Racial susceptibility for QT prolongation in acute drug overdoses

Arrhythmias and ion channelopathies causing sudden cardiac death in Hispanic/Latino and Indigenous populations

The limited literature and increasing interest in studies on cardiac electrophysiology, explicitly focusing on cardiac ion channelopathies and sudden cardiac death in diverse populations, has prompted a comprehensive examination of existing research. Our review specifically targets Hispanic/Latino and Indigenous populations, which are often underrepresented in healthcare studies. This review encompasses investigations into genetic variants, epidemiology, etiologies, and clinical risk factors associated with arrhythmias in these demographic groups. The review explores the Hispanic paradox, a phenomenon linking healthcare outcomes to socioeconomic factors within Hispanic communities in the United States. Furthermore, it discusses studies exemplifying this observation in the context of arrhythmias and ion channelopathies in Hispanic populations. Current research also sheds light on disparities in overall healthcare quality in Indigenous populations. The available yet limited literature underscores the pressing need for more extensive and comprehensive research on cardiac ion channelopathies in Hispanic/Latino and Indigenous populations. Specifically, additional studies are essential to fully characterize pathogenic genetic variants, identify population-specific risk factors, and address health disparities to enhance the detection, prevention, and management of arrhythmias and sudden cardiac death in these demographic groups.

Long QT syndrome after using EGFR-TKIs in older patients with advanced non-small cell lung cancer

BACKGROUND

Long QT syndrome (LQTS) has been reported in older patients with advanced non-small cell lung cancer (NSCLC) following the use of osimertinib, the third-generation epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI). However, there have not been analytic epidemiology studies on this topic. We aimed to compare the risk of LQTS between osimertinib and first/second-generation EGFR-TKIs in older patients with advanced NSCLC.

RESEARCH DESIGN AND METHODS

This retrospective observational study used the 2006-2019 Surveillance, Epidemiology, and End Results (SEER)-Medicare data and included older patients with advanced NSCLC who were treated with either osimertinib or first/second-generation EGFR-TKIs during 2007-2017. Inverse probability of treatment weighting (IPTW) was used to balance the two groups with propensity scores estimated based on the patients' socioeconomic and clinical characteristics. Crude incidence rate (IR) and adjusted hazard ratio (HR) of the primary outcome, incident LQTS, were estimated.

RESULTS

A total of 545 and 1,135 patients were included in the osimertinib and first/second-generation EGFR-TKI groups, which increased to 1,614 and 1,659, respectively, after IPTW. The osimertinib group had a higher IR of LQTS (2.62 per 100 person-years, 95% CI 2.03-3.38) compared to the first/second-generation EGFR-TKI group (1.33 per 100 person-years, 95% CI 0.92-1.92). After adjusting for covariates, the osimertinib group had a higher risk of LQTS than the first/second-generation EGFR-TKI group, with an HR of 1.94 (95% CI 1.23-3.08). The increased LQTS risk in the osimertinib group was even higher in females, whites and patients aged ≥ 75.

CONCLUSIONS

Given the elevated risk of LQTS associated with osimertinib user, close monitoring for cardiac rhythm irregularities of high-risk patients following initiation of EGFR-TKI is recommended.

Association of Torsade de Pointes and QT Prolongation With Antifungal Triazoles: Analysis Using a Pharmacovigilance Database

BACKGROUND/AIM

Torsade de pointes (TdP)/QT prolongation (QTP) is one of the most life-threatening adverse effects of antifungal triazoles. The aim of the present study was to evaluate the association of antifungal triazoles with TdP/QTP by age group and the profile of the time of TdP/QTP onset by analyzing the spontaneous adverse event database for Japan.

PATIENTS AND METHODS

Data registered in the Japanese Adverse Drug Event Report database (JADER) from April 2004 to March 2022 were analyzed. The association between the administration of antifungal triazoles and TdP/QTP according to age was evaluated using an adjusted reporting odds ratio (aROR). In addition, the time-to-onset of TdP/QTP after antifungal triazole treatment was analyzed using the Weibull distribution according to the route of administration.

