Drug- and non-drug-associated QT interval prolongation

Disopyramide as rescue treatment in a critically ill infant with obstructive hypertrophic cardiomyopathy refractory to beta blockers

Hypertrophic obstructive cardiomyopathy (HOCM) is the most common known cause of sudden death in children beyond infancy and in young athletes. Cases reported indicate that steroid-induced HOCM is usually a benign disorder. The normalization of cardiac morphological changes and clinical signs observed after the discontinuation of steroid therapy indicates that the effects on cardiac muscle are dose-dependent and reversible. However, the management of patients with symptomatic-HOCM presenting in infancy represents a major challenge because left ventricular outflow tract obstruction is a major risk factor associated with increased mortality in pediatric patients. We report a critically ill infant with steroid-induced HOCM resistant to beta-blockers who was successfully treated with disopyramide without relevant adverse events. Adult guidelines and pediatric experts suggest pharmacological therapy with beta-blockers or verapamil as the first- and second-line approach. However, these drugs are not always an option, especially in critical patients, hence, alternative therapeutic options are required. For these cases, disopyramide could be an alternative drug in spite of the little evidence on its safety and efficacy in pediatric patients. Our experience supports this cause, and the need for prospective studies on its use in the management of hypertrophic cardiomyopathy in children. <Learning objective: Patients with symptomatic-HOCM resistant to first-line therapy with beta-blockers represent a challenge and are often referred for advanced care. In children, many authors suggest that disopyramide in combination with beta-blockers could be a useful adjunct therapy option in these cases, resulting in decrease of left ventricular outflow tract obstruction, symptoms, and survival improvement, without significant pro-arrhythmia mortality.>.

Prevalence of Electrocardiographic Patterns Associated With Sudden Cardiac Death in the Spanish Population Aged 40 Years or Older. Results of the OFRECE Study

INTRODUCTION AND OBJECTIVES

Some electrocardiographic patterns are associated with an increased risk of sudden cardiac death due to ventricular arrhythmias. There is no information on the prevalence of these patterns in the general population in Spain. The objective of this study was to analyze the prevalence of these patterns and associated clinical and epidemiological factors.

METHODS

This subanalysis of the OFRECE study selected a representative sample of the Spanish population aged ≥ 40 years. We studied the presence or absence of electrocardiographic patterns of Brugada syndrome and QT interval abnormalities. Clinical data and electrocardiograms were available in all participants. Electrocardiograms were evaluated by 2 cardiologists and a third cardiologist was consulted if there was disagreement in the diagnosis. We calculated the weighted prevalence and clinical factors associated with the presence of Brugada-type patterns or QT segment abnormalities.

RESULTS

Overall, 8343 individuals were evaluated (59.2 years, 52.4% female). There were 12 Brugada cases (type 1, 2 cases; type 2, 10 cases; weighted prevalence, 0.13%). For corrected QT (QTc) analysis, we excluded participants with left bundle branch block or without sinus rhythm. Weighted prevalences were as follows: short QTc (< 340ms) 0.18%, borderline QTc (441-469ms) 8.33%, long QTc (≥ 470ms criterion) 1.01% and long QTc (≥ 480 criterion) 0.42%.

CONCLUSIONS

A total of 0.6% to 1.1% of the Spanish population aged ≥ 40 years has an electrocardiographic pattern associated with a higher risk of sudden death (Brugada syndrome, long QT, or short QT).

Inhibition of rapid delayed rectifier potassium current (IKr) by ischemia/reperfusion and its recovery by vitamin E in ventricular myocytes

Ischemia/reperfusion (I/R) induces prolongation of QT interval and action potential duration (APD), which is a major cardiac electrical disorder in patients with arrhythmias. However, the mechanism of QT interval prolongation induced by I/R remains unclear. In the present study, we hypothesized that the rapid component of delayed rectifier potassium (I_Kr) channel plays an important role in I/R-induced QT interval prolongation. We observed a marked attenuation of I_Kr and a significant prolongation of action potential duration (APD) in a simulated I/R system with sodium dithionite (Na₂S₂O₄) in ventricular myocytes of guinea pigs. The I_Kr current density was inhibited by 64% and APD increased by 87% respectively. Moreover, the inhibition of I_Kr is primarily ascribed to overproduction of reactive oxygen species (ROS) by I/R, which can be partly reversed by antioxidant vitamin E (100μmol/L). The value of I_Kr tail current density increased from 0.516±0.040 pA/pF in I/R to 0.939±0.091 pA/pF when treated with vitamin E. Moreover, we also demonstrated that QTc interval was increased by I/R and reversed by Vitamin E in isolated guinea pig hearts. In conclusion, the inhibition of I_Kr is one of the underlying mechanisms of prolongation of QT interval and APD in I/R. Vitamin E might have a benefit in coronary reperfusion therapy.

QTc prolongation during erythromycin used as prokinetic agent in ICU patients

Background

High-dose erythromycin used as antibiotic prolongs QTc interval. Low-dose erythromycin is frequently used as a prokinetic agent, especially in patients in the intensive care unit (ICU). It is unknown whether low-dose erythromycin affects cardiac repolarisation and puts patients at risk for torsades de pointes.

Methods

In this prospective study, we included ICU patients treated with erythromycin as prokinetic in a dose of 200 mg twice a day. An ECG was performed before, 15 min and 24 hours after the start of erythromycin. Cardiac repolarisation was assessed by rate-corrected analysis of the QT interval (QTc) on the ECG by two independent investigators. Starting or stopping other possibly QTc prolonging drugs during the study period was an exclusion criterion. Wilcoxon signed-rank test and Friedman's test were used for statistical analysis to assess prolongation of QTc. Primary outcome was defined by the prolongation of QTc after 15 min and 24 hours.

Results

51 patients were eligible for this study. In these patients, QTc increased significantly from 430 ms at baseline to 439 ms (p=0.03) after 15 min and 444 ms (p=0.01) after 24 hours. After 15 min and 24 hours, the upper limit of 95% CI for prolongation of QTc was well above 10 ms. No QTc-related arrhythmias were seen.

Conclusions

During treatment with erythromycin in a dose of 200 mg twice a day. QTc prolonged mildly but significantly. Sequential ECG registration should be performed when low-dose erythromycin is prescribed, especially in the presence of other risk factor for QTc prolongation.

