Coffee, AFib, And What The Science Says

Coffee and heart rhythm don’t have to be enemies. We dig into a new randomized trial across the US, Canada, and Australia suggesting that caffeinated coffee may lower the risk of recurrent atrial fibrillation compared with abstaining, then connect the dots with real-world monitoring, ablation strategy, and day-to-day choices that influence heart health.

We start by grounding AFib in plain terms: what it is, why so many people never feel it, and how stroke risk rises when the atria stop driving a steady beat. From there, we step into the electrophysiology lab to explain why trouble often starts near the pulmonary veins and how clinicians map and ablate rogue electrical tissue. Along the way, we highlight the role of wearables like Apple Watch in catching silent arrhythmias and guiding decisions, a shift that is rapidly improving detection and management outside the clinic.

Then we unpack the DECAF trial’s headline: coffee drinkers showed meaningfully lower recurrence of AFib or flutter over six months versus those who abstained. We explore possible reasons, from caffeine’s adenosine receptor antagonism and calcium signaling effects to the antioxidant and mitochondrial support offered by coffee’s polyphenols. We also compare with NEJM data in the general population showing no significant increase in ectopy, putting fears into perspective. Finally, we get practical: dosing and timing to protect sleep, what brewing methods change, how dairy proteins can blunt polyphenol absorption, and when unfiltered versus filtered makes sense if you’re balancing lipids and antioxidants.

If you enjoy coffee and live with AFib, these insights can help you personalize your cup without losing sight of the fundamentals: anticoagulation when indicated, smart rate or rhythm control, and balanced training that avoids chronic overload. If this conversation helps you think differently about caffeine, subscribe, share with someone who cares about heart health, and leave a review so others can find it.

For powerpoint slide deck, video recording and reference open-source articles go to: www.thehealthedgepodcast.com

Transcript

Opening And Today’s Big Question

SPEAKER_00 0:00

Welcome to the Health Edge, translating the science of self-care. I am Mark Pettis. Glad to be with you and with my friend, colleague John Bagnulo. Good morning, John.

SPEAKER_01 0:09

Good morning, Barraud. Great to see you.

Coffee’s Reputation Versus New Evidence

SPEAKER_00 0:11

Great to see you as always. It is uh December 11th on the uh home stretch for 2025. Uh and um uh we have uh another really encouraging study as it relates to coffee, John. And this uh is a study that I think um a lot of Health Edge listeners will be interested in. Uh and it relates to the uh connection between coffee consumption and atrial fibrillation, the uh most common cardiac arrhythmia or dysrhythmia. And of course, you know, historically uh the medical community uh tended to frown upon any coffee caffeine consumption in individuals with atrial fibrillation for what intuitively you know would have seemed like an obvious uh provocation, a caffeine having a you know a modest stimulant effect on the heart. And um, and so even today uh uh virtually every cardiologist I know will recommend that any of their patients with atrial fibrillation moderate or eliminate coffee or caffeine. And um so this this study was in the um uh JAMA, the journal of the American Medical Association last month, and it and it uh the the results challenged that conventional wisdom. So it it just it seemed a good uh time to bring coffee back into the spotlight in a again, another positive uh way. I I don't know that I've seen a negative study looking at coffee, John, uh, probably since I was in medical school uh you know 40 years ago.

SPEAKER_01 2:02

Yeah, there are many, unless you get into quality of sleep and it's consumed later in the day for some folks. But um you know, yeah, there's very little. And you know, you you feel like when you know what you do about coffee, and uh I don't I'm not saying this strictly from you know the perspective of how much I enjoy it, which is something that's very near and dear to me and my the start of every day, but when you when you understand that it's the number one source of antioxidants in the average person's life, and you understand all the favorable effects it has on everything from liver health to to blood pressure at the end of the day, right? I mean, it's just it has so many like favorable and positive ubiquitous effects on health that you know you feel compelled to to heighten awareness and to help, you know, by rallying to its defense, I guess you'd say. So we're doing that again here, which I really enjoy.

