Prevalence of QT interval prolongation in patients admitted to cardiac care units and frequency of subsequent administration of QT interval-prolonging drugs: a prospective, observational study in a large urban academic medical center in the US

The Association of Proton Pump Inhibitors and QT Interval Prolongation in Critically Ill Patients

INTRODUCTION

Drug-induced QT interval prolongation has been reported to be related to life-threatening polymorphic ventricular tachycardia (torsade de pointes). Proton pump inhibitors (PPIs) are prescribed widely for hospitalized patients; the QT interval prolongation and torsade de pointes caused by PPIs were reported. We conducted a study to determine the association between PPI treatment and QT interval prolongation in critically ill patients.

METHODS

This study included patients with electrocardiography (ECG) reports from the Medical Information Mart for Intensive Care III database (MIMIC-III). Patients younger than 18 years, missing baseline laboratories and with QT interval prolongation before intensive care unit (ICU) admission were excluded. The end point was the diagnosis of QT interval prolongation reported by ECG.

RESULTS

This study included 24,512 ICU patients. Of them, 11,327 patients were treated with PPIs, 4181 with histamine 2 receptor antagonists (H2RAs) and 6351 without acid suppression therapy (non-AST); the incidence of QT interval prolongation were 8.5%, 3.3% and 3.4% respectively. After adjustment for demographics, electrolytes, comorbidities and medications, PPIs were associated a higher risk of QT interval prolongation compared with H2RAs (OR 1.66, 95% CI 1.36 - 2.03) and non-AST (OR 1.54, 95% CI 1.31 - 1.82), while there was not significant difference between H2RAs and non-AST (OR 0.93, 95% CI 0.73 - 1.17). In the propensity score matching population, the results were consistent. Pantoprazole (OR 2.14, 95% CI 1.52 - 3.03) and lansoprazole (OR 1.80, 95% CI: 1.18 - 2.76) showed a higher QT prolongation risk than omeprazole. Several drugs caused higher QT prolongation risk when used in combination with PPIs.

CONCLUSION

In ICU patients, the association between PPI prescription and increased risk of QT interval prolongation was independent of known QT-prolonging factors; pantoprazole and lansoprazole had a higher risk compared with omeprazole. The combination of PPIs and other QT-prolonging drugs should be avoided.

Genetic QT Score and Sleep Apnea as Predictors of Sudden Cardiac Death in the UK Biobank

Introduction

The goal of this study was to evaluate the association between a polygenic risk score (PRS) for QT prolongation (QTc-PRS), QTc intervals and mortality in patients enrolled in the UK Biobank with and without sleep apnea.

Methods

The QTc-PRS was calculated using allele copy number and previously reported effect estimates for each single nuclear polymorphism SNP. Competing-risk regression models adjusting for age, sex, BMI, QT prolonging medication, race, and comorbid cardiovascular conditions were used for sudden cardiac death (SCD) analyses.

Results

500,584 participants were evaluated (56.5 ±8 years, 54% women, 1.4% diagnosed with sleep apnea). A higher QTc-PRS was independently associated with the increased QTc interval duration (p<0.0001). The mean QTc for the top QTc-PRS quintile was 15 msec longer than the bottom quintile (p<0.001). Sleep apnea was found to be an effect modifier in the relationship between QTc-PRS and SCD. The adjusted HR per 5-unit change in QTc-PRS for SCD was 1.64 (95% CI 1.16 - 2.31, p=0.005) among those with sleep apnea and 1.04 (95% CI 0.95 - 1.14, p=0.44) among those without sleep apnea (p for interaction =0.01). Black participants with sleep apnea had significantly elevated adjusted risk of SCD compared to White participants (HR=9.6, 95% CI 1.24 - 74, p=0.03).

Conclusion

In the UK Biobank population, the QTc-PRS was associated with SCD among participants with sleep apnea but not among those without sleep apnea, indicating that sleep apnea is a significant modifier of the genetic risk. Black participants with sleep apnea had a particularly high risk of SCD.

Navigating the pharmacologic complexities of QTc prolongation: assessing the cumulative burden in individuals with serious mental illness

The scientific progress made in the pharmacologic management of serious mental illness (SMI) has been significant. However, the benefits of medication management must continually be weighed against the risks of adverse effects of the agents prescribed. While many medications pose increased danger of QTc prolongation, which may result in malignant arrhythmia and sudden cardiac death, the combination of medications contributing QTc risk can result in an impact of unpredictable pharmacodynamic magnitude. Pharmacists play a key role in communicating QTc risks to prescribers, however little if any clinical guidance informs clinicians of specific actions to take when initiating or continuing a clinically necessary combination that poses risk. This study is a cross-sectional view of Med Safety Scan (MSS) QT prolongation risk scores, generated from the ranking tool available from the CredibleMeds website, intended to provide greater understanding of overall risk of QT burden to assist in the prescribing of medications to patients with SMI in a psychiatric hospital.

Pollutants, including Organophosphorus and Organochloride Pesticides, May Increase the Risk of Cardiac Remodeling and Atrial Fibrillation: A Narrative Review

Atrial fibrillation (AF) is the most common type of cardiac rhythm disorder. Recent clinical and experimental studies reveal that environmental pollutants, including organophosphorus-organochloride pesticides and air pollution, may contribute to the development of cardiac arrhythmias including AF. Here, we discussed the unifying cascade of events that may explain the role of pollutant exposure in the development of AF. Following ingestion and inhalation of pollution-promoting toxic compounds, damage-associated molecular pattern (DAMP) stimuli activate the inflammatory response and oxidative stress that may negatively affect the respiratory, cognitive, digestive, and cardiac systems. Although the detailed mechanisms underlying the association between pollutant exposure and the incidence of AF are not completely elucidated, some clinical reports and fundamental research data support the idea that pollutant poisoning can provoke perturbed ion channel function, myocardial electrical abnormalities, decreased action potential duration, slowed conduction, contractile dysfunction, cardiac fibrosis, and arrhythmias including AF.

A QTc risk score in patients with obstructive sleep apnea

INTRODUCTION

Patients with obstructive sleep apnea (OSA) are at risk for QTc prolongation, a known risk factor for increased mortality. The pro-QTc score can help identify individuals at increased risk for mortality associated with increased QTc however, it has not been evaluated in patients with OSA. The goal of this study was to evaluate the pro-QTc score in patients with OSA.

METHODS

Medical records of patients undergoing a sleep study at our sleep center from February 2012 to August 2020 were analyzed. Presence or absence of OSA was determined by polysomnography. The pro-QTc score was calculated with 1 point assigned for each of the following: female sex, QT-prolonging diagnoses and conditions, QT-prolonging electrolyte abnormalities, and medications with known risk for QT-prolongation. Mortality was determined from the electronic medical record of an integrated healthcare system.

RESULTS

There were 2246 patients (age 58 ± 15 years, 54% male, 82 dead) with OSA and 421 patients (age 54 ± 18 years, 43% male, 18 dead) without OSA. Of those with OSA, 1628 (72.5%) had at least one risk factor for QTc prolongation. A higher pro-QTc score was associated with greater mortality in patients with OSA (HR 1.48 per pro-QTc score, p < 0.001, 95% CI 1.3-1.7) but not in patients without OSA (HR 1.25 per pro-QTc score, p = 0.30, 95% CI 0.82-1.9), after adjusting for age, body mass index (BMI), and smoking status.

