biostudies-literatureUnknown8(1)Lee DWe report a 66-year-old male with a history of Roux-en-Y gastric bypass surgery who began dabigatran for new onset atrial fibrillation. After 5 weeks of therapy, his transesophageal echocardiogram prior to electrocardioversion showed severe spontaneous echo contrast. Cardioversion was postponed and anticoagulant therapy was continued. The following day, he suffered a thromboembolic stroke. Concern arose that postoperative malabsorption could have resulted in subtherapeutic anticoagulation. This notion was strengthened by a second patient who had subtherapeutic serum levels despite maximal dosing. To the best of our knowledge, we are the first to report impaired absorption of dabigatran following Roux-en-Y gastric bypass surgery. <Learning objective: Dabigatran has a predictable pharmacokinJournal of cardiology casese49-e50https://www.ebi.ac.uk/biostudies/studies/S-EPMC6281513biostudies-literatureSubtherapeutic anticoagulation with dabigatran following Roux-en-Y gastric bypass surgery.PMC6281513DeFilipp ZJudson KKennedy MLee DfalseSubtherapeutic anticoagulation with dabigatran following Roux-en-Y gastric bypass surgery.We report a 66-year-old male with a history of Roux-en-Y gastric bypass surgery who began dabigatran for new onset atrial fibrillation. After 5 weeks of therapy, his transesophageal echocardiogram prior to electrocardioversion showed severe spontaneous echo contrast. Cardioversion was postponed and anticoagulant therapy was continued. The following day, he suffered a thromboembolic stroke. Concern arose that postoperative malabsorption could have resulted in subtherapeutic anticoagulation. This notion was strengthened by a second patient who had subtherapeutic serum levels despite maximal dosing. To the best of our knowledge, we are the first to report impaired absorption of dabigatran following Roux-en-Y gastric bypass surgery. <Learning objective: Dabigatran has a predictable pharmacokin2013-01-01T00:00:00Z2013 Jul2025-04-05T00:32:01.041Z2019-03-27T00:13:08ZS-EPMC62815133054674010.1016/j.jccase.2013.03.013