First-generation antipsychotics and QTc: any role for mediating variables?

Risk Stratification of QTc Prolongation in Critically Ill Patients Receiving Antipsychotics for the Management of Delirium Symptoms

BACKGROUND

Patients experiencing significant agitation or perceptual disturbances related to delirium in an intensive care setting may benefit from short-term treatment with an antipsychotic medication. Some antipsychotic medications may prolong the QTc interval, which increases the risk of potentially fatal ventricular arrhythmias. In this targeted review, we describe the evidence regarding the relationships between antipsychotic medications and QTc prolongation and practical methods for monitoring the QTc interval and mitigating arrhythmia risk.

METHODS

Searches of PubMed and Cochrane Library were performed to identify studies, published before February 2023, investigating the relationships between antipsychotic medications and QTc prolongation or arrhythmias.

RESULTS

Most antipsychotic medications commonly used for the management of delirium symptoms (eg, intravenous haloperidol, olanzapine, quetiapine) cause a moderate degree of QTc prolongation. Among other antipsychotics, those most likely to cause QTc prolongation are iloperidone and ziprasidone, while aripiprazole and lurasidone appear to have minimal risk for QTc prolongation. Genetic vulnerabilities, female sex, older age, pre-existing cardiovascular disease, electrolyte abnormalities, and non-psychiatric medications also increase the risk of QTc prolongation. For individuals at risk of QTc prolongation, it is essential to measure the QTc interval accurately and consistently and consider medication adjustments if needed.

CONCLUSIONS

Antipsychotic medications are one of many risk factors for QTc prolongation. When managing agitation related to delirium, it is imperative to assess an individual patient's risk for QTc prolongation and to choose a medication and monitoring strategy commensurate to the risks. In intensive care settings, we recommend regular ECG monitoring, using a linear regression formula to correct for heart rate. If substantial QTc prolongation (eg, QTc > 500 msec) is present, a change in pharmacologic treatment can be considered, though a particular medication may still be warranted if the risks of discontinuation (eg, extreme agitation, removal of invasive monitoring devices) outweigh the risks of arrhythmias.

AIMS

This review aims to summarize the current literature on relationships between antipsychotic medications and QTc prolongation and to make practical clinical recommendations towards the approach of antipsychotic medication use for the management of delirium-related agitation and perceptual disturbances in intensive care settings.

Abnormal blood lipid and electrocardiogram characteristics in common mental disorders

BACKGROUND

At present, there is not enough evidence to prove the relationship between blood lipid and electrocardiogram (ECG) abnormalities in common mental disorders (CMD). This study aimed to explore the relationship between them, to detect and prevent arrhythmia or sudden death.

METHODS

We collected 272 CMD patients (maintained a fixed drug dose pattern for 1 year or more), including 95 schizophrenias (SC), 90 bipolar disorders (BD) and 87 major depressive disorders (MDD), and 78 healthy controls (HC) from the Third People's Hospital of Foshan, China. We analyzed and compared their blood lipid and ECG indicators, to clarify the relationship between them.

RESULTS

350 participants were included. There were no significant differences in age, gender, total cholesterol (TC), low density lipoprotein (LDL) and QTc (p > 0.05) among subjects. And there were significant differences in body mass index (BMI), triglyceride (TG), high density lipoprotein (HDL), heart rate, PR interval and QRS width (p < 0.05). Person correlation analysis showed that QRS width was positively correlated with BMI and TG. And negatively correlated with HDL. Meanwhile, QTc was positively correlated with BMI. Multiple linear regional analysis further proved that TG (B = 3.849, p = 0.007) and LDL (B = 11.764, p = 0.018) were the risk factors, and HDL (B = -9.935, p = 0.025) was the protective factor for QRS width increase.

CONCLUSION

Long term medication of CMD patients should strengthen weight management, and conduct regular blood lipid and ECG examinations to achieve early detection and intervention in order to promote their health.