Risk factors for QTc-prolongation: systematic review of the evidence

Background QTc-interval prolongation has been associated with serious adverse events, such as Torsade de Pointes and sudden cardiac death. In the prevention of QTc-prolongation, special attention should go to high-risk patients. Aim of the review The aim of this review is to summarize and assess the evidence for different risk factors for QTc-prolongation (demographic factors, comorbidities, electrolytes, QTc-prolonging medication). Methods Potential studies were retrieved based on a systematic search of articles published until June 2015 in the databases Medline and Embase. Both terms about QTc-prolongation/Torsade de Pointes and risk factors were added in the search strategy. The following inclusion criteria were applied: randomized controlled trials and observational studies; inclusion of ≥500 patients from a general population (not limited to specific disease states); assessment of association between QTc-interval and risk factors. For the articles that met the inclusion criteria, the following data were extracted: study design, setting and study population, number of patients and cases of QTc-prolongation, method of electrocardiogram-monitoring, QTc-correction formula, definition of QTc-prolongation, statistical methods and results. Quality assessment was performed using the GRADE approach (for randomized controlled trials) and the STROBE-recommendations (for observational studies). Based on the number of significant results and the level of significance, a quotation of the evidence was allocated. Results Ten observational studies could be included, with a total of 89,532 patients [prospective cohort design: N = 6; multiple regression analyses: N = 5; median STROBE score = 17/22 (range 15-18)]. Very strong evidence was found for hypokalemia, use of diuretics, antiarrhythmic drugs and QTc-prolonging drugs of list 1 of CredibleMeds. Little or no evidence was found for hyperlipidemia, the use of digoxin or statins, neurological disorders, diabetes, renal failure, depression, alcohol abuse, heart rate, pulmonary disorders, hormone replacement therapy, hypomagnesemia, history of a prolonged QTc-interval/Torsade de Pointes, familial history of cardiovascular disease, and the use of only QTc-prolonging drugs of list 2 or 3 of CredibleMeds. Conclusion This systematic review gives a clear overview of the available evidence for a broad range of risk factors for QTc-prolongation.

Determining factors of electrocardiographic abnormalities in patients with epilepsy: A case-control study

Sudden unexpected death in epilepsy (SUDEP) is a major cause of mortality in young patients with epilepsy (PWE). Although its mechanisms are still poorly understood, they may include cardiorespiratory dysfunction. Standard 12-lead electrocardiograms (ECGs) were obtained from 62 consecutive patients (aged 18-66y) with a definite diagnosis of epilepsy, without seizures at the day of ECG, and 57 healthy controls matched for sex, age and body mass index (BMI). All ECGs were evaluated by a blinded board-certified cardiologist. Patients with symptomatic focal epilepsy represented 90.3% (N=56), of whom 56.4% (N=35) had temporal lobe epilepsy, with a mean duration of 22.02±14.96years of epilepsy. We observed more prolonged P-wave (p<0.0001) and PR interval (p=0.01) in patients than in controls. Additionally, longer QT intervals (p<0.01), pathologic QT dispersion (p<0.01) and left atrial overload (p<0.01) were more common in PWE. Multiple linear regression analysis evidenced age, gender and polytherapy as factors associated with altered ECG. Therefore, routine ECG should be requested in PWE, especially for males, increasing age and in polytherapy. Findings such as longer PR and QT interval, and pathologic QT dispersion, may reflect cardiac structural changes and/or autonomic nervous system dysfunction and indicate a risk for SUDEP.

Presence or Absence of QTc Prolongation in Buprenorphine-Naloxone Among Youth With Opioid Dependence

OBJECTIVES

The aim of the study was to evaluate buprenorphine-naloxone effects on the QTc in youth with opioid dependence. Buprenorphine is a partial agonist that is an effective treatment for opioid dependence. Compared with methadone, it has a lower risk of QTc prolongation in adults, but is less studied in the youth. It may also reduce the risk of torsades de pointes (TdP)--an uncommon variant of polymorphic ventricular tachycardia--that can result in syncope, ventricular fibrillation, and sudden death.

METHODS

Secondary analysis of the electrocardiogram data from 95 individuals who participated in a multisite trial for youth with opioid dependence. The participants were randomized to a 2-week (DETOX) or a 12-week course of buprenorphine-naloxone (BUP). At baseline, 12-lead electrocardiograms were done at weeks 4 and 12, and QTc intervals were hand-measured and calculated using Bazett formula. Increases above 60 milliseconds were considered clinically significant, and readings above 450 milliseconds (in men) and 470 milliseconds (in women) indicated a prolonged QTc.

RESULTS

Mean QTc intervals were higher for BUP than for DETOX participants at baseline, week 4, and week 12 (P = 0.045), and women had longer mean QTc intervals than men (P < 0.0005). Variations in the QTc intervals were observed in some; however, none were above 500 milliseconds--the level at which risk for TdP becomes more significant.

CONCLUSIONS

In this randomized trial, the mean QTc at baseline, before randomization, was higher in BUP than in DETOX patients. Minimal changes in the QTc were seen at 4 and 12 weeks in a few patients in both groups. There was no evidence that buprenorphine-naloxone alone increased the QTc to a level that increased the risk for TdP.

Evaluation of the Relationship Between Pharmacokinetics and the Safety of Aripiprazole and Its Cardiovascular Effects in Healthy Volunteers

AIMS

The aim of this study was the evaluation of the possible relationship between pharmacokinetics and the safety of aripiprazole as well as its influence on blood pressure (BP), heart rate (HR), and corrected QT (QTc) interval.

METHODS

The study population comprised 157 healthy volunteers from 6 bioequivalence clinical trials. Subjects were administered a single 10-mg oral dose of each formulation separated by a 28-day washout period. Plasma concentrations were measured using high-performance liquid chromatography coupled to mass spectrometry. Blood pressure was measured at the following times: predose and 0.5, 2, 4, 6, and 8 hours postdose. An electrocardiogram was recorded at predose, 4, and 8 hours postdose.

