Contrary to common belief, coffee does not increase abnormal heart rhythms known as arrhythmias but, rather, helps prevent them, according to a review published in the April 2018 issue of the Journal of the American College of Cardiology: Clinical Electrophysiology.
“There is a public perception, often based on anecdotal experience, that caffeine is a common acute trigger for heart rhythm problems,” stated lead author Peter Kistler, MBBS, PhD, of Alfred Hospital and Baker Heart and Diabetes Institute in Australia. “Our extensive review of the medical literature suggests this is not the case.”
One cup of coffee contains an average of 95 milligrams of caffeine. Caffeine blocks the effects of adenosine, a compound that can facilitate the type of arrhythmia known as atrial fibrillation. Population-based studies have documented an association between a reduction in atrial fibrillation and greater caffeine ingestion. In fact, a meta-analysis that included 228,465 subjects found an inverse relationship between drinking coffee and atrial fibrillation occurrence. While regular coffee drinkers had a 6% average reduction in atrial fibrillation, pooled results from studies with adjustment of potential confounders found a decrease of 11% for low doses and 16% for high doses of caffeine.
Dr Kistler and colleagues determined that caffeine also has no effect on ventricular arrhythmias. Doses of up to 500 milligrams per day have not been associated with ventricular arrhythmia rate or severity. Only at 9-10 cups per day has coffee been associated with an increase in risk.
“Caffeinated beverages such as coffee and tea may have long term antiarrhythmic properties mediated by antioxidant effects and antagonism of adenosine,” Dr Kistler noted. “In numerous population-based studies, patients who regularly consume coffee and tea at moderate levels have a lower lifetime risk of developing heart rhythm problems and possibly improved survival.”