Prevention of torsade de pointes in hospital settings: a scientific statement from the American Heart Association and the American College of Cardiology Foundation

Sudden Cardiac Death: Pharmacotherapy and Proarrhythmic Drugs: A Nationwide Cohort Study in Denmark

OBJECTIVES

This study sought to describe the use of pharmacotherapy in a nationwide cohort of young patients with sudden cardiac death (SCD).

BACKGROUND

Several drugs have been associated with an increased risk of SCD and sudden arrhythmic death syndrome (SADS). It remains unclear how pharmacotherapy may contribute to the overall burden of SCD in the general population.

METHODS

This was a nationwide study that included all deaths that occurred between 2000 and 2009 and between 2007 and 2009 in people age 1 to 35 years and 36 to 49 years, respectively. Two physicians identified all SCDs through review of death certificates. Autopsy reports were collected. Pharmacotherapy prescribed within 90 days before SCD was identified in the Danish Registry of Medicinal Product Statistics.

RESULTS

We identified 1,363 SCDs; median age was 38 years (interquartile range: 29 to 45 years), and 72% (n = 975) were men. Autopsy was performed in 55%. Overall, 58% of SCD cases (n = 786) received at least 1 drug within 90 days before death. The most common drugs were analgesic drugs (n = 239; 18%), antihypertensive drugs (n = 234; 17%), and antibiotic drugs (n = 218; 16%). After multivariable adjustment, prescription of "brugadogenic" drugs or >1 QT-prolonging drug was associated with an increased risk of SADS compared with explained SCD (odds ratio: 2.16 [95% confidence interval: 1.12 to 4.17] and 2.91 [95% confidence interval: 1.46 to 5.81], respectively).

CONCLUSIONS

Pharmacotherapy was identified in 58% of the SCD cases. After multivariable adjustment, there was a 2- and 3-fold increased risk of SADS compared with explained SCD in patients receiving brugadogenic drugs or >1 QT-prolonging drug, respectively. Identification of high-risk patients is warranted to lower the burden of SCD.

Hypokalemia in women and methadone therapy are the strongest non-cardiologic factors associated with QT prolongation in an emergency department setting

BACKGROUND

Our primary objective was to determine the adjusted quantitative associations of clinical predictors with QT prolongation, a defining cause of Torsades de Pointes (TdP).

METHODS

A retrospective cohort study was performed on consecutive emergency department patients identified by ECG acquisition date, and heart rate corrected QT (QTc) and QRS durations. QTc was modeled as a function of clinical predictors with multiple linear regression.

RESULTS

1010 patients were included. The strongest predictors of QTc and their coefficients were: antidysrhythmic (26.1ms, 95% CI 15.6-36.6) and methadone (43.6ms, 95% CI 28.1-59.2) therapies, and genetic long QT syndrome diagnosis (32.6ms, 95% CI -4.7-70.0). The association of QTc with serum potassium was approximated by a two piecewise linear function that differed by sex. For potassium below 3.9mmol/L, QTc increased by 43.0ms (95% CI 26.2-59.7) and 29.5ms (95% CI 19.1-40.0) for every 1mmol/L decrease in potassium in women and men, respectively. TdP occurred in only 4/686 (0.6%) of patients with QTc≥500 and QRS<120, but mortality during the visit including hospitalization was 8.0%.

CONCLUSIONS

QTc duration is highly sensitive to hypokalemia, particularly in women. Methadone prolongs QTc remarkably compared to other non-cardiologic medicines. QTc>500 with normal QRS often signifies profound illness and substantial mortality risk, though not necessarily imminent TdP.

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.

T-Wave Morphology Analysis in Congenital Long QT Syndrome Discriminates Patients From Healthy Individuals

OBJECTIVES

This study aims to assess the capability of T-wave analysis to: 1) identify genotype-positive long QT syndrome (LQTS) patients; 2) identify LQTS patients with borderline or normal QTc interval (≤460 ms); and 3) classify LQTS subtype.

BACKGROUND

LQTS often presents with a nondiagnostic electrocardiogram (ECG). T-wave abnormalities may be the only marker of this potentially lethal arrhythmia syndrome.

METHODS

ECGs taken at rest in 108 patients (43 with LQTS1, 20 with LQTS2, and 45 control subjects) were evaluated for T-wave flatness, asymmetry, and notching, which produces a morphology combination score (MCS) of the 3 features (MCS = 1.6 × flatness + asymmetry + notch) using QT Guard Plus Software (GE Healthcare, Milwaukee, Wisconsin). To assess for heterogeneity of repolarization, the principal component analysis ratio 2 (PCA-2) was calculated.

RESULTS

Mean QTc intervals were 486 ± 50 ms (LQTS1), 479 ± 36 ms (LQTS2), and 418 ± 24 ms (control subjects) (p < 0.05). MCS and PCA-2 differed between LQTS patients and control subjects (MCS: 117.8 ± 57.4 vs. 71.9 ± 16.2; p < 0.001; PCA-2: 20.2 ± 10.4% vs. 14.6 ± 5.5%; p < 0.001), LQTS1 and LQTS2 patients (MCS: 96.3 ± 28.7 vs. 164 ± 75.2; p < 0.001; PCA-2: 17.8 ± 8.3% vs. 25 ± 12.6%; p < 0.001), and between LQTS patients with borderline or normal QTc intervals (n = 17) and control subjects (MCS: 105.7 ± 49.9 vs. 71.9 ± 16.2; p < 0.001; PCA-2: 18.1 ± 7.2% vs. 14.6 ± 5.5%; p < 0.001). T-wave metrics were consistent across multiple ECGs from individual patients based on the average intraclass correlation coefficient (MCS: 0.96; PCA-2: 0.86).

CONCLUSIONS

Automated T-wave morphology analysis accurately discriminates patients with pathogenic LQTS mutations from control subjects and between the 2 most common LQTS subtypes. Mutation carriers without baseline QTc prolongation were also identified. This may be a useful tool for screening families of LQTS patients, particularly when the QTc interval is subthreshold and genetic testing is unavailable.

Influence of Oral Progesterone Administration on Drug-Induced QT Interval Lengthening: A Randomized, Double-Blind, Placebo-Controlled Crossover Study

OBJECTIVES

We tested the hypothesis that oral progesterone administration attenuates drug-induced QT interval lengthening.

BACKGROUND

Evidence from preclinical and human investigations suggests that higher serum progesterone concentrations may be protective against drug-induced QT interval lengthening.

