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

Cardiac arrhythmias after renal I/R depend on IL-1β

AIMS

Cardiac arrhythmias are one of the most important remote complications after kidney injury. Renal ischemia reperfusion (I/R) is a major cause of acute renal injury predisposing to several remote dysfunctions, including cardiac electrical disturbance. Since IL-1β production dependent on NLRP3 represents a link between tissue malfunctioning and cardiac arrhythmias, here we tested the hypothesis that longer ventricular repolarization and arrhythmias after renal I/R depend on this innate immunity sensor.

METHODS AND RESULTS

Nlrp3^-/- and Casp1^-/- mice reacted to renal I/R with no increase in plasma IL-1β, different from WT (wild-type) I/R. A prolonged QJ interval and an increased susceptibility to ventricular arrhythmias were found after I/R compared to Sham controls in wild-type mice at 15 days post-perfusion, but not in Nlrp3^-/- or CASP1^-/- I/R, indicating that the absence of NLRP3 or CASP1 totally prevented longer QJ interval after renal I/R. In contrast with WT mice, we found no renal atrophy and no renal dysfunction in Nlrp3^-/- and Casp1^-/- mice after renal I/R. Depletion of macrophages in vivo after I/R and a day before IL-1β peak (at 7 days post-perfusion) totally prevented prolongation of QJ interval, suggesting that macrophages might participate as sensors of tissue injury. Moreover, treatment of I/R-WT mice with IL-1r antagonist (IL-1ra) from 8 to 15 days post perfusion did not interfere with renal function, but reversed QJ prolongation, prevented the increase in susceptibility to ventricular arrhythmias and rescued a close to normal duration and amplitude of calcium transient.

CONCLUSION

Taken together, these results corroborate the hypothesis that IL-1β is produced after sensing renal injury through NRLP3-CASP1, and IL-1β on its turn triggers longer ventricular repolarization and increase susceptibility to cardiac arrhythmias. Still, they offer a therapeutic approach to treat cardiac arrhythmias that arise after renal I/R.

Prevalence, predictors and clinical implications of prolonged corrected QT in elderly patients with dementia and suspected syncope

BACKGROUND

Long QT and use of QT-prolonging drugs are common among older patients receiving polytherapies, but real-world evidence on their impact in clinical practice is controversial. We investigated prevalence, variables associated and clinical implications of prolonged corrected QT (QTc) among patients from the Syncope and Dementia study.

METHODS

Observational, prospective, multicenter study. Patients≥65 years with dementia and fall suspected for syncope in the previous three months were enrolled. Several clinical variables and the complete list of medications were recorded for each patient. A 12‑lead ECG was obtained and corrected QT was calculated by the Bazett's formula. One-year followup for death and recurrent syncope was performed.

RESULTS

Prolonged QTc was observed in 25% of the 432 enrolled patients (mean age 83.3), and was significantly associated with male gender (OR 2.09; 95% CI 1.34-3.26) and diuretics use (OR 1.85; 95% CI 1.18-2.90). At one-year 23.3% of patients died and 30.4% reported at least one recurrent event. Variables associated with one-year mortality were: age, male gender, atrial fibrillation (AF), use of calcium channel blockers and prolonged QTc (OR 1.80; 95% CI 1.01-3.20). Among patients with prolonged QTc a significant interaction for mortality was found with AF. Recurrent events were associated with the use of antiplatelets, cholinesterase. inhibitors and antipsychotics, but not with prolonged QTc.

CONCLUSIONS

We documented a high prevalence of prolonged QTc, that was associated with male gender and diuretics but not with psychoactive medications. Patients with prolonged QTc had higher one-year mortality, that was four-fold increased in those with concomitant AF.

Evaluation of varenicline usage on ventricular repolarization after smoking cessation

BACKGROUND

Varenicline, which is a selective partial agonist of the alpha4-beta2 nicotinic acetylcholine receptor, is used for the smoking cessation pharmacotherapy. Cardiovascular adverse effects have been reported after varenicline usage in patients who stop smoking. We investigated the effect of varenicline usage on ventricular repolarization after smoking cessation.

METHODS

In this prospective cohort study, we evaluated the cardiac arrhythmic effects of varenicline by comparing smoking patients (n = 214) before and after varenicline usage. Varenicline administered patients were also compared to ex-smoker individuals (n = 50) who quit smoking without varenicline usage in terms of ventricular repolarization parameters.