RESULTS

Area under the curve (AUC), maximum plasma concentration, half-life, and distribution volume corrected for weight were higher in women. Aripiprazole treatment produced a decrease of BP (9.3 mm Hg on systolic and 6.2 mm Hg on diastolic pressure) and an increase in HR (12.1 beats per minute) and QTc interval (9.1 milliseconds). There were sex differences in BP, HR, and QTc interval. Women and subjects with higher AUC and maximum plasma concentration values were more prone to experience adverse drug reactions and gastrointestinal adverse reactions. The AUC was related with systolic BP and diastolic BP decrease and HR increase but there was no relationship between aripiprazole concentrations and QTc increase.

CONCLUSIONS

Aripiprazole decreases BP and increases HR and QTc interval. Pharmacokinetics, pharmacodynamics, and safety of aripiprazole are affected by sex. There is a directly proportional relationship between pharmacokinetic parameters and adverse drug reactions and effect on BP and HR.

Safety of domperidone in treating nausea associated with dihydroergotamine infusion and headache

OBJECTIVE

To determine the safety of domperidone in the treatment of nausea associated with dihydroergotamine (DHE) infusion and headache.

METHODS

We audited our use of domperidone for the inpatient management of nausea, focusing on known safety concerns, particularly potential cardiac arrhythmias.

RESULTS

We reviewed 103 consecutive admissions of 90 patients admitted for IV DHE by infusion. Most admissions were to treat chronic migraine with (n = 53) or without (n = 46) aura. Domperidone was administered in 85 of 103 encounters and was well-tolerated at doses up to 80 mg/d. A significant side effect, akathisia, was observed in one patient. Baseline ECG with corrected QT interval (QTc) was obtained on all patients. Repeat ECG after domperidone was obtained in 21 patients, whose baseline characteristics did not differ from the group as a whole. ECG was interpreted blindly by a cardiac electrophysiologist. QTc did not differ before and after domperidone administration (Wilcoxon signed-rank test, median [interquartile range] 435.0 [410.5-453.0] at admission and 427.0 [399.0-452.5] after domperidone; p = 0.15). In combination with other antiemetics, domperidone was effective in treating nausea such that no patients had refractory nausea severe enough to limit DHE dose.

CONCLUSIONS

This retrospective audit demonstrates that domperidone is safe in the treatment of nausea associated with inpatient DHE infusion and headache. While larger prospective trials are necessary to confirm these results and assess efficacy, current evidence and clinical experience suggests that domperidone is safe and useful for nausea and headache management.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that for patients with headache undergoing DHE infusion, domperidone is safe and effective in the treatment of nausea.

Ibogaine for treating drug dependence. What is a safe dose?

The indole alkaloid ibogaine, present in the root bark of the West African rain forest shrub Tabernanthe iboga, has been adopted in the West as a treatment for drug dependence. Treatment of patients requires large doses of the alkaloid to cause hallucinations, an alleged integral part of the patient's treatment regime. However, case reports and case series continue to describe evidences of ataxia, gastrointestinal distress, ventricular arrhythmias and sudden and unexplained deaths of patients undergoing treatment for drug dependence. High doses of ibogaine act on several classes of neurological receptors and transporters to achieve pharmacological responses associated with drug aversion; limited toxicology research suggests that intraperitoneal doses used to successfully treat rodents, for example, have also been shown to cause neuronal injury (purkinje cells) in the rat cerebellum. Limited research suggests lethality in rodents by the oral route can be achieved at approximately 263mg/kg body weight. To consider an appropriate and safe initial dose for humans, necessary safety factors need to be applied to the animal data; these would include factors such as intra- and inter-species variability and for susceptible people in a population (such as drug users). A calculated initial dose to treat patients could be approximated at 0.87mg/kg body weight, substantially lower than those presently being administered to treat drug users. Morbidities and mortalities will continue to occur unless practitioners reconsider doses being administered to their susceptible patients.

Discontinuation of Dofetilide From QT Prolongation and Ventricular Tachycardia in the Real World

OBJECTIVES

The purpose of this study was to determine the incidence and correlates of QT prolongation or ventricular tachycardia (VT) resulting in discontinuation of dofetilide in a real-world setting.

BACKGROUND

Dofetilide is a class III antiarrhythmic agent approved for achieving and maintaining sinus rhythm in patients with symptomatic atrial fibrillation. Because of a risk of QT prolongation and VT, patients starting dofetilide need to be hospitalized for 3 days to closely monitor telemetry and electrocardiography. In large clinical trials, <3% of patients had to discontinue dofetilide because of QT prolongation, but data from real-world experience are lacking.

METHODS

We examined 114 consecutive patients with atrial fibrillation who were hospitalized for starting dofetilide at the Minneapolis Veterans Affairs Health Care System from 2011 to 2014.

RESULTS

The mean age of the patients was 64 ± 8 years. Dofetilide was discontinued in 22 (19%) patients because of QT prolongation (17%) or VT (2%). A total of 32 (28%) patients were taking other QT-prolonging drugs. Of these, 10 (31%) had to discontinue dofetilide versus 12 (15%) of the 82 patients who were not taking any other QT-prolonging drugs (p = 0.04). Patients who were taking concomitant QT-prolonging drugs were 1.9 times more likely to discontinue dofetilide (95% confidence interval: 1.1 to 3.4; p = 0.04) compared with those who were not taking any other QT-prolonging drugs.

CONCLUSIONS

The incidence of QT prolongation or VT that lead to discontinuation of dofetilide is remarkably higher in the real-world setting than in clinical trials. Concomitant use of other QT-prolonging drugs was associated with discontinuation of dofetilide.

Antidepressant use and mortality in very old people

BACKGROUND

Antidepressant treatment may increase the risk of death. The association between antidepressants and mortality has been evaluated in community-dwelling older people, but not in representative samples of very old people, among whom dementia, multimorbidity, and disability are common.

METHODS

Umeå 85+/GERDA study participants (n = 992) aged 85, 90, and ≥95 years were followed for up to five years. Cox proportional hazard regression models were used to analyze mortality risk associated with baseline antidepressant treatment, adjusted for potential confounders.

RESULTS

Mean age was 89 years; 27% of participants had dementia, 20% had stroke histories, 29% had heart failure, and 16% used antidepressants. In age- and sex-adjusted analyses, antidepressant use was associated with a 76% increased mortality risk (hazard ratio [HR] = 1.76; 95% confidence interval [CI], 1.41-2.19). Adding adjustment for Geriatric Depression Scale score, HR was 1.62 (95% CI, 1.29-2.03). The association was not significant when adjusting for additional confounding factors (HR = 1.08; 95% CI, 0.85-1.38). Interaction analyses in the fully adjusted model revealed a significant interaction between sex and antidepressant use (HR: 1.76; 95% CI, 1.05-2.94). Among male and female antidepressant users, the HRs for death were 0.76 (95% CI, 0.47-1.24) and 1.28 (95% CI, 0.97-1.70), respectively.