METHODS

In this prospective, double-blind, crossover study, 19 healthy female volunteers (21-40 years) were randomized to receive progesterone 400 mg or matching placebo orally once daily for 7 days timed to the menses phase of the menstrual cycle (between-phase washout period = 49 days). On day 7, ibutilide 0.003 mg/kg was infused over 10 minutes, after which QT intervals were recorded and blood samples collected for 12 hours. Prior to the treatment phases, subjects underwent ECG monitoring for 12 hours to calculate individualized heart rate-corrected QT intervals (QT_cI).

RESULTS

Fifteen subjects completed all study phases. Maximum serum ibutilide concentrations in the progesterone and placebo phases were similar (1247±770 vs 1172±709 pg/mL, p=0.43). Serum progesterone concentrations were higher during the progesterone phase (16.2±11.0 vs 1.2±1.0 ng/mL, p<0.0001), while serum estradiol concentrations in the two phases were similar (89.3±62.8 vs 71.8±31.7 pg/mL, p=0.36). Pre-ibutilide lead II QT_cI was significantly lower in the progesterone phase (412±15 vs 419±14 ms, p=0.04). Maximum ibutilide-associated QT_cI (443±17 vs 458±19 ms, p=0.003), maximum percent increase in QT_cI from pretreatment value (7.5±2.4 vs 9.3±3.4%, p=0.02) and area under the effect (QT_cI) curve during the first hour post-ibutilide (497±13 vs 510±16 ms-hr, p=0.002) were lower during the progesterone phase. Progesterone-associated adverse effects included fatigue/malaise and vertigo.

CONCLUSIONS

Oral progesterone administration attenuates drug-induced QT_cI lengthening.

Electrocardiographic Predictors of Torsadogenic Risk During Dofetilide or Sotalol Initiation: Utility of a Novel T Wave Analysis Program

INTRODUCTION

Initiation of class III anti-arrhythmic medications requires telemetric monitoring for ventricular arrhythmias and QT prolongation to reduce the risk of torsades de pointes (TdP). Heart rate-corrected QT interval (QTc) is an indicator of risk, however it is imperfect, and subtle abnormalities of repolarization have been linked with arrhythmogenesis.

PURPOSE

Identification of electrocardiographic predictors of torsadogenic risk through the application of a novel T wave analysis tool.

METHODS

Among all patients admitted to Mayo Clinic for initiation of dofetilide or sotalol, we identified 13 cases who developed drug-induced TdP and 26 age and sex matched controls that did not develop TdP. The immediate pre-TdP ECG of those with TdP was compared to the last ECG performed prior to hospital discharge in controls using a novel T wave program that quantified subtle changes in T wave morphology.

RESULTS

The QTc and 12 T wave parameters successfully distinguished TdP cases from controls. The top performing parameters were the QTc in lead V3 (mean case vs control 480 vs 420 msec, p < 0.001, r = 0.72) and T wave right slope in lead I (mean case vs control -840.29 vs -1668.71 mV/s, p = 0.002, r = 0.45). The addition of T wave right slope to QTc improved prediction accuracy from 79 to 88 %.

CONCLUSION

Our data demonstrate that, in addition to QTc, the T wave right slope is correlated strongly with TdP risk. This suggests that a computer-based repolarization measurement tool that integrates additional data beyond the QTc may identify patients with the greatest torsadogenic potential.

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.

High prevalence of risk factors in elderly patients using drugs associated with acquired torsades de pointes chronically in Colombia

AIMS

Medication is one of the main causes of long QT syndrome (LQTS) and torsades de pointes (TdP), and the older adult population is at particularly high risk. The aim of the present study was to describe the prescription patterns of drugs with a risk of TdP in the Colombian older adult population.

METHODS

Patients older than 65 years who received medication with a risk of TdP during three consecutive months were selected. The medication was obtained and classified according to the QT Drug List from Crediblemeds.org. The data were analysed using SPSS-22.

RESULTS

A total of 55 932 patients were chronically receiving QT-prolonging drugs; 61.9% (n = 34 ,632) were women and the mean age of the sample was 75.6 years. Drugs with a conditional risk were consumed by 95.2% of patients, 5.3% received drugs with a known risk and 2.9% received drugs with a possible risk. Two or more QT-prolonging drugs were consumed by 10.3% of the patients (n = 5786). Most of the sample (96.8%, n = 54 170) had at least one additional risk factor for LQTS, with a mean of 3.1 ± 0.9 risk factors. Patients receiving QT-prolonging drugs for psychiatric and neurological disease were at a higher risk of major polypharmacy [odds ratio (OR) 3.0; 95% confidence interval (CI) 2.80, 3.22) and of receiving high doses of QT-prolonging drugs (OR 3.8; 95% CI 3.52, 4.05).

CONCLUSIONS

The widespread use of medication that causes TdP and the high prevalence of additional risks in the older adult population raise the need for accurate prediction of risk and constant patient monitoring. Patients taking psychiatric drugs are at a higher risk of TdP.

Co-Prescription of QT-Interval Prolonging Drugs: An Analysis in a Large Cohort of Geriatric Patients

BACKGROUND

Drug-induced QT-interval prolongation is associated with occurrence of potentially fatal Torsades de Pointes arrhythmias (TdP). So far, data regarding the overall burden of QT-interval prolonging drugs (QT-drugs) in geriatric patients are limited.

OBJECTIVE

This study was performed to assess the individual burden of QT-interval prolonging drugs (QT-drugs) in geriatric polymedicated patients and to identify the most frequent and risky combinations of QT-drugs.

METHODS

In the discharge medication of geriatric patients between July 2009 and June 2013 from the Geriatrics in Bavaria-Database (GiB-DAT) (co)-prescriptions of QT-drugs were investigated. QT-drugs were classified according to a publicly available reference site (CredibleMeds®) as ALL-QT-drugs (associated with any QT-risk) or High-risk-QT-drugs (corresponding to QT-drugs with known risk of Torsades de Pointes according to CredibleMeds®) and in addition as SmPC-high-risk-QT-drugs (according to the German prescribing information (SmPC) contraindicated co-prescription with other QT-drugs).

