Drinking high doses of caffeine by systolic heart failure patients did not induce arrhythmias (abnormal heart rhythms).The study was published online in JAMA Internal Medicine.
The findings of a small randomized clinical trial challenged the perception of limiting caffeine intake in heart disease patients for the risk of arrhythmias.
The relationship between caffeine consumption and the triggering of arrhythmias remains controversial despite decades of exploration on the matter. Advice to reduce caffeine to high-risk patients is widely recommended in clinical practice, despite a lack of evidence of an arrhythmogenic effect of caffeine on these individuals.
The study included 51 patients: 25 were assigned to receive decaffeinated coffee with caffeine powder and 26 received decaffeinated coffee with placebo lactose powder. The caffeine or placebo was ingested at one-hour intervals for a total of 500 mg of caffeine or placebo during a five-hour period. The study included a treadmill test one hour after the last ingestion.
The authors found no association between caffeine ingestion and arrhythmic episodes, even during the physical stress of a treadmill test, after 500 mg of caffeine was ingested over a five-hour period, according to the article.
The authors note study limitations. While their results showed no effect of acute caffeine use on arrhythmic events, they note that about 50 percent of their patients were habitual coffee drinkers and this could influence the results because routine users may be less prone to the effects of the substance. Although they believe this to be unlikely, they acknowledge they "cannot ensure that long-term and high-dose use of caffeine is not associated with a proarrhythmic effect in patients with HF [heart failure]," the authors report.
"The acute ingestion of high doses of caffeine did not induce arrhythmias in patients with chronic systolic HF at rest and during a symptom-limited physical exercise. To date, there is no solid evidence to support the common recommendation to limit moderate caffeine consumption in patients at risk for arrhythmias," the authors report.