Successful rechallenge of clozapine therapy following previous clozapine-induced myocarditis confirmed on cardiac MRI

Clozapine rechallenge following myocarditis: a systematic review of rechallenge cases

INTRODUCTION AND OBJECTIVES

Clozapine is the antipsychotic medication with the greatest efficacy in treatment-resistant schizophrenia (TRS). Unfortunately, clozapine is ceased in approximately 0.2% to 8.5% of people due to concerns about clozapine-associated myocarditis (CAM). The opportunity for clozapine rechallenge is important for people with TRS and CAM, due to limited alternative treatments. However, there is a lack of consensus regarding the optimal process, monitoring, and dose titration to achieve successful clozapine rechallenge. The study aimed to review the process, monitoring, and dose titration within cases of clozapine rechallenge after CAM, to identify features associated with successful rechallenge.

METHODS

A systematic review of clozapine rechallenge cases following CAM was conducted. PubMed, EMBASE, Cinahl, and PsycINFO were searched for cases. Reference lists of retrieved articles and field experts were consulted to identify additional studies.

RESULTS

Forty-five cases were identified that described clozapine rechallenge, 31 of which were successful. Successful rechallenge cases generally used a slower dose titration regime with more frequent monitoring than standard clozapine initiation protocols; however, this data was not always completely recorded within cases. Six cases referred to published rechallenge protocols to guide their rechallenge.

CONCLUSIONS

The process, monitoring, and dose titration of clozapine rechallenge are inconsistently reported in the literature. Despite this, 69% of case reports detailed a successful rechallenge post CAM; noting limitations associated with reliance on case data. Ensuring published clozapine rechallenge cases report standardised data, including titration speed and monitoring frequencies, is required to guide the development and validation of guidelines for clozapine rechallenge.

When, Why and How to Re-challenge Clozapine in Schizophrenia Following Myocarditis

Clozapine-induced myocarditis (CIM) is among the most important adverse events limiting the use of clozapine as the most effective treatment for schizophrenia. CIM necessitates the immediate termination of clozapine, often resulting in its permanent discontinuation with considerable detrimental effects on patients' psychopathology and long-term outcome. Consequently, a clozapine re-challenge after CIM is increasingly regarded as a viable alternative, with published reports indicating a success rate of approximately 60%. However, published cases of re-challenges after CIM remain limited. Here, we provide a narrative review of the current state of research regarding the epidemiology, pathophysiology, risk factors, diagnosis and clinical management of CIM as well as a synthesis of current recommendations for re-challenging patients after CIM. This includes a step-by-step guide for this crucial procedure based on the current evidence regarding the pathophysiology and risk factors for CIM. Slow dose titration regimes and addressing risk factors including concomitant valproate and olanzapine are crucial both to prevent CIM and to ensure a safe and successful re-challenge. Furthermore, we discuss the utility of C-reactive protein, troponin, N-terminal-pro hormone and brain natriuretic peptide, therapeutic drug-monitoring and cardiac magnetic resonance imaging for CIM screening and diagnosis as well as for post-CIM re-challenges.

Clozapine-induced myocarditis in children and adolescents: a pharmacovigilance study using VigiBase and a systematic literature review

INTRODUCTION

Clozapine-induced myocarditis in children (age ≤18 yo) was studied from a PubMed search (18 July 2022) (9 cases) and from the World Health Organization's pharmacovigilance database, called Vigibase, of adverse drug reaction (ADR) reports (72 non-duplicated cases). VigiBase uses a logarithmic measure of disproportionality called the information component (IC). A logistic regression model of presence/absence (40/32) of seriousness in VigiBase was developed.

AREAS COVERED

VigiBase provided a significant myocarditis IC = 4.2 with an IC₀₂₅ = 3.8; only 4 clozapine-induced myocarditis cases were expected, while 72 were observed. The PubMed search identified 9 cases, while VigiBase identified 72 cases (of which 67 did not overlap with published cases). These 76 combined cases included 35 doubtful (most with missing information on the day of diagnosis), 19 possible and 22 probable, according to the ADR scale. After adjusting for confounders, quetiapine increased the risk of seriousness with an odds ratio (OR) of 17.6 (95% confidence interval CI, 1.56 to 198.6), while Australian origin decreased it with an OR = 0.13 (CI, 0.04 to 0.47).

EXPERT OPINION

These 41 cases of at least possible clozapine-induced myocarditis indicated that this ADR can definitively occur in children, particularly in the first 30 days of up-titration. Children's and adult cases appeared similar.

Successful rechallenge after clozapine-associated myocarditis

Clozapine is a highly effective medication used in management of treatment-resistant schizophrenia. Clozapine-associated myocarditis (CAM) is a rare but increasingly recognised complication of clozapine titration. Following an episode of CAM, clinicians can face a challenging dilemma of balancing the risks of recurrent myocarditis against the harms of ongoing psychosis. We describe the case of a woman in her 60s who developed acute myocarditis during clozapine titration and was then cautiously rechallenged with a successful outcome.