CONCLUSION

In patients with OSA, a higher pro-QTc score was associated with greater mortality.

Relationship between a risk score for QT interval prolongation and mortality across rural and urban inpatient facilities

OBJECTIVES

To evaluate the relationship between a modified Tisdale QTc-risk score (QTc-RS) and inpatient mortality and length of stay in a broad inpatient population with an order for a medication with a known risk of torsades de pointes (TdP).

BACKGROUND

Managing the risk of TdP is challenging due to the number of medications with known risk of TdP and the complexity of precipitating factors. A model to predict risk of mortality may be useful to guide treatment decisions.

METHODS

This was a retrospective observational study using inpatient data from 28 healthcare facilities in the western United States. This risk score ranges from zero to 23 with weights applied to each risk factor based on a previous validation study. Logistic regression and a generalized linear model were performed to assess the relationship between QTc-RS and mortality and length of stay.

RESULTS

Between April and December 2020, a QTc-RS was calculated for 92,383 hospitalized patients. Common risk factors were female (55.0%); age > 67 years (32.1%); and receiving a medication with known risk of TdP (24.5%). A total of 2770 (3%) patients died during their hospitalization. Relative to patients with QTc-RS < 7, the odds ratio for mortality was 4.80 (95%CI:4.42-5.21) for patients with QTc-RS = 7-10 and 11.51 (95%CI:10.23-12.94) for those with QTc-RS ≥ 11. Length of hospital stay increased by 0.7 day for every unit increase in the risk score (p < 0.0001).

CONCLUSION

There is a strong relationship between increased mortality as well as longer duration of hospitalization with an increasing QTc-RS.

Prevalence and risk factors for acquired long QT syndrome in the emergency department: a retrospective observational study

BACKGROUND

Long QT syndrome (LQTS) is a heterogeneous syndrome that may be congenital or, more frequently, acquired. The real-world prevalence of acquired LQTS (aLQTS) in the emergency department (ED) remains to be determined. The aim of this study was to determine prevalence of aLQTS and its impact on symptoms on ED admissions.

METHODS

Electrocardiograms (ECG) of 5,056 consecutively patients admitted in the ED of a tertiary hospital between January 28th and March 17th of 2020 were reviewed. All patients with aLQTS were included. Clinical data with a focus on QT prolonging drugs and clinical factors were recorded. Statistical comparison was made between the groups with and without corrected QT (QTc) interval greater than 500 ms (value that is considered severely increased).

RESULTS

A total of 383 ECGs with prolonged QTc were recognized, corresponding to a prevalence of aLQTS at admission of 7.82%. Patients with aLQTS were more commonly men (53.3%) with an age of (73.49±14.79) years old and QTc interval of (505.3±32.4) ms. Only 20.4% of these patients with aLQTS were symptomatic. No ventricular arrhythmias were recorded. Patients with QT interval greater than 500 ms were more frequently female (59.5%; P<0.001) and were more frequently on QT prolonging drugs (77.3%; P=0.025). Main contributing factor was intake of antibiotics (odds ratio [OR] 4.680) followed by female gender (OR 2.473) and intake of antipsychotics (OR 1.925).

CONCLUSION

aLQTS is particularly prevalent in the ED. Female patients on antibiotics and antipsychotics are at particularly high risk. Efforts must be made to avoid, detect and treat aLQTS as early as possible.

Moderately Prolonged QTc in Computer-Assessed ECG, Random Variation or Significant Risk Factor? A Literature Review

Most ECGs in European hospitals are recorded with equipment giving computer measured intervals and interpretation of the recording. In addition to measurements of interval and QRS axis, this interpretation frequently provides the Bazett’s-corrected QTc time. The introduction of computer-corrected QTc revealed QTc prolongation to be a frequent condition among medical patients. Nevertheless, the finding is frequently overlooked by the treating physician. The authors combine experience from a local hospital with a review of the current literature in this field in order to elucidate the importance of this risk factor both as congenital long QT syndrome and as acquired QT prolongation.

Cardio-Oncology Drug Interactions: A Scientific Statement From the American Heart Association

In the cardio-oncology population, drug interactions are of particular importance given the complex pharmacological profile, narrow therapeutic index, and inherent risk of therapies used to manage cardiovascular disease and cancer. Drug interactions may be beneficial or detrimental to the desired therapeutic effect. Clinicians in both cardiology and oncology should be cognizant of these potential drug-drug interactions that may reduce the efficacy or safety of either cardiovascular or cancer therapies. These risks can be mitigated through increased recognition of potential drug-drug interaction, use of alternative medications when possible, and careful monitoring. This scientific statement provides clinicians with an overview of pharmacodynamic and pharmacokinetic drug-drug interactions in patients with cancer exposed to common cardiovascular and cancer medications.

Vomiting, electrolyte disturbance, and medications; the perfect storm for acquired long QT syndrome and cardiac arrest: a case report

Background

Acquired long QT syndrome is an important and preventable cause of cardiac arrest. Certain medications and electrolyte disturbance are common contributors, and often coexist. In this case, we report five contributors to cardiac arrest.

Case presentation

This case is of a 51-year-old Caucasian female patient who presented with vomiting associated with hypokalemia and hypomagnesemia. She subsequently received ondansetron and metoclopramide, on the background of chronic treatment with fluoxetine. She then suffered an in-hospital monitored cardiac arrest, with features of long QT and torsades de pointes retrospectively noted on her prearrest electrocardiogram. She was diagnosed with acquired long QT syndrome, and her QT interval later normalized after removal of offending causes.

Conclusions

This case highlights the importance of proper consideration prior to prescribing QT prolonging medications, especially in patients who have other risk factors for prolonged QT, such as electrolyte disturbances and pretreatment with QT prolonging medications.

Effect of Replacing Vendor QTc Alerts with a Custom QTc Risk Alert in Inpatients

OBJECTIVE

The aim of the study is to implement a customized QTc interval clinical decision support (CDS) alert strategy in our electronic health record for hospitalized patients and aimed at providers with the following objectives: minimize QTc prolongation, minimize exposure to QTc prolonging medications, and decrease overall QTc-related alerts. A strategy that was based on the validated QTc risk scoring tool and replacing medication knowledge vendor alerts with custom QTc prolongation alerts was implemented.

METHODS

This is a retrospective quasi-experimental study with a pre-intervention period (August 2019 to October 2019) and post-intervention period (December 2019 to February 2020). The custom alert was implemented in November 2019.

RESULTS

In the pre-implementation group, 361 (19.3%) patients developed QTc prolongation, and in the post-implementation group, 357 (19.6%) patients developed QTc prolongation (OR: 1.02, 95% CI: 0.87-1.20, p = 0.81). The odds ratio of an action taken post-implementation compared with pre-implementation was 18.90 (95% CI: 14.03-25.47, p <0. 001). There was also a decrease in total orders for QTc prolonging medications from 7,921 (5.5%) to 7,566 (5.3%) with an odds ratio of 0.96 (95% CI: 0.93-0.99, p = 0.01).

