Impact of Age and Sex on QT Prolongation in Patients Receiving Psychotropics

How much should we still worry about QTc prolongation in rifampicin-resistant tuberculosis? ECG findings from TB-PRACTECAL clinical trial

Regimens for the treatment of rifampicin-resistant tuberculosis currently rely on the use of QT-prolonging agents. Using data from the randomized controlled trial, TB-PRACTECAL, we investigated differences in QTcF among participants in the three interventional arms: BPaL (bedaquiline, pretomanid, and linezolid), BPaLC (BPaL with clofazimine), and BPaLM (BPaL with moxifloxacin). Additionally, we assessed whether age, body mass index, and country were causally associated with QTcF prolongation. The trial included participants from South Africa, Uzbekistan, and Belarus. A post hoc analysis of electrocardiogram data was undertaken. Random effects regression was used to model QTcF longitudinally over 24 weeks and causal frameworks guided the analysis of non-randomized independent variables. 328 participants were included in BPaL-based arms. The longitudinal analysis of investigational arms showed an initial QTcF steep increase in the first week. QTcF trajectories between weeks 2 and 24 differed slightly by regimen, with highest mean peak for BPaLC (QTcF 446.5 ms). Overall, there were 397 QTcF >450 ms (of 3,744) and only one QTcF >500 ms. The odds of QTcF >450 ms among participants in any investigational arm, was 8.33 times higher in Uzbekistan compared to Belarus (95% confidence interval: 3.25-21.33). No effect on QTcF prolongation was found for baseline age or body mass index (BMI). Clinically significant QTc prolongation was rare in this cohort of closely monitored participants. Across BPaL-based regimens, BPaLC showed a slightly longer and sustained effect on QTcF prolongation, but the differences (both in magnitude of change and trajectory over time) were clinically unimportant. The disparity in the risk of QTc prolongation across countries would be an important factor to further investigate when evaluating monitoring strategies.

CLINICAL TRIALS

This study is registered with ClinicalTrials.gov as NCT02589782.

Determinants/Predictors of QT Abnormalities in Patients on Psychotropic Medications in a Nigerian Tertiary Hospital

Cardiovascular disease is a major global burden and a leading cause of premature death among patients with severe mental illness. Over time, research and clinical practice have paid increased attention to the impact of psychiatric medications on cardiac repolarization. In a resource-limited setting, it is common for psychotropic medications to be initiated and maintained in an outpatient setting without baseline or follow up ECG. This study evaluated the determinants and predictors of QT abnormalities among patient taking psychotropic drugs. We conducted a cross-sectional study in a population of 150 psychiatric patients on psychotropics and 75 controls. We studied the effects of various psychotropic drugs on QT dispersion (QTd) and corrected QT interval (QTc) as well as correlation with the types and dosages of psychotropic drugs used. All the subjects had detailed clinical examination and resting electrocardiogram (ECG) at 25 mm/sec done. QTc was determined using Bazett formula and QTd was determined by subtracting shortest from longest QT in 12-lead ECG. The prevalence of prolonged QTc and QTd as well as the mean QTc and QTd were significantly higher in patients than the control group. The mean QTc was significantly higher in patient on typical antipsychotics compared to those on atypical antipsychotics. Age, heart rate and antipsychotic dose in chlorpromazine equivalent were predictors of QTc with the heart rate being the most powerful predictor among them. Psychotropic drugs use is associated with QTc and QTd prolongation with age, heart rate and antipsychotic dose as predictors of QTc.

Factors associated with prolonged QTc interval in Iranian population: MASHAD cohort study

AIM

QTc interval prolongation is a growing global issue which can cause torsades de pointes, a potentially fatal arrhythmia. We aimed to identify risk factors for prolonged QT interval in men and women.

METHODS

The Mashhad stroke and heart atherosclerotic disorder (MASHAD) cohort study collected electrocardiogram interval data. QT was corrected for heart rate using the Bazett's formula. Ordinal logistic regression with crude (univariable) and adjusted (multivariate) association analyses in the form of odds ratio and corresponding 95% confidence interval (CI) were used to identify the factors associated with QTc prolongation.

RESULTS

A total of 8878 individuals including 5318 females and 3560 males, aged 35 to 65 years, were included in this cross-sectional study. Participants with QTc prolongation were more likely to be older and have hypercholesterolemia, hypertension (HTN), and Type 2 diabetes mellitus (T2DM), but to have lower levels of physical activity (P < 0.05). Age (OR = 1.68, 95%CI = 1.18-2.39), hypercholesterolemia (OR = 1.77, 95%CI = 1.24-2.51), HTN (OR = 1.36, 95%CI = 1.06-1.73), T2DM (OR = 1.59, 95%CI = 1.19-2.13), severe anxiety (OR = 1.80, 95%CI = 1.05-3.11) and mild depression (OR = 1.38, 95%CI = 1.01-1.88) were independent risk factors for prolonged QTc interval in men. For women, only HTN (OR = 1.29, 95%CI = 1.02-1.63) and T2DM (OR = 1.50, 95%CI = 1.14-1.97) were independent risk factors.

CONCLUSIONS

Older age, Hypercholesterolemia, HTN, T2DM, severe anxiety and mild depression in men, and HTN and T2DM in women were associated with high risk of prolonged QTc interval. Healthcare practitioners should be aware of the risk factors of QTc interval prolongation and should exercise caution in the management of certain patients.

