Objectives: We investigated in vitro the management of intraprocedural anticoagulation in patients requiring immediate percutaneous coronary intervention (PCI) while using regular direct oral anticoagulants (DOACs).Materials and methods: Twenty-ve patients taking 20mg of rivaroxaban once daily comprised the study group, while ve healthy volunteers included the control group. In the study group, a beginning (24 hours after the last rivaroxaban dose) examination was performed. Then, the effects of basal and four different anticoagulant doses (50 IU/kg unfractionated heparin (UFH), 100 IU/kg UFH, 0.5 mg/kg enoxaparin, and 1 mg/kg enoxaparin) on coagulation parameters were investigated at the 4th and 12th hours following rivaroxaban intake. The effects of four different anticoagulant doses were evaluated in the control group. The anticoagulant activity was assessed mainly by anti-factor Xa (anti-Xa) levels.Results: Beginning anti-Xa levels were signi cantly higher in the study group than in the control group (0.69±0.77 IU/mL vs. 0.20±0.14 IU/mL; p <0.05). The study group's 4th and 12th-hour anti-Xa levels were signi cantly higher than the beginning level (1.96±1.35 IU/mL vs. 0.69±0.77 IU/mL; p <0.001 and 0.94±1.21 IU/mL vs. 0.69±0.77 IU/mL; p <0.05, respectively). Anti-Xa levels increased signi cantly in the study group with the addition of UFH and enoxaparin doses at the 4th and 12th hour than the beginning (p <0.001 at all doses). The safest anti-Xa level (from 0.94±1.21 IU/mL to 2.00±1.02 IU/mL) was achieved 12 hours after rivaroxaban with 0.5mg/kg enoxaparin. Conclusion: Anticoagulant activity was su cient for urgent PCI at the 4th hour after rivaroxaban treatment, and additional anticoagulant administration may not be required at this time. Twelve hours after taking rivaroxaban, administering 0.5mg/kg of enoxaparin may provide adequate and safe anticoagulant activity for immediate PCI. This experimental study result should con rm with clinical trials (NCT05541757).