AFib Basics And Hidden Risks

SPEAKER_00 2:57

Yeah, and you you've always reminded me through the years, John, that uh coffee, particularly if you're not adulterating it with lots of sugar and all these synthetic uh you know creamers, uh, is probably the healthiest beverage, perhaps the healthiest food that uh the average American consumes on a on any given day. And uh it has so many attributes. Well, let's I'm gonna just share my screen for a second here, John, and let's let's look at um just a few general slides on uh atrial fibrillation. Um many people may be aware of this, but this is from the CDC, very recent uh data. And so AFib affects over 10 million U.S. adults, and it's very, very high prevalence, about one in 22. And interestingly, John, is it in this sort of modern environment where people are wearing um uh devices, um, you know, Apple watches and other devices that can more accurately capture heart rhythm, what's clear is that the prevalence of atrial fibrillation is much higher than than what people thought. And that's important uh because um it's one of the great risk factors for a stroke. And many people, and and I've treated thousands of people with atrial fibrillation, John, through the years. Um many people don't know they have it, uh, so this can frequently be silent. And um I've seen instances where the first manifestation of atrial fibrillation for the individual is a stroke. And um because that can be prevented in people with atrial fibrillation, knowing that one has it, particularly when they're otherwise asymptomatic, is so important. And so um this is the most common arrhythmia, and it and it raises stroke risks as we alluded to. It's um obviously a very expensive health issue, both in terms of quality of life as well as as cost of care. And uh like many things, as people get older, the risk uh goes up. And um the the traditional risk factors historically have been hypertension, diabetes, obesity, smokers. It it tends to be the usual suspects, but on occasion you'll see atrial fibrillation in people without any risk factors. And um, so it's just it's an important thing to be aware about uh and aware of.

Unique AFib Cohorts And Mechanisms

SPEAKER_01 5:37

Um yeah, one unique cohort, Mark, if I may, is that's you know, in the last 10 to 15 years that's surfaced is sort of your master's level, you know, kind of older um marathon runners. Uh and there are a lot of you know theories as to why that is, but fibrosis, I guess, or calcification, um, you know, would be some of the mechanisms that might be at play there. But I I've talked to some cardiologists, and I've certainly talked to uh in my work, I've talked to a lot of long-distance runners who inexplicably you know develop AFib in their 40s and 50s, and you know, it's just something where you know that that level of um of continuous stretch and and in pushing against that resistance, which you get with with high intensity running, you know, that it's something that really contributes, I guess, to the pathology for lack of a better description here of that left ventricle and and interferes with normal electrical patterns. So I just wanted to add that that you do have a very unique subset of folks with AFib that don't fall into that you know typical category of higher risk. So it's interesting stuff. And I, you know, again, I don't know how technical we should get on this. We can really geek out on it. Um, but there's there, you know, the couple different mechanisms are at work here, right? I think for a lot of um your typical risk factor, you know, you're you know, you're looking at pushing against a gradient all the time with hypertension, right? And you're getting some you're getting some changes in the way calcium is released from the from the cardiac muscle and how it's re-sequestered, and you're getting changes in that polarization so that you're not getting the the full contraction, you're getting these like little short, right? These little short, abrupt, inefficient contractions. Um and then you know, you've got some folks with fibrosis. Um, but I you know, again, I not to get too technical, I I just think it's it's important because when we get into like how how could caffeine possibly help as opposed to being you know being an agonist, how could it possibly help? I think when you understand that it also influences calcium potential. You know, I think that might be the you know the mechanism we're looking for here. I don't know, and I guess it's not really widely agreed upon, right? As to how it might work.