Practical Guidance for the Use of Long-Acting Injectable Antipsychotics in the Treatment of Schizophrenia

Schizophrenia is a severe mental illness causing a high degree of disability. First- and second-generation antipsychotics (FGAs and SGAs) represent key resources for its acute and long-term management. Since a poor adherence to oral treatments may negatively impact the course of the disorder, long-acting injectable antipsychotics (LAIs) are often used to reduce clinical relapses. Notwithstanding their potential beneficial features, LAIs use in clinical practice remains somewhat hampered by the limited amount of relevant systematic information. This review thus aims at providing a clinical, practical guidance for the use of LAIs in the treatment of schizophrenia. We synthetized main information on indications, dosage, and administration of LAIs approved by the US Food and Drug Administration (FDA) and/or in EU countries, as well as evidence from the most recent systematic reviews and meta-analyses. Currently available information, though heterogeneous, shows that LAIs can prevent relapses and rehospitalizations, improving clinical outcomes and favouring sustained remission among people with schizophrenia. The use of SGA LAIs is supported by more robust evidence than FGA LAIs. Along with their positive impact on the prevention of treatment discontinuation, some LAIs might also enhance individual global functioning and quality of life, without additional adverse events or health-care costs, as compared with oral antipsychotics. Although which LAIs can be considered a first-choice option, as well as their superiority over oral antipsychotics, remain unclear issues, this review offers a comprehensive overview of information available on the use of LAIs for people with schizophrenia, providing clinicians with practical guidance in terms of efficacy and acceptability of single agents. Literature gaps and future research needs are also described.

Psychological and Psychopharmacological Interventions in Psychocardiology

Patients with mental disorders have an increased risk to develop cardiovascular disease (CVD), and CVD are frequently comorbid with especially adjustment, anxiety and depressive disorders. Therefore, clinicians need to be aware of effective and safe psychological and pharmacological treatment strategies for patients with comorbid CVD and mental disorders. Cognitive behavioral therapy and third-wave of cognitive-behavioral therapy are effective for patients with CVD and mental disorders. Internet-based psychological treatments may also be considered. In more severe cases, psychopharmacological drugs are frequently used. Although generally well tolerated and efficacious, drug- and dose-dependent side effects require consideration. Among antidepressants, selective serotonin reuptake inhibitors, selective serotonin and noradrenalin reuptake inhibitors, and newer antidepressants, such as mirtazapine, bupropion, agomelatine, and vortioxetine, can be considered, while tricyclic antidepressants should be avoided due to their cardiac side effects. Mood stabilizers have been associated with arrhythmias, and some first- and second-generation antipsychotics can increase QTc and metabolic side effects, although substantial differences exist between drugs. Benzodiazepines are generally safe in patients with CVD when administered short-term, and may mitigate symptoms of acute coronary syndrome. Laboratory and ECG monitoring is always recommended in psychopharmacological drug-treated patients with CVD. Presence of a heart disease should not exclude patients from necessary interventions, but may require careful risk-benefit evaluations. Effectively and safely addressing mental disorders in patients with CVD helps to improve both conditions. Since CVD increase the risk for mental disorders and vice versa, care providers need to screen for these common comorbidities to comprehensively address the patients' needs.

Estimation of cardiac QTc intervals in people prescribed antipsychotics: a comparison of correction factors

BACKGROUND

A prolonged electrocardiogram (ECG) QT interval is associated with cardiac events and increased mortality. Antipsychotics can prolong the QT interval. The QT interval requires correction (QTc) for heart rate using a formula or QT-nomogram. The QT and QTc can be calculated automatically by the ECG machine or manually; however, machine-measured QT(c) intervals may be inaccurate.

OBJECTIVE

We aimed to investigate the mean QTc and proportion of prolonged QTc intervals in people taking antipsychotic medicines.

