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RCT finds caffeinated coffee not associated with higher daily premature atrial contractions

31st March 2023

Caffeinated coffee consumption did not increase the level of premature atrial contractions compared to avoidance in a recent randomised trial

Researchers from the university of California found that drinking caffeinated coffee did not significantly increase the level of premature atrial contractions compared to avoidance of such drinks.

Both tea and coffee are the most widely consumed caffeinated beverages around the world. However, it is widely assumed that caffeinated drinks have pro-arrhythmic effects and which produce premature cardiac contractions, known as atrial and ventricular ectopy. In fact, it has become recognised that the presence of these premature atrial contractions, can help predict new-onset atrial fibrillation. Furthermore, an increased frequency of premature ventricular contractions has been linked to a higher incidence of congestive heart failure and mortality. Whether or not caffeinated products increase the risk of arrhythmias, is not well defined, although a 2013 systemic review concluded that caffeine exposure does not increase the risk of atrial fibrillation and that low-dose caffeine may even exert a protective effect. Caffeinated coffee has also been shown to have additional health benefits such as improved physical activity performance but may reduce sleep duration.

In the current study, the US researchers examined the acute effects of coffee consumption on several factors including cardiac ectopy, physical activity, sleep, and glucose levels by using continuously recording, wearable sensors. The study was conducted over a 14-day period and during this time, participants were randomly assigned to either consume or avoid, caffeinated coffee, with avoidance continued for two consecutive days. The team set the primary outcome as the mean number of daily premature atrial contractions and compared this figure with those recorded on days without coffee.

Caffeinated coffee and health outcomes

A total of 100 adults with a mean age of 39 years (51% women) were included in the study.

Consumption of caffeinated coffee gave rise a mean of 58 daily premature atrial contractions compared to 53 such events when the beverage was not taken (rate ratio, RR = 1.09, 95% CI 0.98 – 1.20, p = 0.10). In addition, use of caffeinated coffee led to 154 premature ventricular contractions compared to 102 on avoidance days (RR = 1.51, 95% CI 1.18 – 1.94).

On coffee drinking days, individuals also had a higher mean number of daily steps (10,646 vs 9,665), a lower mean number of nightly sleep minutes (397 vs 432 minutes) but similar levels of serum glucose.

The authors concluded that consumption of caffeinated coffee did not result in significantly more daily premature atrial contractions compared to days when the drink was avoided. They added that the secondary outcome data, e.g. higher premature ventricular contractions, more physical activity and less sleep, should be interpreted as hypothesis-generating.

Marcus GM et al. Acute Effects of Coffee Consumption on Health among Ambulatory Adults. N Eng J Med 2023