To Drink or Not to Drink - Caffeine and Its Impact on the Heart
Written by Joseph Kummer, MD, Bryan Heart Cardiologist
Caffeine is the most widely used pharmacologic agent in the world, with about 90% of adults consuming it daily. Despite numerous studies on its cardiovascular effects, the net benefit vs. harm remains unclear. Clearly, many people feel adverse consequences such as palpitations when they consume it, but such effects are mild. We have no data showing any true malignant effects. Considering how many people in the world love their morning coffee, it would be quite hard to significantly change caffeine consumption even if it is ever found to be detrimental to our health. Of course, moderation is often the key as many people have dose dependent effects.
As clinicians, we often find ourselves counseling people against caffeine consumptions as a means of alleviating symptoms such as palpitations. Many arrhythmias are initiated by premature beats, and it is widely thought that caffeine increases the frequency of premature atrial or ventricular beats. Recent evaluation of data from the Multi-Ethnic Study of Atherosclerosis investigation suggested a dose-dependent increase in atrial fibrillation with caffeine use. However, there were potential confounders with this analysis.
Importantly, several other large meta-analyses have failed to show any association with caffeine and atrial fibrillation. Similarly, most studies have failed to show an association with other atrial arrhythmias. Ironically, a few studies have even suggested a protective effect of caffeine against atrial arrhythmias. During electrophysiologic studies, caffeine has not been shown to change the inducibility of atrial arrhythmias.
A recent article in The New England Journal of Medicine reported on the findings of ambulatory cardiac monitoring on a group of volunteers who were alternately assigned to either drink or abstain from coffee over a two week period. The number of premature atrial contractions (PACs), premature ventricular contractions (PVCs), and any sustained arrhythmias were tallied.1
Somewhat surprisingly, the number of PACs did not differ significantly when people drank caffeinated coffee compared to when they did not. The number of PVCs was higher but the absolute difference was very small. Specifically, the number of PACs was 58 when the subjects drank caffeine and 53 when they did not [CI 0.98-1.20]. The number of PVCs was 154 with caffeine vs. 102 on days without [CI 1.18-1.94]. Of note, on days when the subjects drank coffee, they averaged 1,058 more steps (9,665 vs. 10,646). They also averaged 35 minutes less of sleep daily when coffee was consumed (397 minutes vs. 432 minutes).
It may also be surprising that caffeine appears to have only minimal to no significant effect on blood pressure. In people who don’t drink caffeine regularly, there can be a small increase in BP up to 10 mmHg, but in habitual drinkers, blood pressure does not appear to be significantly affected by their caffeine use. LDL may be raised by compounds in unfiltered coffee, but caffeine does not appear to change lipid levels otherwise. There is no data suggesting any increase incidence of severe adverse cardiovascular outcomes such as cardiac mortality, coronary revascularization, or strokes associated with caffeine intake.
In short, moderate caffeine intake probably has very little to no effect on severe cardiac outcomes. This certainly shouldn’t be generalized to intense, high dose caffeine such as in some “energy drinks.” Ironically, caffeine may even be beneficial as it does seem to keep people more physically active. The observed decrease in PACs and PVCs with avoidance of caffeine appears to be smaller than we might expect. Nonetheless, many patients are sensitive to its effects, so recommending a trial of reduced intake in symptomatic patients is certainly reasonable.
As always, Bryan Heart remains committed to partnering with you for the care of your patients. If patients are experiencing palpitations (with or without caffeine consumption), we are here to help.
Source:
- Marcus GM, Rosenthal DG et al. Acute Effects of Coffee Consumption on Health among Ambulatory Adults. NEJM 2023: 388:1092-100.
