Abstract
BACKGROUND: Data on the association between atrial fibrillation (AF) and venous thromboembolism (VTE) are controversial. OBJECTIVES: The purpose of this study was to investigate the risk of VTE in patients with AF according to the time from AF diagnosis. METHODS: Systematic review of MEDLINE (PubMed), Embase, Cumulative Index to Nursing and Allied Health Literature (EBSCO host), Cochrane Central Register of Controlled Trials (2020) in the Cochrane Library, and World Health Organization Global Index Medicus databases and meta-analysis of observational studies. The risk of VTE, deep vein thrombosis (DVT) and pulmonary embolism (PE) was analyzed according to the time of AF onset: 1) short (≤3 months); 2) medium (≤6 months); and 3) long (>6 months) time groups. RESULTS: Eight studies were included with 4,170,027 patients, of whom 650,828 with AF. In the short-term group, AF was associated with the highest risk of either PE (HR: 9.62; 95% CI: 7.07-13.09; I(2) = 0%) or DVT (HR: 6.18; 95% CI: 4.51-8.49, I(2) = 0%). Even if to a lesser extent, AF was associated with a higher risk of VTE (HR: 3.69; 95% CI: 1.65-8.27; I(2) = 79%), DVT (HR: 1.75; 95% CI: 1.43-2.14; I(2) = 0%), and PE (HR: 4.3; 95% CI: 1.61-11.47; I(2) = 68%) in the up to 6 months and long-term risk group >6 months groups (HR: 1.39; 95% CI: 1.00-1.92; I(2) = 72%) and PE (HR: 1.08; 95% CI: 1.00-1.16; I(2) = 0%). CONCLUSIONS: The risk of VTE is highest in the first 3 to 6 months after AF diagnosis and decreases over time. The early initiation of anticoagulation in patients with AF may reduce the risk of VTE.