CONCLUSION

We were able to decrease patient exposure to QTc prolonging medications while not increasing the rate of QTc prolongation as well as improving alert action rate. Additionally, there was a decrease in QTc prolonging medication orders which illustrates the benefit of using a validated risk score with a customized CDS approach compared with a traditional vendor-based strategy. Further research is needed to confirm if an approach implemented at our organization can reduce QTc prolongation rates.

Anti-Ro/SSA Antibodies and the Autoimmune Long-QT Syndrome

Autoimmunity is increasingly recognized as a novel pathogenic mechanism for cardiac arrhythmias. Several arrhythmogenic autoantibodies have been identified, cross-reacting with different types of surface proteins critically involved in the cardiomyocyte electrophysiology, primarily ion channels (autoimmune cardiac channelopathies). Specifically, some of these autoantibodies can prolong the action potential duration leading to acquired long-QT syndrome (LQTS), a condition known to increase the risk of life-threatening ventricular arrhythmias, particularly Torsades de Pointes (TdP). The most investigated form of autoimmune LQTS is associated with the presence of circulating anti-Ro/SSA-antibodies, frequently found in patients with autoimmune diseases (AD), but also in a significant proportion of apparently healthy subjects of the general population. Accumulating evidence indicates that anti-Ro/SSA-antibodies can markedly delay the ventricular repolarization via a direct inhibitory cross-reaction with the extracellular pore region of the human-ether-a-go-go-related (hERG) potassium channel, resulting in a higher propensity for anti-Ro/SSA-positive subjects to develop LQTS and ventricular arrhythmias/TdP. Recent population data demonstrate that the risk of LQTS in subjects with circulating anti-Ro/SSA antibodies is significantly increased independent of a history of overt AD, intriguingly suggesting that these autoantibodies may silently contribute to a number of cases of ventricular arrhythmias and cardiac arrest in the general population. In this review, we highlight the current knowledge in this topic providing complementary basic, clinical and population health perspectives.

Development of a Risk Score for QT Prolongation in the Intensive Care Unit Using Time-Series Electrocardiogram Data and Electronic Medical Records

Objective

Drug-induced QT prolongation can lead to life-threatening arrhythmia. In the intensive care unit (ICU), various drugs are administered concurrently, which can increase the risk of QT prolongation. However, no well-validated method to evaluate the risk of QT prolongation in real-world clinical practice has been established. We developed a risk scoring model to continuously evaluate the quantitative risk of QT prolongation in real-world clinical practice in the ICU.

Methods

Continuous electrocardiogram (ECG) signals measured by patient monitoring devices and Electronic Medical Records data were collected for ICU patients. QT and RR intervals were measured from raw ECG data, and a corrected QT interval (QTc) was calculated by Bazett's formula. A case-crossover study design was adopted. A case was defined as an occurrence of QT prolongation ≥12 hours after any previous QT prolongation. The patients served as their own controls. Conditional logistic regression was conducted to analyze prescription, surgical history, and laboratory test data. Based on the regression analysis, a QTc prolongation risk scoring model was established.

RESULTS

In total, 811 ICU patients who experienced QT prolongation were included in this study. Prescription information for 13 drugs was included in the risk scoring model. In the validation dataset, the high-risk group showed a higher rate of QT prolongation than the low-and low moderate-risk groups.

Conclusions

Our proposed model may facilitate risk stratification for QT prolongation during ICU care as well as the selection of appropriate drugs to prevent QT prolongation.

Proarrhythmia assessment in treatment with hydroxychloroquine and azithromycin hospitalized elderly COVID-19 patients - our experience

The aim of our study was to characterize the repolarization disorders propensity induced by drug-drug interaction. In this observational retrospective study, we report our experience on all elderly patients with ascertained diagnosis of coronavirus disease 2019 through nasopharyngeal swab with real time-polymerase chain reaction at our Pugliese-Ciaccio hospital in Catanzaro, who received hydroxychloroquine (HCQ), with or without azithromycin (AZY). 33 hospitalized patients were examined. We calculated QT value, cQT, QT dispersion, and cQT dispersion and examined possible progression on the basal electrocardiogram (T0) and after the insertion of the drug (T1). The QT value is increased by T0 vs T1 (370±40.74 vs 420±36.91 ms; P=0.000), as well as the cQT value (408±25.40 vs 451.54±58.81; P=0.003), the QT dispersion (QTd: 36.36±14.53 vs 50.90±13.12 ms; P=0.000); the dispersion of cQTc (cQTd 46.27±18.72 vs 63.18±21.93 ms; P=0.001). The ΔQT was 37.44±44.09 while the ΔcQT was 32.01±56.47). The main determinant of QTc prolongation is the number of drug at risk of prolongation of the QT that could influence the ventricular repolarization phase. The use of HCQ in combination with AZY, in patients suffering from severe acute respiratory syndrome-related coronavirus-2, can favor the onset of serious side effects, even potentially fatal. Finally, the measures of QTd and cQTd confirmed additional electrocardiographic parameters useful in identifying patients being treated with drugs at risk of potential adverse arrhythmic events following drug interaction.

Drug-Associated QTc Prolongation in Geriatric Hospitalized Patients: A Cross-Sectional Study in Internal Medicine

Objective

The primary objectives of this prospective cross-sectional study were to estimate the prevalence of drug-related long QT syndrome (LQTS) and the prevalence of use of QT-prolonging drugs in older patients admitted to an internal medicine unit.

Methods

We screened consecutive patients hospitalized in an internal medicine unit over a 2-year period. A 12-lead electrocardiogram using an electrocardiograph with automated measurement of QT interval was recorded. Patient characteristics (age, sex, body mass index), drug treatments, and variables associated with QT interval prolongation, including hypothyroidism, type 2 diabetes mellitus, and cardiac disease, were also recorded. In addition, we also measured serum levels of potassium, calcium, magnesium, and creatinine at admission. The list of medications known to cause or to contribute to LQTS was obtained from CredibleMeds^®.

Results

A total of 243 patients were enrolled: mean ± standard deviation age, 79.65 ± 8.27 years; males, n = 121 (40.8%); mean corrected QT (QTc) interval, 453.70 ± 43.77 ms. Overall, 89/243 (36.6%) patients had a prolonged QTc interval, with 29/243 (11.9%) having QTc interval prolongation > 500 ms (11.9%). A vast majority were prescribed at least one QT-prolonging drug (218/243 [89.7%]), whereas 74/218 (30.5%) were receiving at least one medication with a known risk of Torsades des Pointes (TdP). Proton pump inhibitors were the second most commonly prescribed class of drugs. After logistic regression, male sex was independently associated with LQTS (odds ratio 2.85; 95% confidence interval 1.56–5.22; p = 0.001).

Conclusions

The prevalence of LQTS with QTc interval > 500 ms in geriatric inpatients was > 10%, and QT-prolonging drugs were frequently used on admission (more than 30% of patients were receiving drugs with a known risk of TdP).

Supplementary Information

The online version contains supplementary material available at 10.1007/s40801-021-00234-x.

