Caffeine Study Gives Heart Failure Patients Green Light To Drink Coffee

 

Many people with heart failure are advised to avoid coffee because of fears that caffeine might provoke an arrhythmia. Now a rare example of a randomized controlled trial in the field offers some assuring evidence that these patients can safely drink coffee.

The health effects of coffee have been the subject of considerable debate, including wildly disparate views suggesting that coffee may be either beneficial or harmful. But the field has been hampered by the absence of high quality, randomized controlled trials with clinically relevant endpoints. In their absence observational studies have been used to support a wide variety of positions. Much of the debate has centered on the role of caffeine. Now a small randomized controlled trial sheds light on the effect of coffee in an important patient population.
In a paper published in JAMA Internal Medicine researchers in Brazil report on the short-term electrocardiographic effect of high dose caffeine in 51 patients with moderate to severe heart failure. They performed a double-blind, randomized crossover trial comparing 500 mg of caffeine or placebo. Participants drank 5 cups of coffee over 5 hours, during which time they underwent electrocardiographic monitoring. At the end of the 5 hour period a treadmill test was performed. The researchers found “no association between caffeine ingestion and arrhythmic episodes,” either during ECG monitoring or the treadmill test. They also found no evidence of ventricular or supraventricular premature beats or other arrhythmias.
“Our results challenge the intuitive notion that caffeine intake should be limited or prohibited in patients with heart disease and at risk for arrhythmia,” the authors wrote. “To date, there is no solid evidence to support the common recommendation to limit moderate caffeine consumption in patients at risk for arrhythmias.”

In an accompanying commentary Jacob Kelly and Christopher Granger (Duke Clinical Research Institute) write that the study “is a welcome addition to the literature.” But they note that “the short term nature of the exposure and the small number of patients… preclude any reliable information on clinical outcomes.”
Thomas Whayne, Jr, is a cardiologist at the University of Kentucky who has long been interested in the coffee issue. “I think the results add further support to the safety of moderate coffee drinking (2-4 cups per day). Unless there is a genetic abnormality as was documented in a valley in Costa Rica, coffee does not appear to increase coronary artery events and it decreases adult onset diabetes mellitus. The major clinical implication is that we can reassure our patients that moderate coffee (fully caffeinated) intake is fine if enjoyed, unless bothersome arrhythmias or other bothersome symptoms are associated. In addition, hospitals should offer caffeinated coffee to cardiovascular patients able to ingest it, in moderate levels, instead of prohibiting it for cardiovascular patients as in the past. The limitation as evidence-based medicine is that the study was extremely short-term.”
One important detail of the trial may limit its application to broader populations. Nearly all the patients in the trial were taking a beta-blocker, which slows down the heart and may have prevented or blunted an arrhythmic response. Although caffeine is known to raise the heart rate, no such elevation was observed in the study. Whayne agreed that “not taking one might have made a difference,” though it is important to emphasize that all CHF patients should be ” on a beta blocker unless there is a specific contraindication.”

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The senior author of the paper, Luis Rohde ( Porto Alegre, Brazil) agreed that “based on our results, beta-blockade might have attenuated the potential ‘side-effects’ of caffeine. So I would be careful to translate our findings to other populations. But based on the overall body of scientific evidence about the potential cardiovascular risks and benefits of caffeine ingestion, it seems reassuring that modest to moderate ingestion would be safe for almost everybody (including people without cardiovascular disease).”

A small trial of patients with heart failure finds that ingesting high doses of caffeine does not raise the risk of arrhythmia. The researchers found this to be the case whether patients were at rest or performing a treadmill stress test.

The trial challenges the idea that patients with heart disease and risk for arrhythmia should limit their intake of caffeine.

The findings are published in the journal JAMA Internal Medicine. Luis E. Rohde, of the Federal University of Rio Grande do Sul, Porto Alegre, Brazil, and also chief of cardiology at the Hospital de Clinicas de Porto Alegre, supervised the trial.
Arrhythmia - literally "without rhythm" - is where there is a problem with the rate or rhythm of the heartbeat. It may feel like a fluttering or brief pause.
There are two main kinds of arrhythmia: one where the heart beats too fast (tachycardia), and the other is when it beats too slowly (bradycardia).
Most arrhythmias do no harm. But in some cases, the condition can be serious and even life-threatening, as the heart may not be able to pump enough blood. Lack of blood flow can damage vital organs, including the brain and the heart itself.
The trial investigators say their results challenge the idea that patients with heart disease and risk for arrhythmia should limit their intake of caffeine.

Controversy about caffeine and heart problems

The trial is not the first to challenge perceptions about the link between caffeine intake and heart problems.

Fast facts about arrhythmia

• Even serious arrhythmias can often be successfully treated
• Atrial fibrillation - where electrical signals spread through the chambers of the heart in a disorganized way - is the most common type of arrhythmia
• Most people with arrhythmia are able to live normal, healthy lives.

Learn more about arrhythmia

For example, earlier this year, University of California-San Francisco researchers reported how they found regular caffeine consumption is not linked to extra heartbeats.
The authors reporting the new trial note that despite decades of research, the question of whether caffeine consumption triggers arrhythmias remains unresolved and surrounded by controversy.
They say clinicians and health professionals often advise heart patients at risk for arrhythmia to reduce caffeine intake, despite lack of scientific evidence to support this recommendation.
In the clinical trial record, they note how some animal studies have proposed there is a link between arrhythmias and ingesting high doses of caffeine, but these findings are not repeated in human studies. They add:
"In particular, little is known about the association between caffeine consumption and arrhythmias in patients with heart failure, especially at higher doses of consumption."

Caffeine ingestion not linked to episodes of arrhythmia

The randomized controlled trial recruited 51 patients. The team assigned 25 to receive caffeine in the form of powder dissolved in decaffeinated coffee and 26 to receive a placebo in the form of lactose powder dissolved in decaffeinated coffee.
Both groups ingested their drinks at 1-hour intervals over 5 hours, up to a total of 500 mg of caffeine or placebo. This is the equivalent of about five 5-ounce cups of coffee.
The investigators found no link between caffeine ingestion and episodes of arrhythmia, even during a treadmill test that the participants underwent 1 hour after their last drink of caffeine or placebo.
The authors acknowledge that the results may have been influenced by the fact that around half of the patients were regular coffee drinkers, but they suggest this is unlikely.
However, they note they cannot guarantee that ingesting high doses of caffeine over a long period would not promote arrhythmia in patients with heart failure.

"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."

Luis E. Rohde and colleagues

Learn how coffee may improve exercise endurance.

Written by Catharine Paddock PhD