RESULTS

After calculated according to Fridericia's and Framingham's formulas, QTc intervals were significantly increased when patients compared before and after smoking cessation with varenicline (402.9 ± 24.5 ms vs. 409.1 ± 25.0 ms p < 0.001 and 376.5 ± 15.2 ms, vs. 380.6 ± 13.5 ms; p < 0.001, respectively). There was no arrhythmic event during the follow-up. The change in Tp-e and QTc following varenicline usage was negatively correlated with the smoking packet/year. (ρ: -0.443, p < 0.001 and ρ = -0.601, p < 0.001) CONCLUSION: Varenicline usage was demonstrated to prolong ventricular repolarization parameters similar to animal studies. Varenicline may have a role to predispose cardiac dysrhythmias after utilization in smoking cessation.

Population Prevalence and Correlates of Prolonged QT Interval: Cross-Sectional, Population-Based Study From Rural Uganda

OBJECTIVES

We aimed to estimate the prevalence and correlates of QT interval prolongation in rural Uganda.

BACKGROUND

Major electrocardiographic abnormalities, including prolonged QT interval, have been shown to be independently predictive of adverse cardiovascular events among Western populations. Cardiovascular diseases are on the rise in sub-Saharan Africa with poorly characterized context-specific risk factors. An important question is whether ECG screening might have value in cardiovascular disease risk stratification in SSA.

METHODS

We conducted a cross-sectional survey in a sample of adults participating in an ongoing whole-population cohort in Mbarara, Uganda, in 2015. Of 1,814 subjects enrolled in the parent whole-population cohort, 856 (47%) participated in the study. Participants completed 12-lead electrocardiography and cardiovascular disease risk factors assessment. We summarized sex-specific, heart rate variation-adjusted QT (QTa) defining prolonged QTa as >460 ms in women and >450 ms in men. We fit linear and logistic regression models to estimate correlates of (continuous) QTa interval length and (dichotomous) prolonged QTa. Models included inverse probability of sampling weights to generate population-level estimates accounting for study nonparticipation.

RESULTS

We assessed data from 828 participants with electrocardiograms. The weighted population mean age was 38.4 years (95% confidence interval: 36.3-40.4). The weighted population was 50.4% female, 11.5% had elevated blood pressure, and 57.6% had a high-sensitivity C-reactive protein >1 mg/dl. The population mean QTa was 409.1 ms (95% confidence interval: 405.1-413.1), and 10.3% (95% confidence interval: 7.8-13.5) met criteria for prolonged QTa. Women had a higher mean QTa (421.6 ms vs. 396.3 ms; p < 0.001), and a higher proportion of women had a prolonged QTa (14.0% vs. 9.3%; p = 0.122) than did men. In multivariable-adjusted regression models, female sex and hypertension correlated with higher mean QTa and meeting criteria for prolonged QTa, respectively.

CONCLUSIONS

QT interval prolongation is highly prevalent in rural Uganda and may be more common than in high-income settings. Female sex, age, and high blood pressure correlated with QT interval prolongation. Future work should assess whether genetic predisposition or environmental factors in sub-Saharan African populations contribute to prolonged QT and clarify consequences.

Risk Factors of QTc Prolongation in Women With Hormone Receptor‒positive/Human Epidermal Growth Factor Receptor 2‒negative Metastatic Breast Cancer: A Retrospective Analysis of Health Care Claims Data

PURPOSE

In addition to biomarker status, treatment selection for metastatic breast cancer (mBC) includes individual patient and clinical characteristics such as tumor burden, timing of disease recurrence, and comorbidities. Women with mBC may take medications that can increase the risk of drug-induced toxicities, including prolongation of cardiac repolarization (prolongation of QT interval). Corrected QT (QTc) prolongation, a toxicity associated with many cancer treatments, can lead to potentially life-threatening ventricular arrhythmias. As such, it is important to identify patients at risk for QTc prolongation due to comorbid conditions, concomitant medications, or electrolyte abnormalities. This real-world study estimated the proportion of women with hormone receptor‒positive (HR+)/human epidermal growth factor receptor 2‒negative (HER2‒) mBC who may be at risk of developing QTc prolongation. Results in the elderly are also included.

METHODS

This retrospective, cross-sectional cohort study used the Truven Health MarketScan and Optum Clinformatics administrative claims databases. Patients' medical and pharmacy data were evaluated to assess the risk of QTc prolongation. Prescription and medication administration claims were evaluated during the 7-day period before the index date (ie, first secondary neoplasm diagnosis). In addition, International Classification of Diseases, Ninth/Tenth Revision, Clinical Modification, codes were evaluated 12 months before the index date to describe congenital long QT syndrome, cardiac disease, and electrolyte abnormalities.