RESULTS

Of a cohort of 130,434 geriatric patients (mean age 81 years, 67% women), prescribed a median of 8 drugs, 76,594 patients (58.7%) received at least one ALL-QT-drug. Co-prescriptions of two or more ALL-QT-drugs were observed in 28,768 (22.1%) patients. Particularly risky co-prescriptions of High-risk-QT-drugs or SmPC-high-risk-QT-drugs with at least on further QT-drug occurred in 55.9% (N = 12,633) and 54.2% (N = 12,429) of these patients, respectively. Consideration of SmPCs (SmPC-high-risk-QT-drugs) allowed the identification of an additional 15% (N = 3,999) patients taking a risky combination that was not covered by the commonly used CredibleMeds® classification. Only 20 drug-drug combinations accounted for more than 90% of these potentially most dangerous co-prescriptions.

CONCLUSION

In a geriatric study population co-prescriptions of two and more QT-drugs were common. A considerable proportion of QT-drugs with higher risk only could be detected by using more than one classification-system. Local adaption of international classifications can improve identification of patients at risk.

Drug safety of macrolide and quinolone antibiotics in a tertiary care hospital: administration of interacting co-medication and QT prolongation

PURPOSE

Some macrolide and quinolone antibiotics (MQABs) are associated with QT prolongation and life-threatening torsade de pointes (TdP) arrhythmia. MQAB may also inhibit cytochrome P450 isoenzymes and thereby cause pharmacokinetic drug interactions (DDIs). There is limited data on the frequency and management of such risks in clinical practice. We aimed to quantify co-administration of MQAB with interacting drugs and associated adverse drug reactions.

METHODS

We conducted an observational study within our pharmacoepidemiological database derived from electronic medical records of a tertiary care hospital. Among all users of MQAB associated with TdP, we determined the prevalence of additional QT-prolonging drugs and risk factors and identified contraindicated co-administrations of simvastatin, atorvastatin, or tizanidine. Electrocardiographic (ECG) monitoring and associated adverse events were validated in medical records.

RESULTS

Among 3444 administered courses of clarithromycin, erythromycin, azithromycin, ciprofloxacin, levofloxacin, or moxifloxacin, there were 1332 (38.7 %) with concomitant use of additional QT-prolonging drugs. Among those, we identified seven cases of drug-related QT prolongation, but 49.1 % had no ECG monitoring. Of all MQAB users, 547 (15.9 %) had hypokalemia. Forty-four MQAB users had contraindicated co-administrations of simvastatin, atorvastatin, or tizanidine and three of those related adverse drug reactions.

CONCLUSION

In the studied real-life setting, we found a considerable number of MQAB users with additional risk factors for TdP but no ECG monitoring. However, adverse drug reactions were rarely found, and costs vs. benefits of ECG monitoring have to be weighted. In contrast, avoidable risk factors and selected contraindicated pharmacokinetic interactions are clear targets for implementation as automated alerts in electronic prescribing systems.

Ventricular repolarization measures for arrhythmic risk stratification

Ventricular repolarization is a complex electrical phenomenon which represents a crucial stage in electrical cardiac activity. It is expressed on the surface electrocardiogram by the interval between the start of the QRS complex and the end of the T wave or U wave (QT). Several physiological, pathological and iatrogenic factors can influence ventricular repolarization. It has been demonstrated that small perturbations in this process can be a potential trigger of malignant arrhythmias, therefore the analysis of ventricular repolarization represents an interesting tool to implement risk stratification of arrhythmic events in different clinical settings. The aim of this review is to critically revise the traditional methods of static analysis of ventricular repolarization as well as those for dynamic evaluation, their prognostic significance and the possible application in daily clinical practice.

The Effect of a Combination Treatment Using Palonosetron, Promethazine, and Dexamethasone on the Prophylaxis of Postoperative Nausea and Vomiting and QTc Interval Duration in Patients Undergoing Craniotomy under General Anesthesia: A Pilot Study

Introduction

Postoperative nausea and vomiting (PONV) is a displeasing experience that distresses surgical patients during the first 24 h after a surgical procedure. The incidence of postoperative nausea occurs in about 50%, the incidence of postoperative vomiting is about 30%, and in high-risk patients, the PONV rate could be as high as 80%. Therefore, the study design of this single arm, non-randomized, pilot study assessed the efficacy and safety profile of a triple therapy combination with palonosetron, dexamethasone, and promethazine to prevent PONV in patients undergoing craniotomies under general anesthesia.

Methods

The research protocol was approved by the institutional review board and 40 subjects were provided written informed consent. At induction of anesthesia, a triple therapy of palonosetron 0.075 mg IV, dexamethasone 10 mg IV, and promethazine 25 mg IV was given as PONV prophylaxis. After surgery, subjects were transferred to the surgical intensive care unit or post anesthesia care unit as clinically indicated. Ondansetron 4 mg IV was administered as primary rescue medication to subjects with PONV symptoms. PONV was assessed and collected every 24 h for 5 days via direct interview and/or medical charts review.

Results

The overall incidence of PONV during the first 24 h after surgery was 30% (n = 12). The incidence of nausea and emesis 24 h after surgery was 30% (n = 12) and 7.5% (n = 3), respectively. The mean time to first emetic episode, first rescue, and first significant nausea was 31.3 (±33.6), 15.1 (±25.8), and 21.1 (±25.4) hours, respectively. The overall incidence of nausea and vomiting after 24–120 h period after surgery was 30% (n = 12). The percentage of subjects without emesis episodes over 24–120 h postoperatively was 70% (n = 28). No subjects presented a prolonged QTc interval ≥500 ms before and/or after surgery.

Conclusion

Our data demonstrated that this triple therapy regimen may be an adequate alternative regimen for the treatment of PONV in patients undergoing neurological surgery under general anesthesia. More studies with a control group should be performed to demonstrate the efficacy of this regimen and that palonosetron is a low risk for QTc prolongation.

ClinicalTrials.gov Identifier

NCT02635828 (https://clinicaltrials.gov/show/NCT02635828).

Ventricular repolarization measures for arrhythmic risk stratification

Ventricular repolarization is a complex electrical phenomenon which represents a crucial stage in electrical cardiac activity. It is expressed on the surface electrocardiogram by the interval between the start of the QRS complex and the end of the T wave or U wave (QT). Several physiological, pathological and iatrogenic factors can influence ventricular repolarization. It has been demonstrated that small perturbations in this process can be a potential trigger of malignant arrhythmias, therefore the analysis of ventricular repolarization represents an interesting tool to implement risk stratification of arrhythmic events in different clinical settings. The aim of this review is to critically revise the traditional methods of static analysis of ventricular repolarization as well as those for dynamic evaluation, their prognostic significance and the possible application in daily clinical practice.