RESULTS

Antifungal triazole treatment was associated with TdP/QTP (aROR=1.77, 95% confidence interval=1.52-2.07). In the subgroup analyses by age group, antifungal triazole treatments in patients ≤29 years old and ≥50 (except ≥90) years old were associated with TdP/QTP. The medians (quartiles) of time-to-onset for intravenous and oral antifungal triazole treatment were 8 (6-12) and 23 (8-86) days, respectively. In addition, the shape parameter in the Weibull distribution analysis of oral triazole treatment revealed that the hazard exhibited an early failure profile.

CONCLUSION

TdP/QTP is associated with antifungal triazoles even in young patients, and patients should be monitored for the development of TdP/QTP, especially early after the initiation of treatment.

Polypharmacy, Gender Disparities, and Ethnic and Racial Predispositions in Long QT Syndrome: An In-Depth Review

Long QT syndrome (LQTS) is a complex disorder of cardiac electrophysiology. It is characterized by delayed myocardial polarization leading to QT prolongation and alterations on the ST segment and T wave visible on electrocardiogram (ECG). Syncope is a common manifestation, and torsade de pointes (TdP) can lead to sudden cardiac death. Three major LQTS genes (KCI31, KCNH2, and SCN5) lead to most of the cases of LQTS. Lifestyle modifications, beta blockers, and implantable cardioverter defibrillator (ICD) placement are the main treatments for LQTS. Polypharmacy, including QT-prolonging drugs, has been shown to worsen LQTS. The impact on potassium channels and the human ether-a-go-go-related gene (hERG) is the mechanism behind the QT interval prolongation caused by these medications. There is an increased incidence of LQTS among African-American men and women as compared to Caucasians. Women with LQTS tend to have a higher mortality rate from the condition, especially during menstruation and shortly after giving birth. Genetic testing is reserved to those patientswho exhibit either a strong clinical index of suspicion or experience persistent QT prolongation despite their lack of symptoms. Knowing the genetics, racial, and gender discrepancies can help improve patient management and a better comprehension on each case. Proper understanding of how ion channels function and their interaction with medications will lead to a better comprehension and to develop effective forms to treat those patients.

Prevalence and Correlates of Electrocardiographic Abnormalities in Adults With HIV: Insights From the Randomized Trial to Prevent Vascular Events in HIV (REPRIEVE)

BACKGROUND

People with HIV (PWH) are at increased risk of cardiovasvular disease (CVD) and sudden cardiac death. Previous work has suggested an association between HIV infection and electrocardiographic (ECG) abnormalities. There are limited data on the burden of ECG abnormalities among PWH in a multiracial, multiethnic globally representative population.

SETTING

One hundred twenty sites in the Randomized Trial to Prevent Vascular Events in HIV (REPRIEVE).

METHODS

ECG findings were grouped into clinically relevant categories using sex-specific thresholds when indicated. We used the Fisher exact tests to assess associations of demographic characteristics and ECG abnormalities. We used logistic regression model to assess associations between demographic and HIV management measures, with adjustment.

RESULTS

We analyzed data for 7720 PWH (99% of participants) (median age 50 years, 69% male participants). There were 3346 (43%) Black or African American, 2680 (35%) White, and 1139 (15%) Asian participants. Most of the participants (97%) had viral load that was <400 copies/mL or 400 copies/mL had approximately twice the odds of prolonged QTc compared with those that were undetectable (adjusted OR: 2.05, 95% CI: 1.22 to 3.45).

CONCLUSIONS

Prolonged QTc is common among male, Asian, and REPRIEVE participants with higher viral loads. These relationships warrant future investigation of linkages to ensuing CVD events among PWH.

Prior use of medications for opioid use disorder in ED patients with opioid overdose: prevalence, misuse and overdose severity

OBJECTIVES

Medications for opioid use disorder (MOUD) reduce opioid overdose (OD) deaths; however, prevalence and misuse of MOUD in ED patients presenting with opioid overdose are unclear, as are any impacts of existing MOUD prescriptions on subsequent OD severity.

