Coffee and Real-time Atrial and Ventricular Ectopy (CRAVE)

Atrial fibrillation (AF) and heart failure (HF) are morbid, costly, and incompletely understood diseases that have reached epidemic proportions worldwide. A dose-dependent relationship exists between premature atrial and ventricular contractions (PACs and PVCs) and development of AF and HF, respectively. Identifying and understanding the mechanisms of additional modifiable risk factors for ectopy has the potential to markedly reduce the healthcare burden of these diseases. In considering how to modify the prevalence of these ectopic beats, the investigators believe common exposures in daily life are prime candidates. Current guidelines suggest that caffeine may be an important trigger for frequent ectopy, although large population-based studies have not demonstrated an association between caffeine consumption and development of clinically significant arrhythmias. No study has employed an actual randomization intervention to assess the effects of caffeine on cardiac ectopy. Utilizing the Eureka platform, the investigators plan to utilize the N-of-1 strategy to rigorously investigate the real-time effect of caffeine intake on ectopy.

This study is designed as a N to 1 randomized trial, where each participant will be randomized to consume or abstain from coffee each day of a 14 day monitoring period. Participants will wear an automatically recording electrocardiographic monitor (ZIO® XT Patch), continuous glucose monitor (Dexcom G6), and a fitness tracker (Fitbit INSPIRE) while utilizing Eureka-a mobile application. We will compare participant self-report of caffeine consumption, glucose monitoring, fitness levels, sleep health, and heart rhythm data in order to better understand the relationship between acute caffeine consumption and heart rhythm changes. Participants will also be genotyped for caffeine metabolism-related SNPs. A total of 100 participants will be enrolled at the UCSF study site.

Participants will be randomized in two-day blocks to consume then avoid caffeine ("Start: On Caffeine") or avoid then consume caffeine ("Start: Off Caffeine"). Using an N-of-1 strategy delivered by the NIH-funded, UCSF-run Eureka platform utilizing a mobile smartphone-based application, participants will receive instructions and answer questions to help us understand the relationship between caffeine and heart rhythm.

In this two-day block, participants will be instructed to consume caffeine for one day and avoid caffeine the next day.

In this two-day block, participants will be instructed to avoid caffeine for one day and consume caffeine the next day.

Participants will be wearing a continuously recording ECG monitor for two weeks. The primary outcome will be change in premature atrial contraction (PAC) frequency due to caffeine consumption or avoidance during the enrollment period.

Participants will be wearing a continuously recording ECG monitor for two weeks. A secondary outcome will be change in supraventricular tachycardia (SVT) episodes due to caffeine consumption or avoidance during the enrollment period.

Participants will be wearing a continuously recording ECG monitor for two weeks. A secondary outcome will be change in ventricular tachycardia (VT) episodes episodes due to caffeine consumption or avoidance during the enrollment period.

Participants will be wearing a continuous glucose monitor (Dexcom G6) that will record serum glucose levels. A secondary outcome will be difference in mean daily glucose levels due to caffeine consumption or avoidance during the enrollment period.

Participants will be wearing a fitness tracker (Fitbit INSPIRE) that will record step counts. A secondary outcome will be difference in mean step counts due to caffeine consumption or avoidance during the enrollment period.

Participants will be wearing a fitness tracker (Fitbit INSPIRE) that will record sleep duration. A secondary outcome will be difference in mean sleep duration due to caffeine consumption or avoidance during the enrollment period.

Participants will be wearing a continuously recording ECG monitor for two weeks. The primary outcome will be change in ventricular contraction (PVC) frequency due to caffeine consumption or avoidance during the enrollment period.

Inclusion Criteria: Are age 18 or older Have a smartphone Are able to use the Eureka mobile application Are willing to provide a saliva sample for genetic processing Drink coffee or coffee-based products at least once a year Are willing to abstain from coffee, caffeinated products, or minimally caffeinated products (decaffeinated coffee) for at least 2 days when instructed Exclusion Criteria: Have a history of atrial fibrillation, heart failure Have an ICD or pacemaker Have treatment with beta blockers, non-dihydropyridine calcium channel blockers, or Vaughn-Williams class 1 or 3 antiarrhythmic medications Have a medical reason to avoid coffee

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