Cholinesterase inhibitors-associated torsade de pointes/QT prolongation: a real-world pharmacovigilance study

Objective: Cholinesterase inhibitor (ChEIs) is the first-line drug for Alzheimer's disease (AD). Understanding torsade de pointes (TdP)/QT prolongation with different ChEIs is essential for its safe and rational administration. This study aimed to evaluate the correlation between different ChEIs and TdP/QT prolongation. Methods: All ChEIs related TdP/QT prolongation cases were retrieved from the FAERS database using standard MedDRA query (SMQ) from the first quarter of 2004 to the third quarter of 2022. Disproportionality and sensitivity analysis were used to determine the signal of TdP/QT prolongation related to ChEIs. Results: 557 cases of TdP/QT prolongation related to 3 ChEIs were searched by SMQ. The patients were mostly elderly people, with markedly more female than male. The signals of TdP/QT prolongation for ChEIs were detected by disproportionality analysis, and the signal of Donepezil was the strongest. The sensitivity analysis results indicate a robust and stable correlation between these signals with ChEIs. TdP/QT prolongation usually occurs within 1 month after taking ChEIs. The drug with the highest frequency of combination with donepezil and galantamine is citalopram, and the drug with the highest frequency of combination with rivastigmine is atorvastatin. Conclusion: The signals of TdP/QT prolongation related to ChEIs were strong and stable. It is necessary to be vigilant about the TdP/QT prolongation of various ChEIs, especially in elderly women, the initial stage after taking ChEIs, and when ChEIs combining with drugs that could prolong the QT interval.

Sex Differences in Mouse Cardiac Electrophysiology Revealed by Simultaneous Imaging of Excitation-Contraction Coupling

Males and females differ in the basic anatomy and physiology of the heart. Sex differences are evident in cardiac repolarization in humans; women have longer corrected QT and JT intervals. However, the molecular mechanisms that lead to these differences are incompletely understood. Here, we present that, like in humans, sex differences in QT and JT intervals exist in mouse models; female mice had longer corrected QT and JT intervals compared with age-matched males. To further understand the molecular underpinning of these sex differences, we developed a novel technology using fluorescent confocal microscopy that allows the simultaneous visualization of action potential, Ca2+ transients, and contractions in isolated cardiomyocytes at a high temporal resolution. From this approach, we uncovered that females at baseline have increased action potential duration, decreased Ca2+ release and reuptake rates, and decreased contraction and relaxation velocities compared with males. Additionally, males had a shorter overall time from action potential onset to peak contraction. In aggregate, our studies uncovered male and female differences in excitation-contraction coupling that account for differences observed in the EKG. Overall, a better understanding of sex differences in electrophysiology is essential for equitably treating cardiac disease.

A Real-World Data Driven Pharmacovigilance Investigation on Drug-Induced Arrhythmia Using KAERS DB, a Korean Nationwide Adverse Drug Reporting System

This study aims to investigate the prevalence and seriousness of drug-induced arrhythmia and to identify predictors associated with the seriousness of arrhythmia. Drug-induced arrhythmia cases reported to the Korean Adverse Event Reporting System Database (KAERS DB) from January 2012 to December 2021 were investigated. A disproportionality test was performed to detect the association of the etiologic medication classes and types, along with patient demographic information, with the seriousness of drug-induced arrhythmia. Logistic regression was performed to investigate the predictors that increase the risk of serious arrhythmia. The most common etiologic agent for drug-induced arrhythmia was sevoflurane, whereas serious arrhythmia was most prevalent with narcotics. Antibiotics (reporting odds ratio (ROR) 4.125; 95% CI 1.438-11.835), chemotherapy (ROR 6.994; 95% CI 2.239-21.542), and iodinated contrast media (ROR 8.273; 95% CI 3.062-22.352) had a strong association with the seriousness of drug-induced arrhythmia. Among numerous etiologic agents, ioversol (ROR 16.490; 95% CI 3.589-75.772) and lidocaine (ROR 12.347; 95% CI 2.996-50.884) were more likely to be reported with serious arrhythmia. Aging and comorbidity, primarily cancer, are the most contributing predictors associated with serious arrhythmia. Further studies on the clinical significance of patient-specific predictors for the increased risk of serious drug-induced arrhythmia are warranted to promote drug safety.

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.

Cardiac Conduction Velocity, Remodeling and Arrhythmogenesis

Cardiac electrophysiological disorders, in particular arrhythmias, are a key cause of morbidity and mortality throughout the world. There are two basic requirements for arrhythmogenesis: an underlying substrate and a trigger. Altered conduction velocity (CV) provides a key substrate for arrhythmogenesis, with slowed CV increasing the probability of re-entrant arrhythmias by reducing the length scale over which re-entry can occur. In this review, we examine methods to measure cardiac CV in vivo and ex vivo, discuss underlying determinants of CV, and address how pathological variations alter CV, potentially increasing arrhythmogenic risk. Finally, we will highlight future directions both for methodologies to measure CV and for possible treatments to restore normal CV.

A framework for developing sex-specific engineered heart models

The convergence of tissue engineering and patient-specific stem cell biology has enabled the engineering of in vitro tissue models that allow the study of patient-tailored treatment modalities. However, sex-related disparities in health and disease, from systemic hormonal influences to cellular-level differences, are often overlooked in stem cell biology, tissue engineering and preclinical screening. The cardiovascular system, in particular, shows considerable sex-related differences, which need to be considered in cardiac tissue engineering. In this Review, we analyse sex-related properties of the heart muscle in the context of health and disease, and discuss a framework for including sex-based differences in human cardiac tissue engineering. We highlight how sex-based features can be implemented at the cellular and tissue levels, and how sex-specific cardiac models could advance the study of cardiovascular diseases. Finally, we define design criteria for sex-specific cardiac tissue engineering and provide an outlook to future research possibilities beyond the cardiovascular system.

Just a Reflection: Does Drug Repurposing Perpetuate Sex-Gender Bias in the Safety Profile?

