Abstract and Introduction
Abstract
Background Atrial fibrillation (AF) is the most prevalent sustained arrhythmia, and risk factors are well established. Caffeine exposure has been associated with increased risk of AF, but heterogeneous data exist in the literature.
Objective To evaluate the association between chronic exposure to caffeine and AF.
Design Systematic review and meta-analysis of observational studies.
Data sources PubMed, CENTRAL, ISI Web of Knowledge and LILACS to December 2012. Reviews and references of retrieved articles were comprehensively searched.
Study selection Two reviewers independently searched for studies and retrieved their characteristics and data estimates.
Data synthesis Random-effects meta-analysis was performed, and pooled estimates were expressed as OR and 95% CI. Heterogeneity was assessed with the I test. Subgroup analyses were conducted according to caffeine dose and source (coffee).
Results Seven observational studies evaluating 115 993 individuals were included: six cohorts and one case–control study. Caffeine exposure was not associated with an increased risk of AF (OR 0.92, 95% CI 0.82 to 1.04, I=72%). Pooled results from high-quality studies showed a 13% odds reduction in AF risk with lower heterogeneity (OR 0.87; 95% CI 0.80 to 0.94; I=39%). Low-dose caffeine exposure showed OR 0.85 (95% CI 0.78 to 92, I=0%) without significant differences in other dosage strata. Caffeine exposure based solely on coffee consumption also did not influence AF risk.
Conclusions Caffeine exposure is not associated with increased AF risk. Low-dose caffeine may have a protective effect.
Introduction
Atrial fibrillation (AF) carries a significant burden for both patients and society because it is the most common sustained cardiac arrhythmia, and it is associated with increased cardiovascular morbidity and mortality, mainly due to the higher risk of thromboembolic events. Classical risk factors include advanced age, congestive heart failure, valvular diseases, left ventricular hypertrophy, arterial hypertension, ischaemic heart disease, male gender, diabetes mellitus, endurance exercise and smoking.
Caffeine is a major component of some of the most widely consumed beverages, such as coffee and tea. The association between caffeine exposure and risk of heart disease has received extensive attention in the literature. Inconsistencies between results have been attributed to differences in study design and presence of confounders, in particular tobacco smoking. Results from a recent meta-analysis of observational studies and from large cohort studies suggest a mild-to-moderate inverse association between coffee drinking and cardiovascular risk factors and diseases, including global mortality and death due to heart disease.
The association between caffeine exposure and AF is currently unknown, although a positive association has been suggested in the literature. To further evaluate this putative association, we performed a systematic review and meta-analysis of observational studies.