CONCLUSION

Among very old people, baseline antidepressant treatment does not seem to be independently associated with increased mortality risk. However, the risk may be different in men and women. This difference and the potential risk of initial treatment require further investigation in future cohort studies of very old people.

Development of an Orally Available and Central Nervous System (CNS) Penetrant Toxoplasma gondii Calcium-Dependent Protein Kinase 1 (TgCDPK1) Inhibitor with Minimal Human Ether-a-go-go-Related Gene (hERG) Activity for the Treatment of Toxoplasmosis

New therapies are needed for the treatment of toxoplasmosis, which is a disease caused by the protozoan parasite Toxoplasma gondii. To this end, we previously developed a potent and selective inhibitor (compound 1) of Toxoplasma gondii calcium-dependent protein kinase 1 (TgCDPK1) that possesses antitoxoplasmosis activity in vitro and in vivo. Unfortunately, 1 has potent human ether-a-go-go-related gene (hERG) inhibitory activity, associated with long Q-T syndrome, and consequently presents a cardiotoxicity risk. Here, we describe the identification of an optimized TgCDPK1 inhibitor 32, which does not have a hERG liability and possesses a favorable pharmacokinetic profile in small and large animals. 32 is CNS-penetrant and highly effective in acute and latent mouse models of T. gondii infection, significantly reducing the amount of parasite in the brain, spleen, and peritoneal fluid and reducing brain cysts by >85%. These properties make 32 a promising lead for the development of a new antitoxoplasmosis therapy.

Basic Cardiac Electrophysiology and Common Drug-induced Arrhythmias

Drugs can be a double-edged sword, providing the benefit of symptom alleviation and disease modification but potentially causing harm from adverse cardiac arrhythmic events. Proarrhythmia is the ability of a drug to cause an arrhythmia, the number one reason for drugs to be withdrawn from the patient. Drug-induced arrhythmias are defined as the production of de novo arrhythmias or aggravation of existing arrhythmias, as a result of previous or concomitant pharmacologic treatment. This review summarizes normal cardiac cell and tissue functioning and provides an overview of drugs that effect cardiac repolarization and the adverse effects of commonly administered antiarrhythmics.

Which QT Correction Formulae to Use for QT Monitoring?

Background

Drug safety precautions recommend monitoring of the corrected QT interval. To determine which QT correction formula to use in an automated QT‐monitoring algorithm in our electronic medical record, we studied rate correction performance of different QT correction formulae and their impact on risk assessment for mortality.

Methods and Results

All electrocardiograms (ECGs) in patients >18 years with sinus rhythm, normal QRS duration and rate <90 beats per minute (bpm) in the University Hospitals of Leuven (Leuven, Belgium) during a 2‐month period were included. QT correction was performed with Bazett, Fridericia, Framingham, Hodges, and Rautaharju formulae. In total, 6609 patients were included (age, 59.8±16.2 years; 53.6% male and heart rate 68.8±10.6 bpm). Optimal rate correction was observed using Fridericia and Framingham; Bazett performed worst. A healthy subset showed 99% upper limits of normal for Bazett above current clinical standards: men 472 ms (95% CI, 464–478 ms) and women 482 ms (95% CI 474–490 ms). Multivariate Cox regression, including age, heart rate, and prolonged QTc, identified Framingham (hazard ratio [HR], 7.31; 95% CI, 4.10–13.05) and Fridericia (HR, 5.95; 95% CI, 3.34–10.60) as significantly better predictors of 30‐day all‐cause mortality than Bazett (HR, 4.49; 95% CI, 2.31–8.74). In a point‐prevalence study with haloperidol, the number of patients classified to be at risk for possibly harmful QT prolongation could be reduced by 50% using optimal QT rate correction.

Conclusions

Fridericia and Framingham correction formulae showed the best rate correction and significantly improved prediction of 30‐day and 1‐year mortality. With current clinical standards, Bazett overestimated the number of patients with potential dangerous QTc prolongation, which could lead to unnecessary safety measurements as withholding the patient of first‐choice medication.

A case report of QT prolongation with glycopyrronium bromide in a patient with chronic tamoxifen use

Background

Glycopyrronium bromide has recently been approved as a once daily maintenance inhalation therapy for moderate to severe chronic obstructive pulmonary disease (COPD). Efficacy and safety trial data have found rare cases of significant QT prolongation. To our knowledge, we describe the first case report of QT prolongation >600 ms with initiation of glycopyrronium bromide in a real world setting.

Case presentation

A 78-year-old female with moderate COPD recently started on glycopyrronium bromide, presented to Emergency Department (ED) with syncope. Her past medical history was significant for a left total mastectomy and she had been on Tamoxifen for 9 months. One day prior to her presentation, she had visited a naturopathic clinic for a vitamin infusion resulting in emesis. The following day she continued to feel dizzy and had a witnessed syncopal episode without any reported cardiac or neurological symptoms preceding the event or after regaining consciousness. In the emergency department, she reported dizziness and was found to be hypotensive. Her symptoms completely resolved with intravenous fluids. Lab work was normal however her electrocardiogram (ECG) demonstrated a QTc interval of 603 and 631 ms (Friderica and Bazett’s respectively) with a normal QT interval on her baseline ECG prior to initiating Tamoxifen. She was admitted to the Cardiology service for further work-up of QT prolongation. Her syncope was felt to be due to orthostatic hypotension and the QT prolongation secondary to medications, which were both discontinued during her admission. After 2 days, her QT interval normalized consistent with the half-life of Glycopyrronium bromide (13–57 h) compared to Tamoxifen (8–14 days).

Conclusion

Glycopyrronium bromide is guideline recommended as first line therapy for prevention of exacerbation in moderate to severe COPD however safety data had been limited to select populations. This case report highlights the need for future studies to identify high-risk populations at potential risk of life-threatening arrhythmias who may benefit from periodic ECG surveillance.