Vaccines constitute a strategy to reduce the burden of COVID-19, but the treatment of COVID-19 is still a challenge. The lack of approved drugs for severe COVID-19 makes repurposing or repositioning of approved drugs a relevant approach because it occurs at lower costs and in a shorter time. Most preclinical and clinical tests, including safety and pharmacokinetic profiles, were already performed. However, infective and inflammatory diseases such as COVID-19 are linked with hypoalbuminemia and downregulation of both phase I and phase II drug-metabolizing enzymes and transporters, which can occur in modifications of pharmacokinetics and consequentially of safety profiles. This appears to occur in a sex- and gender-specific way because of the sex and gender differences present in the immune system and inflammation, which, in turn, reflect on pharmacokinetic parameters. Therefore, to make better decisions about drug dosage regimens and to increases the safety profile in patients suffering from infective and inflammatory diseases such as COVID-19, it is urgently needed to study repurposing or repositioning drugs in men and in women paying attention to pharmacokinetics, especially for those drugs that are previously scarcely evaluated in women.

hERG-deficient human embryonic stem cell-derived cardiomyocytes for modelling QT prolongation

Background

Long-QT syndrome type 2 (LQT2) is a common malignant hereditary arrhythmia. Due to the lack of suitable animal and human models, the pathogenesis of LQT2 caused by human ether-a-go-go-related gene (hERG) deficiency is still unclear. In this study, we generated an hERG-deficient human cardiomyocyte (CM) model that simulates ‘human homozygous hERG mutations’ to explore the underlying impact of hERG dysfunction and the genotype–phenotype relationship of hERG deficiency.

Methods

The KCNH2 was knocked out in the human embryonic stem cell (hESC) H9 line using the CRISPR/Cas9 system. Using a chemically defined differentiation protocol, we obtained and verified hERG-deficient CMs. Subsequently, high-throughput microelectrode array (MEA) assays and drug interventions were performed to characterise the electrophysiological signatures of hERG-deficient cell lines.

Results

Our results showed that KCNH2 knockout did not affect the pluripotency or differentiation efficiency of H9 cells. Using high-throughput MEA assays, we found that the electric field potential duration and action potential duration of hERG-deficient CMs were significantly longer than those of normal CMs. The hERG-deficient lines also exhibited irregular rhythm and some early afterdepolarisations. Moreover, we used the hERG-deficient human CM model to evaluate the potency of agents (nifedipine and magnesium chloride) that may ameliorate the phenotype.

Conclusions

We established an hERG-deficient human CM model that exhibited QT prolongation, irregular rhythm and sensitivity to other ion channel blockers. This model serves as an important tool that can aid in understanding the fundamental impact of hERG dysfunction, elucidate the genotype–phenotype relationship of hERG deficiency and facilitate drug development.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02346-1.

Prolonged QTc interval predicts long-term mortality in cirrhosis: a propensity score matching analysis

BACKGROUND

Prolonged corrected QT (QTc) interval is a hallmark of cirrhotic cardiomyopathy (CCM) and has been ascertained to predict mortality in cirrhosis. However, some critical issues remain to be addressed including unanimous cut-off, calculation approach and applicable population.

METHODS

A total of 274 patients with cirrhosis were included. The prolonged QTc interval over 440 ms according to adjusted Fridericia's formula was used to stratify enrolled subjects. Independent predictors of 3-year mortality were identified with Cox regression model. The Kaplan-Meier method was implemented to obtain survival curves. To reduce impact of selection bias and possible confounders, a propensity score matching (PSM) analysis was used.

RESULTS

QTc > 440 ms was an independent risk factor in the entire cohort and PSM subset (HR 2.532, 95% CI 1.431-4.480, p=.001; HR 2.802, 95% CI 1.171-6.701, p=.021, respectively). Subgroup analysis showed that QTc > 440 ms was an independent predictor in cirrhotics with age ≤60 years (HR = 1.02, p=.035) and in the presence of ascites (HR = 1.01, p=.008).

CONCLUSIONS

The prolonged QTc interval might help to identify patients with high-risk of all-cause mortality.

Incidence of Corrected QT Prolongation With Concomitant Methadone and Atypical Antipsychotics in Critically Ill Children

OBJECTIVE

To evaluate the safety of the combination of methadone and an atypical antipsychotic in PICU patients.

METHODS

This was a retrospective observational cohort pilot study in a single-center PICU in an academic children's hospital. Children 1 month to 18 years of age were included if they received methadone, were then initiated on an atypical antipsychotic (i.e., quetiapine or risperidone), and had EKG monitoring before and after medication initiation.

RESULTS

Prolongation of the corrected QT (QTc) interval occurred in 5 of the 34 included patients when an atypical antipsychotic was added to methadone. Of the 5 patients who had a prolonged QTc interval, 4 (80%) were older than 12 years and had a median weight of 91.3 kg. There were statistical differences between age and weight when comparing patients who experienced QTc prolongation, but no differences in sex, ethnicity, electrolyte deficiencies, number of additional QTc-prolonging medications, and number of additional drug-drug interactions were identified. When comparing atypical antipsychotics, 9.5% of patients receiving risperidone had a prolonged QTc interval, versus 23% of patients receiving quetiapine (p = 0.04). The net change in QTc interval after initiation of methadone was 0.19 milliseconds (IQR: -3, 15), which increased after atypical antipsychotic initiation to 4 milliseconds (IQR: -16, 15).

CONCLUSIONS

Our pilot trial suggests there is no clinically significant difference in incidence of QTc prolongation with addition of atypical antipsychotics to methadone.

