No association between coffee consumption and risk of atrial fibrillation: A Mendelian randomization study

Background and aims: Some observational studies have found that habitual coffee and caffeine consumption might reduce the risk of atrial fibrillation (AF). We conducted a two-sample Mendelian randomization study to explore the potential association between coffee consumption and AF. Methods and results: This study was based on summary-level data from the Atrial Fibrillation Consortium, including 588 190 individuals (65 446 cases and 522 744 non-cases). Nine single-nucleotide polymorphisms associated with coffee consumption at significance level of P < 5 x 10(-8) were used as instrumental variables and were obtained from a genome-wide association study that included up to 375 833 individuals. The odds ratio of AF per genetically-predicted 50% increase of coffee consumption was 0.98 (95% confidence interval, 0.88, 1.10; P = 0.80) in the standard inverse-variance weighted analysis. Results were consistent in sensitivity analyses using the weighted median and MR-Egger methods, and no directional pleiotropy (P = 0.37) was observed. Moreover, complementary analyses that separated the coffee-related single-nucleotide polymorphisms based on their association with blood levels of caffeine metabolites (lower, higher, unrelated or unknown association) revealed no association with AF. Conclusions: This study does not support a causal association between habitual coffee consumption and risk of AF. (C) 2019 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.