EP Insights And Pulmonary Vein Focus

SPEAKER_00 8:06

Yeah, you know, I think it's still um a bit unclear the exact mechanisms. What I've always found interesting about it when when you talk to um cardiologists that do EP electrophysiology, uh much of the um pathology, if you will, is is not in the heart itself. It's in the pulmonary artery, it's in that that first part of the artery that exits the heart to deliver uh blood to the to the lungs. And um, those are the areas where often they're finding these uh ectopic or um uh dysregulated electrical uh uh foci or or areas uh that they will ultimately relate with radio wave. So um clearly it's uh it's an electromagnetic uh problem. Um it it it one does tend to see high shear forces uh in those proximal great blood vessels, you know, when blood is leaving the left ventricle, it's you know, it's this vortex of pressure and uh at least on some level there probably are um either anatomic predispositions or or people who really are um exerting themselves on a on a long-term basis where those shear forces may create um focal areas of uh scarring and fibrosis, and you know, with the electrical system of the heart, and we often refer to the heart as the second brain. It's just loaded with electrical um activity, neurons and receptors, and and so those areas do seem vulnerable from the standpoint of mechanical damage and shear force, and and certainly people with hypertension, people um with lung disease, smokers will will tend to have higher pulmonary pressures. Uh when we're measuring a blood pressure in the arm, we're measuring pressures of the left side of the circulatory system, the left ventricle pumping through the aorta. What we're talking about here is the right side of the uh uh cardiovascular system. That's the pulmonary artery in the right ventricle. Ordinarily, those pressures are very low, um, a fraction of what you see on the left side of the heart. But many things will elevate those pressures, and certainly um many of the of the chronic morbidities that that we talk about can do that. Um, and I and I think hyperdynamic uh cardio pulmonary um um function in people who who are endurance athletes and uh ultramarathoners. There is clearly a point of uh uh diminishing return in terms of benefit. I think beyond a certain level of sheer stress and who knows what else. Uh but um yeah, you know, it's it's it's an interesting problem. And I I do think that uh when I look at ablation, um, you know, these you're essentially just Hey Mark, you want to explain, you might want to explain to our listeners what what ablation actually does to that cardiac tissue. So what what electrophysiologists will do is they'll take that that patient to the cardiac cathodization lab, and generally they're going through uh the groin, the femoral artery, uh, but but sometimes now they'll use the radial artery. Um and they can measure and map electrical activity to try to get a sense of, and again, usually this will be in the pulmonary vein, where are often one or more um areas where the electrical activity appears to be autonomous? It it's sort of on its own, it's not getting feedback, it's not regulating itself. And that allows them to then map electrically, electromagnetically, where the anatomic areas of interest are. Um and then they, through the that same catheter approach, they can apply um usually radio frequency. This is high frequency um radio wave that will ultimately destroy that um uh excited tissue purposefully uh to then diminish that that roadblock, that excitable spot. And um uh you know, many people will go back into a regular rhythm once that is ablated. Um and so occasionally you might need more than one um intervention. Uh many people certainly will require some medication as well to try to help them maintain that regularity of rhythm. And uh and important for all people with atrial fibrillation, being on a blood thinner to uh prevent stroke risk, until which time you can demonstrate many, many months of regular rhythm uh before you're you come off those medications. So yeah, that's kind of uh my way of thinking.

SPEAKER_01 13:38

Yeah, thanks. I think it's incredible. It's incredible to think that the technology is there to do that.

How Ablation Works

SPEAKER_00 13:45

Yeah, yeah. I I always enjoy talking with interventional cardiologists. Uh, you know, that it's it's really become sophisticated field. Um let's um I'll just go back quickly, uh John, a few slides here, and then we'll uh dive into this study. Um, you know, as we as we were really just talking about, uh, you know, these are the atria of the heart. Uh and and ordinarily there's a tremendous synchronicity. Uh, you know, when you're looking at an EKG, you tend to see this very regular pattern. The atria contract into the ventricles, then the ventricles contract into the general circulation, and that happens with tremendous precision and regularity. Uh and so atrial fibrillation is instead of getting this nice rhythmic contraction of the atria, you you really have more of a rapid uh mild contraction. So you lose function, both both the timing and the quality of that contraction is uh impaired. And uh again, some people may notice that as an irregular heartbeat or palpitation. Uh they might notice it as feeling lightheaded. Um But many people, as we as we talked about, John, will have no symptoms at all. But when you look at an EKG or uh you know a smartwatch, what you'll find on the tracing is you know, there's really no regular pattern. You got beats that are close together, some are further apart, and that's uh the classic um uh feature of atrial fibrillation. So this is the study that that we're referring to here today, John. This was published last month, uh hot off the press from JAMA, a very uh you know, well-respected peer-reviewed um journal. And the the title this was a randomized uh clinical trial called Dcaf. Uh they always have uh very cute uh um sort of acronyms uh and caffeinated coffee consumption or abstinence to reduce atrial fibrillation. And um uh this slide is a kind of a nice summary slide uh from the study. But the question being asked is does consumption of caffeinated coffee have a beneficial, detrimental, or neutral effect on the risk of recurrent atrial fibrillation? So these are individuals with atrial fibrillation, and then they're randomized. Um they're gonna consume coffee. This was a six-month trial or or abstain.

