical features of C57BL/6NCrl mice maintained on chronic oral corticosterone

Metabolic syndrome is a condition that typically includes central obesity, insulin resistance, glucose intolerance, dyslipidemia, and hypertension. Disruption of the hypothalamic-pituitary-adrenal axis, a regulator of corticosterone secretion, occurs in some cases of metabolic syndrome and obesity, and Cushing hypercortisolemia is associated with obesity and metabolic disorders. We therefore assessed anatomic and clinical pathology in C57BL/6NCrl mice to evaluate the effects of chronic corticosterone in the drinking water at doses of 25, 50, and 100 μg/mL for 25 d. Treated mice developed obesity, glucose intolerance, electrolyte aberrations, and dyslipidemia that were dose-dependent and most severe in the 100-mu;g/mL treatment group. To evaluate return to normal function, additional C57BL/6NCrl mice received corticosterone-free water for 2 wk after the 25-d treatment period. According to results of gross examination, mice appeared to recover within days of exogenous corticosterone withdrawal; however, adrenal gland vacuolation and protein, lipid, and electrolyte abnormalities persisted. Together, these findings support chronic corticosterone exposure through the drinking water as a potentially useful, noninvasive method to induce some features of metabolic syndrome.

Mice with cardiac overexpression of peroxisome proliferator-activated receptor γ have impaired repolarization and spontaneous fatal ventricular arrhythmias

BACKGROUND

Diabetes mellitus and obesity, which confer an increased risk of sudden cardiac death, are associated with cardiomyocyte lipid accumulation and altered cardiac electric properties, manifested by prolongation of the QRS duration and QT interval. It is difficult to distinguish the contribution of cardiomyocyte lipid accumulation from the contribution of global metabolic defects to the increased incidence of sudden death and electric abnormalities.

METHODS AND RESULTS

In order to study the effects of metabolic abnormalities on arrhythmias without the complex systemic effects of diabetes mellitus and obesity, we studied transgenic mice with cardiac-specific overexpression of peroxisome proliferator-activated receptor γ 1 (PPARγ1) via the cardiac α-myosin heavy-chain promoter. The PPARγ transgenic mice develop abnormal accumulation of intracellular lipids and die as young adults before any significant reduction in systolic function. Using implantable ECG telemeters, we found that these mice have prolongation of the QRS and QT intervals and spontaneous ventricular arrhythmias, including polymorphic ventricular tachycardia and ventricular fibrillation. Isolated cardiomyocytes demonstrated prolonged action potential duration caused by reduced expression and function of the potassium channels responsible for repolarization. Short-term exposure to pioglitazone, a PPARγ agonist, had no effect on mortality or rhythm in WT mice but further exacerbated the arrhythmic phenotype and increased the mortality in the PPARγ transgenic mice.

CONCLUSIONS

Our findings support an important link between PPARγ activation, cardiomyocyte lipid accumulation, ion channel remodeling, and increased cardiac mortality.