The impact of acute energy drink consumption on electrical heart disease: A systematic review and meta-analysis

AIMS

Energy Drink (ED)-associated cardiovascular emergency visits have increased in recent years. Although a toxicity threshold has been established for caffeine, the safety profile of whole ED consumption has not yet been defined.

METHODS

This systematic review was conducted following the PRISMA guidelines. Three reviewers conducted two separate systematic searches on PubMed on October 24 and December 3, 2019. Out of 250 potential records, 43 prospective clinical studies assessing the effects of ED on heart rate (HR) and/or any electrocardiographic (ECG) parameters were included. A meta-analysis was conducted to estimate pooled p-values using metap command for STATA 10.0.

RESULTS

After ED consumption, resting HR increased in 71.1% of studies (pooled p-value <0.001) but was only significant in 38%; HR during and after exercise increased in 55.5% (pooled p-value <0.001) and 71.4% of studies, respectively; QRS increased in all but two protocols; evidence on PR interval was contradictory, and corrected QT interval (QTc) increased compared to baseline in all but one study, exceeding the pathological limit value in two of them. T wave changes were seen in two studies, and one study reported a ratio of 5 to 1 in the number of ectopic beats.

CONCLUSION

Acute consumption of ED can alter the ECG in certain risk populations, posing a risk whose magnitude is yet to be determined. Caution should be exercised among at-risk and underage individuals but further research in these populations is warranted before restrictions are made.

QTc monitoring in adults with medical and psychiatric comorbidities: Expert consensus from the Association of Medicine and Psychiatry

OBJECTIVE

Several psychiatric medications have the potential to prolong the QTc interval and subsequently increase the risk for ventricular arrhythmias such as torsades de pointes (TdP). There is limited guidance for clinicians to balance the risks and benefits of treatments.

METHODS

After a review of the existing literature, clinical-educators from the Association of Medicine and Psychiatry developed expert consensus guidelines for ECG monitoring of the QTc interval for patients with medical and psychiatric comorbidities who are prescribed medications with the potential to prolong the QTc interval. A risk score was developed based on risk factors for QTc prolongation to guide clinical decision-making.

RESULTS

A baseline ECG may not be necessary for individuals at low risk for arrythmia. Those individuals with a risk score of two or more should have an ECG prior to the start of a potentially QTc-prolonging medication or be started on a lower risk agent. Antipsychotics are not equivalent in causing QTc prolongation. A consensus-based algorithm is presented for the management of those identified at high (QTc >500 msec), intermediate (males with QTc 450-499 msec or females with QTc > 470-499 msec), or low risk.

CONCLUSIONS

The proposed algorithm can help clinicians in determining whether ECG monitoring should be considered for a given patient. These guidelines preserve a role for clinical judgment in selection of treatments that balance the risks and benefits, which may be particularly relevant for complex patients with medical and psychiatric comorbidities. Additional studies are needed to determine whether baseline and serial ECG monitoring reduces mortality.

Long term use of donepezil and QTc prolongation

BACKGROUND

The neurocognitive benefits of donepezil are well recognised, but the potential side effects on cardiac conduction remain unclear.

OBJECTIVE

To investigate whether long-term donepezil therapy is associated with electrocardiographic (ECG) changes and in particular to assess its effects on the QT interval.

METHODS

We conducted a single centre retrospective analysis of patients admitted to our trust on donepezil therapy over a 12-month period. An admission resting 12-lead ECG was obtained and compared to their ECG prior to commencement of donepezil therapy to assess for any significant difference in ECG parameters.

RESULTS

We identified 59 patients suitable for analysis. PR (177.0 ± 29.0 ms vs. 186.1 ± 34.2 ms, p = 0.04), QRS (101.7 ± 20.3 ms vs. 104.7 ± 22.3 ms, p = 0.04) and QT (393.3 ± 35.6 ms vs. 411.9 ± 44.6 ms, p = 0.002) interval prolongation were all associated with donepezil use. The increase in QT intervals remained significant on correction for heart rate; resulting in 8 (13.6%) patients developing high arrhythmogenic risk based on assessment using QT nomogram plots. Concomitant use of tricyclic antidepressants was associated with significant QT prolongation (QTcB: r _pb = 0.344, p = 0.008, QTcFred: r _pb = 0.382, p = 0.003, QTcFram: r _pb = 0.379, p = 0.003, QTcH: r _pb = 0.352, p = 0.006), while the use of rate-limiting calcium channel blockers was associated with significant PR prolongation (r _pb = 0.314, p = 0.030), and beta-blockers with a reduction in heart rate (r _pb = 0.256, p = 0.050).

CONCLUSION

Our results clearly demonstrate that long-term use of donepezil is associated with prolongation of the QT interval. We suggest ECG evaluation should take place before and after donepezil initiation, and clinicians should be even more vigilant in those prescribed tricyclic antidepressants.

Prevalence of QTc interval prolongation and its associated risk factors among psychiatric patients: a prospective observational study

BACKGROUND

QT interval prolongation is a growing concern worldwide, posing psychiatric patients to life-threatening fatal arrhythmias i.e., torsade de pointes. This study aimed to identify the prevalence of QT interval prolongation, its associated risk factors and prescribing patterns of QT prolonging drugs among psychiatric patients.

METHOD

A prospective observational study was conducted that included psychiatric patients from a tertiary care hospital and a psychiatry clinic in Peshawar, Khyber Pakhtunkhwa, Pakistan. Electrocardiogram was recorded of those patients who were using psychotropic medications for ≥7 days, aged 18 years or more, and of either gender, male or female. The Fredericia correction formula was used for measuring QTc values (corrected QT). Chi-square test was applied to estimate differences between patients with or without prolonged QTc interval whereas, logistic regression analysis was performed to identify various predictors of QT interval prolongation.