Should We be Worried About QTc Prolongation Using Citalopram? A Review

Purpose:

Summarize available information regarding clinical impact of citalopram on the QTc interval.

Methods:

A literature search was conducted in Pubmed, EMBASE, and Cochrane databases using the MeSH term “long QT syndrome” and key word “citalopram” on July 11, 2014.

Results:

Thirty-one studies were evaluated with 4 included in this review. Studies were excluded if they reported acute overdoses of citalopram or did not report on patient-specific risk factors for long QT syndrome (eg, hypokalemia, bradycardia, and increased age). The majority of the available data is derived from case reports. A number of confounders complicate the determination of a causal link between QTc prolongation and citalopram. Of the 4 studies included for review, none identified significant QTc prolongation in patients taking citalopram 20 to 60 mg daily without the patients having one or more patient-specific risk factors for prolonged QTc.

Conclusion:

There is insufficient evidence to establish a causal link between citalopram 20 to 60 mg orally daily and increased risk of TdP. Further research is required to determine the clinical impact and association between citalopram 20 to 60 mg daily and QTc prolongation.

Evaluation of baseline corrected QT interval and azithromycin prescriptions in an academic medical center

BACKGROUND

Azithromycin is used in the inpatient setting for a variety of conditions. In 2013, the US Food and Drug Administration released a warning regarding risk for corrected QT (QTc) prolongation and subsequent arrhythmias. Knowledge of inpatient prescribing patterns of QTc prolonging medications with respect to patient risk factors for adverse cardiovascular events can help recognize safe use in light of these new warnings.

OBJECTIVE

To assess inpatient prescribing patterns, risk factors for QTc prolongation, and relationship between drug-drug interactions and cardiac monitoring in patients receiving azithromycin.

DESIGN

Retrospective cohort study.

PARTICIPANTS

One hundred inpatients ≥ 19 years of age were randomly selected from 1610 patient encounters between October 2012 and April 2013 who were administered at least 1 dose of azithromycin.

MEASUREMENTS

Length of stay, reason for use, therapy duration, and concomitant medications were recorded. Telemetry charges and baseline electrocardiogram (ECG) prior to administration were assessed.

RESULTS

Seventy-nine percent of azithromycin use was empiric. Sixty-five percent of patients received a baseline ECG prior to prescribing azithromycin, of which 60% had borderline or abnormal QTc prolongation. Seventy-six percent of patients were prescribed 2 or more QTc prolonging medications, of which there were more abnormal ECGs at baseline (P = 0.03) despite having telemetry ordered less than half of the time.

CONCLUSIONS

In a cohort of hospitalized patients, azithromycin was prescribed despite risk factors for QTc prolongation and administration of interacting medications. Selection of azithromycin by providers appears to be independent from these risk factors, and education and vigilance to drug-drug interactions may be useful in limiting cardiac events with prescribing azithromycin.

Antidepressant or Antipsychotic Overdose in the Intensive Care Unit - Identification of Patients at Risk

It is often advised that patients who have ingested an overdose of antidepressants (AD) or antipsychotics (AP) are monitored with continuous ECG for minimum of 12-24 hr. These patients are often observed in an ICU. Our aim was to identify the number of patients with AD and/or AP overdose without adverse signs at hospital admission that turned out to need intensive care treatment. The effect of the antidepressants overdose risk assessment (ADORA) system was evaluated in patients with antidepressant as well as antipsychotic overdose. Our hypothesis was that patients with low ADORA do not need intensive care treatment. This retrospective study was conducted in adult patients admitted to the ICU at Odense University Hospital after an overdose with AP and/or AD between 1 January 2009 and 1 September 2014. Patients with predefined adverse signs in the emergency department were excluded due to obvious need of intensive care. Of the 157 patients included, 12 patients (8%) developed events during the ICU stay. Only 3 patients received intubation, vasoactive drugs and/or dialysis. None developed ventricular dysrhythmias. There were no fatalities. All the patients with low-risk assessment by ADORA within the first 6 hr did not develop events within the first 24 hr after hospital admission. The vast majority of patients with AD and/or AP overdose and no adverse signs at admission did not require intensive care treatment. Low-risk ADORA identified patients with antidepressant as well as antipsychotic overdose who would not require initial intensive care treatment. This is the first time the ADORA system has been evaluated in patients with antidepressant as well as antipsychotic overdose.

Validation of continuous QTc measurement in critically ill patients

INTRODUCTION

Prolongation of the corrected QT interval (QTc) can lead to torsades de pointes. This study is designed to determine the validity of the continuous QTc (cQTc) measurement in critically ill patients.

METHODS

In a retrospective cohort study, QTc analysis was performed with manual measurements on a single selected lead from a 12-lead ECG and cQTc measurement obtained at the same time. In addition, automated QTc measurement from the 12-lead ECG was also included in the study. Validation was performed by calculating intraclass correlation coefficient (ICC), Pearson's correlation and Bland-Altman plot.

RESULTS

119 patients with QRS<120 ms were included with a mean cQTc of 468 ms (standard deviation (SD) 37) and mean manually measured QTc of 449 ms (SD 41) (p<0.001). Pearson's correlation was 0.65 (p<0.01), ICC was 0.65 (95% CI: 0.53-0.74). Bland-Altman plot shows a mean difference of 19.5 ms (limits of agreement (LOA) -44.6 to 83.7). For cQTc compared to automated QTc from the 12-lead ECG the intraclass correlation coefficient was 0.77 (95% CI: 0.68-0.83, p<0.001) and the Bland-Altman plot shows a mean difference of 7.8 ms (LOA -40.2 to 55.8).

CONCLUSION

cQTc measurement in critically ill patients with a QRS duration shorter than 120 ms shows an acceptable accuracy to be used in routine care.