Specific prediction of clinical QT prolongation by kinetic image cytometry in human stem cell derived cardiomyocytes

INTRODUCTION

A priority in the development and approval of new drugs is assessment of cardiovascular risk. Current methodologies for screening compounds (e.g. HERG testing) for proarrhythmic risk lead to many false positive and false negative results, resulting in the attrition of potentially therapeutic compounds in early development, and the advancement of other candidates that cause adverse effects. With improvements in the technologies of high content imaging and human stem cell differentiation, it is now possible to directly screen compounds for arrhythmogenic tendencies in human stem cell derived cardiomyocytes (hSC-CMs).

METHODS

A training panel of 90 compounds consisting of roughly equal numbers of QT-prolonging and negative control (non-QT-prolonging) compounds, and a follow-up blinded study of 35 compounds including 16 from the 90 compound panel and 2 duplicates, were evaluated for prolongation of the calcium transient in hSC-CMs using kinetic image cytometry (KIC), a specialized form of high content analysis.

RESULTS

The KIC-hSC-CM assay identified training compounds that prolong the calcium transient with 98% specificity, 97% precision, 80% sensitivity, and 89% accuracy in predicting clinical QT prolongation by these compounds. The follow-up study of 35 blinded compounds confirmed the reproducibility and strong diagnostic accuracy of the assay.

DISCUSSION

The correlation of the KIC-hSC-CM results to clinical observations met or surpassed traditional preclinical assessment of cardiac risk utilizing animal models. Thus, the KIC-hSC-CM assay, which can be accomplished in high throughput and at relatively low cost, is an effective new model system for testing chemicals for cardiovascular risk.

Heart rate, blood pressure and repolarization effects of an energy drink as compared to coffee

The goal of this study was to investigate the impact of energy drinks on haemodynamic and cardiac physiology. Comparisons were made to coffee as well as water consumption. In Protocol #1 the caffeine content was normalized to body weight to represent a controlled environment. Heart rate, blood pressure and cardiac QTc interval were assessed in 15 participants, on 4 days, prior to and for 6·5 h postconsumption of (i) energy drink (2 mg caffeine per kg body weight; low dose), (ii) energy drink (3 mg caffeine per kg body weight; medium dose), (iii) coffee (2 mg caffeine per kg body weight) and (iv) 250 ml water. In Protocol #2, the beverages were consumed in volumes that they are purchased to represent real-life conditions. The aforementioned measurements were repeated in 15 participants following (i) 1 16 oz can of energy drink (16 oz Monster), (ii) 1 24 oz can of energy drink (24 oz Monster), (iii) 1 packet of Keurig K-Cup Starbucks coffee (coffee) and (iv) 250 ml water. The order of the beverages was performed in a randomized double-blinded fashion. For both protocols, QTc interval, heart rate and systolic blood pressure were unchanged in any condition (P>0·05). Diastolic blood pressure and mean blood pressure were slightly elevated in Protocol #1 (P<0·05, main effect of time) with no difference between beverages (P<0·05, interaction of beverage × time); however, they were unaffected in Protocol #2 (P>0·05). These findings suggest that acute consumption of these commonly consumed beverages has no negative effect on cardiac QTc interval.

Decreased heart rate and enhanced sinus arrhythmia during interictal sleep demonstrate autonomic imbalance in generalized epilepsy

We hypothesized that epilepsy affects the activity of the autonomic nervous system even in the absence of seizures, which should manifest as differences in heart rate variability (HRV) and cardiac cycle. To test this hypothesis, we investigated ECG traces of 91 children and adolescents with generalized epilepsy and 25 neurologically normal controls during 30 min of stage 2 sleep with interictal or normal EEG. Mean heart rate (HR) and high-frequency HRV corresponding to respiratory sinus arrhythmia (RSA) were quantified and compared. Blood pressure (BP) measurements from physical exams of all subjects were also collected and analyzed. RSA was on average significantly stronger in patients with epilepsy, whereas their mean HR was significantly lower after adjusting for age, body mass index, and sex, consistent with increased parasympathetic tone in these patients. In contrast, diastolic (and systolic) BP at rest was not significantly different, indicating that the sympathetic tone is similar. Remarkably, five additional subjects, initially diagnosed as neurologically normal but with enhanced RSA and lower HR, eventually developed epilepsy, suggesting that increased parasympathetic tone precedes the onset of epilepsy in children. ECG waveforms in epilepsy also displayed significantly longer TP intervals (ventricular diastole) relative to the RR interval. The relative TP interval correlated positively with RSA and negatively with HR, suggesting that these parameters are linked through a common mechanism, which we discuss. Altogether, our results provide evidence for imbalanced autonomic function in generalized epilepsy, which may be a key contributing factor to sudden unexpected death in epilepsy.

Post-mortem whole-exome sequencing (WES) with a focus on cardiac disease-associated genes in five young sudden unexplained death (SUD) cases

Sudden death of healthy young adults in the absence of any medical reason is generally categorised as autopsy-negative sudden unexplained death (SUD). Approximately 30 % of all SUD cases can be explained by lethal sequence variants in cardiac genes causing disturbed ion channel functions (channelopathies) or minimal structural heart abnormalities (cardiomyopathies). The aim of this study was to perform whole-exome sequencing (WES) in five young SUD cases in order to identify potentially disease-causing mutations with a focus on 184 genes associated with cardiac diseases or sudden death. WES analysis enabled the identification of damaging-predicted cardiac sequence alterations in three out of five SUD cases. Two SUD victims carried disease-causing variants in long QT syndrome (LQTS)-associated genes (KCNH2, SCN5A). In a third case, WES identified variants in two genes involved in mitral valve prolapse and thoracic aortic aneurism (DCHS1, TGFβ2). The genome of a fourth case carried several minor variants involved in arrhythmia pointing to a multigene influence that might have contributed to sudden death. Our results confirm that post-mortem genetic testing in SUD cases in addition to the conventional autopsy can help to identify familial cardiac diseases and can contribute to the identification of genetic risk factors for sudden death.