RESULTS

Out of 405 patients, the QTc interval was prolonged in 23 (5.7%) patients including 1 (0.2%) patient with highly abnormal prolonged QTc interval (> 500 ms). QT drugs (91.6%), female sex (38.7%) and hypertension (10.6%) were the most common QT prolonging risk factors. Prolonged QTc interval was significantly higher among male patients (p = 0.007).

CONCLUSION

In the present study, QT interval prolongation was observed in a considerable number of psychiatric patients. While, the high prevalence of QT prolonging risk factors among these patients warrants the increased risk of fatal arrhythmias. Therefore, risk assessment and electrocardiographic monitoring, and prescription of safer alternatives are highly recommended.

Association between citalopram, escitalopram and QTc prolongation in a real-world geriatric setting

BACKGROUND

Although the US Food and Drug Administration (FDA) recommended upper limits for citalopram dosing in older adults due to risk of corrected-QT (QTc) prolongation, which was adopted, and extended to escitalopram by Health Canada, the scientific basis is unclear. The objective of this study was to assess the relationship between citalopram/escitalopram dosages and QTc interval in a real-world geriatric setting.

METHODS

We reviewed electronic health records at a university-affiliated geriatric health care center, over a 7-year period, to identify patients prescribed citalopram and escitalopram, who had an ECG within 90 days of initiation or dosage change. Linear regression analyses were conducted to assess the relationship between antidepressant dosage and QTc interval.

RESULTS

137 patients were identified (citalopram=97, escitalopram=40). No association was found between citalopram, escitalopram and QTc, in unadjusted or adjusted analyses. Among covariates, older age was significantly associated with QTc prolongation in the escitalopram group.

LIMITATIONS

Limitations to the current study include its retrospective design and the small sample size.

CONCLUSIONS

These data do not support the FDA or Health Canada's recommended maximum dosages of citalopram or escitalopram in the elderly. Therefore, for patients already on higher doses of these medications, the risk of QTc prolongation may not always outweigh the risk of dose lowering, such as relapse. Until larger prospective studies become available, the decision to comply or not with these federal agencies' recommendations should be weighed on an individual basis, taking into consideration all potential risk factors.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A literature-based algorithm for the assessment, management, and monitoring of drug-induced QTc prolongation in the psychiatric population

BACKGROUND

Certain psychotropics and a number of other medications used to treat medical conditions in psychiatric patients can increase the risk of prolonging the corrected QT (QTc) interval on the electrocardiogram, which puts patients at risk of life-threatening ventricular arrhythmias such as torsades de pointes. Pharmacists are often consulted about medications which are known to prolong the QTc interval. Although this information is often accessible, advising how to identify, assess, manage, and refer psychiatric patients at risk for drug-induced QTc prolongation is more challenging.

OBJECTIVES

The objective of this project was first to review the literature, which describes guidelines and recommendations for the assessment and management of drug-induced QTc prolongation, and then to design an algorithm to be used by pharmacists working closely with mental health professionals or who provide care to psychiatric patients.

METHODS

A review of the literature was undertaken. Predefined keywords were used to perform the database search in MEDLINE, EMBASE, and International Pharmaceutical Abstracts to identify reviews, reports and guidelines on the assessment, prevention and monitoring of drug-induced QTc prolongation with an emphasis on psychotropic medications and management in the psychiatric population.

RESULTS

The electronic database search retrieved 637 relevant citations. These were initially screened by title and all duplicates were removed. The abstracts were then reviewed for relevancy based on the inclusion/exclusion criteria. Additional citations were retrieved from the bibliography of the articles identified in the initial search. A total of 79 articles describing QTc prolongation in the psychiatric population were thoroughly examined, but only 31 articles were selected to guide the development of the algorithm.

CONCLUSION

The literature-based algorithm developed provides a stepped-based approach for the assessment, monitoring, and management of drug-induced QTc prolongation in the psychiatric population. The algorithm may assist mental health clinicians in the decision-making process when psychiatric patients are prescribed medications known to increase the QTc interval.

Use of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors in older patients with ER-positive HER2-negative breast cancer: Young International Society of Geriatric Oncology review paper

The current standard of care for the management of estrogen receptor (ER)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer has been redefined by the introduction of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors. Although adults aged 65 years and older account for the majority of patients with breast cancer, limited data are available about the age-specific dosing, tolerability, and benefit of CDK4/6 inhibitors in this growing population. Older adults are under-represented in clinical trials and as a result, clinicians are forced to extrapolate from findings in younger and healthier patients when making treatment decisions for older patients. In this article, we review the limited age-specific evidence on the efficacy, toxicity, and quality of life (QoL) outcomes associated with the use of CDK4/6 inhibitors in older adults. We also describe ongoing trials evaluating CDK4/6 inhibitors in the older population and highlight that only a minority of adjuvant and metastatic trials of CDK4/6 inhibitors in the general breast cancer population includes geriatric assessments. Finally, we propose potential strategies to help guide decision making for fit and unfit older patients based on disease endocrine sensitivity, the need for rapid response and geriatric assessment.

