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Drug Danger
GI, Anti-Psychotic Drugs Cause Big Increase in
Sudden Cardiac Deaths
May be responsible for up to 15,000 deaths a year in
USA and Europe
 May
11, 2005 - Gastrointestinal and anti-psychotic drugs that interfere with
the electrical activity controlling the heartbeat are associated with a
three-fold risk of sudden cardiac death, according to Dutch research
published today in the European Heart Journal. They estimate up to
15,000 may be dying annually in Europe and the USA from these drugs.
In a study of 775 cases of sudden cardiac deaths
and over 6,000 matched controls in the Netherlands the researchers found
that the use of certain anti-psychotic and gastro-intestinal drugs
listed on the website of the International Registry for Drug-induced
Arrhythmias was probably responsible for 320 sudden cardiac deaths a
year in the Netherlands and, by extrapolation, a total of around 15,000
in Europe and the USA.
The drugs examined were cisapride and domperidone
(GI drugs), chlorpromazine, haloperidol and pimozide (anti-psychotics)
and erythromycin and clarithomycin (antibiotics). Cisapride has been
unavailable to American consumers since August 2000, after maker Janssen
Pharmaceuticals pulled it from drugstore shelves following reports
linking use of the drug to dangerous cardiac arrhythmias, some fatal,
according to HealthDay News..
They have all previously been implicated in cardiac
arrhythmia, but the new study is believed to be the first to evaluate
the link between them and sudden cardiac death.
These drugs prolong the QTc interval in the heart.
The QTc interval is the duration (as measured by electrocardiogram) of
the electrical activity controlling contraction of the cells of the
heart muscle. It is the measure of how long it takes to repolarize the
myocardial cells in the heart, a process that is necessary before the
heart can contract. Drugs that prolong the QTc interval can interfere
with repolarization and cause life-threatening arrhythmias.
However, the report's senior author, Dr Bruno
Stricker from the Erasmus Medical Center in Rotterdam, said that
although these drugs did significantly raise the risk of sudden cardiac
death it was important to keep the risk in perspective. The normal
annual incidence of sudden cardiac death was one to two deaths a year
per thousand of the population in the western world. This risk rises to
around three per thousand per year in those taking the drugs.
"These drugs are vital treatments for serious
conditions in many cases, so it is essential that patients should not
stop taking them on their own initiative. If they are concerned they
should talk to their doctor," said Dr Stricker, who is also working as
senior medical officer at the Inspectorate for Healthcare The Hague.
"The risk of sudden cardiac death was higher among
recent starters (within around 90 days) and was significantly increased
in users of GI medication and anti-psychotics," said Dr Stricker. "Past
use was not associated with increased risk. Although the antibiotics
have been reported to be linked to sudden cardiac death, we found no
statistically significant increase in our study, although that may have
been due to the limited number of cases."
The highest risk level was for those using higher
daily doses of GI or anti-psychotic medications. Risk also tended to be
higher among women than men and among older patients than younger,
although these differences were not statistically significant.
Dr Stricker said that their study had some
potential limitations – some misclassifications could not be excluded
and some deaths may have been missed, although these would have been
minimal. Also, not all acute deaths may have been heart-related. But,
even if some confounding factors existed they would be unlikely to
explain the strong link the study found between the drugs and sudden
cardiac death.
"Although prolongation of the QTc interval by
non-cardiac drugs is not an unusual finding, potentially fatal
arrhythmias and sudden cardiac death are relatively uncommon," said Dr
Stricker. "Nevertheless, our results suggest that 320 cases a year of
sudden cardiac death can be attributed to QTc-prolonging medication in
the Netherlands and, by extrapolation, around 9,000 in Europe and 6,000
the USA."
He concluded: "These findings are important to
regulatory authorities because QTc prolongation is used as a surrogate
marker for the prediction of serious adverse drug effects and the
authorities have to evaluate the clinical significance of QTc
prolongation observed in relatively small clinical trials where there
were no cases of sudden cardiac death."
More information available at the Heart Rhythm
Society:
sudden cardiac death.
> News source: the European Heart Journal.
> Non-cardiac QTc-prolonging drugs and the risk of
sudden cardiac death. European Heart Journal.doi:10.1093/eurheartj/ehi312.
> A list of QTc-prolonging drugs and their
classification according to their risk of inducing prolonged QTc or
Toursade de Pointes (cardiac arrthymia), can be found on:
http://www.qtdrugs.org/medical-pros/drug-lists/drug-lists.htm
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