METHODS

We conducted an observational retrospective chart review and data analysis of all consecutive patients taking antipsychotics, with an ECG record, admitted to the psychiatric unit of a large tertiary hospital in Brisbane, Australia, between 1 January 2017 and 30 January 2019. We investigated the mean QTc of people taking antipsychotics to determine differences using (a) machine versus manual QT interval measurement and (b) QTc correction formulae (Bazett, Fridericia, Framingham, Hodges and Rautaharju) and the QT-nomogram. We also determined the number of people with a prolonged QTc using different methods and compared rates of prolonged QTc with antipsychotic monotherapy and polypharmacy.

RESULTS

Of 920 included people, the mean (±SD) machine-measured, Bazett-corrected QT interval (recorded from the ECG) was 435 ms (±27), significantly longer (p < 0.001) than the mean manually measured corrected QT intervals with Fridericia 394 ms (±24), Framingham 395 ms (±22), Hodges 398 ms (±22) and Rautaharju 400 ms (±24) formulae. There were significantly more people with a prolonged QTc using machine-measured QT and the Bazett formula (12.0%, 110/920) when compared with manually measured QT and the Fridericia formula (2.2%, 20/920) or QT-nomogram (0.7%, 6/920). Rates of QTc prolongation did not differ between people taking antipsychotic polypharmacy compared with monotherapy.

CONCLUSION

Machine-measured QTc using the Bazett formula overestimates the QTc interval length and number of people with a prolonged QTc, compared with other formulae and the QT-nomogram. We recommend manually measuring the QT and correcting with the Fridericia formula or QT-nomogram prior to modifying antipsychotic therapies.

The Role of Attitudes Toward Medication and Treatment Adherence in the Clinical Response to LAIs: Findings From the STAR Network Depot Study

Background: Long-acting injectable (LAI) antipsychotics are efficacious in managing psychotic symptoms in people affected by severe mental disorders, such as schizophrenia and bipolar disorder. The present study aimed to investigate whether attitude toward treatment and treatment adherence represent predictors of symptoms changes over time. Methods: The STAR Network "Depot Study" was a naturalistic, multicenter, observational, prospective study that enrolled people initiating a LAI without restrictions on diagnosis, clinical severity or setting. Participants from 32 Italian centers were assessed at three time points: baseline, 6-month, and 12-month follow-up. Psychopathological symptoms, attitude toward medication and treatment adherence were measured using the Brief Psychiatric Rating Scale (BPRS), the Drug Attitude Inventory (DAI-10) and the Kemp's 7-point scale, respectively. Linear mixed-effects models were used to evaluate whether attitude toward medication and treatment adherence independently predicted symptoms changes over time. Analyses were conducted on the overall sample and then stratified according to the baseline severity (BPRS < 41 or BPRS ≥ 41). Results: We included 461 participants of which 276 were males. The majority of participants had received a primary diagnosis of a schizophrenia spectrum disorder (71.80%) and initiated a treatment with a second-generation LAI (69.63%). BPRS, DAI-10, and Kemp's scale scores improved over time. Six linear regressions-conducted considering the outcome and predictors at baseline, 6-month, and 12-month follow-up independently-showed that both DAI-10 and Kemp's scale negatively associated with BPRS scores at the three considered time points. Linear mixed-effects models conducted on the overall sample did not show any significant association between attitude toward medication or treatment adherence and changes in psychiatric symptoms over time. However, after stratification according to baseline severity, we found that both DAI-10 and Kemp's scale negatively predicted changes in BPRS scores at 12-month follow-up regardless of baseline severity. The association at 6-month follow-up was confirmed only in the group with moderate or severe symptoms at baseline. Conclusion: Our findings corroborate the importance of improving the quality of relationship between clinicians and patients. Shared decision making and thorough discussions about benefits and side effects may improve the outcome in patients with severe mental disorders.