Progress in the risk assessment of hydroxychloroquine in frail elderly people

Hydroxychloroquine (HCQ) is an antimalarial drug also known to have anti-inflammatory and antiviral effects. The antiviral action of HCQ has been a point of interest for many researchers because of its mechanism of action and the potential use it could have during the current COVID-19 pandemic. However, HCQ can cause QT interval prolongation. The current therapies used in COVID-19 are changing as the pandemic develops. The aim of this article is to promote a validated risk score for QT prolongation in multidimensional assessment of COVID-19 patients, especially in elderly and polypathological patients.

Impact of a clinical decision support tool targeting QT-prolonging medications

PURPOSE

To evaluate the impact of a newly implemented clinical decision support (CDS) tool targeting QT interval-prolonging medications on order verification and provider interventions.

METHODS

A multicenter, retrospective quasi-experimental study was conducted to evaluate provider response to CDS alerts triggered during ordering of QT-prolonging medications for adult patients. The primary outcome was the proportion of orders triggering QTc alerts that were continued without intervention during a specified preimplementation phase (n = 49) and during a postimplementation phase (n = 100). Patient risk factors for QTc prolongation, provider alert response, and interventions to reduce the risk of QTc-associated adverse events were evaluated.

RESULTS

The rate of order continuation without intervention was 82% in the preimplementation phase and 37% in the postimplementation phase, representing an 55% reduction in continued verified orders following implementation of the QT-focused CDS tool. Most alerts were initially responded to by the prescriber, with pharmacist intervention needed in only 33% of cases. There were no significant differences in patient QTc-related risk factors between the 2 study groups (P = 0.11); the postimplementation group had a higher proportion of patients using at least 2 QTc-prolonging medications (48%, compared to 26% in the preimplementation group; P = 0.02).

CONCLUSION

Implementation of the CDS tool was associated with a reduction in the proportion of orders continued without intervention in patients at high risk for QTc-related adverse events.

Predictive Validity of a QTc Interval Prolongation Risk Score in the Intensive Care Unit

BACKGROUND

Torsade de pointes is a form of polymorphic ventricular tachycardia associated with heart rate-corrected QT (QT_c ) interval prolongation. With approximately 24-61% of critically ill patients experiencing QT_c interval prolongation, a predictive tool to identify high-risk patients could assist in the monitoring and management in the intensive care unit (ICU). The Tisdale et al. Risk Score (TRS) is a predictive tool that was developed and validated in a cardiac critical care unit.

OBJECTIVES

The objective of this study was to evaluate the predictive validity (sensitivity and specificity) and likelihood ratios of the TRS in a medical ICU.

METHODS

This was a longitudinal, retrospective, cohort study of consecutive patients who met the inclusion criteria from October 2017 to June 2018 with a sample size of 264 patients. The sample size was derived based on the number of TRS covariates and an exploratory variable. Baseline characteristics and risk factors were documented from electronic health records. The first occurrence of QT_c interval prolongation, defined as a QT_c interval > 500 ms or an increase ≥ 60 ms above baseline, was the primary endpoint.

MAIN RESULTS

The sensitivity and specificity of the TRS for low-risk patients against the moderate-risk and high-risk patients were 97% (95% CI 91-99%) and 16% (95% CI 11-23%), respectively. These results corresponded to a positive likelihood ratio of 1.15 (95% CI 1.07-1.24) and a negative likelihood ratio of 0.20 (95% CI 0.06-0.65).

CONCLUSIONS

In conclusion, the TRS showed a high sensitivity, making it useful in identifying patients at risk of developing QT_c interval prolongation. Furthermore, patients categorized as low risk by the tool can be considered as having minimal risk of developing QT_c interval prolongation. Given the tool's low specificity, it does not reliably identify all patients at low risk of QT_c interval prolongation.

The effects of ondansetron versus dexamethasone on electrocardiographic markers of ventricular repolarization in children undergoing cochlear implant

INTRODUCTION

Congenital hearing loss is associated with cardiac rhythm disturbances namely long Q-T syndrome. This study was designed to investigate the effect of anti-emetic doses of ondansetron and dexamethasone on ECG recordings in children undergoing cochlear implant surgery.

METHODS

Sixty-three pediatric patients scheduled for elective cochlear implantation were enrolled in the study. Two patients were excluded as their baseline ECG showed long QT syndrome. Anesthesia was induced with fentanyl, propofol and atracurium and maintained with propofol. Dexamethasone 0.1 mg.kg^-1or ondansetron 0.2 mg.kg^-1was randomly administered for the participants approximately 30 min before the end of surgery. ECG recording was performed 15 min after induction of anesthesia and 15 min after dexamethasone/ondansetron administration. RR interval, QRS duration, QT interval, and Tp-e interval were measured by a blinded cardiologist.

RESULTS

Ondansetron resulted in no significant changes in RR, JTc and QTc intervals; while prolongedTp-e interval. Multivariable logistic regression analysis showed that use of ondansetron was an independent predictor of QTc prolongation after adjustment for age, gender and baseline QTc (OR = 17.94, CI 95% 1.97-168.70, p = 0.011). The incidence of postoperative retching/vomiting in ondansetron group was significantly lower than dexamethasone group. (3.2% vs. 26.7%, p = 0.011).

CONCLUSION

The risk of arrhythmias with the use of ondansetron in otherwise healthy candidates of cochlear implant is very low. However, the drug may induce significant changes in ECG parameters. The clinical significance of these changes in patients with cardiac conduction abnormalities should be investigated in further studies.

Predictors of Ventricular Dysrhythmias in Neurology Intensive Care Unit Patients with Prolonged QTc

INTRODUCTION

Acute neurological injury and several medications commonly administered in the Neuro ICU pose a risk of fatal cardiac dysrhythmias. The objective of this study is to identify the predictors of ventricular dysrhythmias in the Neuro ICU patients with prolonged QTc, thereby helping the clinicians make important treatment decisions.

METHODS

We performed a retrospective review of all consecutive adults admitted to the Neuro ICU from January 2015 to September 2015 with a QTc interval ≥ 450 ms on electrocardiogram.

RESULTS

A total of 170 patients with a mean age of 66 years (SD ± 16) were included in the final analysis. Eighty-seven patients (51%) were women. Median duration of hospitalization was 9 days (IQR 4-16). Most common primary diagnosis was ischemic stroke (38%) followed by cerebral hemorrhage (19%) and subarachnoid hemorrhage (8%). Mean QTc was 487 ms (SD ± 35, range 450-659 ms). There were 27 episodes (16%) of monomorphic non-sustained ventricular tachycardia and one episode of Torsades (1%). Three cardiac arrests (2%) were recorded, none resulting from ventricular dysrhythmias. In multivariate analysis, prolonged QTc ≥ 492 ms (p = 0.0008), supratentorial acute ischemic stroke (p = 0.005), prolonged hospitalization (p = 0.03), and premature ventricular complexes on ECG (p = 0.047) were all independently associated with increased risk of ventricular dysrhythmias.

CONCLUSIONS

In this group of patients with prolonged QTc in the Neuro ICU, we observed several episodes of non-sustained ventricular tachycardia and identified important risk factors associated with their occurrence. This knowledge is essential to inform clinical decisions.

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.