METHODS

This was a prospective observational cohort of ED patients with opioid OD at two tertiary-care hospitals from 2015 to 19. Patients with confirmed opioid OD (via urine toxicology) were included, while patients with alternate diagnoses, insufficient data, age < 18, and prisoners were excluded. OD severity was defined using: (a) hospital LOS (days); and (b) in-hospital mortality. Time trends by calendar year and associations between MOUD and study outcomes were calculated.

RESULTS

In 2829 ED patients with acute drug OD, 696 with confirmed opioid OD were included. Overall, 120 patients (17%) were previously prescribed any MOUD, and MOUD prevalence was significantly higher in 2018 and 2019 compared to 2016 (20.1% and 27.8% vs. 8.8%, p < 0.05). Odds of MOUD misuse were significantly higher for methadone (OR 3.96 95% CI 2.57-6.12) and lowest for buprenorphine (OR 1.16, p = NS). Mean LOS was over 50% longer for methadone (3.08 days) compared to buprenorphine and naltrexone (both 2.0 days, p = NS). Following adjustment for confounders, buprenorphine use was associated with significantly shorter LOS (IRR -0.44 (95%CI -0.85, -0.04)). Odds of death were 30% lower for patients on any MOUD (OR 0.70, 95%CI 0.09-5.72), but highest in the methadone group (OR 0.82, 95%CI 0.10-6.74).

CONCLUSIONS

While MOUD prevalence significantly increased over the study period, MOUD misuse occurred for patients taking methadone, and OD LOS overall was lower in patients with any prior buprenorphine prescription.

Genetic and Molecular Aspects of Drug-Induced QT Interval Prolongation

Long QT syndromes can be either acquired or congenital. Drugs are one of the many etiologies that may induce acquired long QT syndrome. In fact, many drugs frequently used in the clinical setting are a known risk factor for a prolonged QT interval, thus increasing the chances of developing torsade de pointes. The molecular mechanisms involved in the prolongation of the QT interval are common to most medications. However, there is considerable inter-individual variability in drug response, thus making the application of personalized medicine a relevant aspect in long QT syndrome, in order to evaluate the risk of every individual from a pharmacogenetic standpoint.

The Pharmacodynamics of Antipsychotic Drugs in Women and Men

Background: Animal and human experiments have confirmed sex differences in the expression of hepatic enzymes that metabolize antipsychotic drugs and that may, in this way, be partly responsible for the clinical sex/gender differences observed in the efficacy and tolerability of antipsychotic treatment. Aim: The aim of this mini review is to synthesize the literature on the pharmacodynamics of male/female differential response to antipsychotic drugs. Method: Relevant search terms were used to search for pre-clinical and human trials and analysis of antipsychotic differential drug response and occurrence/severity of adverse effects in women and men. Results: The search found that sex influences drug response via the amount of a given drug that enters the brain and the number of neurotransmitter receptors to which it can bind. Consequently, sex partly determines the efficacy of a specific drug and its liability to induce unwanted effects. There are other factors that can overshadow or enhance the dimorphic effect of sex, for instance, the host's age, hormonal status, diet and life style as well as the molecular structure of the drug and its dose, and the method of its administration. Most of all, the host's individual genetics affects each step of a drug's pharmacodynamics. Conclusion: On average, women's psychotic symptoms respond to antipsychotic drugs at doses lower than men's. This means that many women may be de facto overdosed and, thus, experience unnecessary adverse effects. That being said, factors such as genetics and age probably determine drug response and tolerability to a greater degree than do biological sex or gender social roles.