QT interval prolongation noted in one percent of 2553 Asian patients with schizophrenia: Findings from the REAP-AP survey

Although the association between antipsychotic use and corrected QT interval (QTc) prolongation has been repeatedly confirmed, the relationship has been rarely studied in a practical setting. Using data from the Research on Asian Psychotropic Prescription Patterns for Antipsychotics (REAP-AP) survey, our study aimed to investigate the prevalence and clinical correlates of QTc prolongation in 2553 Asian patients with schizophrenia. After adjusting for the potential effect of confounding factors, the baseline and clinical characteristics of the schizophrenia patients with and without QTc prolongation were compared using analyses of covariance and binary logistic analyses. In addition, a binary logistic analysis model with a forward selection method was used to identify the distinctive clinical correlates of QTc prolongation. QTc prolongation was noted in 1.1% of Asian patients with schizophrenia. Schizophrenia patients were characterized by lower proportions of disorganized speech and negative symptoms; higher use of amisulpride and clozapine; and higher proportions of rigidity, hypercholesterolemia, and sedation than those without QTc prolongation. Finally, a binary logistic mode showed that amisulpride, clozapine, rigidity, and hypercholesterolemia might be the distinctive clinical correlates of QTc prolongation in Asian patients with schizophrenia. These findings indicate the clinical implications that the uses of amisulpride and clozapine and the occurrences of rigidity and hypercholesterolemia may be potential risk factors for QTc prolongation of schizophrenia patients.

The relationship between atypical antipsychotics drugs, QT interval prolongation, and torsades de pointes: implications for clinical use

Introduction: Increased mortality has been observed in patients with mental health disorders. Specifically, exposure to antipsychotic medications conveys a greater than 2 fold risk of sudden death, thought to be mediated through effects on QT prolongation and risk of torsades de pointes.Areas covered: We review the association between antipsychotic drugs and sudden cardiac death, the physiologic basis for these associations, assessment of patients at risk, and strategies to minimize risk of sudden cardiac death.Expert opinion: Despite the prevalence of antipsychotic medication use for many decades, there remain considerable challenges in reducing the associated risk of sudden cardiac death. A structured algorithm that incorporates patient clinical factors and antipsychotic drug factors may improve risk assessment and reduce the risk of adverse cardiac events. Future advancements in genetics and artificial intelligence may allow for enhanced risk stratification and predicting response (efficacy and adverse effects) to therapy.

Long-term metabolic and cardiovascular effects of antipsychotic drugs. A meta-analysis of randomized controlled trials

Most of the randomized controlled trials (RCTs) on antipsychotics (APs) have efficacy as their primary endpoint, leading to a lack of evidence on long-term metabolic effects of APs. The aim of the present meta-analysis is to compare different APs for the long-term modification of risk of major adverse cardiovascular events (MACE) and related mortality, in patients with schizophrenia and bipolar disorder. All RCTs found on Medline/Embase of at least 52 weeks up to 19 December 2017, enrolling patients with bipolar disorder or schizophrenia and comparing an AP with another AP or placebo were included. The primary outcome of this analysis was the association of APs with the incidence of cardiovascular death, myocardial infarction (MI), and stroke. 3013 studies were screened, 92 met the selection criteria. MI, stroke and cardiovascular death were reported in 11, 6 and 24 studies, respectively. No significant difference was observed with respect to MI and Stroke; a significantly higher cardiovascular mortality was observed for sertindole when compared to risperidone (Mantel-Haenszel Odds Ratio: 2.56, 95% CI: 1.33 - 5). Long-term cardiovascular effects of APs deserve to be studied more extensively. The request by regulatory authorities of cardiovascular safety data from specifically designed trials would be useful.

