"Our data reassures that most patients with heart disease might drink moderate doses of caffeine-rich beverages with no major risks," said lead researcher Dr. Luis Rohde. He's from the division of cardiology at the Federal University of Rio Grande do Sul in Porto Alegre.
Caffeine-rich beverages have long been suspected of causing several heart-related symptoms, such as palpitations or rapid or irregular heartbeats, Rohde said.
"Because of this assumption, counseling to reduce or avoid caffeine consumption is still widely recommended in clinical practice by most physicians for patients with any heart disease," he said.
But Rohde's team found no link between caffeine and abnormal heartbeats in the short term. "In fact, our results challenge the perception that patients with heart disease and at risk for arrhythmias should avoid or limit caffeine intake," he said.
Heart failure occurs when the heart can't pump enough blood to meet the body's needs.
The study included 51 people with heart failure. The researchers randomly assigned them to two groups. One group was given decaffeinated coffee that contained 100 milligrams (mg) of caffeine powder. The other group received decaffeinated coffee with a milk powder.
Patients drank the brews at one-hour intervals during a five-hour period. Those given caffeine received a total of 500 milligrams. The study also included a treadmill "stress" test one hour after the last cup of coffee.
Although no effect of caffeine on heart rhythms was seen, the researchers pointed out that the study was small. About half of the study volunteers were regular coffee drinkers, so they might have been less prone to the effects of caffeine.
The study also didn't look at long-term use of caffeine and its effect on abnormal heart rhythms among patients with heart failure, the researchers said.
The report was published online Oct. 17 in the journal JAMA Internal Medicine.
Dr. Christopher Granger is a professor of medicine at Duke University in Durham, N.C. He said that "this study adds to the body of evidence that coffee and caffeine consumption appears to be safe from a cardiovascular perspective.
"Even in a high-risk group, a group you might be most concerned about drinking caffeine, it looked like modest caffeine consumption was safe," said Granger, who co-authored an accompanying journal editorial.
But he cautioned that caffeine is a stimulant and can slightly increase blood pressure, even though it didn't have an effect on the heart rate of the study participants.
Granger noted that this study doesn't exonerate all forms of caffeine for heart patients either. "It did not take into account energy drinks that contain a lot of caffeine; there may be adverse effects from that," he said.
The bottom line from this study is that "modest amounts of coffee are safe even for people who have heart problems," Granger said.
For more information on heart failure, visit the American Heart Association.
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