Drug-specific risk of severe QT prolongation following acute drug overdose

Background: Severe QT prolongation (SQTP) has been identified as a strong predictor of adverse cardiovascular events in acute drug overdose, but drug-specific causes of SQTP in the setting of acute drug overdose remain unclear. We aimed to perform the most definitive study to date describing drug-specific risk of SQTP following acute drug overdose.Methods: This was a prospective multicenter cohort study at >50 hospital sites across the US using the ToxIC Registry between 2015 and 2018. Inclusion criteria were adults (≥18 years) receiving medical toxicology consultation for acute drug overdose. The primary outcome was SQTP, which was defined using the computer automated Bazett QT correction (QTc) on the ECG with the previously validated cut point of 500 milliseconds. Mean difference in QTc was also calculated for specific drugs. Drugs associated with SQTP were analyzed using multivariable logistic regression to control for known confounders of QT risk (age, sex, race, cardiac disease).Results: From 25,303 patients screened, 6473 met inclusion criteria with SQTP occurring in 825 (13%). Drugs associated with increased adjusted odds of SQTP included Class III antidysrhythmics (sotalol), sodium channel blockers (amitriptyline, diphenhydramine, doxepin, imipramine, nortriptyline), antidepressants (bupropion, citalopram, escitalopram, trazodone), antipsychotics (haloperidol, quetiapine), and the antiemetic serotonin antagonist ondansetron.Conclusions: This large US cohort describes drug-specific risk of SQTP following acute drug overdose. Healthcare providers caring for acute drug overdoses from any of these implicated drugs should pay close attention to cardiac monitoring for occurrence of SQTP.

An Observational Study of QTc Prolongation in Critically Ill Patients: Identification of Incidence and Predictors

AIMS

Despite the importance of abnormal QTc interval values in intensive care unit (ICU) patients, there is a paucity of information on this topic. The current study was designed to identify the incidence and predictors of QTc prolongation in medical (M), surgical (S), and emergency (E) ICUs.

MATERIALS AND METHODS

A prospective observational study was conducted for 6 months. Patients more than 18 years old who admitted to MICU, SICU, and EICU were included in the study. Electrocardiogram (ECG) was taken on day 1, 3, and 5 of ICU admission. The QTc intervals >460 ms in male and >470 ms in female and increased >60 ms above baseline were considered QTc prolongation. Comparative analysis was done between two groups of patients (normal vs prolonged QTc). Logistic regression models were carried out to determine the predictors of QTc prolongation.

RESULTS

Incidence of QTc prolongation was 6.5, 9.8, and 15.7% on day 1, 3, and 5 of ICU admission, respectively. On day 1, the history of alcohol addiction and the reason of ICU admission were associated with a prolonged QTc. A significant association was demonstrated between administration of azithromycin and QTc prolongation on day 3. High serum creatinine and hospitalization in EICU were predictors of QTc prolongation on day 5 of ICU admission.

CONCLUSION

The QTc prolongation is relatively common among patients admitted to ICUs and its incidence increases with increasing length of hospital stay. Predictors of QTc prolongation may be affected by the duration of ICU admission. Physicians should consider these predictors particularly before prescribing QTc-prolonging drugs.

HOW TO CITE THIS ARTICLE

Farzanegan B, Hosseinpoor Z, Baniasadi S, Seyyedi SR, Rajabi M. An Observational Study of QTc Prolongation in Critically Ill Patients: Identification of Incidence and Predictors. Indian J Crit Care Med 2020;24(4):270-275.

Clinical predictors of adverse cardiovascular events for acute pediatric drug exposures

Context: Risk factors for adverse cardiovascular events (ACVE) from drug exposures have been well-characterized in adults but not studied in children. The objective of the present study is to describe the incidence, characteristics, and risk factors for in-hospital ACVEs among pediatric emergency department (ED) patients with acute drug exposures.Methods: This is a prospective cohort design evaluating patients in the Toxicology Investigators Consortium (ToxIC) Registry. Pediatric patients (age <18 years) who were evaluated at the bedside by a medical toxicologist for a suspected acute drug exposure were included. The primary outcome was in-hospital ACVE (myocardial injury, shock, ventricular dysrhythmia, or cardiac arrest). The secondary outcome was in-hospital death. Multiple logistic regression analyses were performed to examine novel clinical risk factors and extrapolate adult risk factors (bicarbonate <20 mEq/L; QTc ≥500 ms), for the primary/secondary outcomes.Results: Among the 13,097 patients (58.5% female), there were 278 in-hospital ACVEs (2.1%) and 39 in-hospital deaths (0.3%). Age and drug class of exposure (specifically opioids and cardiovascular drugs) were independently associated with ACVE. Compared with adolescents, children under 2 years old (OR: 0.41, 95% CI: 0.21-0.80), ages 2-6 (OR: 0.37, 95% CI: 0.21-0.80), and ages 7-12 (OR: 0.51, 95% CI: 0.27-0.95) were significantly less likely to experience an ACVE. Serum bicarbonate concentration <20 mEq/L (OR: 2.31, 95% CI: 1.48-3.60) and QTc ≥ 500 ms (OR: 2.83, 95% CI: 1.67-4.79) were independently associated with ACVE.Conclusion: Previously derived clinical predictors of ACVE from an adult drug overdose population were successfully extrapolated to this pediatric population. Novel associations with ACVE and death included adolescent age and opioid drug exposures. In the midst of the opioid crisis, these findings urgently warrant further investigation to combat adolescent opioid overdose morbidity and mortality.

