Electrocardiographic abnormalities in patients treated with clozapine

Effects of intramuscular olanzapine vs. haloperidol and placebo on QTc intervals in acutely agitated patients

Prolongation of the QTc interval has been reported during treatment with oral antipsychotic agents and may be more pronounced during parenteral administration. Pooled QTc interval data from acutely agitated patients across four double-blind trials were compared. Databases included: placebo-controlled [two schizophrenia, one bipolar mania trials (n=565)]; haloperidol-controlled [two schizophrenia trials (n=482)]; geriatric placebo-controlled [1 dementia trial (n=204)]. Patients received 1-3 injections of intramuscular (IM) olanzapine (2.5-10 mg/injection), IM haloperidol (7.5 mg/injection), or IM placebo. At 2 and 24 h after IM olanzapine treatment, the mean QTc interval decreased approximately 3 ms from baseline in the placebo- and haloperidol-controlled databases. When there was a statistically significant difference between IM olanzapine and IM placebo, QTc intervals decreased during treatment with IM olanzapine and increased with IM placebo. The incidences of prolonged (endpoint >/=99th percentile of healthy adults or >/=500 ms) or lengthened (increase >/=60 ms) QTc intervals during treatment with IM olanzapine (<3% placebo- and haloperidol-controlled databases, <12% geriatric placebo-controlled database) were never significantly greater than with comparators. These data suggest that IM olanzapine has a favorable QTc interval profile in acutely agitated patients with schizophrenia, bipolar mania, or dementia.

Antipsychotics and QT prolongation

OBJECTIVE

To evaluate literature relating to cardiac QT prolongation and the use of antipsychotic drugs.

METHOD

Literature searches of EMBASE, Medline, PsychLIT were performed in December 2001 and reference sections of retrieved papers scrutinized for further relevant reports.

RESULTS

The Cardiac QTc interval is difficult to measure precisely or accurately but appears to be a useful predictor of risk of dysrhythmia (specifically torsade de pointes) and sudden death. It is less clear that drug-induced QTc prolongation gives rise to similar risks but data are emerging, linking antipsychotic use to increased cardiac mortality. Many antipsychotics have been clearly associated with QTc prolongation. Methodological considerations arguably preclude assuming that any antipsychotic is free of the risk of QTc prolongation and dysrhythmia.

CONCLUSION

Available data do not allow assessment of relative or absolute risk of dysrhythmia or sudden death engendered by antipsychotics but caution is advised. Risk of dysrhythmia can very probably be reduced by careful prescribing of antipsychotics in low doses in simple drug regimens which avoid metabolic interactions. Electrocardiographic monitoring may also help to reduce risk but review by specialist cardiologist may be necessary.

Antipsychotic-related QTc prolongation, torsade de pointes and sudden death

Sudden unexpected deaths have been reported with antipsychotic use since the early 1960s. In some cases the antipsychotic may be unrelated to death, but in others it appears to be a causal factor. Antipsychotics can cause sudden death by several mechanisms, but particular interest has centred on torsade de pointes (TdP), a polymorphic ventricular arrhythmia that can progress to ventricular fibrillation and sudden death. The QTc interval is a heart rate-corrected value that represents the time between the onset of electrical depolarisation of the ventricles and the end of repolarisation. Prolongation of the QTc interval is a surrogate marker for the ability of a drug to cause TdP. In individual patients an absolute QTc interval of >500 msec or an increase of 60 msec from baseline is regarded as indicating an increased risk of TdP. However, TdP can occur with lower QTc values or changes. Concern about a relationship between QTc prolongation, TdP and sudden death applies to a wide range of drugs and has led to the withdrawal or restricted labelling of several. Among antipsychotics available in the UK, sertindole was voluntarily suspended, droperidol was withdrawn, and restricted labelling introduced for thioridazine and pimozide. The degree of QTc prolongation is dose dependent and varies between antipsychotics reflecting their different capacity to block cardiac ion channels. Significant prolongation is not a class effect. Among currently available agents, thioridazine and ziprasidone are associated with the greatest QTc prolongation. Virtually all drugs known to cause TdP block the rapidly activating component of the delayed rectifier potassium current (I(kr)). Arrhythmias are more likely to occur if drug-induced QTc prolongation coexists with other risk factors, such as individual susceptibility, presence of congenital long QT syndromes, heart failure, bradycardia, electrolyte imbalance, overdose of a QTc prolonging drug, female sex, restraint, old age, hepatic or renal impairment, and slow metaboliser status. Pharmacodynamic and pharmacokinetic interactions can also increase the risk of arrhythmias. Further research is needed to quantify the risk of sudden death with antipsychotics. The risk should be viewed in the context of the overall risks and benefits of antipsychotic treatment. It seems prudent, where possible, to select antipsychotics that are not associated with marked QTc prolongation. If use of a QTc-prolonging drug is warranted, then measures to reduce the risk should be adopted.

