The investigators study aims to test the correlation between the Cascade Abrazo point-of-care testing (POCT) device (Helena Laboratories, USA) and plasma levels of apixaban, dabigatran, edoxaban and rivaroxaban, and to determine the diagnostic accuracy of POCT to rule out or detect relevant levels of direct oral anticoagulants (DOAC) in real-life patients.

Inclusion Criteria:

• Part A only: planned initiation of treatment with apixaban, dabigatran, edoxaban or rivaroxaban
• Part B only: ongoing treatment with apixaban, dabigatran, edoxaban or rivaroxaban
• Age ≥ 18 years
• Written informed consent by patient

Exclusion Criteria:

• Part A only: intake of vitamin K antagonists or direct oral anticoagulants (DOAC) ≤ 14 days prior to study participation
• Part B only: intake of vitamin K antagonists or different DOAC ≤ 14 days prior to study participation
• Intake of unfractionated heparin ≤ 12 hours, low-molecular-weight heparin ≤ 24h, heparinoids (e.g. fondaparinux) ≤ 72h, or direct thrombin inhibitors other than dabigatran ≤ 72h prior to study participation
• Part A only: abnormal routine coagulation test values at baseline (defined by INR > 1.2, Quick < 70% or aPTT > 40 sec)
• History of coagulopathy

Part A: patients, who are newly started on oral anticoagulation with apixaban, dabigatran, edoxaban or rivaroxaban for secondary prevention of thromboembolic events.

Part B: patients, on-treatment with apixaban, dabigatran, edoxaban or rivaroxaban.