by Salynn Boyles, Contributing Writer
April 17, 2018

That morning cup of coffee or espresso drink may not only be safe for people with atrial fibrillation (Afib) and other heart arrhythmias, it just may reduce arrhythmia frequency, Australian researchers reported.

Based on a comprehensive review of studies examining the impact of caffeinated beverages on cardiac rhythm, there was no evidence that drinking moderate amounts of coffee or tea triggered Afib and ventricular arrhythmias, according to Peter Kistler, MBBS, PhD, of the Alfred Heart Centre in Melbourne, and colleagues.

Coffee and tea consumption were associated with a reduced number of arrhythmia episodes in most studies, with one large meta-analysis showing a 6% reduction in Afib frequency among regular coffee drinkers, and another showing a 13% reduction in incident Afib risk, they wrote in JACC: Clinical Electrophysiology.

Drinking energy drinks, on the other hand, was determined to be a potential trigger for arrhythmia, and the authors concluded that they should be avoided by patients with pre-existing heart conditions.

Energy drinks typically contain a lot more caffeine than coffee, up to 500 mg per drink. Three-quarters of patients with pre-existing heart conditions in one study who consumed two or more energy drinks a day reported palpitations within 24 hours.

A single cup of coffee has around 95 mg of caffeine and a shot of espresso has around 65 mg.

“There is a public perception, often based on anecdotal experience, that caffeine is a common acute trigger for heart rhythm problems,” Kistler noted in a written press statement. “Our extensive review of the medical literature suggests this is not the case.”

The researchers identified studies examining the impact of coffee, tea, and energy drinks through searches of Medline, PubMed, EMBASE, and Web of Science. Key search terms were “caffeine,” “coffee,” “tea,” and “energy drinks” in combination with “arrhythmias,” “atrial fibrillation,” “sudden death,” “ectopy,” and “ventricular arrhythmias.”

Their analysis showed a consistent decrease in Afib associated with coffee and tea consumption, and little impact on ventricular arrhythmias.

Kistler’s group identified 11 human studies of caffeine and Afib involving close to 361,000 participants.

They reported that in a 2016 population-based cohort study, higher coffee intake was associated with a lower rate of incident Afib. Compared with nondrinkers, drinking two to three cups of coffee a day (odds ratio 0.86, 95% CI, 0.71 to 1.04) and six to seven cups per day (OR 0.79, 95% CI, 0.64 to 0.98) were both associated with lower Afib.

Also, drinking green tea was associated with lower incident Afib in a 2016 case-control study (multivariate OR 0.349, 95% CI, 0.25 to 0.48) in a dose-dependent manner (P=0.00

1 for trend). In a population-based cohort study reported in 2015, no association between coffee consumption and risk of incident Afib was seen at all levels of consumption (multivariate RR 0.98 for 2-3 cups/day, RR 1.01 for ≥5 cups/day; P=0.64 for trend).

In a 2011 retrospective cohort study, higher coffee intake was associated with lower rates of hospitalization for AF (HR: 0.81; 95% CI, 0.69 to 0.96 for ≥4 cups/day).

Caffeine doses of up to 500 mg daily (the equivalent of six cups of coffee) were not found to increase the severity or rate of ventricular arrhythmias.

In a 2016 randomized trial which included 103 heart attack survivors, regular caffeine intake (average 353 mg/day) was associated with improved heart rate variability, increased parasympathetic activity, and no significant increase in arrhythmias versus controls.

The researchers noted that recent large epidemiological studies suggest regular caffeine drinkers have lower cardiovascular and all-cause mortality.

“Large-scale population-based studies and randomized controlled trials suggest coffee and tea are safe and may even reduce the incidence of arrhythmia. Although there is no clearly defined threshold for caffeine harm, a regular intake of up to 300 mg/day appears to be safe and may even be protective against heart rhythm disorders,” they concluded.

• Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner