Relationship between Mediterranean diet and time in therapeutic range in atrial fibrillation patients taking Vitamin K antagonists

AIMS: It is unclear if atrial fibrillation (AF) patients treated with oral vitamin K antagonists (VKAs) must follow a specific diet to avoid interference with anticoagulation. The aim of this study was to assess if Mediterranean diet (Med-Diet) may affect quality of anticoagulation, as expressed by the time in therapeutic range (TTR). METHODS AND RESULTS: A prospective observational study including 553 non-valvular AF patients. Time in therapeutic range was calculated for all patients treated with VKAs, and adherence to Med-Diet was evaluated with a validated nine-item dietary questionnaire. Cardiovascular events (CVEs), such as cardiovascular death and fatal/non-fatal stroke or myocardial infarction, and bleedings were recorded. The median follow-up was 31.6 months. The median number of international normalized ratios for each patient was 63.0 (35.0-98.0) and 38 730 blood samples were analysed. In the whole cohort, the mean TTR was 65.5 ± 17.8%. The mean Med-Diet score was 5.19 ± 1.6, with frequent use of olive oil (90.1%), fruits (88.4%), and vegetables (69.3%) and low meat intake (71.2%). There were no differences among tertiles of Med-Diet score regarding TTR. A multivariable linear regression analysis showed that diabetes (β: -0.105, P = 0.015) and the use of angiotensin converting enzyme inhibitor/angiotensin receptor blockers (β: 0.153, P < 0.001) were associated with TTR. Compared with those without, AF patients with a CVE had significantly lower TTR (65.9 ± 17.9 vs. 59.6 ± 15.9, P = 0.029) and Med-Diet score (5.2 ± 1.5 vs. 4.4 ± 1.9, P = 0.004). A reduction of CVE was observed for each point of the Med-Diet score (hazard ratio 0.790, P = 0.017). CONCLUSION: In our cohort of AF patients, Med-Diet is not associated with changes in TTR, and thus can be recommended for AF patients who are taking VKAs.