Acquired Long QT Syndrome and Electrophysiology of Torsade de Pointes

Congenital long QT syndrome (LQTS) has been the most investigated cardiac ion channelopathy. Although congenital LQTS remains the domain of cardiologists, cardiac electrophysiologists and specialised centres, the much more frequently acquired LQTS is the domain of physicians and other members of healthcare teams required to make therapeutic decisions. This paper reviews the electrophysiological mechanisms of acquired LQTS, its ECG characteristics, clinical presentation, and management. The paper concludes with a comprehensive review of the electrophysiological mechanisms of torsade de pointes.

Acquired long QT syndrome and torsade de pointes

Since its initial description by Jervell and Lange-Nielsen in 1957, the congenital long QT syndrome (LQTS) has been the most investigated cardiac ion channelopathy. Although congenital LQTS continues to remain the domain of cardiologists, cardiac electrophysiologists, and specialized centers, the by far more frequent acquired drug-induced LQTS is the domain of all physicians and other members of the health care team who are required to make therapeutic decisions. This report will review the electrophysiological mechanisms of LQTS and torsade de pointes, electrocardiographic characteristics of acquired LQTS, its clinical presentation, management, and future directions in the field.

Impact of Drug Induced Long QT Syndrome: A Systematic Review

Background

Drug induced long QT syndrome is quite common in daily clinical practice but its impact is unknown.

Methods

PubMed and EMBASE databases (until May 2, 2017) were searched to identify studies reporting drug induced long QT syndrome and followed the PRISMA guidelines. The main outcomes measured in these studies were QTc prolongation, ventricular arrhythmias, torsade de pointes (TdP) and death.

Results

Out of 176 non-duplicate reports, 36 studies satisfied inclusion criteria and provided data on patients exposed to drugs that can potentially cause long QT. Totally, 14,756 patients were exposed and 930 patients (6.3%) were found to have QTc prolongation. The number of males was 6,400 and females were 5,723 patients. The mean age of the patients was 43.8 ± 9.36 years. Ventricular arrhythmias were found in 379 patients (2.6%), 26 patients were found to have premature atrial contractions (PACs) and premature ventricular contractions (PVCs). TdP was found in 49 patients (0.33 %), sudden cardiac death (SCD) was found in five patients and 586 patients were found to have all-cause mortality.

Conclusions

Around 6% of patients have risk of QT prolongation when exposed but only 0.3% developed TdP and 2.6% developed ventricular arrhythmias. Risk of developing arrhythmias is higher with concomitant use of multiple QT prolonging drugs.

Pharmacogenetics of Adverse Drug Reactions

Adverse drug reactions (ADRs) are an important cause of morbidity and mortality. Genetic factors predispose to many ADRs, affecting susceptibility to both type A and type B reactions. The overall contribution of genetics will vary according to drug and ADR, and should be considered when attempting to predict and prevent ADRs. Genetic risk factors are considered in detail for a number of type A ADRs, especially those relating to warfarin and thiopurines, and type B ADRs affecting skin, the liver, and the heart. As the availability of whole genome sequencing increases, it is likely that prospective genotype for particular ADRs prior to drug prescription will become more common in the future. Current examples of genetic testing to prevent ADRs which have already been implemented and future prospects for developments in the field are discussed in detail.