Heart Disease and Stroke Statistics-2020 Update: A Report From the American Heart Association

BACKGROUND

The American Heart Association, in conjunction with the National Institutes of Health, annually reports on the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The American Heart Association, through its Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update. The 2020 Statistical Update is the product of a full year's worth of effort by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. This year's edition includes data on the monitoring and benefits of cardiovascular health in the population, metrics to assess and monitor healthy diets, an enhanced focus on social determinants of health, a focus on the global burden of cardiovascular disease, and further evidence-based approaches to changing behaviors, implementation strategies, and implications of the American Heart Association's 2020 Impact Goals.

RESULTS

Each of the 26 chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policy makers, media professionals, clinicians, healthcare administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Development of a predictive model for drug-associated QT prolongation in the inpatient setting using electronic health record data

PURPOSE

We aimed to construct a dynamic model for predicting severe QT interval prolongation in hospitalized patients using inpatient electronic health record (EHR) data.

METHODS

A retrospective cohort consisting of all adults admitted to 2 large hospitals from January 2012 through October 2013 was established. Thirty-five risk factors for severe QT prolongation (defined as a Bazett's formula-corrected QT interval [QTc] of ≥500 msec or a QTc increase of ≥60 msec from baseline) were operationalized for automated EHR retrieval; upon univariate analyses, 26 factors were retained in models for predicting the 24-hour risk of QT events on hospital day 1 (the Day 1 model) and on hospital days 2-5 (the Days 2-5 model).

RESULTS

A total of 1,672 QT prolongation events occurred over 165,847 days of risk exposure during the study period. C statistics were 0.828 for the Day 1 model and 0.813 for the Days 2-5 model. Patients in the upper 50th percentile of calculated risk scores experienced 755 of 799 QT events (94%) allocated in the Day 1 model and 804 of 873 QT events (92%) allocated in the Days 2-5 model. Among patients in the 90th percentile, the Day 1 and Days 2-5 models captured 351 of 799 (44%) and 362 of 873 (41%) QT events, respectively.

CONCLUSION

The risk models derived from EHR data for all admitted patients had good predictive validity. All risk factors were operationalized from discrete EHR fields to allow full automation for real-time identification of high-risk patients. Further research to test the models in other health systems and evaluate their effectiveness on outcomes and patient care in clinical practice is recommended.

Drug interactions and creatinine levels are associated with QTc prolongation in intensive care units: a prospective, observational study

Background Prolongation of the QTc interval may lead to life threatening arrhythmias. QTc prolongation is common in intensive care unit (ICU) patients. The objectives of this study were to identify the role of drug-drug interactions (DDIs) and other predictors (age, sex, cardiovascular diseases, and electrolyte abnormalities) in life threatening QTc prolongation in patients admitted to medical (M), surgical (S) and emergency (E) ICUs. Methods This prospective, observational study included patients above the age of 18 years who were admitted to SICU, EICU, and MICU at a tertiary respiratory referral center. Electrocardiogram (ECG) monitoring was performed during the first 5 days of ICU admission. Risk factors and DDIs which were anticipated to be associated with the prolongation of the QTc interval were assessed for all patients. Results Two hundred patients were included in the study. QTc prolongation occurred in 10.7% of patients and the majority of patients presenting with QTc prolongation had creatinine levels above 1.3 mg/dL during their 5 days of ICU admission. Incidence of pharmacodynamic (PD) DDIs was significantly higher in patients with QTc prolongation vs. other patients. Creatinine levels above 1.3 mg/dL and PD DDIs were associated with QTc prolongation during 5 days of ICU admission. Conclusions High serum creatinine and PD DDIs can increase the risk of QTc prolongation in patients admitted to the ICU. QTc interval measurements should be performed prior to initiation or after starting any drug that is associated with QT prolongation, specifically in patients with the known risk factors.

Reining in the QTc: reducing the risk of Torsades de Pointes across a major health system

Hospitalized patients have a high prevalence of prolonged QTc and are a high-risk population for Torsades de Pointes (TdP). One modifiable risk factor for TdP is the use of QT prolonging drugs. Electronically alerting providers who are ordering QT prolonging drugs in at-risk patients may help to achieve safer prescribing practices. Our previous study decreased inappropriate prescription of IV haloperidol by 36% using a targeted "smart" electronic alert. We wanted to assess an approach to expanding this type of electronic alert to commonly used QT prolonging medications and evaluate how this would affect prescribing practice. This retrospective cohort study evaluated the impact of these alerts for 12 frequently prescribed high-risk medications across a major health system. Between October 2016 and June 2017, a total of 6453 alerts fired and resulted in 3020 (46.8%) orders being cancelled by the provider. Our focused electronic alert significantly decreased prescribing of QT prolonging medications in high-risk patients.

Predictors of mortality in high-risk patients with QT prolongation in a community hospital

Aims

To determine predictors of mortality in patients with corrected QT interval (QTc) ≥ 500 ms in a community hospital.

Methods and results

In this retrospective observational study, we searched the electrocardiogram (ECG) database at Telemark Hospital Trust, Norway, from January 2004 to December 2014. Medication, electrolyte abnormalities, and medical conditions known to prolong the QT interval were recorded. From the medical records, we assessed whether the prolonged QTc was noted by the health care providers. We identified 1531 patients (age = 70 ± 15 years, 59% female) with an ECG with QTc ≥ 500 ms. All-cause mortality during 952 (range 0-4161) days of follow-up was 50% (n =  765/1531). Main predictors of mortality were aborted cardiac arrest [hazard ratio (HR) 2.40, 95% confidence interval (CI) 1.44-4.01; P = 0.001], cerebral stroke/head trauma (HR 2.28, 95% CI 1.70-3.05; P < 0.001), and heart failure (HR 1.74, 95% CI 1.43-2.12; P< 0.001). Females with prolonged QTc had better survival compared with males (P = 0.006). We constructed a risk-weighted QTc mortality score. QT prolongation was acknowledged in the medical records in 12% of the cases.

Conclusions

QTc ≥ 500 ms was associated with high all-cause mortality with increased mortality in males compared with females. A new QTc mortality score was constructed to predict mortality. Only a minority of cases with prolonged QTc ≥ 500 ms were acknowledged in the medical records.

Incidence and outcomes of long QTc in acute medical admissions

AIMS

Prolonged QT interval on electrocardiogram (ECG) increases the risk of ventricular arrhythmia. Patients admitted to acute medical units (AMU) may be at risk of QT prolongation from multiple, recognised risk factors. Few data exist regarding incidence or outcomes of QT prolongation in acute general medical admissions. The aims were to determine the incidence of Bazett's-corrected QT (QTc) prolongation upon admission to AMU; the relationship between QTc and inpatient mortality, length of stay and readmission; proportion with prolonged QTc subsequently administered QT interval-prolonging drugs.

METHODS

Retrospective, observational study of 1000 consecutive patients admitted to an AMU in a large urban hospital.

EXCLUSION CRITERIA

age <18 years, ventricular pacing, poor quality/absent ECG. QTc determined manually from ECG obtained within 4-hours of admission. QTc prolongation considered ≥470 milliseconds (males) and ≥480 milliseconds (females). In both genders, >500 milliseconds was considered severe. Study end-points, (a) incidence of QTc prolongation at admission; (b) inpatient mortality, length of stay and readmission rates; (c) proportion with QTc prolongation subsequently administered QT interval-prolonging drugs.