SPEAKER_01 16:39

Only one cup a day.

Reading Rhythms And AFib On Devices

The DCAF Randomized Trial Results

SPEAKER_00 16:41

Yeah, yeah. Well, I think it was one or more. Of course, the you know, those consuming averaged more, but as little as one cup a day um was associated with uh a beneficial effect. This was a multi-center trial, US, Canada, Australia. And again, it's much easier today in a an ambulatory, non-invasive way to just measure heart rhythm in real time. And so much so that I think the cardiology community sees, for example, the Apple Watch as a an essential uh tool for monitoring and measuring heart rate in people with atrial fibrillation. I I'm not sure if insurers are paying for that yet, but uh they they probably should. Uh and so they they monitor people over six months and really just looking at the um these rates of of atrial fibrillation. And the coffee drinkers had about 40 percent, uh 47 percent um showed uh you know this this persistence uh of atrial fibrillation, um some worsening. Uh and those that abstained from coffee had a much higher uh rate of of uh atrial flutter or fibrillation over that six-month period. And it was a pretty significant difference. Uh abstinence 64 percent, consumption 47 percent. Uh so that's a that's a like a 39 percent what what uh researchers would call relative risk reduction. And absolute risk reduction is basically the difference between these two. And so, you know, that's about a 17% absolute risk reduction, which means that if you have a hundred people with atrial fibrillation and um you uh take that hundred people and uh let's say they don't drink coffee, and uh, but maybe you know the reason they don't drink it is because they're fearful of it, not because they don't like it or they're not sensitive to the caffeine effects. Uh you put those hundred people on one or more cups of coffee a day, and uh, you know, one out of seven, uh, one out of six will will show a benefit. So um you don't the the number needed to treat, as we would think about it, is relatively small to see a possible effect is how I would interpret that.

SPEAKER_01 19:25

Hey, Mark, I'm curious. Uh you know, one of the the theories here, it may be a little bit more than a theory now, um, is that caffeine is an antagonist to adenosine uh at the adenosine receptor. I'm just curious, like what medications, you know, for AFib are also adenosine antagonists. I'm I'm just not familiar with that um, you know, with that target of of of medications. So do you know of any comparative I I know we don't have a comparative study of like coffee versus um you know, one of these medications. But are you are you familiar with any of those medications and what type of risk reduction you get with those?