Polymorphisms associated with fentanyl pharmacokinetics, pharmacodynamics and adverse effects

Fentanyl is an agonist of the μ-opioid receptor commonly used in the treatment of moderate-severe pain. In order to study whether pharmacogenetics explains some of the variability in the response to fentanyl, several genes related to fentanyl receptors, transporters and metabolic enzymes have been analysed. Thirty-five healthy volunteers (19 men and 16 women) receiving a single 300 μg oral dose of fentanyl were genotyped for 9 polymorphisms in cytochrome P450 (CYP) enzymes (CYP3A4 and CYP3A5), ATP-binding cassette subfamily B member 1 (ABCB1), opioid receptor mu 1 (OPRM1), catechol-O-methyltransferase (COMT) and adrenoceptor beta 2 (ADRB2) by real-time PCR. Fentanyl concentrations were measured by ultra-performance liquid chromatography combined with tandem mass spectrometry (UPLC-MS/MS). Fentanyl pharmacokinetics is affected by sex. Carriers of the CYP3A4*22 allele, which is known to reduce the mRNA expression, showed higher area under the concentration-time curve (AUC) and lower clearance (Cl) values. Although this finding might be of importance, its validity needs to be confirmed in other similar settings. Furthermore, carriers of the ABCB1 C1236T T/T genotype presented a lower AUC and higher Cl, as well as lower half-life (T_1/2 ). As volunteers were blocked with naltrexone, the effect of fentanyl on pharmacodynamics might be biased; however, we could observe that fentanyl had a hypotensive effect. Moreover, ADRB2 C523A A allele carriers showed a tendency towards reducing systolic blood pressure. Likewise, OPRM1 and COMT minor allele variants were risk factors for the development of somnolence. CYP3A5*3, ABCB1 C3435T and ABCB1 G2677T/A were not associated with fentanyl's pharmacokinetics, pharmacodynamics and safety profile.

QTc interval in patients with schizophrenia receiving antipsychotic treatment as monotherapy or polypharmacy

OBJECTIVE

Antipsychotics are associated with a polymorphic ventricular tachycardia, torsades de pointes, which, in the worst case, can lead to sudden cardiac death. The QT interval corrected for heart rate (QTc) is used as a clinical proxy for torsades de pointes. The QTc interval can be prolonged by antipsychotic monotherapy, but it is unknown if the QTc interval is prolonged further with antipsychotic polypharmaceutical treatment. Therefore, this study investigated the associations between QTc interval and antipsychotic monotherapy and antipsychotic polypharmaceutical treatment in schizophrenia, and measured the frequency of QTc prolongation among patients.

METHODS

We carried out an observational cohort study of unselected patients with schizophrenia visiting outpatient facilities in the region of Central Jutland, Denmark. Patients were enrolled from January of 2013 to June of 2015, with follow-up until June of 2015. Data were collected from clinical interviews and clinical case records.

RESULTS

Electrocardiograms were available for 65 patients, and 6% had QTc prolongation. We observed no difference in average QTc interval for the whole sample of patients receiving no antipsychotics, antipsychotic monotherapy, or antipsychotic polypharmaceutical treatment (p=0.29). However, women presented with a longer QTc interval when receiving polypharmacy than when receiving monotherapy (p=0.01). A limitation of this study was its small sample size.

CONCLUSIONS

We recommend an increased focus on monitoring the QTc interval in women with schizophrenia receiving antipsychotics as polypharmacy.

QT interval and dispersion in drug-free anorexia nervosa adolescents: a case control study

Long QT values have been reported in patients with anorexia nervosa of the restricting type (ANr) potentially increasing the risk of fatal arrhythmia, especially if psychotropic drug treatment is required. Nevertheless, the previous studies on this topic are biased by drug exposure, long disease durations, and small sample sizes. This study is aimed at assessing QTc and QTcd values in ANr adolescents with recent onset and drug free, as compared to subjects affected by psychiatric disorders other than ANr. We evaluated QTc and its dispersion (QTcd) in a population of 77 drug-free ANr female adolescents and compared to an equal number of healthy controls (H-CTRL) and pathological controls (P-CTRL, mixed psychiatric disorders). The QT determination was performed on a standard simultaneous 12-lead ECG in blind by a single experienced investigator. QTc was calculated by the Bazett's formula and QTcd was determined as the difference between the maximum and minimum QTc intervals in different leads. Only for ANr patients, clinico-demographic data, hormones, and electrolytes were obtained. QTc was slightly reduced in ANr patients (27.7 ms, < 10%, p < 0.0003) vs. controls, while QTcd was increased in P-CTRL (30%, p < 0.0003). Heart rate was significantly lower in ANr patients vs. controls (25%; p < 0.003). Tyroid hormones and serum potassium showed weak although significant positive correlations with QTc in ANr patients. QTcd displayed a weak negative correlation with the BMI percentile (r = - 0.262, p = 0.03). We reject the hypothesis that QTc and QTcd are increased in drug-free ANr adolescents with a relatively short-disease duration. Further studies are needed to understand if the previously reported increase might be related to other associated chronic disorders, such as hormonal or electrolyte imbalance.

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

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

Drug-induced life-threatening arrhythmias and sudden cardiac death: A clinical perspective of long QT, short QT and Brugada syndromes

Sudden cardiac death is a major public health challenge, which can be caused by genetic or acquired structural or electrophysiological abnormalities. These abnormalities include hereditary channelopathies: long QT, short QT and Brugada syndromes. These syndromes are a notable concern, particularly in young people, due to their high propensity for severe ventricular arrhythmias and sudden cardiac death. Current evidence suggests the involvement of an increasing number of drugs in acquired forms of long QT and Brugada syndromes. However, drug-induced short QT syndrome is still a rarely reported condition. Therefore, there has been speculation on its clinical significance, since few fatal arrhythmias and sudden cardiac death cases have been described so far. Drug-induced proarrhythmia is a growing challenge for physicians, regulatory agencies and the pharmaceutical industry. Physicians should weigh the risks of potentially fatal outcomes against the therapeutic benefits, when making decisions about drug prescriptions. Growing concerns about its safety and the need for more accurate predictive models for drug-induced fatal outcomes justify further research in these fields. The aim of this article is to comprehensively and critically review the recently published evidence with regard to drug-induced life-threatening arrhythmias and sudden cardiac death. This article will take into account the provision of data to physicians that are useful in the identification of the culprit drugs, and thus, contribute to the prompt recognition and management of these serious clinical conditions.

