BackgroundThe prognostic impact of atrial fibrillation (AF) and oral anticoagulation (OAC) therapy in patients with type B acute aortic dissection (AAD) remains unclear. Therefore, we investigated the prognostic impact of AF and OAC therapy in patients with type B AAD.MethodsConsecutive patients diagnosed with AAD were included in this single‐center, retrospective study. Patients with type B AAD were selected from the study population and divided into three groups: AF(+)/OAC(+), AF(+)/OAC(−), and AF(−)/OAC(−). The primary end point was major adverse cardiovascular and cerebrovascular events (MACCE), including all‐cause death, progressive aortic events, cerebral infarction, and organ malperfusion.ResultsIn total, 139 patients diagnosed with type B AAD were analyzed. AF was observed in 27 patients (19%). Among them, 13 patients (9%) received OAC therapy for AF. MACCE occurred in 32 patients (23%) during the observation period: all‐cause death in four patients, progressive aortic events in 24 patients, cerebral infarction events in two patients, and malperfusion events in two patients. The incidence of MACCE was higher in the AF(+)/OAC(+) group than in the AF(+)/OAC(−) group (hazard ratio[HR]: 3.875; 95% confidence interval [CI]: 1.153–17.496). In contrast, there was no significant difference in the incidence of MACCE between the AF(+)/OAC(−) and AF(−)/OAC(−) groups (HR: 1.001, 95% CI: 0.509–1.802).ConclusionAmong patients with type B AAD, the use of OAC for AF was associated with a higher risk of MACCE.