Today we’re talking about coffee.
The topic comes up very frequently in my clinic, where patients with various arrhythmias will ask if they can consume coffee.
There's this conventional wisdom that coffee increases the risk for heart rhythm disturbances or electrical problems with the heart, which is my clinical subspecialty.
And yet, we and others in conducting recent observational studies generally have failed to find a clear association between coffee and arrhythmias.
In their new study, Marcus and his colleagues randomly assigned 100 people to either drink or not drink coffee each day for a period of two weeks.
And they receive these instructions via text message, and they were randomly assigned to either go ahead and drink all the coffee you want, versus on other random days, avoid all caffeine today.
They had participants wear a heart monitor, a FitBit and a continuous glucose monitor.
They also had them download an app on their phone that collected GPS location data so the researchers could see when people were actually visiting coffee shops.
With the heart monitors, what were they looking at?
They were measuring two things: the number of what are called premature atrial contractions and premature ventricular contractions.
It's very common for everyone to have an early beat arising from the upper chambers of the heart called premature atrial contractions, or PACs, once in a while.
But research has shown that having too many of these beats puts you at risk of atrial fibrillation, which is a dangerously irregular, rapid heart beat.
This is associated with a very high risk for stroke, dementia, and death.
Then there’s the other kind of irregular heartbeat:
Premature ventricular contractions are early beats that arise from the lower chambers of the heart.
Again, we all have those sometimes, but those with more are at higher risk of developing heart failure or a weakening of the heart.
They found that drinking coffee did not result in more premature atrial contractions—the early heart beats associated with atrial fibrillation.
That’s good news for people who were worried about that.
That is reassuring. But what about the other bad beats, the premature contractions in the heart’s lower chambers?
Those were slightly more common on days when people were told to drink coffee, or on days when they drank more coffee—but not enough to be really worrisome.
And that’s not all they found.
Coffee consumption was also associated with a higher number of daily steps.
On days when people drank coffee—and the more coffee they drank—the more steps they took.