FINDINGS

A cohort of 24,340 women with HR+/HER2‒ mBC were identified, including 5059 women aged 65-74 years and 4851 aged ≥75 years. Based on an overall analysis of risk factors (congenital long QT syndrome, cardiovascular disease, electrolyte abnormalities, or concomitant medications), 29.5% of all patients, 33.2% of patients aged 65-74 years, and 40.5% of patients aged ≥75 years had risk factors for QTc prolongation.

IMPLICATIONS

This analysis of real-world data indicates that almost 1 in 3 women with HR+/HER2‒ mBC had congenital long QT syndrome, cardiovascular disease, and/or electrolyte abnormalities or received a concomitant medication that could increase the risk of developing QTc prolongation. The risk factors for congenital long QT syndrome, cardiovascular disease, or electrolyte abnormalities were more common in older patients. This analysis emphasizes the importance of individualized benefit/risk assessment during treatment decisions, especially when considering drugs with known or possible QTc prolongation risk.

Dihydroxyacetone as a definitive treatment for aluminium phosphide poisoning in rats

Aluminium phosphide (AlP), a very toxic pesticide also known as the rice tablet, releases phosphine gas upon contact with water, moisture, or gastric acid. Its mortality rate in humans is 70-100 % due to cardiogenic shock and refractory hypotension. Dihydroxyacetone (DHA) is a simple ketonic carbohydrate, mainly used for sunless skin tanning. It also plays a beneficial role in the treatment of hypotension and cardiogenic shock by restoring blood volume and cellular respiration. The aim of this study was to investigate the its effect on the haemodynamics and electrocardiogram (ECG) in male rats poisoned with AlP. The animals were divided into the following groups: control (received 1 mL corn oil, orally), AlP (received 15 mg kg-1 AlP solved in corn oil, orally), AlP plus DHA (treated with 50 mg kg-1 of DHA 30 min after receiving AlP), and AlP plus N-acetyl cysteine (NAC) (treated with 200 mg kg-1 of NAC 30 min after receiving AlP). The animals were then anaesthetised and ECG, blood pressure, and heart rate were recorded for 120 min. Treatment with AlP alone and in combination with NAC was associated with progressive hypotension, tachycardia, and ECG disturbances in rats, resulting in 100 % mortality 3 h after poisoning. However, DHA achieved 100 % survival in the poisoned rats and prevented AlP-induced ECG and haemodynamic abnormalities. The main mechanism of DHA in the treatment of AlP poisoning is unclear, but the findings suggest the promising therapeutic potential of DHA against AlP poisoning.

Identification of Patients At-Risk of QT Interval Prolongation during Medication Reviews: A Missed Opportunity?

The prolongation of the QT interval is a relatively rare but serious adverse drug reaction. It can lead to torsade de pointes, which is potentially life-threatening. The study’s objectives were: determine the use of QT interval-prolonging drugs in an elderly community-dwelling population at risk of medication misadventure and identify recommendations regarding the risk of QT interval prolongation made by pharmacists when performing medication reviews. In a retrospective evaluation, 500 medication review reports from Australian pharmacists were analysed. In patients taking at least one QT interval-prolonging drug, the individual risk of drug-induced QT interval prolongation was assessed. Recommendations of pharmacists to avoid the occurrence of this drug-related problem were examined. There was a high prevalence of use of potentially QT interval-prolonging drugs (71% patients), with 11% of patients taking at least one drug with a known risk. Pharmacists provided specific recommendations in only eight out of 35 patients (23%) with a high-risk score and taking drugs with known risk of QT interval prolongation. Pharmacists’ recommendations, when present, were focused on drugs with known risk of QT interval prolongation, rather than patients’ additional risk factors. There is a need to improve knowledge and awareness of this topic among pharmacists performing medication reviews.