QTc dispersion and interval changes in drug-free borderline personality disorder adolescents

Emotional instability and dysregulation represent a core feature of borderline personality disorder (BPD) and abnormal patterns of sympathetic/parasympathetic activity have been repeatedly investigated in individuals with this disorder. Such abnormalities may represent the substrate for an arrhythmogenic risk that could materialize the following specific drug exposure. In this work, we decided to assess basal-corrected QT interval and dispersion (QTc and QTcd) for estimating such risk in a sample of drug-free adolescents with diagnosis of BPD. In this cross-sectional comparative study, we recruited n = 70 female adolescent BPD (14.7 ± 1.3 years), free of medications, alcohol or recreational drugs. Furthermore, n = 70 matched female healthy controls (CTRL, 14.6 ± 1.5 years) were enrolled. QTc and QTcd were manually assessed on a standard 12-lead ECG by a single experienced investigator who was unaware of clinical outcomes. QTcd was increased by 7 ms on average in BPD vs. CTRL (+ 18%, p = 0.03). QTc was decreased by about 15 ms on average in BPD vs. CTRL (p = 0.003). A mild correlation was found between QTc and QTcd in BPD (r = 0.25, p = 0.03) that was not present in CTRL. No correlation was found between either QTc or QTcd, and age in both groups. Mildly increased QTcd characterizes the cardiac activity regardless of drug exposure in female adolescents with BPD. This information may be of value to clinicians striving to use neuroleptic and antidepressant drugs with a lower risk of QTcd increase.

Reasons for initiating long-acting antipsychotics in psychiatric practice: findings from the STAR Network Depot Study

BACKGROUND

Long acting injectable (LAI) antipsychotics have been claimed to ensure treatment adherence and possibly reduce the daily burden of oral formulations. So far, only surveys investigating the theoretical prescribing attitudes of clinicians have been employed. On this basis, we aimed to investigate reasons for prescribing LAIs in a real-world, unselected sample of patients.

METHODS

The STAR Network Depot Study is an observational, multicentre study consecutively enrolling adults initiating a LAI over a 12-months period. Clinical severity was assessed with the Brief Psychiatric Rating Scale, and patient's attitude toward medications with the Drug Attitude Inventory 10 items. Psychiatrists recorded reasons for LAI prescribing for each study participant. Responses were grouped into six non-mutually exclusive categories: aggressiveness, patient engagement, ease of drug taking, side-effects, stigma, adherence.

RESULTS

Of the 451 patients included, two-thirds suffered from chronic psychoses. Improving patient engagement with the outpatient psychiatric service was the most common reason for prescribing LAIs (almost 80% of participants), followed by increasing treatment adherence (57%), decreasing aggressiveness (54%), and improving ease of drug taking (52%). After adjusting for confounders, logistic regression analyses showed that reasons for LAI use were associated with LAI choice (e.g. first-generation LAIs for reducing aggressiveness).

CONCLUSION

Despite the wide availability of novel LAI formulation and the emphasis on their wider use, our data suggest that the main reasons for LAI use have remained substantially unchanged over the years, focusing mostly on improving patient's engagement. Further, clinicians follow implicit prescribing patterns when choosing LAIs, and this may generate hypotheses for future experimental studies.

Prevalence of ECG abnormalities and risk factors for QTc interval prolongation in hospitalized psychiatric patients

BACKGROUND

Psychiatric patients are at risk of cardiovascular diseases, and many psychotropic drugs can prolong QTc interval. Requirements for electrocardiogram (ECG) monitoring have been set up in our psychiatric university hospital. The objective of this study was to determine the proportion of adult patients who had an ECG during their hospitalization, the prevalence of ECG abnormalities, the evolution of the QTc after admission, and the risk factors for QTc prolongation.

METHODS

Retrospective analysis of ECGs and clinical data of all patients with a complete hospitalization in 2015. Assessment of the influence of covariates on QTc using linear mixed-effects models.

