Older people at risk of heart disorder from antipsychotic medications

Key points:

• Approximately 350,000 Australians are prescribed at least one antipsychotic medication each year

• Researchers at the Victor Chang Cardiac Research Institute have called for more intensive monitoring of people treated with pharmacological approaches to psychosis

• Anti-psychotic medications are used to treat schizophrenia, psychosis and some of the more aggressive symptoms of dementia

Researchers at the Victor Chang Cardiac Research Institute have issued a warning following a new study that found two different types of antipsychotic medication were associated with an increased risk of ventricular arrhythmias and a twofold increased risk of sudden cardiac death.

The two drugs in question — quetiapine and haloperidolis — are classed as two separate types of antipsychotic medication, the former being ‘atypical’ and the latter being ‘typical.’ Typical antipsychotics tend to block dopamine, whereas atypical antipsychotics impact serotonin, which is how the brain transmits information and coordinates with the body in complex ways.

Scientists have warned that older people may be at greater risk and that the findings could extend to other types of antipsychotic that were not directly tested during the study, e.g. risperidone — often used to treat people with dementia in Australia with persistent aggressive symptoms.

Deputy Director of the Victor Chang Cardiac Research Institute Professor Jamie Vandenberg, who co-authored the editorial accompanying the study, said whilst the study focused on just two drugs, many other antipsychotic drugs shared the same risk.

“These results suggest it would be prudent to undertake an [electrocardiogram] before and after commencement of an antipsychotic drug and especially in older patients,” he said.

“The risks of cardiac arrhythmias associated with the use of antipsychotics have long been known but we now finally know the scale of the problem in a real-world setting and we need to try and reduce the risk and manage people more closely.

“If it is an option, one could stop a drug causing QT prolongation and try a different antipsychotic.”

Antipsychotic drugs can cause a drug-induced QT prolongation, which causes the heart muscle to take longer than normal to recharge between beats. If untreated and undiagnosed it can cause lethal cardiac arrhythmias.

“If this is not practical, one should pay particular attention to reducing other risk factors, such as the prescription of other drugs that may exacerbate QT prolongation and be vigilant for hypokalaemia — a common electrolyte imbalance that can raise the risk of developing arrhythmias,” Dr Vandenberg added.

Although many drugs have been pulled from the market over the past three decades due to the noted risk of lethal ventricular arrhythmias, scientists have cited the need to address sudden cardiac deaths related to cardiac arrhythmia-inducing forms of treatment. Typically, these drugs remain on the market due to their medical necessity, despite the risks.

A new study, published in the journal Heart Rhythm, assessed the two antipsychotic drugs and their usage across Taiwan and found that up to 10 percent of patients developed severe QT prolongation during follow-up and the increased risk of ventricular arrhythmias and sudden cardiac death in quetiapine or haloperidol users who developed severe QT prolongation.

Clifford TeBay, a co-author of the editorial alongside Professor Vandenberg, said there is a whole range of drugs ranging from antibiotics to antihistamines that can cause heart rhythm disturbances.

“It’s vital we understand the real risk of these drugs so we can improve the safety of these drugs and monitor patients more closely to ensure no one dies from a sudden cardiac arrest unnecessarily,” Clifford said.

Mr TeBay is part of a team led by the Institute’s Dr Adam Hill to use computer monitoring for cardiac safety in drug screening.

Are you concerned about your heart health? Check out the Aged Care Guide for recognising the signs of heart failure.

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Related content:

What is dementia?

A guide to psychosis in older people

Mental health services for older people in aged care