Chest Pain in a Psychiatric Patient Due to Clozapine-Induced Myopericarditis

Drug-induced myocarditis is a rare, but underrecognized complication of clozapine therapy for schizophrenia. We present a case of clozapine-induced myocarditis with recovery of cardiac function after drug cessation and summarize the literature to highlight the variable presentation of this condition.

Clozapine-Associated Myocarditis: A Protocol for Monitoring Upon Clozapine Initiation and Recommendations for How to Conduct a Clozapine Rechallenge

BACKGROUND

Clozapine is the only medication with Food and Drug Administration approval for treatment-resistant schizophrenia. However, it is underutilized in the United States because of several life-threatening adverse effects, including clozapine-associated myocarditis (CAM), and a limited understanding of how to manage these complications. To date, recommendations for rechallenging patients with CAM that incorporate the cardiac literature or cardioprotective medications have not been developed.

FINDINGS

In this article, we outline a protocol developed with cardiologists and guided by the cardiac literature that provides direction on how to monitor for the initial development of CAM and how to rechallenge patients with CAM. Furthermore, we present 2 successful cases of clozapine rechallenge that were managed using this protocol.

CONCLUSIONS

In both cases, the patients showed marked improvement in their psychiatric symptoms and functioning, demonstrating the importance of considering rechallenge in patients after CAM.

Clozapine-Related Myocarditis and Rechallenge: A Case Series and Clinical Review

PURPOSE/BACKGROUND

That clozapine is the only agent with an indication for treatment-resistant schizophrenia presents real challenges if clozapine-related myocarditis (CIM) occurs. Clinicians have chosen to rechallenge with a second trial of clozapine in the face of CIM. However, there is very limited literature of this topic.

METHODS/PROCEDURES

Three cases who underwent clozapine rechallenge after CIM are reviewed and discussed in the context of existing literature and current recommendations.

FINDINGS/RESULTS

We present 3 young male patients with schizophrenia and schizoaffective disorder who developed CIM during a first clozapine trial, stopped treatment, and subsequently underwent a second clozapine trial. In all cases, the rechallenge was discontinued owing to suspected CIM. A review of the literature includes reports of both successful and unsuccessful clozapine rechallenges after CIM and suggests certain risk factors. Clozapine rechallenge after CIM may be undertaken, as now occurs on occasion with agranulocytosis, although rates of success may be lower. Any such undertaking calls for education, careful monitoring, cautious titration, and a multidisciplinary approach. The balance of risk versus benefits must be considered, and strategies may include a drug holiday, more frequent monitoring upon reinitiation, and slower titration.

IMPLICATIONS/CONCLUSIONS

Pressure to undertake a rechallenge reflects clozapine's unique role in treatment-resistant schizophrenia and absence of other comparable options. However, it is not without risk, and more research is needed to understand those at increased risk, as well as established strategies that diminish this.

Clozapine and cardiotoxicity - A guide for psychiatrists written by cardiologists

This review discusses the rare but potentially life-threatening cardiovascular side-effects of myocarditis and dilated cardiomyopathy associated with the use of Clozapine. The clinical presentation of these conditions is non-specific, making it difficult to both risk-stratify and identify patients who develop these consequences. This review aims to examine the proposed aetiologies, diagnostic approaches and subsequent management strategies of cardiotoxicity associated with clozapine use; offering guidance to psychiatrists and general physicians. Current evidence highlights the importance of accurate diagnosis to prevent premature and unnecessary cessation of clozapine. Guidance on monitoring and reintroduction of the drug is emerging and current practice recommends a combination of regular monitoring of biomarkers and imaging to make a diagnosis of cardiotoxicity although further work is needed to establish evidence-based guidelines.

Clozapine Rechallenge After Major Adverse Effects: Clinical Guidelines Based on 259 Cases

BACKGROUND

Clozapine is widely prescribed for treatment-refractory schizophrenia, but its use is limited by many potentially life-threatening adverse effects. The risk of rechallenge after these complications has never been comprehensively assessed in controlled studies. Thus, clinical guidelines must rely on the published case reports. The number of such reports is likely to increase over time, and updated analyses of larger samples are needed, as they may lead to changes in clinical guidelines.

STUDY QUESTIONS

How safe is the clozapine rechallenge after life-threatening adverse effects?

STUDY DESIGN

The published case reports of clozapine rechallenge were identified in a MEDLINE search. We added 121 cases reported from 2012 through 2017 to the 138 cases reported from 1972 through 2011 analyzed by us in a previous publication. The 95% confidence intervals (CIs) of the successful rechallenge rate were calculated for each adverse effect with at least 5 published case reports. The rechallenge was considered a valid clinical option when the lower end of the CI range was at least 50%.