RESULTS

At least one ECG (n = 600) was performed during 37.6% of the stays (n = 1198) and in 45.5% of the patients (n = 871). Among the patients with an ECG, 17.9% had significant ECG abnormalities, including 7.6% with a prolonged QTc. QTc measured at admission and during hospitalization did not change significantly (n = 46, 419.4 ± 29.7 ms, 417.2 ± 27.6 ms, p = 0.71). In the multivariate model (292 patients, 357 ECGs), the covariates significantly associated with the QTc were gender (+15.9 ms if female, p < 0.0001), age (+0.4 ms/year, p = 0.0001), triglyceride levels (+5.7 ms/mmol/l, p = 0.005), and drugs with known risk of torsades de pointes (+6.2 ms if ⩾1 drug, p = 0.028).

CONCLUSIONS

The prevalence of hospitalized psychiatric patients with an abnormal ECG indicates that ECGs should be performed systematically in this population. Prescription of psychotropic drugs should be done cautiously, particularly in patients with QTc prolongation risk factors.

Direct and indirect effects of psychopharmacological treatment on the cardiovascular system

Background Severe mental disorders, i.e. psychotic disorders, unipolar and bipolar disorders are associated with increased morbidity and mortality from cardiovascular and metabolic disorders. The underlying cause of this association is complex and comprises disorder specific alterations such as dysfunctions of immunological and hormonal systems, body-composition changes and health associated behaviors (smoking, sedentary lifestyle, alcohol intake and treatment compliance). Furthermore, some psychopharmacological drugs may exert unwanted side effects that impact the cardiovascular system. Methods This paper reviews studies concerning commonly used antidepressant and antipsychotics drugs with a particular focus on direct and indirect cardiovascular side effects. Results Newer antidepressant drugs have a favorable cardiovascular safety profile compared to tricyclic antidepressants. However, QTc prolongation, increased blood pressure and potentially higher risks of bleeding have been observed in some newer antidepressants. Some second generation (atypical) antipsychotics have raised concern because of indirect cardiovascular, metabolic side effects such as weight gain and disturbances in lipid and glucose metabolism. Conclusions Psychiatrists need to be aware of potential direct and indirect cardiovascular side effects and to include them in the risk/benefit assessment when choosing a specific individualized treatment.

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.

Safety of antipsychotics for the treatment of schizophrenia: a focus on the adverse effects of clozapine

Clozapine, a dibenzodiazepine developed in 1961, is a multireceptorial atypical antipsychotic approved for the treatment of resistant schizophrenia. Since its introduction, it has remained the drug of choice in treatment-resistant schizophrenia, despite a wide range of adverse effects, as it is a very effective drug in everyday clinical practice. However, clozapine is not considered as a top-of-the-line treatment because it may often be difficult for some patients to tolerate as some adverse effects can be particularly bothersome (i.e. sedation, weight gain, sialorrhea etc.) and it has some other potentially dangerous and life-threatening side effects (i.e. myocarditis, seizures, agranulocytosis or granulocytopenia, gastrointestinal hypomotility etc.). As poor treatment adherence in patients with resistant schizophrenia may increase the risk of a psychotic relapse, which may further lead to impaired social and cognitive functioning, psychiatric hospitalizations and increased treatment costs, clozapine adverse effects are a common reason for discontinuing this medication. Therefore, every effort should be made to monitor and minimize these adverse effects in order to improve their early detection and management. The aim of this paper is to briefly summarize and provide an update on major clozapine adverse effects, especially focusing on those that are severe and potentially life threatening, even if most of the latter are relatively uncommon.

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.

Antipsychotic drug exposure and risk of myocardial infarction

Patients experiencing psychoses and in need of antipsychotic agents may be exposed to a higher risk of myocardial infarction (MI) than the general population. As there have been no randomised studies investigating this association, a recent systematic review and meta-analysis included all observational studies that compared the incidence of MI among patients receiving antipsychotics v. no treatment. It found nine studies and calculated that the odds (risk) for developing MI were 1.88-fold higher in antipsychotic users compared with individuals who had not taken antipsychotic drugs. In this commentary, the results of this systematic review are discussed in view of their clinical implications for everyday clinical practice.