Clinical Use of Digitalis: A State of the Art Review

The history of digitalis is rich and interesting, with the first use usually attributed to William Withering and his study on the foxglove published in 1785. However, some knowledge of plants with digitalis-like effects used for congestive heart failure (CHF) was in evidence as early as Roman times. The active components of the foxglove (Digitalis purpurea and Digitalis lanata) are classified as cardiac glycosides or cardiotonic steroids and include the well-known digitalis leaf, digitoxin, and digoxin; ouabain is a rapid-acting glycoside usually obtained from Strophanthus gratus. These drugs are potent inhibitors of cellular membrane sodium-potassium adenosine triphosphatase (Na⁺/K⁺-ATPase). For most of the twentieth century, digitalis and its derivatives, especially digoxin, were the available standard of care for CHF. However, as the century closed, many doubts, especially regarding safety, were raised about their use as other treatments for CHF, such as decreasing the preload of the left ventricle, were developed. Careful attention is needed to maintain the serum digoxin level at ≤ 1.0 ng/ml because of the very narrow therapeutic window of the medication. Evidence for benefit exists for CHF with reduced ejection fraction (EF), also referred to as heart failure with reduced EF (HFrEF), especially when considering the combination of mortality, morbidity, and decreased hospitalizations. However, the major support for using digoxin is in atrial fibrillation (AF) with a rapid ventricular response when a rate control approach is planned. The strongest support of all for digoxin is for its use in rate control in AF in the presence of a marginal blood pressure, since all other rate control medications contribute to additional hypotension. In summary, these days, digoxin appears to be of most use in HFrEF and in AF with rapid ventricular response for rate control, especially when associated with hypotension. The valuable history of the foxglove continues; it has been modified but not relegated to the garden or the medical history book, as some would advocate.

Limited Evidence for Risk Factors for Proarrhythmia and Sudden Cardiac Death in Patients Using Antidepressants: Dutch Consensus on ECG Monitoring

Currently, there is a lack of international and national guidelines or consensus documents with specific recommendations for electrocardiogram (ECG) screening and monitoring during antidepressant treatment. To make a proper estimation of the risk of cardiac arrhythmias and sudden (cardiac) death during antidepressant use, both the drug and patient-specific factors should be taken into account; however, solid evidence on how this should be done in clinical practice is lacking. Available recommendations on the management of QT(c) prolongation (with antidepressant treatment) emphasize that special attention should be given to high-risk patients; however, clinicians are in need of more concrete suggestions about how to select patients for ECG screening and monitoring. Based on a review of the literature, a Dutch multidisciplinary expert panel aimed to formulate specific guidelines to identify patients at risk for cardiac arrhythmias and sudden death by developing a consensus statement regarding ECG screening before, and monitoring during, antidepressant use. We first reviewed the literature to identify the relative risks of various risk factors on cardiac arrhythmia and sudden (cardiac) death during antidepressant use. These relative contributions of risk factors could not be determined since no systematic reviews or meta-analyses quantitatively addressed this topic. Because evidence was insufficient, additional expert opinion was used to formulate recommendations. This resulted in readily applicable recommendations for clinical practice for selection of high-risk patients for ECG screening and monitoring. ECG screening and monitoring is recommended before and following the start of QTc-prolonging antidepressants in the presence of vulnerability to QTc prolongation or two or more risk factors (age > 65 years, female sex, concomitant use of a QTc-prolonging drug or concomitant use of a drug that influences the metabolism of a QTc-prolonging drug, cardiac disease, excessive dosing and specific electrolyte disturbances).

The risk of cardiac events in patients who received concomitant levofloxacin and amiodarone

OBJECTIVES

Levofloxacin and amiodarone are both known to prolong the QT interval. This study was conducted to estimate the risk of cardiac events in patients receiving concomitant levofloxacin and amiodarone.

METHODS

The study included patients who were admitted to a large academic community medical center from 1/2012 to 12/2015 and received both levofloxacin and amiodarone at some point during their hospitalization. Patients received concomitant or non-concomitant levofloxacin and amiodarone during hospitalization. The primary outcome was the occurrence of cardiac events during therapy. The secondary outcome was the proportion of patients with an electrocardiogram performed before and after initiation of therapy. Odds ratios for cardiac events were calculated using a multivariable logistic regression model with and without adjusting for the study variables. The concomitant group was further evaluated for predictors of the primary outcome using multivariable logistic regression.

RESULTS

This study included 240 patients, 164 (68.3%) of whom received concomitant levofloxacin and amiodarone. Concomitant medication therapy was associated with a greater than six-fold increased risk of cardiac events after adjusting for the study variables (Odds Ratio=6.20; 95% Confidence Interval=1.34-28.62).

CONCLUSIONS

Patients receiving concomitant amiodarone and levofloxacin experienced a five-fold increase in cardiac events compared to patients given either medication alone.

Effect of serum electrolytes within normal ranges on QTc prolongation: a cross-sectional study in a Chinese rural general population

Background

Many previous clinical studies have reported that prolongation of the QT interval corrected for heart rate (QTc) is associated with an increased risk of sudden cardiac death and all-cause mortality. This study aimed to explore associations between serum electrolytes and QTc prolongation in the north-eastern Chinese rural general population.