Adenosine, Caffeine, And Rate Control

Population Data From NEJM

SPEAKER_00 20:06

That's a really interesting question, John. I don't know the answer to that. Um I I suspect many of the current um anti-arrhythmic agents uh for atrial fibrillation will have some effect on adenosine. Um many of them will alter calcium sodium channel potassium channel signaling and and all of those mechanisms do tend to be interrelated. A good number of people John will not revert to a regular rhythm on those anti-arrhythmic medications. They have variable efficacy many people uh will still go on to require ablation and for some um you you particularly uh when you look at the heart uh people that have really large atria if you do an echo or a sound uh and and on that echo not only is that that that right atrium um dilated but you can also measure pulmonary artery pressures what we talked about yeah initially which can be quite high those people have a very low probability of of getting into and maintaining a normal sinus rhythm so what what cardiologists will often do on those people is say look atrial fibrillation is probably always going to be your baseline rhythm let's just focus on controlling the rate how rapid your your ventricle is is going and what you know medication can help with that and just to focus on blood thinning and preventing a stroke um from that so um these can be complex in terms of the hemodynamics and some of these other variables um but yeah that's a really good question John you know when when somebody has a uh a potentially life threatening rapid we call it a supra ventricular tachycardia um some call it SVT or PAT paroxysmal tachycardia is the now we're getting heart rates greater than 100, 110 beats per minute, right? These are up to 180, 200. Wow uh wow and you know associated usually with low blood pressure and uh uh one of the first linecologic approaches is to give adenosine oh interesting so adenosine is given uh and it and it does it tends to um block the electrical conduction from the atria to the ventricle it's it's not designed to convert somebody into sinus rhythm it's designed to slow down the ventricle because if the atria is going at 200 which which often it will in atrial fibrillation you don't want each of those little tiny erratic contractions. You want you want longer slower contractions right yeah exactly so that's where adenosine can slow the heart down until which time you that individual is rendered stable hemodynamically so adenosine is interesting and from that perspective it it can slow uh contraction but but but why blocking adenosine for example in at a cellular level in the pulmonary vein might might help is yeah is and alcohol makes aphib worse in most people right yes very considerably worse yes yeah exactly uh so this was uh just another way of showing the difference uh John between those that consumed one or more cups a day versus those that abstained over the six month period and uh looking at the probability of recurring atrial fibrillation or flutter and again very from a very early on it didn't take long to begin to see differences uh you know within a week yeah uh pretty significant differences overall that uh you know maintain themselves these differences maintain themselves over that full uh six month period and um uh you know one other study that I thought was relevant to this John was was published in the New England Journal of Medicine this was 2023 so also a recent study and they just looked at the effects of coffee consumption uh on on health in general but with an emphasis on heart rhythm and um uh essentially found that uh whether you were a coffee drinker or not um there wasn't a huge difference one way or the other um uh whether it was atrial contractions which is what atrial fibrillation is or you know PVC some of them appear to be a little higher with coffee consumption but these were not statistically significant uh the supraventricular tachy tachycardias we talked about again a little bit less in the coffee consumption but not statistically significant so this basically um uh uh this was in the general population unlike the JAMA study where these were people with established atrial fibrillation and looking at um the ability to um uh either uh revert to a a regular rhythm or to continue to confront these recurrent episodes so the JAMA article had uh by definition higher risk individuals than what you see in the in the normal you know but in both cases mark it's it's good to see this early vindication uh of coffee for different reasons I mean it's been maligned for the last you know 50 years for for one reason or another right I mean AFib yes and also I I'm sure you remember you know 15 20 years ago uh you know like the Harvard School of Public Health came out with a statement about how you know how coffee raised cholesterol levels and you know we need to be careful with that because of cafaic acid's effect on on blood lipids and then we've learned that of course it may in in you know in a certain percentage of adults it may raise cholesterol levels 5% somewhere along that line but it at the same time it makes those LDLs larger and more buoyant.

Coffee, Lipids, And Mitochondria

SPEAKER_01 26:47

It protects them against oxidative stress. And in fact I've seen some you know epidemiological evidence or associations with unfiltered coffee actually having a uh having those those populations having a reduced risk for neurodegenerative as well as cardiovascular disease. So again it's it's that 2023 paper you know that you just talked about I think it's good because it just shows how at the very least it's not causing problems in people. And there may be you know again mild benefit to significant benefit and I you know you look at coffee's influences on cellular physiology and the one thing we haven't even got into that I know some people feel might play a role in AFib um it's hard to say but the mitochondria of cardiac muscle I mean look it's I mean I I I put it right there with the brain in terms of the overall metabolic burden right I mean it's you got to think about the amount of work the heart is doing all the time and and the mitochondria really kind of shouldering shouldering all of that metabolic responsibility and they're gonna burn out right they're gonna be exposed to very very high levels of oxidative stress and so when you take that into account and we know that what caffeine and what coffee some of the polyphenols offer to mitochondrial health it's just it's one more reason to look at it in a favorable lens.