Clinical effectiveness of dolutegravir in the treatment of HIV/AIDS

Dolutegravir (DTG) is a second-generation integrase strand transfer inhibitor (INSTI), which has now been licensed to be used in different countries including the UK. Earlier studies have demonstrated that DTG when used with nucleoside backbone in treatment-naïve and - experienced patients has been well tolerated and demonstrated virological suppression comparable to other INSTIs and superiority against other first-line agents, including efavirenz and boosted protease inhibitors. Like other INSTIs, DTG uses separate metabolic pathways compared to other antiretrovirals and is a minor substrate for CYP-450. It does not appear to have a significant interaction with drugs, which uses the CYP-450 system. Nonetheless, it uses renal solute transporters that may potentially inhibit the transport of other drugs and can have an effect on the elimination of other drugs. However, the impact of this mechanism appears to be very minimal and insignificant clinically. The side effect profiles of DTG are similar to raltegravir and have been found to be well tolerated. DTG has a long plasma half-life and is suitable for once daily use without the need for a boosting agent. DTG has all the potential to be used as a first-line drug in combination with other nucleoside backbones, especially in the form of a single tablet in combination with abacavir and lamivudine. The purpose of this review article is to present the summary of the available key information about the clinical usefulness of DTG in the treatment of HIV infection.

Rare genetic variants previously associated with congenital forms of long QT syndrome have little or no effect on the QT interval

AIMS

We studied whether variants previously associated with congenital long QT syndrome (cLQTS) have an effect on the QTc interval in a Danish population sample. Furthermore, we assessed whether carriers of variants in cLQTS-associated genes are more prone to experience syncope compared with non-carriers and whether carriers have an increased mortality compared with non-carriers.

METHODS AND RESULTS

All genetic variants previously associated with cLQTS were surveyed using the Human Gene Mutation Database. We screened a Danish population-based sample with available whole-exome sequencing data (n = 870) and genotype array data (n = 6161) for putative cLQTS genetic variants. In total, 33 of 1358 variants previously reported to associate with cLQTS were identified. Of these, 10 variants were found in 8 or more individuals. Electrocardiogram results showed normal mean QTc intervals in carriers compared with non-carriers. Syncope data analysis between variant and non-variant carriers showed that 4 of 227 (1.8%) and 95 of 5861 (1.6%) individuals, respectively, had experienced syncope during follow-up (P = 0.80). There was no significant difference in overall mortality rates between carriers [7/217 (3.2%)] and non-carriers [301/6453 (4.7%)] (P = 0.24).

CONCLUSION

We present QTc data and register data, indicating that 26 cLQTS-associated variants neither had any effect on the QTc intervals nor on syncope propensity or overall mortality. Based on the frequency of individual gene variants, we suggest that the 10 variants frequently identified, assumed to relate to cLQTS, are less likely to associate with a dominant monogenic form of the disease.

Long QT Syndrome: An Emerging Role for Inflammation and Immunity

The long QT syndrome (LQTS), classified as congenital or acquired, is a multi-factorial disorder of myocardial repolarization predisposing to life-threatening ventricular arrhythmias, particularly torsades de pointes. In the latest years, inflammation and immunity have been increasingly recognized as novel factors crucially involved in modulating ventricular repolarization. In the present paper, we critically review the available information on this topic, also analyzing putative mechanisms and potential interplays with the other etiologic factors, either acquired or inherited. Accumulating data indicate inflammatory activation as a potential cause of acquired LQTS. The putative underlying mechanisms are complex but essentially cytokine-mediated, including both direct actions on cardiomyocyte ion channels expression and function, and indirect effects resulting from an increased central nervous system sympathetic drive on the heart. Autoimmunity represents another recently arising cause of acquired LQTS. Indeed, increasing evidence demonstrates that autoantibodies may affect myocardial electric properties by directly cross-reacting with the cardiomyocyte and interfering with specific ion currents as a result of molecular mimicry mechanisms. Intriguingly, recent data suggest that inflammation and immunity may be also involved in modulating the clinical expression of congenital forms of LQTS, possibly triggering or enhancing electrical instability in patients who already are genetically predisposed to arrhythmias. In this view, targeting immuno-inflammatory pathways may in the future represent an attractive therapeutic approach in a number of LQTS patients, thus opening new exciting avenues in antiarrhythmic therapy.

Electrocardiographic findings in systemic lupus erythematosus: data from an international inception cohort

OBJECTIVE

To estimate the early prevalence of various electrocardiographic (EKG) abnormalities in patients with systemic lupus erythematosus (SLE) and to evaluate possible associations between repolarization changes (increased corrected QT [QTc] and QT dispersion [QTd]) and clinical and laboratory variables, including the anti-Ro/SSA level and specificity (52 or 60 kd).

METHODS

We studied adult SLE patients from 19 centers participating in the Systemic Lupus International Collaborating Clinics (SLICC) Inception Registry. Demographics, disease activity (Systemic Lupus Erythematosus Disease Activity Index 2000 [SLEDAI-2K]), disease damage (SLICC/American College of Rheumatology Damage Index [SDI]), and laboratory data from the baseline or first followup visit were assessed. Multivariate logistic and linear regression models were used to asses for any cross-sectional associations between anti-Ro/SSA and EKG repolarization abnormalities.

RESULTS

For the 779 patients included, mean ± SD age was 35.2 ± 13.8 years, 88.4% were women, and mean ± SD disease duration was 10.5 ± 14.5 months. Mean ± SD SLEDAI-2K score was 5.4 ± 5.6 and mean ± SD SDI score was 0.5 ± 1.0. EKG abnormalities were frequent and included nonspecific ST-T changes (30.9%), possible left ventricular hypertrophy (5.4%), and supraventricular arrhythmias (1.3%). A QTc ≥440 msec was found in 15.3%, while a QTc ≥460 msec was found in 5.3%. Mean ± SD QTd was 34.2 ± 14.7 msec and QTd ≥40 msec was frequent (38.1%). Neither the specificity nor the level of anti-Ro/SSA was associated with QTc duration or QTd, although confidence intervals were wide. Total SDI was significantly associated with a QTc interval exceeding 440 msec (odds ratio 1.38 [95% confidence interval 1.06, 1.79]).

CONCLUSION

A substantial proportion of patients with recent-onset SLE exhibited repolarization abnormalities, although severe abnormalities were rare.

The INCA trial (Impact of NOD2 genotype-guided antibiotic prevention on survival in patients with liver Cirrhosis and Ascites): study protocol for a randomized controlled trial

BACKGROUND

Patients with liver cirrhosis have a highly elevated risk of developing bacterial infections that significantly decrease survival rates. One of the most relevant infections is spontaneous bacterial peritonitis (SBP). Recently, NOD2 germline variants were found to be potential predictors of the development of infectious complications and mortality in patients with cirrhosis. The aim of the INCA (Impact of NOD2 genotype-guided antibiotic prevention on survival in patients with liver Cirrhosis and Ascites) trial is to investigate whether survival of this genetically defined high-risk group of patients with cirrhosis defined by the presence of NOD2 variants is improved by primary antibiotic prophylaxis of SBP.