Cardiac effects of current treatments of chronic obstructive pulmonary disease

We review the cardiac safety of the drugs available at present for the maintenance treatment of chronic obstructive pulmonary disease (COPD) in stable disease, focusing on inhaled long-acting muscarinic antagonists (LAMA) and long-acting β2 agonists (LABA), used either as a monotherapy or as a fixed-dose combination. We report the difficulties of, and pitfalls in, the investigation of the safety of drug treatments in COPD, which is hampered by the so-called COPD trial paradox: on the one hand, COPD is defined as a systemic disease and is frequently associated with comorbidities (especially cardiovascular comorbidities), which have an important effect on the prognosis of individual patients; on the other hand, patients with COPD and cardiovascular or other coexisting illnesses are often excluded from participation in randomised controlled clinical trials. In these trials, inhaled long-acting bronchodilators, both LAMA or LABA, or both, seem to be safe when used in the appropriate dose in adherent patients with COPD without uncontrolled cardiovascular disease or other notable comorbidities. However, the cardiac safety of LAMA and LABA is less evident when used inappropriately (eg, overdosing) or in patients with COPD and substantial cardiovascular disease, prolonged QTc interval, or polypharmacy. Potential warnings about rare cardiac events caused by COPD treatment from meta-analyses and observational studies need to be confirmed in high quality large randomised controlled trials. Finally, we briefly cover the cardiac safety issues of chronic oral drug treatments for COPD, encompassing theophylline, phosphodiesterase inhibitors, and macrolides.

Levorphanol use: past, present and future

Levorphanol is a potent opioid analgesic that was first approved for use in the United States in 1953. Levorphanol is approved for use in moderate to severe pain where an opioid analgesic is appropriate. Levorphanol has a wide range of activities including mu opioid agonism, delta agonism, kappa1 and kappa3 receptor agonism, N-methyl-d-aspartate receptor antagonism and reuptake inhibition of both norepinephrine and serotonin. This multimodal profile might prove effective for pain syndromes that are refractory to other opioid analgesics, such as central and neuropathic pain and opioid-induced hyperalgesia. Levorphanol is well suited as a first-line opioid and can also be used during opioid rotation. It has no known effect on the cardiac QT interval or drug-drug interactions involving hepatic cytochrome P450s enzymes. In these regards, levorphanol may offer a superior safety profile over methadone and other long-acting opioids. Despite its prospective value of multiple mechanisms of action and the potential for treating various types of pain, levorphanol use has been largely supplanted by other recently approved opioids. Its waning use over the years has caused it to be referred to as the "Forgotten Opioid" and resulted in what some consider its underutilization. In fact, levorphanol is relatively unfamiliar to most prescribers. The purpose of this review is to inform practitioners about the attributes of this opioid and reintroduce it to clinicians as an option for treating moderate to severe pain when alternative treatment options are inadequate, not indicated or contraindicated.

Azithromycin and the risk of cardiovascular complications

The purpose of this review was to evaluate the literature to assess the incidence and true clinical relevance of recent Food and Drug Administration warnings regarding QT prolongation with azithromycin, given its widespread use, with over 40 million US outpatient prescriptions written in 2011. A literature search of MEDLINE (1946 to May 2013) and International Pharmaceutical Abstracts (1970 to May 2013) was conducted using the terms azithromycin, QT prolongation, torsades de pointes, arrhythmia, and cardiovascular death. A bibliographic search was also performed. Several relevant studies and case reports were identified and reviewed. One cohort study revealed an increased risk of cardiovascular death with azithromycin compared to no antibiotic, especially in those with higher cardiovascular risk. Another cohort study comparing azithromycin, penicillin V, and no antibiotic in a younger Danish population with less cardiac risk found no increased cardiovascular death associated with azithromycin use. The majority of case reports involved ill and/or elderly patients with multiple comorbidities and concomitant medications who were already at a higher risk of cardiovascular events. Although there is evidence that azithromycin may induce QT prolongation and adverse cardiac events, the incidence is fairly limited to patients with high baseline risk, including those with preexisting cardiovascular conditions and concomitant use of other QT-prolonging drugs.

Potential drug-drug interactions in Alzheimer patients with behavioral symptoms

The use of multi drug regimens among the elderly population has increased tremendously over the last decade although the benefits of medications are always accompanied by potential harm, even when prescribed at recommended doses. The elderly populations are particularly at an increased risk of adverse drug reactions considering comorbidity, poly-therapy, physiological changes affecting the pharmacokinetics and pharmacodynamics of many drugs and, in some cases, poor compliance due to cognitive impairment and/or depression. In this setting, drug–drug interaction may represent a serious and even life-threatening clinical condition. Moreover, the inability to distinguish drug-induced symptoms from a definitive medical diagnosis often results in addition of yet another drug to treat the symptoms, which in turn increases drug–drug interactions. Cognitive enhancers, including acetylcholinesterase inhibitors and memantine, are the most widely prescribed agents for Alzheimer’s disease (AD) patients. Behavioral and psychological symptoms of dementia, including psychotic symptoms and behavioral disorders, represent noncognitive disturbances frequently observed in AD patients. Antipsychotic drugs are at high risk of adverse events, even at modest doses, and may interfere with the progression of cognitive impairment and interact with several drugs including anti-arrhythmics and acetylcholinesterase inhibitors. Other medications often used in AD patients are represented by anxiolytic, like benzodiazepine, or antidepressant agents. These agents also might interfere with other concomitant drugs through both pharmacokinetic and pharmacodynamic mechanisms. In this review we focus on the most frequent drug–drug interactions, potentially harmful, in AD patients with behavioral symptoms considering both physiological and pathological changes in AD patients, and potential pharmacodynamic/pharmacokinetic drug interaction mechanisms.

Effects of phenobarbital and levetiracetam on PR and QTc intervals in patients with post-stroke seizure

BACKGROUND AND OBJECTIVES

Sudden unexplained/unexpected death (SUDEP) is related to high mortality in patients with epilepsy. The prolongation of QT interval, involved in cardiac arrhythmia-related SUDEP, may be precipitated by antiepileptic drugs (AEDs). In this study, we evaluated the effects of phenobarbital and levetiracetam on PR-QTc intervals in patients with post-stroke seizures.

METHODS

We performed an open-label, parallel group, prospective, multicenter study between June 2009 and December 2013 in patients older than 18 years of age with a clinical diagnosis of post-stroke seizure and treated with phenobarbital or levetiracetam. In order to exclude a role of cerebral post-stroke injury on modulation of PR and QTc intervals, patients with cerebral post-stroke injury and without seizures were also enrolled as controls.