Prevalence and prognostic significance of prolonged QTc interval in emergency medical patients: A prospective observational study

Introduction:

QTc interval is affected by many factors and prolongation of same may have prognostic significance. A significant number of patients admitted in medical emergency are acutely ill, have multiple comorbidities and are on medications, all of these factors might affect QTc interval and prognosis.

Materials and Methods:

Single-center, prospective, observational study was carried out on 279 patients of different illnesses recruited from emergency medical services attached to the Department of Internal Medicine at Postgraduate Institute of Medical Education and Research, Chandigarh, India, a tertiary care hospital.

Results:

Out of 279 patients, 95 were found to have prolonged QTc interval with the prevalence of 34.1%. Fifteen patients (5.4%) had markedly prolonged QTc interval (QTc >500 ms). Of various medical conditions, we found statistically significantly higher number of patients of chronic kidney disease (P = 0.047), chronic liver disease (P < 0.001), hemorrhagic cerebrovascular accident (P = 0.026), and heart failure (P = 0.009) with prolonged QTc interval. Among laboratory abnormalities, patients with low hemoglobin (P = 0.032), with deranged renal functions (P = 0.033), and with hypokalemia (P = 0.026) had a greater share of patients with prolonged QTc interval. There was no difference in duration of hospital stay and frequency of hospital mortality between two groups, although, on subgroup analysis, patients with markedly prolonged QTc interval had significantly higher hospital mortality (P = 0.029). The frequency of ventricular tachycardia was also significantly higher in patients with prolonged QTc interval (P = 0.008).

Conclusion:

High prevalence of prolonged QTc interval was found in Indian emergency medical patients. There was no difference in hospital mortality though on subgroup analysis, patients with markedly prolonged QTc interval had significantly more episodes of in-hospital ventricular tachycardia and hospital mortality.

Effect of Polymorphisms on the Pharmacokinetics, Pharmacodynamics and Safety of Sertraline in Healthy Volunteers

Sertraline is a selective serotonin reuptake inhibitor widely metabolized in the liver by cytochrome P450 (CYP) enzymes. Besides, it is a P-glycoprotein substrate. Moreover, serotonin transporters and serotonin receptors are involved in its efficacy and safety. The aim of this study was to evaluate the role of polymorphisms of metabolizing enzymes, transporters and receptors on the pharmacokinetics, pharmacodynamics and tolerability of sertraline in healthy volunteers. Forty-six healthy volunteers (24 men and 22 women) receiving a 100-mg single oral dose of sertraline were genotyped for 17 genetic variants of CYP enzymes (CYP2B6, CYP2C9, CYP2C19, CYP2D6), ATP-binding cassette subfamily B member 1 (ABCB1), solute carrier family 6 member 4 (SLC6A4), 5-hydroxytryptamine receptor 2A (HTR2A) and 5-hydroxytryptamine receptor 2C (HTR2C) genes. Pharmacokinetic and pharmacodynamic parameters were similar in men and women. Polymorphisms in CYP2C19 and CYP2B6 genes influenced sertraline pharmacokinetics, with a greater effect of CYP2C19. Individuals carrying defective alleles for CYP2C19 and CYP2B6 showed higher area under the curve (AUC) and half-life (T_1/2 ). Moreover, CYP2C19*17 was related to a decreased AUC and T_1/2 . No significant effect was found for polymorphisms in CYP2C9, CYP2D6 and ABCB1 on sertraline pharmacokinetics. Sertraline had a small heart rate-lowering effect, directly related to maximum concentration (C_max ) and the presence of ABCB1 minor alleles. Sertraline had no significant effect on blood pressure and QTc. There was a tendency to present more adverse drug reactions in women and individuals with higher AUC of sertraline, such as CYP2C19 intermediate metabolizers and CYP2B6 G516T T/T individuals.

Combinations of QTc-prolonging drugs: towards disentangling pharmacokinetic and pharmacodynamic effects in their potentially additive nature

BACKGROUND

Whether arrhythmia risks will increase if drugs with electrocardiographic (ECG) QT-prolonging properties are combined is generally supposed but not well studied. Based on available evidence, the Arizona Center for Education and Research on Therapeutics (AZCERT) classification defines the risk of QT prolongation for exposure to single drugs. We aimed to investigate how combining AZCERT drug categories impacts QT duration and how relative drug exposure affects the extent of pharmacodynamic drug-drug interactions.

METHODS

In a cohort of 2558 psychiatric inpatients and outpatients, we modeled whether AZCERT class and number of coprescribed QT-prolonging drugs correlates with observed rate-corrected QT duration (QTc) while also considering age, sex, inpatient status, and other QTc-prolonging risk factors. We concurrently considered administered drug doses and pharmacokinetic interactions modulating drug clearance to calculate individual weights of relative exposure with AZCERT drugs. Because QTc duration is concentration-dependent, we estimated individual drug exposure with these drugs and included this information as weights in weighted regression analyses.

RESULTS

Drugs attributing a 'known' risk for clinical consequences were associated with the largest QTc prolongations. However, the presence of at least two versus one QTc-prolonging drug yielded nonsignificant prolongations [exposure-weighted parameter estimates with 95% confidence intervals for 'known' risk drugs + 0.93 ms (-8.88;10.75)]. Estimates for the 'conditional' risk class increased upon refinement with relative drug exposure and co-administration of a 'known' risk drug as a further risk factor.

CONCLUSIONS

These observations indicate that indiscriminate combinations of QTc-prolonging drugs do not necessarily result in additive QTc prolongation and suggest that QT prolongation caused by drug combinations strongly depends on the nature of the combination partners and individual drug exposure. Concurrently, it stresses the value of the AZCERT classification also for the risk prediction of combination therapies with QT-prolonging drugs.

