coffee DOES NOT cause arrhythmia?

[itdood]

A lot of us have been told by our doctors to cut out caffeine when we walk in the door with tach or ectopics.  A lot of us report here that it doesn't help.   Well, a study published this week shows an interesting trend in the data.  People who drank more coffee had less arrhythmia related hospitalization.  The control, those who drank decaffeinated coffee, did not show this correlation.  This suggest that the mechanism of protection is the caffeine.  A leading theory is that caffeine competes for adenosine receptors.  This means caffeine is an adenosine antagonist.   Adenosine's job is to make us feel tired and primarily works in the brain.  This is why caffeine can keep you up.  

Adenosine also affects the conduction system of the heart through receptors on your cardiomyocytes.   This affects depolarization times and heart rate variability.  Heart rate variability has big implication fo arrhythmias.  HRV isn't the timing between QRS complexes or variability in your pulse rate.  HRV relates to specific timing in the QRS complex itself.  This means timing in the ST segment, or QT segment, etc.    Changes in these timings can mean a lot, for example, prolonged QT interval can mean there's muscle damage.  QT interval is the time from when the ventricles receive the AV trigger to beat to when they recover.

I think the study backs up a lot of the anecdotal evidence we see.

Here's the gotcha though.  This is where epidemiologist need to be careful with studies.  They show something called a "correlation" between caffeine intake and hospitalizations.  This does not mean there's "causation".  These are very different things and causation is difficult to prove.  As an example, perhaps the reasons caffeine drinkers show less arrhythmia is because they are a population of people who aren't prone to it and thus drink more coffee.  People who are prone to palps will cut the habit.  

My advice, I still think caffeine does play a role in arrhythmia.  This was a population study.  Population studies are good at showing correlation but really bad at proving causation.  A better study would be to actually observe the effects of caffeine on patients with arrhythmia to see what happens on EKGs.

If you're interested in the study please google the search terms "CCDEP coffee arrhythmia".  

[malan]

Hi,
When I first started getting arrhythmia around 5 yrs back, my doctor told me to stop coffee. I did, but it seemed to make no difference to my palps. So I got back to 2 cups a day. I am now happy to read that more may be better !

[itdood]

Hi Ireneo, all I can find is that the study was supported by a grant from the Kaiser Foundation Research Institute and the Robert Wood Johnson Foundation.

The authors did not make any financial disclosures.

I'm almost positive that the coffee industry sponsored the study.  The reason is that they ascertain that caffeine is the mechanism but they squarely focused on coffee as the source of the caffeine.    

[ireneo]

I saw this article. I don't drink coffee and won't start drinking coffee because it might help with my arrhythmias. Any idea if the coffee industry had a hand in this study? ;-)