RESULTS

A successful outcome was documented in 128/203 patients rechallenged after neutropenia (63.0%, CI, 56.0%-69.6%), 3/17 after agranulocytosis (17.7%, CI, 4.7%-44.2%), 11/17 after myocarditis (64.7%, CI, 38.6%-84.7%), and 7/7 after neuroleptic malignant syndrome (100%, CI, 56.1%-100%). Among the 15 patients with other clozapine-induced adverse effects, the rechallenge was successful in those with eosinophilia, cardiac complications other than myocarditis (QTc prolongation, pericarditis, cardiomyopathy, and atrial flutter), and gastrointestinal hypomotility. The rechallenge failed in patients who had developed pancreatitis or renal insufficiency.

CONCLUSION

Clozapine rechallenge is a reasonable clinical option after return to baseline for patients who had developed neutropenia and neuroleptic malignant syndrome, but not after agranulocytosis or myocarditis. Data are insufficient to formulate rechallenge guidelines for any other clozapine-related adverse effects.

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.

Cardiovascular Disease in Clozapine-Treated Patients: Evidence, Mechanisms and Management

Myocarditis occurs in about 3% of those initiated on clozapine but monitoring reduces the risk of serious outcome. Cardiomyopathy may develop after myocarditis, or from prolonged tachycardia. Monitoring using echocardiography is not deemed cost effective. Tachycardia, orthostatic hypotension and reduced heart rate variability are a group of clozapine-related adverse effects associated with autonomic dysfunction and may have serious consequences in the long term. Elevated heart rate and poor heart rate variability can be treated with a β-blocker or a non-dihydropyridine calcium channel blocker, while orthostatic hypotension can be alleviated by increased fluid intake and abdominal binding, but may require pharmacological intervention. Adequate correction for heart rate may show that clozapine does not prolong the QT interval. Other cardiovascular effects, pulmonary embolism, metabolic syndrome, sudden cardiac death and particularly the excessive mortality from cardiovascular disease events may be more strongly associated with the combination of mental illness, lifestyle factors and poor treatment of cardiovascular disease and its risk factors than with clozapine treatment. In view of the efficacy of clozapine and the evidence of reduced mortality relative to other antipsychotics, clozapine should be prescribed when indicated and recipients should be enrolled in lifestyle programmes to increase exercise and improve diet, and referred for diagnosis and treatment of cardiovascular disease and its risk factors.

Successful clozapine re-challenge following myocarditis

OBJECTIVE

To explore the evidence around clozapine re-challenge following myocarditis.

CONCLUSION

This case adds to the 17 cases of clozapine re-challenge following myocarditis, of which 71% were successful (12 cases). This demonstrates that re-challenge could be performed safely and effectively in the context of clozapine-induced myocarditis, if accompanied by a strict and rigorous monitoring protocol.

Systematic Review of Clozapine Cardiotoxicity

Clozapine is exceptionally effective in psychotic disorders and can reduce suicidal risk. Nevertheless, its use is limited due to potentially life-threatening adverse effects, including myocarditis and cardiomyopathy. Given their clinical importance, we systematically reviewed research on adverse cardiac effects of clozapine, aiming to improve estimates of their incidence, summarize features supporting their diagnosis, and evaluate proposed monitoring procedures. Incidence of early (≤2 months) myocarditis ranges from <0.1 to 1.0 % and later (3-12 months) cardiomyopathy about 10 times less. Diagnosis rests on relatively nonspecific symptoms, ECG changes, elevated indices of myocardial damage, cardiac MRI findings, and importantly, echocardiographic evidence of developing ventricular failure. Treatment involves stopping clozapine and empirical applications of steroids, diuretics, beta-blockers, and antiangiotensin agents. Mortality averages approximately 25 %. Safety of clozapine reuse remains uncertain. Systematic studies are needed to improve knowledge of the epidemiology, avoidance, early identification, and treatment of these adverse effects, with effective and practicable monitoring protocols.

Clozapine-induced myocarditis, a widely overlooked adverse reaction

OBJECTIVE

We review the published cases of clozapine-induced myocarditis and describe reasons for the higher incidence in Australia (>1%) than elsewhere (<0.1%).

METHOD

Medline was searched to September 2014 using 'clozapine' as the sole term.

RESULTS

A total of around 250 cases of clozapine-induced myocarditis have been published. Fever among patients commencing clozapine has been reported internationally, and very few of these cases were investigated for myocarditis. The time to onset of fever is consistent with its being part of a prodrome of undiagnosed myocarditis, and the risk factors are similar to those for myocarditis. In more severe cases, clozapine is discontinued, avoiding fatalities which may occur with myocarditis. Furthermore, cases of sudden death and respiratory illness may well have been undiagnosed myocarditis. The diagnosis of myocarditis is confounded by the non-specific nature of the signs and symptoms, and it depends on appropriate investigations being conducted at the time of myocardial involvement or, for fatal cases, the affected area of the myocardium being sampled for histology.

CONCLUSION

It is likely that the incidence of myocarditis is around 3%. Implementation of monitoring procedures will increase case ascertainment and result in more patients benefiting from this valuable medication.