Energy drinks may be fatal for people with heart disease

Drinking even a small amount of caffeinated energy drinks may trigger serious cardiac events in people with a genetic heart condition, which may lead to rapid, irregular heartbeat, a new study warns.

Researchers from University of Sydney and Centenary Institute in Australia assessed the acute cardiovascular responses to energy drink consumption in patients with familial congenital long QT syndrome (LQTS).

They also analysed whether any identified cardiovascular effects correlate with changes in blood levels of the active ingredients - caffeine and taurine. LQTS is a condition that affects one in 2000 and can cause rapid, irregular heartbeat that can lead to sudden death.

Researchers recruited 24 patients aged 16 to 50. More than half were symptomatic before diagnosis and receiving beta-blocker therapy. Participants were assigned to energy drink or control drink groups.

The energy drink consisted of two sugar-free cans totalling 160 milligrammes (mg) of caffeine and 2000mg of taurine, totalling 500 millilitre (ml). The control drink was a 500ml drink with no caffeine or taurine.

Electrocardiograms and blood pressure were recorded every 10 minutes, while signal-averaged electrocardiogram (SAECG) testing and repeat bloods were collected every 30 minutes for a total observation time of 90 minutes.

Results showed that three patients (12.5 per cent) exhibited dangerous QT prolongation following energy drink consumption and two of the three had sharp increases in blood pressure.

These patients all had a documented family history of sudden cardiac death and two of them had previously experienced severe clinical manifestations and received an implantable cardioverter-defibrillator for recurrent syncope, researchers said.

"Some individual patients may be at a higher risk. We therefore suggest caution in allowing the consumption of energy drinks in young patients with LQTS," said Christopher Semsarian, professor at University of Sydney and Centenary Institute. The study was published in the International Journal of Cardiology.