With atrial fibrillation (a problem with the rhythm of the heartbeat), the electrical system of the heart malfunctions, causing fibrillation — or very fast, irregular contractions of the upper chambers of the heart. Some say that, if you could see the heart with atrial fibrillation, it would look like a bowl of quivering Jell-O. The condition raises the risk of stroke and cardiac arrest.
For years, people have associated drinking strong coffee with causing palpitations (a feeling that the heart is pounding or racing). A new investigation has found that caffeine exposure was not linked to a higher risk of atrial fibrillation, and low doses of caffeine may actually have a protective effect.
"Ask a doctor about how coffee may affect your heart."
Daniel Caldeira, MD, with the Laboratory of Clinical Pharmacology and Therapeutics in the Faculty of Medicine at the University of Lisbon and the Cardiology Department at Hospital Garcia de Orta, Almada in Portugal, and fellow scientists reviewed data from seven observational studies involving 115,993 individuals.
The average age of subjects ranged between 51 and 62 years old, and they included coffee and non-coffee drinkers, as well as patients with and without atrial fibrillation.
According to the Centers for Disease Control and Prevention (CDC), an estimated 2.66 million people had atrial fibrillation in 2010 and as many as 12 million people will have it by 2050.
The scientists based their conclusions about caffeine exposure on coffee consumption. They considered three levels of daily caffeine intake: low, moderate and high. Low intake was less than 350 milligrams, moderate intake was 350 to 699 milligrams, and high intake was greater than or equal to 700 milligrams.
For this study, the authors considered each cup of coffee to have an amount of caffeine related to the geographic region. For example, coffee in the United Kingdom and Northern Europe was typically stronger with 140 milligrams of caffeine per cup as opposed to 85 milligrams per cup on average in the United States.
Depending on the study, the coffee drinkers consumed anywhere from a cup or less to an average of 248 milligrams of caffeine per day.
Among all the coffee drinkers, investigators discovered no significant link between consuming caffeine and the likelihood of atrial fibrillation.
When looking at just those with a low caffeine intake, the risk for atrial fibrillation was slightly lower compared with non-coffee drinkers.
“The exposure to low doses of caffeine may offer a small protective effect against atrial fibrillation,” wrote the authors. “There are no data to support the hypothesis that long-term caffeine exposure is associated with an increased risk of atrial fibrillation.”
This research lends support to previous reports showing that coffee may have a protective influence on the heart.
In a previous large study of about 400,000 people published in 2012 in The New England Journal of Medicine, investigators found "...a significant inverse association between coffee consumption and mortality,” specifically with deaths due to heart disease, respiratory disease, stroke, injuries and accidents, diabetes and infections.
The authors of that prior study wrote, “Our results provide reassurance with respect to the concern that coffee drinking might adversely affect health.”
This study on atrial fibrillation was published in September in the journal Heart, an international peer-reviewed journal for health professionals and researchers in all areas of cardiology.