RESULTS

Of 1000 patients, 288 patients were excluded, therefore final sample was n = 712. Patient age (mean ± SD) was 63.1 ± 19.4 years; females 49%. QTc prolongation was present in n = 50 (7%) at admission; 1.7% had QTc interval >500 ms. Of the 50 patients admitted with prolonged QTc, 6 (12%) were subsequently administered QT interval-prolonging drugs. QTc prolongation was not associated with worse inpatient mortality or readmission rate. Length of stay was greater in those with prolonged QTc, 7.2 (IQR 2.4-13.2) days vs 3.3 (IQR 1.3-10.0; P = 0.004), however, in a regression model, presence of QTc did not independently affect length of stay.

CONCLUSIONS

QTc interval prolongation is frequent among patients admitted to AMU. QT interval-prolonging drugs are commonly prescribed to patients presenting with prolonged QTc but whether this affects clinical outcomes is uncertain.

High prevalence of the risk factors for QT interval prolongation and associated drug-drug interactions in coronary care units

OBJECTIVES

Patients admitted in coronary care units are susceptible to QT interval prolongation due to numerous risk factors. The purpose of this study was to identify the prevalence of risk factors for QT interval prolongation; QT prolonging medications; drug-drug interactions; their predictors; and torsades de pointes risks of drugs.

METHODS

After obtaining approval, this cross-sectional study was carried out during one-year period in coronary care units of two major tertiary care hospitals of Khyber Pakhtunkhwa, Pakistan. The Arizona Center for Education and Research on Therapeutics QT drugs lists and Micromedex DrugReax® were used to identify the QT prolonging medications and QT prolonging drug-drug interactions.

RESULTS

Total 649 patients were included in this study. The most frequent QT prolonging risk factors included use of ≥ 1 QT prolonging drugs (74.9%) and myocardial infarction (61.3%). Total 181 patients were presented with 361 QT prolonging drug-drug interactions. There was significant association of the occurrence of QT prolonging drug-drug interactions with female gender (p = 0.01), 9-10 prescribed medications (p = 0.001), and > 10 prescribed medications (p < 0.001).

CONCLUSIONS

The majority of patients presented with multiple risk factors for QT prolongation in coronary care units which may precipitate lethal outcomes.

QTc interval prolongation in critically ill patients: Prevalence, risk factors and associated medications

PURPOSE

To investigate the prevalence and risk factors of acquired long QT syndrome (LQTS) on admission to a general Intensive Care Unit (ICU), and to assess the risk of LQTS associated with prescribed medications.

METHODS

Prospective observational, cross-sectional study approved by the Institutional Review Board. Between May 2014 and July 2016, 412 patients >18 years-old consecutively admitted to the ICU of a university hospital were included. LQTS was defined as a QT interval on the admission electrocardiogram corrected using Bazett's formula (QTc) >460 ms for men and >470 ms for women. All medications administered within 24 hours before admission were recorded. Logistic regression was used.

RESULTS

LQTS prevalence was 27.9%. In LQTS patients, 70.4% had ≥ 1 LQTS-inducing drug prescribed in the 24 hours prior to ICU admission versus 70.4% in non-LQTS patients (p = 0.99). Bradycardia and Charlson morbidity index score are independent risk factors for LQTS. Haloperidol (OR 4.416), amiodarone (OR 2.509) and furosemide (OR 1.895) were associated with LQTS, as well as another drug not yet described, namely clopidogrel (OR 2.241).

CONCLUSIONS

The LQTS is highly prevalent in critically ill patients, ICU patients are often admitted with LQTS-inducing medications, and patients with slow heart rate or with high Charlson comorbidity index should be evaluated for LQTS.

Monitoring the corrected QT in the acute care setting: A comparison of the 12‑lead ECG and bedside monitor

INTRODUCTION

Prolongation of the QT interval is a well-recognized complication associated with many commonly used medications. Emergency Department monitoring of the corrected QT (QTc) both before and after medication administration is typically performed using the 12‑lead electrocardiogram (ECG). The purpose of this study is to compare the QTc reported on the 12‑lead ECG to that reported by single brand of bedside monitor.

METHODS

A convenience sample of emergency department patients over the age of 18 undergoing bedside monitoring and who had an ECG ordered by their treating physician were enrolled. These patients underwent simultaneous ECG and monitor QTc calculation. The primary outcome of interest was the correlation between the monitor and ECG QTc. Secondary outcomes included ability of each method to identify patients with a QTc >500ms and the ability of each method to identify patients with a QTc <450ms.

RESULTS

A total of 125 patients had simultaneous ECG and monitor QTc measurements recorded. There was moderate correlation between the monitor and ECG QTc (Pearson's correlation coefficient=0.55). The median difference between the ECG QTc and the monitor QTc (ECG QTc minus monitor QTc) was -7ms (IQR -23 to 11ms).

CONCLUSION

We found that there was moderate correlation between the QTc reported on the 12 lead ECG and that reported by the bedside monitor. This correlation is not strong enough to support the use of the bedside monitor as a substitute for the 12‑lead ECG when evaluating a patient's QTc.

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.

Providers' Response to Clinical Decision Support for QT Prolonging Drugs

Commonly used drugs in hospital setting can cause QT prolongation and trigger life-threatening arrhythmias. We evaluate changes in prescribing behavior after the implementation of a clinical decision support system to prevent the use of QT prolonging medications in the hospital setting. We conducted a quasi-experimental study, before and after the implementation of a clinical decision support system integrated in the electronic medical record (QT-alert system). This system detects patients at risk of significant QT prolongation (QTc>500ms) and alerts providers ordering QT prolonging drugs. We reviewed the electronic health record to assess the provider's responses which were classified as "action taken" (QT drug avoided, QT drug changed, other QT drug(s) avoided, ECG monitoring, electrolytes monitoring, QT issue acknowledged, other actions) or "no action taken". Approximately, 15.5% (95/612) of the alerts were followed by a provider's action in the pre-intervention phase compared with 21% (228/1085) in the post-intervention phase (p=0.006). The most common type of actions taken during pre-intervention phase compared to post-intervention phase were ECG monitoring (8% vs. 13%, p=0.002) and QT issue acknowledgment (2.1% vs. 4.1%, p=0.03). Notably, there was no significant difference for other actions including QT drug avoided (p=0.8), QT drug changed (p=0.06) and other QT drug(s) avoided (p=0.3). Our study demonstrated that the QT alert system prompted a higher proportion of providers to take action on patients at risk of complications. However, the overall impact was modest underscoring the need for educating providers and optimizing clinical decision support to further reduce drug-induced QT prolongation.

QT interval prolongation in hospitalized patients on cardiology wards: a prospective observational study

PURPOSE

Prolonged QT interval may lead to a lethal form of arrhythmia, torsades de pointes (TdP), which is associated with cardiovascular mortality. Therefore, we aimed to identify prevalence of QT interval prolongation, compare clinical characteristics of patients with normal and prolonged QT interval, and identify predictors of QT interval prolongation.

METHODS

A prospective observational study was conducted in cardiology wards of two teaching hospitals in Pakistan. Bazett's correction formula was used for the calculation of QTc interval. Prevalence of QT prolongation and pro-QTc scores were calculated. Comparative analysis was performed with respect to various clinical characteristics by applying t test and chi-square test. Odds ratios were calculated using regression analysis.