RESULTS

Interictal electrocardiography analysis revealed no significant difference in PR interval between patients treated with an AED (n = 49) and control patients (n = 50) (181.25 ± 12.05 vs. 182.4 ± 10.3 ms; p > 0.05). In contrast, a significantly longer QTc interval was recorded in patients treated with an AED compared with control patients (441.2 ± 56.6 vs. 396.8 ± 49.3 ms; p < 0.01). Patients treated with phenobarbital showed a significantly longer QTc interval than patients treated with levetiracetam (460.0 ± 57.2 vs. 421.5 ± 50.1 ms; p < 0.05).

CONCLUSIONS

The study reported that in patients with late post-stroke seizures, phenobarbital prolonged QTc interval more so than levetiracetam.

Repolarization effects of multiple-cycle chemotherapy and predictors of QTc prolongation: a prospective female cohort study on >2000 ECGs

PURPOSE

Oncological patients are at increasing risk of QT prolongation, a risk factor for ventricular arrhythmia. We assessed impact and risk factors for corrected QT (QTc) prolongation during multiple-cycle chemotherapy.

METHODS

We enrolled 100 outpatients initiating chemotherapy in a university center specializing in female cancer. Clinical, drug, laboratory, and 12-lead ECG data collection at baseline and at each chemotherapy cycle was performed.

RESULTS

Enrolled patients were followed for 992 chemotherapy cycles (median 7; interquartile range 6-13); 2438 ECGs were recorded (20; 18-31) 36.8% pre-therapy, 36.8% following chemotherapy, and 22.5% 7-10 days after chemotherapy. Maximum QTc (Max-QTc) was recorded after 4 chemotherapy administrations in >50% of the entire cohort and also within every subset of patients with prolonged QTc (57% 471-480 ms; 54% 481-500 ms; 66% >500 ms). No cumulative effect on QTc was shown. QTc prolongation was comparable among the various protocols. Prophylactic/supportive drugs were not associated with additional QTc prolongation. Variables independently associated with QTc prolongation >470 ms were age (OR 1.056 95% CI 1.006-1.108, p = 0.028) and the baseline-first chemotherapy averaged QTc (BC-QTc) (OR 1.092 95% CI 1.051-1.136), a novel parameter devised for this study. Only BC-QTc maintained significance for QTc >480 ms. BC-QTc >435 ms identified 100 % of patients with Max-QTc >500 ms, 96% with Max-QTc 481-500 ms, and 66% with Max-QTc 471-480 ms. Only 29% of patients with Max-QTc ≤470 ms presented a BC-QTc >435 ms.

CONCLUSIONS

Our results confirm the high prevalence of QTc prolongation after chemotherapy. Most of the patients reached Max-QTc after several cycles. BC-QTc may help in stratifying arrhythmic risk in real-world clinical practice.

Malaria medicines: a glass half full?

Despite substantial scientific progress over the past two decades, malaria remains a worldwide burden that causes hundreds of thousands of deaths every year. New, affordable and safe drugs are required to overcome increasing resistance against artemisinin-based treatments, treat vulnerable populations, interrupt the parasite life cycle by blocking transmission to the vectors, prevent infection and target malaria species that transiently remain dormant in the liver. In this Review, we discuss how the antimalarial drug discovery pipeline has changed over the past 10 years, grouped by the various target compound or product profiles, to assess progress and gaps, and to recommend priorities.

Evaluation of opicapone on cardiac repolarization in a thorough QT/QTc study

Opicapone, a novel third-generation catechol-O-methyltransferase inhibitor for use as adjunctive therapy in levodopa-treated Parkinson's disease patients, was investigated on cardiac repolarization in healthy adult volunteers. This was a single-center, randomized, double-blind, placebo-controlled, open-label active-controlled, 4-period crossover study conducted in 64 subjects. In each period, subjects received a single oral dose of 50 mg opicapone, 800 mg opicapone, placebo, or 400 mg moxifloxacin and 24-hour 12-lead Holter monitoring was performed on day -1 (baseline) and after each single dose. After a single oral administrations of 50 and 800 mg opicapone, opicapone was the major entity in the circulation, with a median tmax of 1.5-2.0 hours. Opicapone was rapidly eliminated, with an elimination half-life of 1-2 hours. There was no clinically relevant effect of 50 and 800 mg opicapone versus placebo on cardiac depolarization or repolarization. All upper bounds of the 1-sided 95% confidence interval (CI) were below 10 milliseconds, confirming that opicapone has no QT-prolonging effect. Moxifloxacin caused an increase in the QTcI, with a lower bound of the 2-sided 95% CI always higher than 5 milliseconds, around the tmax of peak concentration, demonstrating assay sensitivity. In conclusion, administration of opicapone at therapeutic (50 mg) and supratherapeutic (800 mg) doses did not induce a clinically significant prolongation of the QTc interval.

A detailed description and assessment of outcomes of patients with hospital recorded QTc prolongation

Corrected QT (QTc) interval prolongation has been shown to be an independent predictor of mortality in many clinical settings and is a common finding in hospitalized patients. The causes and outcomes of patients with extreme QTc interval prolongation during a hospital admission are poorly described. The aim of this study was to prospectively identify patients with automated readings of QTc intervals >550 ms at 1 academic tertiary hospital. One hundred seventy-two patients with dramatic QTc interval prolongation (574 ± 53 ms) were identified (mean age 67.6 ± 15.1 years, 48% women). Most patients had underlying heart disease (60%), predominantly ischemic cardiomyopathy (43%). At lease 1 credible and presumed reversible cause associated with QTc interval prolongation was identified in 98% of patients. The most common culprits were QTc interval-prolonging medications, which were deemed most responsible in 48% of patients, with 25% of these patients taking ≥2 offending drugs. Two patients were diagnosed with congenital long-QT syndrome. Patients with electrocardiograms available before and after hospital admission demonstrated significantly lower preadmission and postdischarge QTc intervals compared with the QTc intervals recorded in the hospital. In conclusion, in-hospital mortality was high in the study population (29%), with only 4% of patients experiencing arrhythmic deaths, all of which were attributed to secondary causes.

[Drug-induced QT interval prolongation: do we know the risks?]