Methods

We performed a cross-sectional study including 10,334 (4820 men and 5514 women) from the general population aged ≥35 years in the Liaoning Province from 2012 to 2013. Anthropometric measurements, laboratory examinations and self-reported lifestyle factor information, echocardiography and electrocardiogram were collected by trained personnel. The associations between serum electrolytes and QTc prolongation were tested using multiple linear regression and logistic regression analyses.

Results

The mean QTc interval were 415.6 ± 18.8 and 470.1 ± 23.1 ms in normal group and QTc prolongation group respectively. The prevalence of QTc prolongation increased significantly with a decrease in serum potassium and an increase in magnesium. Stepwise multiple linear regression showed that age, hypertension, waist circumference were prominently positive associated with QTc interval both in male and female population. But serum potassium was significantly inversely associated with QTc interval. Serum magnesium and calcium also showed a positive relationship with QTc interval. Furthermore, multiple logistic regression found that lower quartile of serum potassium had higher risk for QTc prolongation, especially in female population (Q2 vs. Q4: OR: 1.54, 95%CI: 1.01–2.35; Q1 vs. Q4: OR: 2.02, 95%CI: 1.36–3.01). In addition, the higher serum magnesium increased the risk of QTc prolongation, which was significantly only in male population.

Conclusions

In present Chinese rural general population, even with normal range, a decrease in serum potassium and an increase in serum magnesium are important risk factors for QTc prolongation.

Electronic supplementary material

The online version of this article (10.1186/s12872-018-0906-1) contains supplementary material, which is available to authorized users.

Predisposition of functional genetic variants of A-kinase anchoring protein 10 toward acquired repolarization disorders in high-risk vascular surgery patients

Purpose

We aimed at assessing the predisposition of A-kinase anchoring protein 10 (AKAP10) polymorphism toward acquired repolarization disorders in high-risk vascular surgery patients.

Patients and methods

One hundred adult patients (age =44–85 years), scheduled for an elective high-risk “open” vascular surgery procedure, were recruited. The electrocardiogram Holter monitor was used to assess repolarization stability from the beginning of the operation up to 24 hours afterward. The AKAP10 gene rs203462 polymorphism and cardiac complications were analyzed.

Results

Repolarization disturbances defined as QT interval duration corrected for heart rate (QTc) interval prolongation >500 ms and QTc interval dispersion >65 ms were recorded in 46 patients. A model of multivariate logistic regression showed that only the presence of allele G of the AKAP10 polymorphism was an independent risk factor for repolarization disturbances in the perioperative period (odds ratio =14.35; 95% CI =4.65–44.23; p<0.0001).

Conclusion

When the acquired QTc interval prolongation or QTc dispersion is associated with AKAP10 polymorphism, it may remain clinically silent.

Early Gestational Hypoxia and Adverse Developmental Outcomes

Hypoxia is a normal and essential part of embryonic development. However, this state may leave the embryo vulnerable to damage when oxygen supply is disturbed. Embryofetal response to hypoxia is dependent on duration and depth of hypoxia, as well as developmental stage. Early postimplantation rat embryos were resilient to hypoxia, with many surviving up to 1.5 hr of uterine clamping, while most mid-gestation embryos were dead after 1 hour of clamping. Survivors were small and many had a range of defects, principally terminal transverse limb reduction defects. Similar patterns of malformations occurred when embryonic hypoxia was induced by maternal hypoxia, interruption of uteroplacental flow, or perfusion and embryonic bradycardia. There is good evidence that high altitude pregnancies are associated with smaller babies and increased risk of some malformations, but these results are complicated by increased risk of pre-eclampsia. Early onset pre-eclampsia itself is associated with small for dates and increased risk of atrio-ventricular septal defects. Limb defects have clearly been associated with chorionic villus sampling, cocaine, and misoprostol use. Similar defects are also observed with increased frequency among fetuses who are homozygous for thalassemia. Drugs that block the potassium current, whether as the prime site of action or as a side effect, are highly teratogenic in experimental animals. They induce embryonic bradycardia, hypoxia, hemorrhage, and blisters, leading to transverse limb defects as well as craniofacial and cardiovascular defects. While evidence linking these drugs to birth defects in humans is not compelling, the reason may methodological rather than biological. Birth Defects Research 109:1358-1376, 2017.© 2017 Wiley Periodicals, Inc.

Androgen Deprivation Therapy Is Associated With Prolongation of QTc Interval in Men With Prostate Cancer

CONTEXT

Androgen deprivation therapy (ADT) for prostate cancer (PCa) is associated with increased cardiovascular mortality and sudden cardiac death, with some events occurring early after initiation of ADT. Testosterone levels are inversely associated with corrected QT (QTc) interval duration; therefore, prolongation of QTc duration could be responsible for some of these events during ADT.