Dose, Sleep, And Practical Caveats

Brewing Methods, Dairy, And Polyphenols

SPEAKER_00 28:14

Yeah no question and so misunderstood through the years uh um and we we've I would encourage um our listeners to go back at prior episodes we've done yeah on coffee consumption all of which in some way demonstrate and these are these are often uh epidemiologic or observational studies that certainly don't establish cause and effect but but have very strong associative risk reductions across for all cardiometabolic risk factors from obesity to diabetes and insulin resistance and hypertension and obesity um it it it's uh um and and and as we always talk about with respect to the Bradford Hall sort of criteria uh is that you see dose response, right? Uh yeah those that consume two to three or more have an even greater risk reduction. So um you know minus some of the sleep issues that you you touched on join and those are big issues certainly for for those that uh are sensitive drinking coffee mid-late afternoon or later can be problematic but um uh the virtues live on and uh uh and and really good studies and the example of what we've looked at today uh confirm that so it it is interesting though right john because we we often talk about how long it can take for a a study to translate into some meaningful consensus or or changes and recommendations so um uh I I suspect most people are still going to continue to hear oh if you've got atrial fibrillation stay away from coffee who who knows how long it'll take for this to there's some lag time yeah there's definitely going to be some lag time yeah but definitely reassuring uh data so uh yeah that that's pretty much it john that that's um uh always fun to look at coffee and uh yeah one one thing I'll add uh you know I'm not sure how much you know how useful it'll be for our listeners but all the research on the metabolism of the different aspects of coffee right so we've got things like chlorogenic acid cafeic acid obviously the caffeine which is front and center um a lot of those polyphenols in molecules the absorption is blunted by by the addition of milk or half and half or even cream you know some of those um you know some of those dairy additions will will bind onto the polyphenols in a very unique way and will reduce some of their I guess you'd say uh you know metabolic effects so to speak so again if someone's interested in drinking I mean again by all means if you need cream to enjoy your coffee I get it uh I don't want to ever ruin anybody's cup of coffee but you mentioned earlier about how sometimes coffee gets adulterated right with non-dairy creamers and things along those lines but you know the cream is probably going to be better than the half and half and the half and half is going to be better than the milk because it's the casein component and there are small fractions of casein even in cream it's like a sponge it's like a sponge for for some of these really unique and very medicinal polyphenols.

SPEAKER_01 31:54

So I just thought I'd add that and obviously running coffee through a filter paper filters tend to remove much much more of uh some of these beneficial these beneficial molecules and not filtering coffee which isn't for everybody but it leaves more of those intact so I just thought I'd add that um because I know some of our listeners are really into coffee so which is a great thing.

Closing Notes And What’s Next

SPEAKER_00 32:17

Really helpful John and uh yeah you you uh you've often talked about uh sourcing and high altitude and um uh different ways that we can prepare and consume all of which have subtle and and sometimes very meaningful differences in the in the final beverage that you're consuming. So that's that's great stuff. Always a lot of fun um chatting John and talking stuff. I've got a few papers that I'm looking at now uh that I'll pass along to you um uh the one that uh just came out um is uh sort of challenging this historical perspective that one minute of um uh strenuous activity intense uh activity exercise is equal to say two minutes of more more moderate uh uh cardiopulmonary activity uh exercise I look forward to that and uh I look forward to that yeah because you know the high intensity training not to get ahead of ourselves here but it's it's you know it's now front and center people want to make everything is like efficiency and convenience right like what can I get done in the shortest amount of time but it neglects I think to where we're going with this and you and I haven't even had a chance to talk about it yet but it it does neglect the benefits of the lower intensity longer duration bigger windows of time when you get you know more capillary involvement and things like that.

SPEAKER_01 33:53

So I I I really look forward to that I can't wait to see those papers.

SPEAKER_00 33:56

Yeah yeah good stuff John well listen you have a a great um rest of the week weekend you as well bro stay well and uh love to all and uh we will uh connect next week I look forward to love you man take care of you too and for the health edge listeners please uh check out our website thehealth edge podcast dot com all of our um any PowerPoint slides that we share the audio the video and and papers that are open source that we're able to share will be posted there if you're looking for a little more detail we're we're very grateful uh for those that uh listen in and uh if you find value in this uh please share it with those you love um uh I think uh we're at this time now where we're all flooded with information and it it can be harder than ever to separate the you know that which is really meaningful from that which might be less so and and so uh if this resonates if it feels right uh um please share with those you love and uh we will see you soon