Healthy adults experienced no increase in atrial arrythmias and less supraventricular tachycardia on days they consumed vs. abstained from caffeinated coffee as well as an increase in wearable-measured physical activity in the CRAVE study.
Results presented at the American Heart Association Scientific Sessions also revealed a 54% increase in premature ventricular contractions with coffee consumption; those who metabolized caffeine more quickly experienced a heightened response to premature ventricular contractions with coffee exposure.
Gregory M. Marcus
“Overall, the acute yet everyday physiological effects of coffee are complex,” Gregory M. Marcus, MD, MAS, associate chief of cardiology for research and endowed professor of atrial fibrillation research at the University of California, San Francisco, said during a press conference at the American Heart Association Scientific Sessions. “These data add to the growing evidence that those with supraventricular tachycardia or AF or those at risk for those diseases should not necessarily avoid coffee. However, those prone to ventricular arrythmias may benefit from coffee abstinence, but genetic differences influence risk.”
Device-measured responses to coffee
Most coffee-related research has been observational and prone to confounding, with examined long-term effects less relevant to immediate consequences, Marcus said.
The researchers sought to capture the real-time physiologic consequences of coffee consumption in healthy adults using multiple wearable devices.
For CRAVE, 100 healthy volunteers (mean age, 38 years; 51% women; 48% white) were fitted with a continuously recording ECG device (Zio Patch, iRhythm), a wrist-worn Fitbit to measure step counts and sleep, and a continuous glucose monitor (Dexcom). Participants also downloaded a smartphone app for collection of geolocation data (Eureka, UCSF); participant DNA was genotyped for caffeine metabolism-related single nucleotide polymorphisms.
Researchers randomly assigned volunteers to consume or avoid coffee every day for 14 days, communicated via daily texts and reminders.
To measure adherence, participants pressed a button via the Zio patch to timestamp every coffee drink and completed daily surveys recounting coffee consumed the previous day. All date-stamped receipts with coffee purchases were reimbursed. Visits to coffee shops were tracked via geofencing.
Adherence assessments revealed compliance with coffee assignments by every metric employed, Marcus said (P < .01 for all). In the intention-to-treat analyses, random assignment to consume coffee was associated with a 54% increase in premature ventricular contractions (95% CI, 19-200; P = .001), 1,058 additional Fitbit-measured steps per day (95% CI, 441-1675; P = .001) and 36 fewer minutes of Fitbit-measured sleep per night (95% CI, 22-50; P < .001). There were no between-group differences in CGM-measured glucose.
Discussing the findings, Marcus acknowledged that enrolling only regular coffee drinkers could bias the findings.
“Individuals perhaps most prone to coffee-induced problems, such insomnia, palpitations or arrythmias that occur with coffee, may have been excluded,” Marcus said. “If anything, we would think that that would lead to us underestimating heart effects, rather than explaining any false positives.”
‘Innovative but small’ study
Elaine Hylek, MD, MPH, professor of medicine at Boston University School of Medicine and member of the AHA’s Committee on Scientific Sessions Programming, said CRAVE was “an innovative but small study,” calling the findings on atrial arrythmias “somewhat reassuring.”
Hylek said, “if anything, it seems individuals were increasing their physical activity; hopefully that would translate into better CV health. Hopefully, for healthy individuals, we do not have to be too worried about the finding of the [premature ventricular contractions]. For [measured] sleep, it would be nice to know if that was fitful sleep. Were these individuals feeling rested the next day?”
Hylek said the clinical relevance and meaning of a person with a brief episode of AF is still an understudied area.
“We can’t necessarily extrapolate any findings to the persistent and permanent AF group,” Hylek said.
PERSPECTIVE
Sana M. Al-Khatib, MD, MHS, FHRS
To date, data on this topic have been conflicting and have resulted from observational studies. But this is a question that we get asked very frequently by patients. These facts underscore the importance of the CRAVE trial.
The study suggests that coffee consumption does not increase the risk of atrial arrhythmias, but it increases the premature ventricular contraction count. It increases exercise activity and reduces sleep. Despite the importance of the trial, the sample size was relatively small (only 100 participants), and the research participants were healthy volunteers. They are very different from the average patient we see in clinical practice. Also, the study included short-term outcomes. I would love to see more data on long-term outcomes, including harder endpoints such as sustained ventricular arrhythmias and sudden cardiac death.
While we still need more data, I think these results should give us some reassurance that coffee consumption does not appear to increase the risk for AF. The association with premature ventricular contractions and ventricular arrhythmias deserves further study.
I like the fact that the researchers effectively utilized a digital health platform to conduct the study. I commend them on the very creative design.
Sana M. Al-Khatib, MD, MHS, FHRS
Professor of Medicine
Duke University School of Medicine
Duke Clinical Research Institute
ARYAN'S BLOG 