OBJECTIVE

To evaluate changes in QTc duration during ADT.

DESIGN AND INTERVENTIONS

A 6-month prospective cohort study that enrolled men with PCa about to undergo ADT (ADT group) and a control group of men who previously underwent prostatectomy for PCa and never received ADT (non-ADT group).

PATIENTS

At study entry, all participants were eugonadal and had no history of cardiac arrhythmias or complete bundle branch block.

OUTCOMES

Difference in change in QTc duration from baseline on a 12-lead electrocardiogram at 6, 12, and 24 weeks after initiation of ADT compared with electrocardiograms performed at the same intervals in the non-ADT group. PR, QRS, and QT interval durations were also evaluated.

RESULTS

Seventy-one participants formed the analytical sample (33 ADT and 38 non-ADT). ADT was associated with prolongation of the QTc by 7.4 ms compared with the non-ADT group [95% confidence interval (CI) 0.08 to 14.7 ms; P = 0.048]. ADT was also associated with shortening of the QRS interval by 2.4 ms (95% CI -4.64 to -0.23; P = 0.031). Electrolytes did not change.

CONCLUSIONS

Men undergoing ADT for PCa experienced prolongation of the QTc. These findings might explain the increased risk of sudden cardiac death seen in these patients.

Association between a frailty index based on common laboratory tests and QTc prolongation in older adults: the Rugao Longevity and Ageing Study

BACKGROUND

Risk factors for heart rate-corrected QT interval (QTc) proglongation should be explored to stratify high-risk individuals to aid the prevention of incident cardiovascular events and mortality. The diversity of risk factors for QTc prolongation suggests that use of the frailty index (FI), indicating general health deficits, may be an effective approach, especially in the elderly, to identify the risk of QTc prolongation.

METHODS

We used the data of 1,780 individuals aged 70-87 years from the Rugao Longevity and Ageing Study (RuLAS), a community-based longitudinal study. The FI was constructed using 20 routine laboratory tests, plus the body mass index and measures of systolic and diastolic blood pressures (FI-Lab).

RESULTS

The mean FI-Lab value was 0.24±0.09. The mean heart rate-corrected QT interval (QTc) was 407±38 ms. The prevalence of QTc prolongation was 5.2% in elderly community populations aged 70-87 years. A higher FI-Lab value was associated with a higher risk for QTc prolongation. Each 10% increase in the FI-Lab value increased the odds ratio (OR) by 33% (OR: 1.33; 95% CI: 1.07-1.64). Compared with the lowest quartile, the top quartile FI-Lab score was associated with a 2.50-fold QTc prolongation risk in elderly individuals (95% CI: 1.21-5.19).

CONCLUSION

An FI based on routine laboratory data can identify older adults at increased risk for QTc prolongation. The FI approach may therefore be useful for the risk stratification of QTc prolongation.

Electrocardiogram Changes of Donepezil Administration in Elderly Patients with Ischemic Heart Disease

Objective

Donepezil, a widely used cholinesterase inhibitor for treating Alzheimer's disease, has been reported to induce bradyarrhythmias and torsade de pointes. In this study, we aimed at determining electrocardiogram changes of donepezil administration in elderly patients with ischemic heart disease, who tend to suffer from cognitive disorders.

Methods

Sixty patients with ischemic heart disease and mild cognitive impairment were treated with donepezil (5 mg/day) and followed up for at least four weeks. A twenty-four-hour ambulatory electrocardiogram was performed for the analysis of heart rate variability. The ECG parameters including heart rate (HR), PR and RR intervals, QT interval, and QRS duration were recorded at the baseline and after donepezil administration.

Results

Donepezil administration resulted in significant reduction in mean HR and the lowest HR and prolongation of PR and RR intervals, whereas it had no significant effects on QRS duration and QT parameters including QT, corrected QT interval, QT dispersion, and T_peak-end interval. HRV analysis showed that donepezil administration significantly improved parasympathetic function, indicated by decreased low/high frequency (LF/HF) ratio and high frequency (HF) components and oscillation of RR intervals.

Conclusions

These data demonstrated that donepezil administration decreased HR, prolonged PR interval, and increased parasympathetic function without affecting QRS duration and QT intervals, suggesting that it can be used safely in elderly patients with ischemic heart disease.