METHODS/DESIGN

The INCA trial is a double-blind, placebo-controlled clinical trial with two parallel treatment arms (arm 1: norfloxacin 400 mg once daily; arm 2: placebo once daily; 12-month treatment and observational period). Balanced randomization of 186 eligible patients with stratification for the protein content of the ascites (<15 versus ≥ 15 g/L) and the study site is planned. In this multicenter national study, patients are recruited in at least 13 centers throughout Germany. The key inclusion criterion is the presence of a NOD2 risk variant in patients with decompensated liver cirrhosis. The most important exclusion criteria are current SBP or previous history of SBP and any long-term antibiotic prophylaxis. The primary endpoint is overall survival after 12 months of treatment. Secondary objectives are to evaluate whether the frequencies of SBP and other clinically relevant infections necessitating antibiotic treatment, as well as the total duration of unplanned hospitalization due to cirrhosis, differ in both study arms. Recruitment started in February 2014.

DISCUSSION

Preventive strategies are required to avoid life-threatening infections in patients with liver cirrhosis, but unselected use of antibiotics can trigger resistant bacteria and worsen outcome. Thus, individualized approaches that direct intervention only to patients with the highest risk are urgently needed. This trial meets this need by suggesting stratified prevention based on genetic risk assessment. To our knowledge, the INCA trial is first in the field of hepatology aimed at rapidly transferring and validating information on individual genetic risk into clinical decision algorithms.

TRIAL REGISTRATIONS

German Clinical Trials Register DRKS00005616 . Registered 22 January 2014. EU Clinical Trials Register EudraCT 2013-001626-26 . Registered 26 January 2015.

Cardiac risks associated with antibiotics: azithromycin and levofloxacin

INTRODUCTION

Azithromycin and levofloxacin have been shown to be efficacious in treating infections. The adverse drug events associated with azithromycin and levofloxacin were considered rare. However, the US FDA released warnings regarding the possible risk of QT prolongation with azithromycin and levofloxacin.

AREAS COVERED

Case reports/case series, observational studies and clinical trials assessing cardiovascular risks associated with azithromycin and levofloxacin were critically reviewed, including 15 case reports/series, 5 observational studies and 5 clinical trials that investigated the cardiac risks associated azithromycin and levofloxacin.

EXPERT OPINION

Results are discordant. Two retrospective studies utilizing large databases demonstrated an increased risk of cardiovascular death with azithromycin, when azithromycin was compared with amoxicillin. Two other retrospective studies found no difference in cardiovascular death associated with azithromycin and other antibiotics. For levofloxacin, the increased risk of cardiovascular death was only found in one retrospective study. Therefore, the risks and benefits of antibacterial therapies should be considered when making prescription decisions. This study should not preclude clinicians from avoiding azithromycin and levofloxacin. If a patient has an indication to receive an antibiotic and if azithromycin or levofloxacin is needed, it may be used, but the potential risks must be understood.

Droperidol for the Treatment of Acute Migraine Headaches

Objective: To evaluate the safety and efficacy of droperidol for the relief of acute migraine headaches. Data Sources: A MEDLINE search (1946 to August 2014) was performed using the following keywords and associated medical subject headings: droperidol, inapsine, headache, migraine, and migraine disorder.Study Selection and Data Extraction: The search was conducted to identify randomized controlled trials comparing droperidol with placebo or an active control in adult patients with acute migraine headaches that were published in English. Primary end points included acute headache improvement after the intervention. Safety end points included the frequency of extrapyramidal symptoms, somnolence, and cardiac adverse effects. Data Synthesis: In all, 5 manuscripts are included in this review. Patients presenting to the emergency department with acute headache desire rapid pain relief, which was the primary objective in each of the evaluated studies. Droperidol was better than placebo and at least as effective as comparator drugs such as prochlorperazine, meperidine, or olanzapine using droperidol doses of 2.5 to 5 mg, given either intramuscularly (IM) or intravenously (IV). The most commonly reported adverse effects were extrapyramidal symptoms and sedation. Cardiac adverse effects were not reported in any of the studies; however, only 2 articles described using cardiac monitoring. Conclusions: Parenteral droperidol is an effective option for the treatment of acute migraine. The minimum effective dose is 2.5 mg given IM or IV. Clinicians must be aware of the risk for adverse events, select appropriate patients, perform EKG monitoring for patients at risk of QTc prolongation, and institute treatment if necessary.

Quantitative T-wave alternans analysis for guiding medical therapy: an underexploited opportunity

Reducing the toll of sudden cardiac death (SCD) remains a major challenge in cardiology, as it is the leading cause of adult mortality in the industrially developed world, claiming 310,000 lives annually in the United States alone. The main contemporary noninvasive index of cardiovascular risk, left ventricular ejection fraction (LVEF), has not proved adequately reliable, as the majority of individuals who die suddenly have relatively preserved cardiac mechanical function. Monitoring of T-wave alternans (TWA), a beat-to-beat fluctuation in ST-segment or T-wave morphology, is an attractive approach to risk stratification on both scientific and clinical grounds, as this ECG phenomenon has been shown using the FDA-cleared Spectral and Modified Moving Average methods to assess risk for cardiovascular mortality including SCD in studies enrolling >12,000 individuals with depressed or preserved LVEF. The evidence supporting TWA as a therapeutic target is reviewed.

Impact of clinical decision support preventing the use of QT-prolonging medications for patients at risk for torsade de pointes

We developed and implemented a 'CPOE-QT Alert' system, that is, clinical decision support integrated in the computerized physician order entry system (CPOE), in 2011. The system identifies any attempts to order medications with risk of torsade de pointes (TdP) for patients with a history of significant QT prolongation (QTc ≥500 ms) and alerts the provider entering the order. We assessed its impact by comparing orders and subsequent medication administration before and after activation of the system. We found a significant decrease in the proportion of completed order per ordering attempt after system activation (94% (1293/1379) vs 77% (1888/2453), difference 16.8%; p<0.001). This resulted in a 13.9% reduction in the administration of those medications to patients. A significant decrease was observed across all provider types, educational levels, and specialties. The CPOE-QT Alert system successfully reduced exposure to QT-prolonging medications in high risk patients.