Cancer Pain Management: Opioid Analgesics, Part 2

Opioid analgesics are the cornerstone of moderate to severe cancer pain management, and do not have ceiling doses unless unmanageable adverse effects occur. Oral, short-acting pure μ agonists such as morphine are most frequently used, but other agents and administration formulations allow finding the right opioid and dose for most patients. In addition, clinicians must understand the metabolism, pharmacokinetics, and elimination of particular drugs to individualize opioid selection, select initial doses, and appropriately escalate doses to satisfactory pain relief or uncontrollable toxicity. Anticipation and proactive management of possible adverse effects, particularly constipation, confusion or delirium, opioid-specific adverse effects, and opioid abuse, are also integral to primary and secondary prophylaxis and management.

Pharmacogenetics of Drug-Induced QT Interval Prolongation: An Update

A prolonged QT interval is an important risk factor for ventricular arrhythmias and sudden cardiac death. QT prolongation can be caused by drugs. There are multiple risk factors for drug-induced QT prolongation, including genetic variation. QT prolongation is one of the most common reasons for withdrawal of drugs from the market, despite the fact that these drugs may be beneficial for certain patients and not harmful in every patient. Identifying genetic variants associated with drug-induced QT prolongation might add to tailored pharmacotherapy and prevent beneficial drugs from being withdrawn unnecessarily. In this review, our objective was to provide an overview of the genetic background of drug-induced QT prolongation, distinguishing pharmacokinetic and pharmacodynamic pathways. Pharmacokinetic-mediated genetic susceptibility is mainly characterized by variation in genes encoding drug-metabolizing cytochrome P450 enzymes or drug transporters. For instance, the P-glycoprotein drug transporter plays a role in the pharmacokinetic susceptibility of drug-induced QT prolongation. The pharmacodynamic component of genetic susceptibility is mainly characterized by genes known to be associated with QT interval duration in the general population and genes in which the causal mutations of congenital long QT syndromes are located. Ethnicity influences susceptibility to drug-induced QT interval prolongation, with Caucasians being more sensitive than other ethnicities. Research on the association between pharmacogenetic interactions and clinical endpoints such as sudden cardiac death is still limited. Future studies in this area could enable us to determine the risk of arrhythmias more adequately in clinical practice.

QT interval prolongation associated with low magnesium in chronic alcoholics

BACKGROUND

Alcoholism is a psychoactive drug-dependence with high prevalence throughout the world. Alcoholism has already been shown to be associated with electrical heart disorders, such as QT interval prolongation. Long QT, rare among healthy individuals (0.0017-0.31%), can trigger tachyarrhythmias and sudden death and might be caused by alcohol consumption itself and the resulting hypomagnesaemia.

METHODS

This case-control study assessed active alcoholics and alcoholics who have been abstinent for at least seven days to compare changes in electrocardiographic, clinical and laboratory analyses among groups.

RESULTS

A total of 166 alcoholics were evaluated, of which 62 were active and 104 abstinent alcoholics. Long QT was more prevalent among active alcoholics compared to abstinent alcoholics (16% vs. 2%, respectively, odds ratio (OR) 9.81, p=0.011), as was hypomagnesaemia (23% vs. 10%, OR 3.11, p=0.013). Serum magnesium levels were inversely proportional to the length of the corrected QT interval among active alcoholics (β=-35.1ms, p=0.005).

CONCLUSIONS

Active chronic alcoholics exhibited a higher association of long QT and hypomagnesaemia. Low serum magnesium levels were predictive of QT interval prolongation. Because the above changes potentially trigger fatal arrhythmias, it is of fundamental importance to consider the diagnostic possibility by routinely requesting electrocardiograms and serum magnesium level assessment during the treatment of chronic alcoholic patients.

Medical toxicologists' practice patterns regarding drug-induced QT prolongation in overdose patients: a survey in the United States of America, Europe, and Asia Pacific region

OBJECTIVE

To describe practice patterns of medical toxicologists in the United States of America (USA), Europe, and Asia Pacific Region regarding management of drug induced QT prolongation and torsades de pointes in overdose.