RESULTS

Among 417 patients, 44.6% were found having prolonged QT interval, of which, 17.3% presented with an abnormally high QTc interval (> 500 ms). Significant difference was recorded between the groups (normal vs. prolonged) with respect to age, all prescribed medications, QT drugs, number of risk factors, QT-DDIs (QT-prolonging drug-drug interactions), gender, and diuretics use. Multivariate logistic regression analysis showed significant results for various predictors such as male gender (p = 0.03), various age categories 41-50 years (p = 0.04), 51-60 years (p = 0.01), and > 60 years (p < 0.001), and diuretics (p = 0.008).

CONCLUSION

A substantial number of patients in cardiology wards presented with QT prolongation. Proper considerations are needed in order to minimize the associated risk particularly in patients with abnormally high QT prolongation, old age, polypharmacy, one or more QT-prolonging drugs, and high pro-QTc scores.

Drug-Induced QTc Prolongation

QTc prolongation has a high prevalence of and is associated with increased all-cause mortality. Nonetheless, QTc prolonging medications are often used during patient hospitalizations despite baseline prolongation and QTc changes. Data regarding the real-world relative risk of QTc prolongation in the hospital setting are lacking. In this study, we sought to quantify the degree and relative risk of QTc prolongation in patients receiving Arizona Center for Education and Research on Therapeutics (AzCERT) "known risk" medications. Electronic medical records of patients receiving an electrocardiogram at the University of Chicago, admitted in 2011 were analyzed. The longest QTc interval and medications administered within the preceding 24 hours were evaluated. Medications were classified into 4 categories according to the AzCERT classification. Of a total of 14,804 patients, mean QTc intervals were 485 versus 454 ms for men and 469 versus 453 ms for women receiving known risk medications compared with those receiving no risk medications (p <0.001). The rate of QTc prolongation was 71% versus 48% for men and 50% versus 34% for women, respectively. There was no significant increase in QTc prolongation for patients administered multiple QT-relevant medications or for those administered only conditional or possible risk medications. In conclusion, the prevalence of significant QTc prolongation in patients receiving AzCERT known risk medications is high. This may be a reflection of inadequate awareness or overall quality inadequacies.

Provider Response to QTc Prolongation on Standard 12-Lead EKG: Do We Notice or Do We Care?

BACKGROUND

Drugs and electrolyte imbalances are widely recognized as common triggers of a prolonged QT interval. We conducted a chart review to assess provider response to prolonged QT reported on a standard 12-lead electrocardiogram (EKG).

METHODS

We identified all Veterans Affairs Pittsburgh Healthcare System patients in a 6-month period with an EKG reporting a corrected QT (QTc) >500 ms. We excluded confounding or uninterpretable EKGs. Charts were reviewed to assess medications and electrolytes at the time of the EKG as well as the setting (inpatient vs outpatient) in which the EKG was obtained. Provider documentation of QTc and any corrective measures were sought.

RESULTS

After exclusions, 106 patients were included in this analysis (87 [82%] inpatient and 19 [18%] outpatient). Most were male (101, 95%) with a mean age of 63.5 ± 10.6 years. At the time of index EKG, most patients were receiving at least one (72, 68%), and frequently two or more (35, 33%), QTc prolonging medications. Providers documented QTc prolongation in 20 inpatients (19%). Drugs were adjusted or discontinued in only two inpatients (2%). There were 14 patients (14%) with potassium level <3.6 mmol/L and 10 of 69 (14%) patients had a magnesium level <1.7 mg/dL.

CONCLUSION

Patients with prolonged QTc on EKG were more likely to be inpatients than outpatients. Inpatients were more likely to be receiving multiple types and classes of QTc prolonging medications. In the vast majority of cases, providers did not address the prolonged QTc and only rarely initiated remedial actions.

Clinical pharmacists' opportunities to reduce inappropriate prescription of QT-prolonging medications: calls to action

All biologically active agents carry the potential to lead to adverse reactions in certain individuals, including serious cardiac adverse reactions. Since 2005, there has been an international regulatory landscape governing the investigation of a new drug's propensity to lead to the polymorphic ventricular tachycardia Torsades de Pointes (Torsades), a rare but potentially fatal occurrence. When a regulatory agency considers it appropriate, warning information is placed in a medicine's patient information leaflet (label) concerning drug-induced QT interval prolongation, a phenomenon associated with Torsades. In busy hospital settings, however, prescribers, including cardiologists, make injudicious prescribing decisions that put patients at risk. The science of cardiac safety, including the clinical trials that generate the information about QT prolongation in patient information leaflets, is frequently not part of the curriculum at Schools of Pharmacy. Given that medication-induced cardiotoxicity is extremely serious, we advocate that schools integrate the science of cardiac safety into existing therapeutics/therapeutic medication monitoring courses. Given their expert knowledge of pharmacology, pharmacists working as part of a hospital's clinical team would then be even better placed to review prescribing decisions concerning medications that prolong the QT interval, and alert prescribers in cases where reassessing their decisions seems prudent. National pharmacy societies or other pertinent professional societies could create practice guidelines to support graduates once employed as clinical pharmacists. Clinical pharmacists are well placed to be influential arbiters of safer prescribing decisions. Cardiac safety education during their pharmacy training and practice guideline support from professional societies during their careers can optimize this role.

Is There a Role for Genetics in the Prevention of Sudden Cardiac Death?

The identification of patients at risk for sudden cardiac death (SCD) is fundamental for both acquired cardiovascular diseases (such as coronary artery diseases, CAD) and inherited arrhythmia syndromes (such as the long-QT syndrome, LQTS). Genetics may play a role in both situations, although the potential to exploit this information to reduce the burden of SCD varies among these two groups. Concerning acquired cardiovascular diseases, which affect most of the general population, preliminary data suggest an association between genetics and the risk of dying suddenly. The maximal utility, instead, is reached in inherited arrhythmia syndromes, where the discovery of monogenic diseases such as LQTS tracked the way for the first genotype-phenotype correlations. The aim of this review is to provide a general overview focusing on the current genetic knowledge and on the present and future applicability for prevention in these two populations at risk for SCD.

Severe Torsades de Pointes with acquired QT prolongation

Torsades de pointes (TdP) is a fatal polymorphic ventricular tachycardia in association with congenital or acquired QT prolongation. Concomitant electrolyte disturbances and drugs potentiate the development of TdP. We describe a severe case of refractory TdP in the setting of methadone, cocaine, hypokalemia and hypomagnesemia. The successful treatment was achieved with the administration of magnesium, isoproterenol, and electrolyte replacement.