Sudden cardiac death is an important cause of mortality in developed countries, most of them being consequence of acute ventricular arrhythmias. These arrhythmias, in some cases, owe to QT interval prolongation. A major risk factor for this condition is the use of drugs that prolong the QT interval. In fact, in recent years, one of the most common reasons for drug withdrawal or usage restrictions has been drug induced QT interval prolongation that involves both cardiovascular and non-cardiovascular drugs. Taking into account the severity that the occurrence of such an event may have, it is important for clinicians to know the risks of these drugs in certain patients. In this review we analyze the drugs that prolong the QT interval, the risk factors that can enhance QT prolongation and the drug interactions that can increase these risks.

Xanthine oxidase inhibition alleviates the cardiac complications of insulin resistance: effect on low grade inflammation and the angiotensin system

BACKGROUND

We have previously shown that hyperuricemia plays an important role in the vascular complications of insulin resistance (IR). Here we investigated the effect of xanthine oxidase (XO) inhibition on the cardiac complications of IR.

METHODS

IR was induced in rats by a high fructose high fat diet for 12 weeks. Allopurinol, a standard XO inhibitor, was administered in the last 4 weeks before cardiac hemodynamics and electrocardiography, serum glucose, insulin, tumor necrosis factor alpha (TNFα), 8-isoprostane, uric acid, lactate dehydrogenase (LDH) and XO activity were measured. Expression of cardiac angiotensin II (AngII) and angiotensin receptor 1 (AT1) were assessed by immunofluorescence.

RESULTS

IR animals had significant hyperuricemia which was inhibited by allopurinol administration. IR was associated with impaired ventricular relaxation (reflected by a decreased diastolic pressure increment and prolonged diastolic duration) and XO inhibition greatly attenuated impaired relaxation. IR was accompanied by cardiac ischemia (reflected by increased QTc and T peak trend intervals) while XO inhibition alleviated the ECG abnormalities. When subjected to isoproterenol-induced ischemia, IR hearts were less resistant (reflected by larger ST height depression and higher LDH level) while XO inhibition alleviated the accompanying ischemia. In addition, XO inhibition prevented the elevation of serum 8-isoprostane and TNFα, and blocked elevated AngII and AT1 receptor expression in the heart tissue of IR animals. However, XO inhibition did not affect the developed hyperinsulinemia or dyslipidemia.

CONCLUSIONS

XO inhibition alleviates cardiac ischemia and impaired relaxation in IR through the inhibition of low grade inflammation and the angiotensin system.

Surgical Cardiac Denervation Therapy for Treatment of Congenital Ion Channelopathies in Pediatric Patients

Background:

Congenital ion channel disorders, including congenital long QT syndrome (LQTS), cause significant morbidity in pediatric patients. When medication therapy does not control symptoms or arrhythmias, more invasive treatment strategies may be necessary. This study examines our institution’s clinical experience with surgical cardiac denervation therapy for management of these arrhythmogenic disorders in children.

Methods:

An institutional review board–approved retrospective review identified ten pediatric patients with congenital ion channelopathies who underwent surgical cardiac denervation therapy at a single institution between May 2011 and April 2014. Eight patients had a diagnosis of congenital LQTS, two patients were diagnosed with catecholaminergic polymorphic ventricular tachycardia (CPVT). All patients underwent sympathectomy and partial stellate ganglionectomy via video-assisted thoracoscopic surgery (VATS).

Results:

Six of the ten patients had documented ventricular arrhythmias preoperatively, and 70% of the patients had preoperative syncope. The corrected QT interval decreased in 75% of patients with LQTS following sympathectomy. Postoperative arrhythmogenic symptoms were absent in 88% of congenital LQTS patients, but both patients with CPVT continued to have symptoms throughout the duration of follow-up. All patients were alive after a median follow-up period of 10 months.

Conclusions:

Surgical cardiac denervation therapy via VATS is a useful treatment strategy for congenital LQTS patients who fail medical management, and its potential benefit in the management of CPVT is unclear. A prospective comparison of the efficacy of surgical cardiac denervation therapy and implantable cardioverter-defibrillator use in congenital ion channelopathies is timely and crucial.

Treating drug dependence with the aid of ibogaine: a retrospective study

Ibogaine is an alkaloid purported to be an effective drug dependence treatment. However, its efficacy has been hard to evaluate, partly because it is illegal in some countries. In such places, treatments are conducted in underground settings where fatalities have occurred. In Brazil ibogaine is unregulated and a combined approach of psychotherapy and ibogaine is being practiced to treat addiction. To evaluate the safety and efficacy of ibogaine, we conducted a retrospective analysis of data from 75 previous alcohol, cannabis, cocaine and crack users (72% poly-drug users). We observed no serious adverse reactions or fatalities, and found 61% of participants abstinent. Participants treated with ibogaine only once reported abstinence for a median of 5.5 months and those treated multiple times for a median of 8.4 months. This increase was statistically significant (p < 0.001), and both single or multiple treatments led to longer abstinence periods than before the first ibogaine session (p < 0.001). These results suggest that the use of ibogaine supervised by a physician and accompanied by psychotherapy can facilitate prolonged periods of abstinence, without the occurrence of fatalities or complications. These results suggest that ibogaine can be a safe and effective treatment for dependence on stimulant and other non-opiate drugs.

Acute and subchronic toxicities of QX100626, a 5-HT4 receptor agonist, in rodents and Beagle dogs

Serotonin 5-hydroxytryptamine 4(5-HT4) receptor agonists have been widely prescribed as a prokinetics drug for patients with gastro-esophageal reflux disease and functional dyspepsia. QX100626, one of the 5-HT4 receptor agonists, has been studied as a promising agent for this clinical use. The objective of the present study was to identify possible target organs of toxicity and propose a non-toxic dose of QX100626 for clinical usage. After single lethal dose oral and intravenous testing in rodents, some signs indicative of adverse CNS effects were observed. The minimum toxic dose of QX100626 for a single oral administration for dogs was 90.0mg/kgb.w., and the severe toxic dose was more than 300mg/kgb.w. The No Observed Adverse Effect Level (NOAEL) of QX100626 by daily oral administration for rats and dogs was 20mg/kg and 10mg/kg, respectively, whereas the minimum toxic dosages were 67 and 30mg/kg, respectively. All of the adverse effects suggested that kidney, digestive tract, as well as nervous, hematological, and respiratory systems might be the target organs of toxicity for humans induced by QX100626. The compound could be a safe alternative to other existing prokinetic agents for the treatment of functional bowel disorders.