No Evidence Coffee Consumption Increases Risk of Arrhythmias, UCSF Study Finds

Gregory Marcus, MD

A look at the association between coffee consumption and risk of cardiac arrhythmia in a patient population of more than 375,000 has returned positive results for habitual coffee drinkers.

Using data from the UK Biobank cohort, a team from the University of California, San Francisco (UCSF) found no evidence moderate coffee consumption was linked to increased risk of arrhythmia and even uncovered evidence suggesting each additional cup of coffee was associated with a 3% lower risk of incident arrhythmia, including atrial fibrillation and supraventricular tachycardia.

"Coffee is the primary source of caffeine for most people, and it has a reputation for causing or exacerbating arrhythmias," said senior and corresponding author Gregory Marcus, MD, professor of medicine in the Division of Cardiology at UCSF, in a press release from UCSF. "But we found no evidence that caffeine consumption leads to a greater risk of arrhythmias. Our population-based study provides reassurance that common prohibitions against caffeine to reduce arrhythmia risk are likely unwarranted."

Despite a heightened focus and long-standing interest, the debate around habitual coffee intake and cardiovascular health is one that continues to this day. With this in mind, Marcus and colleagues from UCSF designed the current study with the intent of providing further clarity on the issue. To do so, investigators designed their study as a retrospective analysis of patients from within the UK Biobank cohort.

The overall UK Biobank cohort had a median coffee intake per day of 2 cups (IQR, 1-4). Of the 502,543 participants within the cohort, 386,258 met criteria and were included in statistical analyses. Of these, 310,061 reported consumption of caffeinated coffee, 74,371 reported consuming noncaffeinated coffee, and 83,228 reported not drinking coffee. Compared to their counterparts consuming less than the daily median amount of coffee, those with increased intake e daily median amount of coffee were more likely to be older, White, male, have peripheral artery disease, have cancer, be a current smoker, or drink alcohol and less likely to have hypertension, diabetes, chronic kidney disease, and to drink tea.

Outcomes of interest for the analyses was the incidence of any cardiac arrhythmia, including atrial fibrillation or flutter, supraventricular tachycardia, ventricular tachycardia, premature atrial complexes, and premature ventricular complexes. Exposures used in analyses included caffeine intake and a group of genetic polymorphisms that impact caffeine metabolism.

Over a mean follow-up of 4.5 (SD, 3.1) years, 16,979 participants developed an incident arrhythmia. In analyses adjusted for demographic characteristics, comorbidities, and lifestyle factors, results suggested consumption of each additional cup of coffee was associated with a 3% (HR, 0.97; 95% CI, 0.96-0.98; P <.001) reduction in his of incident arrhythmia. Additionally, analyses assessing individuals forms of arrhythmia indicated statistically significant associations were observed for atrial fibrillation or flutter (HR, 0.97; 95% CI, 0.96-0.98; P <.001) and supraventricular tachycardia (HR, 0.96; 95% CI, 0.94-0.99; P=.002).

Investigators also pointed out interaction analyses, including one using a caffeine metabolism-related polygenic score of 7 genetic polymorphisms and other restricted to CYP1A2 rs762551 alone, failed to produce evidence of effect modification. In a Mendelian randomization study using these same genetic variants, results suggested no significant association existed between underlying propensities to differing metabolism and risk of incident arrhythmia.

In the aforementioned press release, Marcus acknowledged the inherent limitations of their study due to the nature of its design.

“Only a randomized clinical trial can definitively demonstrate clear effects of coffee or caffeine consumption," said Marcus. "But our study found no evidence that consuming caffeinated beverages increased the risk of arrhythmia. Coffee's antioxidant and anti-inflammatory properties may play a role, and some properties of caffeine could be protective against some arrhythmias."

This study, "Coffee Consumption and Incident Tachyarrhythmias—Reported Behavior, Mendelian Randomization, and Their Interactions,” was published in JAMA Internal Medicine