Efficacy and safety of haloperidol prophylaxis for delirium prevention in older medical and surgical at-risk patients acutely admitted to hospital through the emergency department: study protocol of a multicenter, randomised, double-blind, placebo-controlled clinical trial

BACKGROUND

Delirium is associated with substantial morbidity and mortality rates in elderly hospitalised patients, and a growing problem due to increase in life expectancy. Implementation of standardised non-pharmacological delirium prevention strategies is challenging and adherence remains low. Pharmacological delirium prevention with haloperidol, currently the drug of choice for delirium, seems promising. However, the generalisability of randomised controlled trial results is questionable since studies have only been performed in selected postoperative hip-surgery and intensive care unit patient populations. We therefore present the design of the multicenter, randomised, double-blind, placebo-controlled clinical trial on early pharmacological intervention to prevent delirium: haloperidol prophylaxis in older emergency department patients (The HARPOON study).

METHODS/DESIGN

In six Dutch hospitals, at-risk patients aged 70 years or older acutely admitted through the emergency department for general medicine and surgical specialties are randomised (n = 390) for treatment with prophylactic haloperidol 1 mg or placebo twice daily for a maximum of seven consecutive days. Primary outcome measure is the incidence of in-hospital delirium within seven days of start of the study intervention, diagnosed with the Confusion Assessment Method, and the Diagnostic and Statistical Manual of Mental Disorders, fourth edition criteria for delirium. Secondary outcome measures include delirium severity and duration assessed with the Delirium Rating Scale Revised 98; number of delirium-free days; adverse events; hospital length-of-stay; all-cause mortality; new institutionalisation; (Instrumental) Activities of Daily Living assessed with the Katz Index of ADL, and Lawton IADL scale; cognitive function assessed with the Six-item Cognitive Impairment Test, and the Dutch short form Informant Questionnaire on Cognitive Decline in the Elderly. Patients will be contacted by telephone three and six months post-discharge to collect data on cognitive- and physical function, home residency, all-cause hospital admissions, and all-cause mortality.

DISCUSSION

The HARPOON study will provide relevant information on the efficacy and safety of prophylactic haloperidol treatment for in-hospital delirium and its effects on relevant clinical outcomes in elderly at-risk medical and surgical patients.

TRIAL REGISTRATION

EudraCT Number: 201100476215; ClinicalTrials.gov Identifier: NCT01530308; Dutch Clinical Trial Registry: NTR3207.

Absence of an association between anti-Ro antibodies and prolonged QTc interval in systemic sclerosis: a multicenter study of 689 patients

OBJECTIVE

To examine the association between anti-Ro antibodies, namely anti-Ro60/SS-A and anti-Ro52/TRIM21, together and separately, and a prolonged QT interval corrected for heart rate (QTc) in systemic sclerosis (SSc) patients.

METHODS

A total of 689 SSc patients enrolled in a multicenter cohort study underwent a 12-lead resting EKG at baseline. The QTc interval was measured, and a QTc ≥ 440ms was considered prolonged. Detailed clinical data and sera of these patients were collected and positivity for anti-Ro60/SS-A and anti-Ro52/TRIM21 antibodies was determined using an addressable laser bead immunoassay (ALBIA).

RESULTS

QTc prolongation was common in this SSc cohort (25%). In a univariate analysis, Ro antibodies, together or separately, were not associated with prolongation of the QTc interval [mean difference in QTc in anti-Ro antibody positive versus negative subjects was -2.2ms (p = 0.5748), in anti-Ro60/SS-A antibody positive versus negative subjects was 1.3ms (p = 0.8616), and in anti-Ro52/TRIM21 antibody positive versus negative subjects was -3.3ms (p = 0.4106)]. In a multivariate logistic regression analysis adjusting for possible confounders, there was no association between prolonged QTc and anti-Ro antibodies [odds ratio (OR) = 0.74, 95% confidence interval (CI): 0.45, 1.22], anti-Ro60/SS-A antibodies (OR = 1.57, 95% CI: 0.72, 3.41), and anti-Ro52/TRIM21 antibodies (OR = 0.76, 95% CI: 0.46, 1.26). However, in both univariate and multivariate analyses, QTc prolongation was associated with longer disease duration, greater disease severity, and the presence of anti-RNA polymerase III antibodies.

CONCLUSIONS

QTc prolongation is common in SSc, although anti-Ro antibodies do not seem to be associated with it as is the case in systemic lupus erythematosus. The reasons for this difference as well as the cause of abnormalities in cardiac repolarization in SSc will require additional studies.

Corrected QT-interval prolongation and variability in intensive care patients

PURPOSE

Critically ill patients are at risk for prolongation of the interval between the Q wave and the T wave in the electrocardiogram (corrected QT [QTc]). Corrected QT prolongation is probably a dynamic process. It is unknown how many patients have a QTc prolongation during their intensive care stay and how variable QTc prolongation is.

MATERIALS AND METHODS

In a prospective cohort study, continuous 5-minute QTc measurements of 50 consecutive patients were collected. A prolonged QTc interval was more than 500 milliseconds for at least 15 minutes. The QT variance and variability index was used to evaluate QTc variation.

RESULTS

Fifty-two percent of included patients had a prolonged QTc interval. In a single patient, 0.2% to 91.3% of the QTc intervals over time were prolonged. The use of erythromycin and amiodarone was associated with the mean QTc (P = .02 and P = .006, respectively). The Acute Physiology and Chronic Health Evaluation IV and Sequential Organ Failure Assessment scores were significantly higher in patients with a prolonged QTc interval (30.8 vs 8.6 and 7 vs 5.5, respectively). Eighty-four percent of all patients received at least 1 QTc-prolonging drug. The QT variance and QTc variance were significantly higher in patients with a prolonged QTc (P = .019 and P = .001, respectively).

CONCLUSION

Continuous QTc monitoring showed a prolonged QTc interval in 52% of intensive care patients. Severity of illness and QT and QTc variances are higher in these patients.

Frequency of use of QT-interval prolonging drugs in psychiatry in Belgium

INTRODUCTION

Drug-induced QT-prolongation is an established risk factor for Torsade de pointes and sudden cardiac death. The list of QT-prolonging drugs is extensive and includes many drugs commonly used in psychiatry.

AIM

In this study we performed a cross-sectional analysis of medication profiles to assess the prevalence of drug interactions potentially leading to QT-prolongation.

SETTING

6 psychiatric hospitals in Flanders, Belgium.

