Consuming energy drinks may raise the risk of life-threatening cardiac arrhythmias -- an irregular heartbeat condition, especially among patients with genetic heart diseases, finds a study on 6 June.

Increased caffeine content and additional unregulated ingredients in these beverages known to alter heart rate, blood pressure, and cardiac contractility may be the reason, said researchers from the Mayo Clinic in the US.

They explained that energy drinks contain caffeine ranging from 80 mg to 300 mg per serving, compared with 100 mg in an 8-ounce cup of brewed coffee.

However, most of these energy drinks contain other stimulating ingredients in addition to caffeine that are unregulated by the US Food and Drug Administration (FDA), such as taurine and guarana.

The study published in the journal Heart Rhythm examined a cohort of 144 sudden cardiac arrest survivors at Mayo Clinic, of which seven patients (5 per cent) had consumed one or more energy drinks near their cardiac event.

"Unusual consumption of energy drinks most likely combined with other variables to create a 'perfect storm' of risk factors, leading to sudden cardiac arrest in these patients," said Michael J. Ackerman, Genetic Cardiologist at the Clinic.

"While the study did not prove direct causation, caution is advised, and doctors recommend that patients consume energy drinks in moderation," the researchers said.

Michael noted that the energy drink market has grown consistently in the past few years. It raises "concerns about the potential combined effects of caffeine consumption and additional unregulated ingredients in these beverages", said the lead investigator.