METHODS

A survey was developed to assess current practice patterns and consistency with guidelines published by the American Heart Association (AHA), American College of Cardiology (ACC), and European Society of Cardiology (ESC). It was reviewed by our department research committee and the American College of Medical Toxicology (ACMT). The ACMT, European Association of Poisons Centres and Clinical Toxicologists, and Asia Pacific Association of Medical Toxicology electronically disseminated the survey to their physician members in the USA, Europe and Asia Pacific Region.

RESULTS

The overall response rate was 37% (229/617) (36% USA; 32% Europe; 52% Asia Pacific Region). Twelve toxicologists from Asia Pacific Region and Europe used the QT nomogram (Australia-5, New Zealand-1, United Kingdom-1) or QT alone (France-1, Russia-1, Romania-1, Germany-1, Philippines-1), in lieu of the corrected QT (QTc) to determine risks of developing torsades de pointes. Because only those who used QTc could proceed through the remainder of the survey, only 217 could do so. Approximately half of the respondents (52%) did not calculate QTc manually and based decisions on the electrocardiogram machines automated measurement. For those who corrected the QT interval themselves, the most common formula used was Bazett's (40%). There is great variation in the QTc value considered prolonged. Most responders considered QTc greater than 450 ms in men (28%) and 460 ms in women (25%) to be prolonged. Interestingly, approximately 15% of participants did not consider the QTc prolonged until it exceeded 500 ms in both men and women. Given an overdose scenario of a male patient with a QTc of 560 ms, heart rate of 90 beats/minute, 59% would not recommend administering intravenous magnesium sulfate. Forty-five percent and 36% believed magnesium could shorten QTc and prevent torsades de pointes, respectively. In addition, almost 90% believed administering 1-2 boluses of intravenous magnesium is safe, even when serum magnesium is not available. In regards to cardiac pacing of patients with QT prolongation and torsades de pointes, only 38% of the participating toxicologists' responses agreed with AHA/ACC/ESC recommendations. Furthermore, 21% would not pace a patient who developed torsades de pointes regardless of the scenario.

DISCUSSION AND CONCLUSIONS

The results indicate that medical toxicologists have considerable heterogeneity in terms of management practices for overdose patients with QT prolongation and torsades de pointes. Medical toxicologists may benefit from developing evidence-based consensus guidelines for the management of this relatively common finding in overdose of QT-prolonging drugs.

Meta-analysis on efficacy of statins for prevention of contrast-induced acute kidney injury in patients undergoing coronary angiography

Contrast-induced acute kidney injury (CIAKI) is a leading cause of hospital-acquired acute kidney injury, and pretreatment with hydroxymethylglutaryl CoA reductase inhibitors (statins) have shown promise in prevention. A systematic review and meta-analysis was performed including randomized controlled trials of short-term high-dose statins (compared with either low-dose statin or placebo) for CIAKI prevention in patients undergoing coronary angiography. Study-specific odds ratios (ORs) were calculated, and between-study heterogeneity was assessed using the I(2) statistic. We used a random-effects model meta-analysis to pool the OR. Twelve RCTs, including 5,564 patients, were included. CIAKI occurred in 94 of 2,769 patients (3.4%) pretreated with high-dose statins and 213 of 2,795 patients (7.6%) in the low-dose or no-statin group (OR 0.43, 95% confidence interval [CI] 0.33 to 0.55, I(2) = 19%, p <0.001). Subgroup analysis showed that the occurrence of CIAKI did not differ in patients with diabetes (OR 0.60, 95% CI 0.43 to 0.85, I(2) = 0%, p = 0.004) or in patients with documented renal insufficiency (creatinine clearance <60 ml/min/m(2); OR 0.66, 95% CI 0.45 to 0.96, I(2) = 0%, p = 0.03). In conclusion, pretreatment with high-dose statins, compared with low-dose statins or placebo, in patients undergoing coronary angiography reduces the incidence of CIAKI. This benefit was seen irrespective of the presence of diabetes and chronic kidney disease. Future studies should identify optimum dosing protocols for each statin.