METHODS

For each patient, the full medication list was screened for the presence of interactions, with special attention to those with an increased risk for QT-prolongation. Current practice on QT monitoring and prevention of drug-induced arrhythmia was assessed.

MAIN OUTCOME MEASURE

Number of drug interactions with risk of QT-prolongation.

RESULTS

592 patients (46 % female; mean age 55.7 ± 17.1 years) were included in the analysis. 113 QT-prolonging interactions were identified in 43 patients (7.3 %). QT-prolonging interactions occurred most frequently with antidepressants (n = 102) and antipsychotics (n = 100). The precautions and follow-up provided by the different institutions when combining QT-prolonging drugs were very diverse.

CONCLUSION

Drug combinations that are associated with QT-prolongation are frequently used in the chronic psychiatric setting. Persistent efforts should be undertaken to provide caregivers with clear guidelines on how to use these drugs in a responsible and safe way.

Effectiveness of a clinical decision support system for reducing the risk of QT interval prolongation in hospitalized patients

BACKGROUND

We evaluated the effectiveness of a computer clinical decision support system (CDSS) for reducing the risk of QT interval prolongation in hospitalized patients.

METHODS AND RESULTS

We evaluated 2400 patients admitted to cardiac care units at an urban academic medical center. A CDSS incorporating a validated risk score for QTc prolongation was developed and implemented using information extracted from patients' electronic medical records. When a drug associated with torsades de pointes was prescribed to a patient at moderate or high risk for QTc interval prolongation, a computer alert appeared on the screen to the pharmacist entering the order, who could then consult the prescriber on alternative therapies and implement more intensive monitoring. QTc interval prolongation was defined as QTc interval >500 ms or increase in QTc of ≥60 ms from baseline; for patients who presented with QTc >500 ms, QTc prolongation was defined solely as increase in QTc ≥60 ms from baseline. End points were assessed before (n=1200) and after (n=1200) implementation of the CDSS. CDSS implementation was independently associated with a reduced risk of QTc prolongation (adjusted odds ratio, 0.65; 95% confidence interval, 0.56-0.89; P<0.0001). Furthermore, CDSS implementation reduced the prescribing of noncardiac medications known to cause torsades de pointes, including fluoroquinolones and intravenous haloperidol (adjusted odds ratio, 0.79; 95% confidence interval, 0.63-0.91; P=0.03).

CONCLUSIONS

A computer CDSS incorporating a validated risk score for QTc prolongation influences the prescribing of QT-prolonging drugs and reduces the risk of QTc interval prolongation in hospitalized patients with torsades de pointes risk factors.

Chemotherapy and QT Prolongation: Overview With Clinical Perspective

OPINION STATEMENT

Cardiotoxic adverse events are of concern to physicians treating cancer patients; they are encountered with a variety of agents. Cardiac events may delay the approval of new drugs or impose burdensome monitoring requirements as either part of the pre-approval process or in the daily use of these agents. Among the cardiac issues are the development of QT prolongation and the fear of torsades de pointes (TdP), an unusual yet potentially fatal form of ventricular tachycardia associated with QT prolongation. Several risk factors, including electrolyte imbalance and polypharmacy with concomitant QT prolonging agents use can increase the risk of TdP in cancer patients; separating the individual contributions of the various triggers for TdP remains problematic. Understanding the individual risk of QT prolongation associated with particular chemotherapies can better differentiate between those shown to have higher risk vs. those with lower risk potential. Cardiac monitoring and electrocardiogram analysis require recognition of the common challenges with regard to the precise measurement of the QT interval such as the presence of U waves, intraventricular conduction delays, and heart rate correction. Rapid identification and treatment of QT prolongation and TdP is critical in mitigating the risk of sudden cardiac death in cancer patients. A multidisciplinary treatment approach among cardiologists and oncologists should be employed to help facilitate an appropriate balance between oncologic efficacy and adverse cardiac events.

Dofetilide induced torsade de pointes: mechanism, risk factors and management strategies

Dofetilide is an effective antiarrhythmic agent for conversion of atrial fibrillation and atrial flutter as well as maintenance of sinus rhythm in appropriately selected patients. However, as with other antiarrhythmic agents, proarrhythmia is a known adverse effect. The risk of dofetilide induced torsade de pointes (Tdp) is low when used with strict dosing criteria guided by renal function, QT interval and concomitant drug therapy. Benefit from dofetilide use must be individualized and weighed against the side effects and the role of other available treatment options. In this review, we discuss the underlying mechanism, risk factors and precautionary measures to avoid dofetilide induced QT prolongation and ventricular tachycardia/Tdp. We suggest a scheme for the management of QT prolongation, ventricular arrhythmia and Tdp as well.

Gene-environment interaction between SCN5A-1103Y and hypokalemia influences QT interval prolongation in African Americans: the Jackson Heart Study

BACKGROUND

African-American ancestry, hypokalemia, and QT interval prolongation on the electrocardiogram are all risk factors for sudden cardiac death (SCD), but their interactions remain to be characterized. SCN5A-1103Y is a common missense variant, of African ancestry, of the cardiac sodium channel gene. SCN5A-1103Y is known to interact with QT-prolonging factors to promote ventricular arrhythmias in persons at high risk for SCD, but its clinical impact in the general African-American population has not been established.

METHODS

We genotyped SCN5A-S1103Y in 4,476 participants of the Jackson Heart Study, a population-based cohort of African Americans. We investigated the effect of SCN5A-1103Y, including interaction with hypokalemia, on QT interval prolongation, a widely-used indicator of prolonged myocardial repolarization and predisposition to SCD. We then evaluated the two sub-components of the QT interval: QRS duration and JT interval.

RESULTS

The carrier frequency for SCN5A-1103Y was 15.4%. SCN5A-1103Y was associated with QT interval prolongation (2.7 milliseconds; P < .001) and potentiated the effect of hypokalemia on QT interval prolongation (14.6 milliseconds; P = .02). SCN5A-1103Y had opposing effects on the two sub-components of the QT interval, with shortening of QRS duration (-1.5 milliseconds; P = .001) and prolongation of the JT interval (3.4 milliseconds; P < .001). Hypokalemia was associated with diuretic use (78%; P < .001).

CONCLUSIONS

SCN5A-1103Y potentiates the effect of hypokalemia on prolonging myocardial repolarization in the general African-American population. These findings have clinical implications for modification of QT prolonging factors, such as hypokalemia, in the 15% of African Americans who are carriers of SCN5A-1103Y.