Drug-induced Proarrhythmia and Torsade de Pointes: A Primer for Students and Practitioners of Medicine and Pharmacy

Multiple marketing withdrawals due to proarrhythmic concerns occurred in the United States, Canada, and the United Kingdom in the late 1980s to early 2000s. This primer reviews the clinical implications of a drug's identified proarrhythmic liability, the issues associated with these safety-related withdrawals, and the actions taken by the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) and by regulatory agencies in terms of changing drug development practices and introducing new nonclinical and clinical tests to asses proarrhythmic liability. ICH Guidelines S7B and E14 were released in 2005. Since then, they have been adopted by many regional regulatory authorities and have guided nonclinical and clinical proarrhythmic cardiac safety assessments during drug development. While this regulatory paradigm has been successful in preventing drugs with unanticipated potential for inducing the rare but potentially fatal polymorphic ventricular arrhythmia torsade de pointes from entering the market, it has led to the termination of drug development programs for other potentially useful medicines because of isolated results from studies with limited predictive value. Research efforts are now exploring alternative approaches to better predict potential proarrhythmic liabilities. For example, in the domain of human electrocardiographic assessments, concentration-response modeling conducted during phase 1 clinical development has recently become an accepted alternate primary methodology to the ICH E14 "thorough QT/QTc" study for defining a drug's corrected QT interval prolongation liability under certain conditions. When a drug's therapeutic benefit is considered important at a public health level but there is also an identified proarrhythmic liability that may result from administration of the single drug in certain individuals and/or drug-drug interactions, marketing approval will be accompanied by appropriate directions in the drug's prescribing information. Health-care professionals in the fields of medicine and pharmacy need to consider the prescribing information in conjunction with individual patients' clinical characteristics and concomitant medications when prescribing and dispensing such drugs.

Predictive factors for clinically significant pharmacist interventions at hospital admission

Pharmaceutical care activities at hospital admission have a significant impact on patient safety. The objective of this study was to identify predictive factors for clinically significant pharmacist interventions (PIs) performed during medication reconciliation and medication review at patient hospital admission.A 4-week prospective study was conducted in 4 medicine wards. At hospital admission, medication reconciliation and medication review were conducted and PIs were performed by the pharmaceutical team. The clinical impact of PIs was determined using the clinical economic and organizational (CLEO) tool. Clinical characteristics, laboratory results, and medication data for each patient were collected and analyzed as potential predictive factors of clinically significant PIs. Univariate and multivariate binary logistic regression were subsequently used to identify independent predictive factors for clinically relevant PIs.Among 265 patients admitted, 150 patients were included. Among 170 PIs performed at hospital admission, 71 were related to unintentional discrepancies (41.8%) during medication reconciliation, and 99 were related to drug-related problems (DRPs) (58.8%) during medication review. Overall, 115 PIs (67.7%) were considered to have a clinical impact. By multivariate analysis, number of medications ≥5 (P = .01) based on the best possible medication history, and Charlson comorbidity index score ≥2 (P < .01) were found to be independent predictive factors of clinically significant PIs at hospital admission.Identifying predictive factors of clinically significant PIs is valuable to optimize clinical pharmacist practices at hospital admission during both medication reconciliation and medication review. These 2 steps of the pharmaceutical care process improve medication safety at hospital admission.

Cardiac repolarization during fingolimod treatment in patients with relapsing-remitting multiple sclerosis

Background

Fingolimod is a sphingosine-1-phosphate receptor modulator for the treatment of relapsing-remitting multiple sclerosis (RRMS). Despite an established effect on heart rate, the effect of fingolimod on cardiac repolarization is not completely known.

Methods

Twenty-seven patients with RRMS underwent 24-hr ambulatory ECG before fingolimod (baseline), at the day of fingolimod initiation (1D) and after three-month treatment (3M). The mean values of RR-interval as well as QT-interval corrected by Bazzet's (QTcBaz) and Fridericia's (QTcFri) formula were compared between baseline, 1D, and 3M over 24-hr period as well as at daytime and nighttime.

Results

QTcBaz over 24-hr was shorter at 1D (414 ± 20 ms, p < .001) and at 3M (414 ± 20 ms, p < .001) than at baseline (418 ± 20 ms). In contrast, QTcFri over 24-hr was longer at 1D (410 ± 19 ms, p < .001) but similar at 3M (406 ± 19 ms, p = .355) compared to baseline (407 ± 19 ms). Daytime QTcBaz was shorter at 1D (p < .001) and at 3M (p = .007), whereas daytime QTcFri was longer at 1D (p < .05) but similar at 3M (p = ns) compared to baseline. During the night, changes were observed neither in QTcBaz nor in QTcFri between baseline, 1D, and 3M.