Pharmacogenetics of trazodone in healthy volunteers: association with pharmacokinetics, pharmacodynamics and safety

Aim: The aim was to evaluate the effect of polymorphisms in metabolizing enzymes and transporters on the pharmacokinetics, pharmacodynamics and adverse effects of trazodone in healthy volunteers. Materials & methods: 36 healthy volunteers receiving a single 100-mg oral dose of trazodone were genotyped for 11 variants in CYP3A4, CYP3A5, CYP2D6 and ABCB1 by real-time PCR. Plasma concentrations were measured using liquid chromatography-tandem mass spectrometry method. Results & conclusion: Sex affected the pharmacokinetics of trazodone with higher clearance in women. Polymorphisms in ABCB1, but not in CYP3A or CYP2D6, influenced trazodone pharmacokinetics. Trazodone decreased blood pressure and prolonged the corrected QT interval interval. CYP2D6 and ABCB1 polymorphisms were associated with the incidence of dizziness and prolonged corrected QT interval, respectively. Subjects with adverse drug reactions had lower concentrations of trazodone suggesting its metabolite (m-chlorophenylpiperazine) could be responsible for these effects.

Human Induced Pluripotent Stem Cell (hiPSC)-Derived Cells to Assess Drug Cardiotoxicity: Opportunities and Problems

Billions of US dollars are invested every year by the pharmaceutical industry in drug development, with the aim of introducing new drugs that are effective and have minimal side effects. Thirty percent of in-pipeline drugs are excluded in an early phase of preclinical and clinical screening owing to cardiovascular safety concerns, and several lead molecules that pass the early safety screening make it to market but are later withdrawn owing to severe cardiac side effects. Although the current drug safety screening methodologies can identify some cardiotoxic drug candidates, they cannot accurately represent the human heart in many aspects, including genomics, transcriptomics, and patient- or population-specific cardiotoxicity. Despite some limitations, human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are a powerful and evolving technology that has been shown to recapitulate many attributes of human cardiomyocytes and their drug responses. In this review, we discuss the potential impact of the inclusion of the hiPSC-CM platform in premarket candidate drug screening.

Prevalence and Risk Factors of Drug-Associated Corrected QT Prolongation in Elderly Hospitalized Patients: Results of a Retrospective Analysis of Data Obtained Over 6 Months

OBJECTIVES

Little information exists on the frequency and determinants of drug-associated long QT syndrome in older adults. The objectives of this study were to assess the prevalence and identify risk factors of drug-associated long QT syndrome in a population of elderly hospitalized patients.

METHODS

This was a retrospective study performed over 6 months in hospital geriatric medicine. Various QT-correction equations were fitted to the individual QT-RR data to evaluate the most appropriate equation. Long QT syndrome was defined as corrected QT ≥450 ms. Available data were compared in patients with and without long QT syndrome. Logistic regression and classification and regression tree analysis were performed to identify determinants of long QT syndrome.

RESULTS

Thirty-three of 152 patients (22%) exhibited corrected QT ≥450 ms. The different QT correction equations provided similar results, except the Bazett equation. In patients with long QT syndrome, there was a higher proportion of male subjects (58 vs. 33%, p = 0.009) and a higher number of QT-prolonging drugs than in patients without long QT syndrome. Male sex (odds ratio, 3.25) and the number of prescribed QT-prolonging agents (odds ratio, 1.77) were significantly associated with the probability of long QT syndrome. The number of QT-prolonging drugs had a stronger influence on the risk of long QT syndrome in men than in women.

CONCLUSION

Male sex was found to be a significant risk factor of corrected QT prolongation in elderly hospitalized patients. The risk also increased with the number of QT-prolonging agents, especially in men. Those findings may help to mitigate the risk of long QT syndrome in elderly patients in clinical practice.

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Antipsychotic Dose Mediates the Association between Polypharmacy and Corrected QT Interval

Antipsychotic (AP) drugs have the potential to cause prolongation of the QT interval corrected for heart rate (QTc). As this risk is dose-dependent, it may be associated with the number of AP drugs concurrently prescribed, which is known to be associated with increased cumulative equivalent AP dosage. This study analysed whether AP dose mediates the relationship between polypharmacy and QTc interval. We used data from a cross-sectional survey that investigated the prevalence of QTc lengthening among people with psychiatric illnesses in Italy. AP polypharmacy was tested for evidence of association with AP dose and QTc interval using the Baron and Kenny mediational model. A total of 725 patients were included in this analysis. Of these, 186 (26%) were treated with two or more AP drugs (AP polypharmacy). The mean cumulative AP dose was significantly higher in those receiving AP polypharmacy (prescribed daily dose/defined daily dose = 2.93, standard deviation 1.31) than monotherapy (prescribed daily dose/defined daily dose = 0.82, standard deviation 0.77) (z = -12.62, p < 0.001). Similarly, the mean QTc interval was significantly longer in those receiving AP polypharmacy (mean = 420.86 milliseconds, standard deviation 27.16) than monotherapy (mean = 413.42 milliseconds, standard deviation 31.54) (z = -2.70, p = 0.006). The Baron and Kenny mediational analysis showed that, after adjustment for confounding variables, AP dose mediates the association between polypharmacy and QTc interval. The present study found that AP polypharmacy is associated with QTc interval, and this effect is mediated by AP dose. Given the high prevalence of AP polypharmacy in real-world clinical practice, clinicians should consider not only the myriad risk factors for QTc prolongation in their patients, but also that adding a second AP drug may further increase risk as compared with monotherapy.