ARE YOU A PERSON who may have uttered this quote? — “The most dangerous drinking game is seeing how long I can go without coffee.” If so, I have some good news for you.
Today, we turn to the effects of coffee consumption on the risk of a heart condition known as atrial fibrillation. Atrial fibrillation (Afib) is one of the most common forms of serious heart rhythm problems and has recently increased incidence.
A new study sheds some light on the relationship between coffee and Afib. First, a primer on atrial fibrillation.
Atrial fibrillation — The facts
The authors of a study of trends over the last 50 years believe the increase in the incidence of atrial fibrillation in the community is probably partly due to enhanced surveillance. The US Centers for Disease Control and Prevention offers these observations:
About 9 percent of those older than 65 (and two percent of people under 65 years) live with atrial fibrillation in the United States.
Did you know that individuals of European descent are more likely to have atrial fibrillation than are African Americans? Or that the incidence of the condition increases with age? Given that women generally live longer than men, more women than men experience atrial fibrillation.
Atrial fibrillation — What is it?
Your heart typically contracts and relaxes to a reasonably regular beat. The sinus node in your heart is a natural pacemaker — it creates electrical signals that cause the heart to squeeze and pump blood. Your care team may use an electrocardiogram (ECG) to record and evaluate these electrical signals.
In atrial fibrillation (Afib), the heart’s two small upper chambers (atria) beat irregularly and too quickly. The heart quivers rather than making a nice muscular contraction. As a result, some blood may not be pumped efficiently from the atria into the ventricles during atrial fibrillation. The blood that is left behind can pool in the atria and form dangerous blood clots.
Symptoms
How do you know if you have atrial fibrillation? Sometimes there are no symptoms, but signs may include:
- a fast and irregular heartbeat
- heart palpitations (a “fluttering sensation” in the chest
- light-headedness or fainting
- chest pressure or pain
- shortness of breath, especially when you are lying down
- Tiring more easily
If left undetected or untreated, atrial fibrillation can lead to serious medical problems, including heart attack, heart failure, a stroke, or sudden cardiac arrest. The American Heart Association offers this frightening statistic:
The risk of stroke is about five times higher in people with atrial fibrillation. This risk increases because blood can pool in the atria, and blood clots can form.
Fortunately, there are often effective management tools. Some options may include one or more of these:
- Medications to slow your heart rate (such as digoxin, beta-blockers, or certain calcium channel blockers);
- Medication to bring back a regular heart rhythm (antiarrhythmics or beta-blockers);
- Procedures to control the electrical impulses causing the atrial fibrillation (electrical cardioversion or catheter ablation);
- “Blood thinners” (anticoagulants or antiplatelet medicines) to reduce clot risk;
- Placement of a pacemaker (or other surgery).
Let’s get back to coffee. We already know many risk factors for atrial fibrillation, high blood pressure, diabetes, heart valve disease, heart failure, obesity, hyperthyroidism, and ischemic heart disease. Unfortunately, few studies have looked at the role of dietary habits on atrial fibrillation risk.
We know that coffee promotes the release of adrenal-like substances and increases the sensitivity of heart muscle to calcium. Such changes can affect your heart rhythm.
The available clinical literature does not provide a clear answer. For example, the Women’s Health Study showed an increased risk of Afib with two to three cups of caffeinated coffee daily. On the other hand, an analysis of a collection of studies (meta-analysis) showed no significant impact of coffee on men.
Recognizing these discordant results and the widespread consumption of coffee worldwide, researchers took another look at whether coffee is associated with atrial fibrillation risk among men.
The Coffee and Real-time Atrial and Ventricular Ectopy (CRAVE) trial used digital health tools to look at the effect of caffeine consumption on heart rhythm disorders in 100 healthy participants.
Here’s the innovative study design: Participants drank as much coffee as they wanted for one day and avoided all caffeine the next day, alternating this pattern in two-day blocks over two weeks. The subjects got daily coffee assignments via a smartphone app. They wore a continuous recording heart monitor, a continuous blood sugar monitor, and a Fitbit Flex 2 (to record sleep duration and step counts).
The participants pushed a button to record each coffee drink consumed. The researchers reimbursed the participants for their coffee purchases and used smartphone geolocation to track coffee shop visits.
The results? Coffee does not appear to play a role in developing atrial fibrillation or increasing problematic heart rhythms’ frequency (or severity).
Here’s the take of expert coffee researcher Chip Lavie, MD: “Unless coffee consumption is excessive, such as over 5 cups per day in young people, all of the evidence points to coffee and caffeine being safe.
My take
While the study is well-done, I look forward to follow-up research involving more subjects over a longer time period to see the long-term impact of coffee consumption. I would also note that the study participants were young and healthy, with an average age of 38 and an average body mass index.
In this context, if you are concerned about the effects of coffee on your health, you know the drill: Please check in with your healthcare provider. Finally, the researchers have not yet published their study in a peer-reviewed journal.
Interestingly, while the coffee tended to rob folks of sleep, the subjects took about 1,000 more steps than they typically would for every additional cup of coffee consumed. Don’t know if they were walking to the coffee shop or simply caffeine-fueled!
