[Minimizing the risks associated with QTc prolongation in people with schizophrenia. A consensus statement by the Cardiac Safety in Schizophrenia Group].
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abstract
Schizophrenia is one of the most debilitating mental illnesses, complicated by an increased incidence of suicide amongst patients compared with the general population. A recent report has also demonstrated a 33% increase in -relative risk of death associated with circulatory disease, indicating that the latter may be a more critical factor than either suicide or accidental death in this population. Indeed, the average life expectancy of a person with schizophrenia is currently approximately a decade less than that of the general population. Additionally, it has been shown that in over 50% of people with schizophrenia, there is a reduction in their chance of reaching psychosocial goals. Since the arrival of the first antipsychotic drugs in the middle of the last century, the outlook for patients with schizophrenia has improved markedly. In particular, the introduction of the new generation (atypical) class of antipsychotic agents in the 1980s and 90s has resulted in a significant reduction in the incidence of violent and aggressive episodes in treated patients. A better side-effect profile of these drugs, especially reduced extra pyramidal symptoms (EPS), has resulted in improved patient outcomes and the possibility of good long-term control of the disorder. However, while the introduction of antipsychotic agents has undoubtedly revolutionised the prognosis for patients with schizophrenia, these medications are not without their own problems. One of the concerns to emerge over the last fifteen years is unpredictable, sudden and unexplained death in patients taking antipsychotic drugs. The cause of sudden death in this population is controversial and the role of drugs is not clear. People with schizophrenia also appear to be at higher risk of cardiovascular disease compared with the general population. Many factors may play a role in this including a higher prevalence of smoking, poorer diet, more sedentary lifestyle and a greater likelihood of alcoholism and substance abuse. However, it is possible that the impact of adverse effects on the cardiovascular system related to certain antipsychotic drug use may well increase the prevalence of mortality and morbidity due to cardiovascular events and may also play a significant role in the reduced life expectancy of the patient with schizophrenia. The range of mechanisms whereby antipsychotic drugs can influence cardiovascular function is very broad and includes: receptor blockade; conduction disturbance (eg bundle branch block); delayed ventricular repolarisation (prolonged QTc interval); left ventricular dysfunction; sinus node abnormalities; myocarditis; postural hypotension; polydipsia-hyponatremia syndrome; weight gain; glucose intolerance. Of these, QTc interval prolongation, with the risk of progression to the potentially fatal ventricular tachyarrhythmia Torsades de Pointes (TdP), is of particular concern as this arrhythmia is unpredictable and difficult to manage. Coupled with these clinical concerns are regulatory issues regarding several compounds that have received warnings or been withdrawn from the market. Recently, there has been no clear guidance for psychiatrists regarding QTc interval prolongation and TdP. This document seeks: 1) to explore drug-induced ventricular arrhythmias with particular emphasis on QTc interval prolongation as a warning of increased vulnerability, 2) to provide guidelines on the therapeutic management of the patient with schizophrenia to minimize the risk of iatrogenic cardiotoxicity. Several guidance documents have previously been published in this area including the report published by the UK Working Group of the Royal College of Psychiatrists' Psychopharmacology Sub-Group in 1997, and the policy document on the potential for QTc prolongation and proarrhythmia by non-antiarrhythmic drugs published in June 1999 under the auspices of the European Society of Cardiology. This document seeks to supplement currently published guidelines.