Conclusions

Changes in cardiac repolarization after fingolimod initiation were mild and occurred at daytime. Ambiguously, QTcBaz demonstrated shortening, whereas QTcFri showed prolongation in cardiac repolarization after fingolimod initiation. The formula applied for QT-interval correction needs to be taken carefully into account as evaluating pharmacovigilance issues related to fingolimod.

Pain medication and long QT syndrome

Long QT syndrome is a cardiac repolarization disorder and is associated with an increased risk of torsades de pointes. The acquired form is most often attributable to administration of specific medications and/or electrolyte imbalance. This review provides insights into the risk for QT prolongation associated with drugs frequently used in the treatment of chronic pain. In the field of pain medicine all the major drug classes (i.e. NSAIDs, opioids, anticonvulsive and antidepressant drugs, cannabinoids, muscle relaxants) contain agents that increase the risk of QT prolongation. Other substances, not used in the treatment of pain, such as proton pump inhibitors, antiemetics, and diuretics are also associated with long QT syndrome. When the possible benefits of therapy outweigh the associated risks, slow dose titration and electrocardiography monitoring are recommended.

Enhanced basal late sodium current appears to underlie the age-related prolongation of action potential duration in guinea pig ventricular myocytes

Aging hearts have prolonged QT interval and are vulnerable to oxidative stress. Because the QT interval indirectly reflects the action potential duration (APD), we examined the hypotheses that 1) the APD of ventricular myocytes increases with age; 2) the age-related prolongation of APD is due to an enhancement of basal late Na⁺ current (I_NaL); 3) inhibition of I_NaL may protect aging hearts from arrhythmogenic effects of hydrogen peroxide (H₂O₂). Experiments were performed on ventricular myocytes isolated from one-month (young) and one-year (old) guinea pigs (GPs). The APD of myocytes from old GPs was significantly longer than that from young GPs and was shortened by the I_NaL inhibitors GS967 and tetrodotoxin. The magnitude of I_NaL was significantly larger in myocytes from old than from young GPs. The CaMKII inhibitors KN-93 and AIP and the Na_V1.5-channel blocker MTSEA blocked the I_NaL. There were no significant differences between myocytes from young and old GPs in L-type Ca²⁺ current and the rapidly- and slowly-activating delayed rectifier K⁺ currents, although the inward rectifier K⁺ current was slightly decreased in myocytes from old GPs. H₂O₂ induced more early afterdepolarizations in myocytes from old than from young GPs. The effect of H₂O₂ was attenuated by GS967. The results suggest that 1) the APD of myocytes from old GPs is prolonged, 2) a CaMKII-mediated increase in Na_V1.5-channel I_NaL is responsible for the prolongation of APD, and 3) Inhibition of I_NaL may be beneficial for maintaining electrical stability under oxidative stress in myocytes of old GPs.

Humans Vary, So Cardiac Models Should Account for That Too!

The utilization of mathematical modeling and simulation in drug development encompasses multiple mathematical techniques and the location of a drug candidate in the development pipeline. Historically speaking they have been used to analyze experimental data (i.e., Hill equation) and clarify the involved physical and chemical processes (i.e., Fick laws and drug molecule diffusion). In recent years the advanced utilization of mathematical modeling has been an important part of the regulatory review process. Physiologically based pharmacokinetic (PBPK) models identify the need to conduct specific clinical studies, suggest specific study designs and propose appropriate labeling language. Their application allows the evaluation of the influence of intrinsic (e.g., age, gender, genetics, disease) and extrinsic [e.g., dosing schedule, drug-drug interactions (DDIs)] factors, alone or in combinations, on drug exposure and therefore provides accurate population assessment. A similar pathway has been taken for the assessment of drug safety with cardiac safety being one the most advanced examples. Mechanistic mathematical model-informed safety evaluation, with a focus on drug potential for causing arrhythmias, is now discussed as an element of the Comprehensive in vitro Proarrhythmia Assay. One of the pillars of this paradigm is the use of an in silico model of the adult human ventricular cardiomyocyte to integrate in vitro measured data. Existing examples (in vitro—in vivo extrapolation with the use of PBPK models) suggest that deterministic, epidemiological and clinical data based variability models can be merged with the mechanistic models describing human physiology. There are other methods available, based on the stochastic approach and on population of models generated by randomly assigning specific parameter values (ionic current conductance and kinetic) and further pruning. Both approaches are briefly characterized in this manuscript, in parallel with the drug-specific variability.

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.