Daijiworld Media Network – New Delhi
New Delhi, Aug 12: Drinking caffeinated coffee may not worsen atrial fibrillation (AF) and could potentially reduce the risk of the condition returning, according to findings from the Does Eliminating Coffee Avoid Fibrillation (DECAF) trial.
Coffee and caffeine have traditionally been considered possible triggers of AF, leading doctors to advise some patients to limit or avoid caffeinated beverages. However, previous observational studies have generally not found an increased risk of developing AF among coffee drinkers, while some have suggested that regular coffee consumption could be associated with a lower risk.
Earlier randomized studies, including I-STOP-AFib and CRAVE, also found no significant increase in AF or premature atrial contractions associated with caffeine exposure or caffeinated coffee.
The DECAF trial was designed to directly examine whether coffee consumption affects AF recurrence. It was an investigator-initiated, international, multicenter randomized clinical trial involving 200 patients with persistent AF or atrial flutter with a history of AF who were scheduled to undergo electrical cardioversion.
All participants had consumed at least one cup of caffeinated coffee daily at some point during the previous five years. Some had stopped drinking coffee because they believed it could worsen AF or had been advised to do so by doctors.
After successful cardioversion, participants were randomly assigned either to drink at least one cup of caffeinated coffee daily or to abstain from coffee, including decaffeinated coffee, and other caffeinated products. They were followed for six months or until AF or atrial flutter recurred.
The median coffee consumption among participants assigned to the coffee group was seven cups per week, while those in the abstinence group consumed no coffee.
The primary analysis found that participants assigned to caffeinated coffee had a 39% lower risk of clinically diagnosed recurrent AF or atrial flutter compared with those assigned to abstain from coffee and caffeine. The hazard ratio was 0.61, with a 95% confidence interval of 0.42 to 0.89 and a P value of 0.01. No significant difference in adverse events was observed between the two groups.
The researchers said the findings challenge the long-held belief that caffeinated coffee can trigger or aggravate AF. At the very least, the results suggest that moderate consumption of caffeinated coffee, roughly one cup a day, is unlikely to worsen AF in most people. Whether coffee itself has a protective effect, however, remains uncertain.
Researchers said several biological mechanisms could potentially explain the findings. Caffeine blocks certain adenosine receptors, which could influence processes involved in triggering AF. Coffee also contains compounds with possible anti-inflammatory, antioxidant and antifibrotic effects. It may additionally influence factors associated with AF, including blood pressure, physical activity, body weight and heart failure.
At the same time, the researchers noted that caffeine can have potentially pro-arrhythmic effects, including increased calcium release and blood pressure, while lifestyle factors associated with coffee consumption may also influence heart rhythm.
The study had several limitations. The planned follow-up period was initially 12 months but was reduced to six months because maintaining prolonged caffeine abstinence was expected to make recruitment difficult. Nearly 2,000 patients had to be screened to enroll the 200 participants.
The researchers therefore said further randomized studies are needed before the findings can be used to make broader changes to clinical practice.
Overall, the DECAF trial suggests that routinely asking people with atrial fibrillation to completely avoid caffeinated coffee may not be necessary. For patients undergoing cardioversion, modest caffeinated coffee consumption was associated with a lower rate of AF or atrial flutter recurrence over six months, although more research is needed to determine whether the association reflects a genuine protective effect.