Drug-induced QT interval prolongation and torsades de pointes: Role of the pharmacist in risk assessment, prevention and management

Torsades de pointes (TdP) is a life-threatening arrhythmia associated with prolongation of the corrected QT (QTc) interval on the electrocardiogram. More than 100 drugs available in Canada, including widely used antibiotics, antidepressants, cardiovascular drugs and many others, may cause QTc interval prolongation and TdP. Risk factors for TdP include QTc interval >500 ms, increase in QTc interval ≥60 ms from the pretreatment value, advanced age, female sex, acute myocardial infarction, heart failure with reduced ejection fraction, hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, treatment with diuretics and elevated plasma concentrations of QTc interval-prolonging drugs due to drug interactions, inadequate dose adjustment of renally eliminated drugs in patients with kidney disease and rapid intravenous administration. Pharmacokinetic drug interactions associated with the highest risk of TdP include antifungal agents, macrolide antibiotics (except azithromycin) and drugs to treat human immunodeficiency virus interacting with amiodarone, disopyramide, dofetilide or pimozide. Other important pharmacokinetic interactions include antidepressants (bupropion, duloxetine, fluoxetine, paroxetine) interacting with flecainide, quinidine or thioridazine. Pharmacists play an important role in minimizing the risk of drug-induced QTc interval prolongation and TdP through knowledge of drugs that are associated with a known or possible risk of TdP, individualized assessment of risk of drug-induced QTc interval prolongation, awareness of drug interactions most likely to result in TdP and attention to dose reduction of renally eliminated QTc interval-prolonging drugs in patients with kidney disease. Treatment of hemodynamically stable TdP consists of discontinuation of the offending drug(s), correction of electrolyte abnormalities and administration of intravenous magnesium sulfate 1 to 2 g.

Incidence of Sustained Ventricular Tachycardia in Patients with Prolonged QTc After the Administration of Azithromycin: A Retrospective Study

Background

Azithromycin has been associated with abnormalities of cardiac repolarization and development of torsades de pointes. Observational data suggest that the risk of death from cardiovascular causes is increased in patients taking azithromycin. Little is known regarding the risk of ventricular arrhythmia in patients with prolongation of the corrected QT interval who receive azithromycin.

Objective

The purpose of this study was to determine the incidence of sustained ventricular tachycardia in patients with prolonged corrected QT (QTc) who subsequently received azithromycin.

Methods

We performed a retrospective cohort analysis of the incidence of sustained ventricular tachycardia in patients with prolonged QTc (greater than 450 ms) who successively received intravenous (IV) and/or oral azithromycin. Patients hospitalized in a tertiary care teaching hospital between November 2009 and June 2012 were included in the study. The primary outcome was sustained ventricular tachycardia documented in patients on telemetry.

Results

Of the 103 patients enrolled in the study, only one patient experienced the primary outcome (0.97 %). The event occurred 1 day after the administration of a single dose of 500 mg IV azithromycin.

Conclusion

The risk of sustained ventricular tachycardia was 0.97 % in our cohort of patients with prolonged QTc who subsequently received azithromycin. Given the small size of this study, additional research is needed to determine the true incidence of arrhythmia in the population.

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.

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.

Genetic screening in sudden cardiac death in the young can save future lives

Background

Autopsy of sudden cardiac death (SCD) in the young shows a structurally and histologically normal heart in about one third of cases. Sudden death in these cases is believed to be attributed in a high percentage to inherited arrhythmogenic diseases. The purpose of this study was to investigate the value of performing post-mortem genetic analysis for autopsy-negative sudden unexplained death (SUD) in 1 to 35 year olds.

Methods and results

From January 2009 to December 2011, samples from 15 cases suffering SUD were referred to the Department of Clinical Genetics, Umeå University Hospital, Sweden, for molecular genetic evaluation. PCR and bidirectional Sanger sequencing of genes important for long QT syndrome (LQTS), short QT syndrome (SQTS), Brugada syndrome type 1 (BrS1), and catecholaminergic polymorphic ventricular tachycardia (CPVT) (KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2, and RYR2) was performed. Multiplex ligation-dependent probe amplification (MLPA) was used to detect large deletions or duplications in the LQTS genes. Six pathogenic sequence variants (four LQTS and two CPVT) were discovered in 15 SUD cases (40 %). Ten first-degree family members were found to be mutation carriers (seven LQTS and three CPVT).

Conclusion

Cardiac ion channel genetic testing in autopsy-negative sudden death victims has a high diagnostic yield, with identification of the disease in 40 % of families. First-degree family members should be offered predictive testing, clinical evaluation, and treatment with the ultimate goal to prevent sudden death.

Association between a prolonged corrected QT interval and outcomes in patients in a medical Intensive Care Unit

Introduction:

Patients admitted into a medical Intensive Care Unit (ICU) have varying illnesses and risk factors. An electrocardiogram (ECG) is a useful tool to assess the cardiac status. The aim of the study was to determine the prevalence of QT prolongation of the ECG in patients admitted to a medical ICU in a tertiary hospital, to assess outcomes in terms of mortality, cardiovascular events, and duration of ICU stay.

Materials and Methods:

Prospective observational study, 6 months duration, assessing the prevalence of prolonged corrected QT interval (QTc) at admission into a medical ICU. A QTc calculated by Bazett's formula, of >440 ms for males and >460 ms for females was considered prolonged. Details of illness, clinical and lab parameters were monitored.

Results:

The total number of patients screened was 182. There was a high prevalence of prolonged QTc (30%) on admission to the ICU. This reduced to 19% on day 3 (P = 0.011). In patients with a prolonged QTc the odds ratio of adverse outcome from ICU was 3.17 (confidence interval [CI]: 1.52–6.63) (P = 0.001) and of adverse outcome for hospital stay was 2.27 (CI: 1.11–4.66) (P = 0.014). In the study, 35% of all patients received drugs with QT prolonging action. Of patients with a prolonged QTc at admission 18 (35%) received a QT prolonging drug.

Conclusions:

We found that prolonged QTc is common (30%) in our medical ICU at admission and a large proportion (35%) received drugs capable of prolonging QT interval. These patients with QTc prolongation have a higher odds ratio for adverse outcomes.

The prevalence of long QT interval in post-operative intensive care unit patients

The severity of patient illnesses and medication complexity in post-operative critically ill patients increase the risk for a prolonged QT interval. We determined the prevalence of prolonged QTc in surgical intensive care unit (SICU) patients. We performed a prospective cross-sectional study over a 15-month period at a major academic center. SICU pre-admission and admission EKGs, patient demographics, and laboratory values were analyzed. QTc was evaluated as both a continuous and dichotomous outcome (prolonged QTc > 440 ms). 281 patients were included in the study: 92 % (n = 257) post-operative and 8 % (n = 24) non-operative. On pre-admission EKGs, 32 % of the post-operative group and 42 % of the non-operative group had prolonged QTc (p = 0.25); on post-admission EKGs, 67 % of the post-operative group but only 33 % of the non-operative group had prolonged QTc (p < 0.01). The average change in QTc in the post-operative group was +30.7 ms, as compared to +2 ms in the non-operative group (p < 0.01). On multivariable adjustment for long QTc as a dichotomous outcome, pre-admission prolonged QTc (OR 3.93, CI 1.93-8.00) and having had an operative procedure (OR 4.04, CI 1.67-9.83) were associated with developing prolonged QTc. For QTc as a continuous outcome, intra-operative beta-blocker use was associated with a statistically-significant decrease in QTc duration. None of the patients developed a lethal arrhythmia in the ICU. Prolonged QTc is common among post-operative SICU patients (67 %), however lethal arrhythmias are uncommon. The operative experience increases the risk for long QTc.

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.