Cardiovascular effects of novel antipsychotic medications

This article reviews current knowledge of cardiovascular effects and drug interactions of the most commonly used novel antipsychotics, including clozapine and the atypical antipsychotics. The literature was reviewed through MEDLINE and PSYCINFO searches of articles published from 1980 to 2001. Materials were located using search terms such as antipsychotics and atypical antipsychotics, matched with the terms cardiovascular disease, coronary artery disease, cardiac risk factor, cardiovascular effects, and cardiac effects. Individual drug names were also searched and their 2001 package inserts were reviewed. Drug compendiums from 1998 to 2001 and some psychopharmacology texts were also used for this review. This article focuses on direct cardiovascular effects of these medications and the most common interactions between the antipsychotic and cardiovascular medications.

Psychotropic drugs and the ECG: focus on the QTc interval

The QT interval measuring depolarisation and repolarisation has, when lengthened, been implicated as a risk factor for the development of torsades de pointes and sudden death, particularly in patients predisposed to these complications due to cardiovascular impairment. Since some of the medications used in psychiatry have been implicated, an extensive review of available literature was made of the major classes, including antipsychotics, antidepressants, lithium, anticonvulsants and benzodiazepines. Further, where no publications were found on a particular medication, the pharmaceutical firms responsible for these items were contacted concerning possibly unpublished data. Results of the survey indicate that there may be difficulty in one of three situations: immediate (in the first minutes to hours after oral or parenteral administration), short-term use of 4 - 12 weeks or long-term use of 6 months. Based on this approach, the greatest concern is directed at the immediate application of haloperidol, droperidol, pimozide and trazodone, the short-term use of thioridazine, pimozide, sertindole, nortriptyline, clomipramine, doxepin and the long-term use of clozapine, olanzapine and carbamazepine. It is of interest that a reduction in QTc is reported with aripiprazole. Among the antidepressants, the tertiary tricyclic antidepressants (imipramine, amitriptyline and doxepin) appear to have a more general impact, while the secondary tricyclic antidepressants (nortriptyline, desipramine) may impact more on children and the elderly. Among other antidepressants, the only reports of torsades de pointes appeared to occur with mirtazapine. It was also of interest to find data showing no effect or reductions in QTc produced by sertraline, citalopram, paroxetine and bupropion in multiple studies. Effects of medications on other heart parameters are also briefly reviewed. In particular, the safety of sertraline in post-MI patients and of bupropion in heart disease patients is highlighted. Little information was available on other classes of medications used in psychiatric disorders. What is available concerning lithium, the anticonvulsants and the benzodiazepines indicates little effect on the QTc, although there may be effects on other cardiovascular parameters.

Cardiovascular side effects of novel antipsychotics

Since the introduction of clozapine, several novel antipsychotic agents have been introduced and more are in Phase II/III studies. Because these agents are used clinically as first-line treatment, we need to be more familiar with their side-effect profiles. This manuscript reviews the cardiovascular side effects of currently available novel antipsychotics. The medications reviewed include clozapine, risperidone, olanzapine, quetiapine, and ziprasidone. Guidelines are suggested for the use of these medications in clinical practice.

Sudden cardiac death with clozapine and sertraline combination

OBJECTIVE

To report a case of sudden cardiac death in a patient receiving combination therapy with clozapine and sertraline.

CASE SUMMARY

A 26-year-old white man was discovered dead at his residence. His medical history included chronic paranoid schizophrenia, obsessive-compulsive disorder, major depressive disorder, obstructive sleep apnea, and akathisia. He had no prior history of cardiovascular disease. His medication regimen included clozapine 100 mg twice daily (started 4 y prior to his death), risperidone 3 mg twice daily, sertraline 200 mg once daily, atenolol 50 mg twice daily, and lorazepam 0.5 mg four times daily. Autopsy and toxicology studies revealed cardiomegaly suggestive of idiopathic cardiomyopathy, single-vessel coronary artery disease, sertraline and clozapine blood concentrations in the expected range, undetectable lorazepam and risperidone blood concentrations, obesity, and moderate fatty changes to the liver. The most likely cause of death was sudden cardiac death due to acute cardiac arrhythmia.

DISCUSSION

Clozapine is structurally similar to the tricyclic antidepressants, which have type 1 A antiarrhythmic properties. Case reports have described electrocardiographic abnomalities, cardiomyopathy, and fatal myocarditis associated with its use. Unexplained death in patients on clozapine therapy has also been reported. Sertraline appears to have less cardiac effect; however, one report has observed clinically significant QT prolongation during sertraline therapy.

CONCLUSIONS

Clozapine-induced cardiomyopathy and cardiac arrhythmia from clozapine and/or sertraline use may have contributed to this man's death.