Blood thinner levels under microscope to prevent clots and bleeding

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion criteria: * Age ≥ 8 years old; * Diagnosed with one of the following diseases and in need of long - term anticoagulant therapy: non - valvular atrial fibrillation (CHA₂DS₂ - VA score ≥ 1); venous thromboembolism (deep vein thrombosis or pulmonary embolism); having other indications for using NOACs to prevent and treat thrombotic diseases; * Currently receiving NOAC treatment (rivaroxaban, apixaban, dabigatran etexilate, edoxaban); * Willing and able to comply with the requirements of the research protocol and the follow - up plan; * Signed the informed consent form. * Age ≥ 18 years old; * Assessed as patients at high risk of bleeding within 72 hours after the onset of symptoms; * Receiving indobufen treatment for the first time after admission; * Willing and able to comply with the requirements of the research protocol and the follow - up plan; * Signed the informed consent form. Exclusion criteria: * Having contraindications to the use of NOACs or being allergic to NOACs; * Having been enrolled in other clinical trials. * Being allergic to or having contraindications to indobufen; * Needing to change antithrombotic drugs or combine with other antiplatelet/anticoagulant therapies (such as clopidogrel, ticagrelor, warfarin, heparin, etc.) during the study; * Cardiogenic stroke or stroke induced by angioplasty/vascular surgery; * Having a history of aneurysm (intracranial or peripheral); * Severe abnormal liver and kidney functions; * Pregnant, lactating women or women of childbearing age who are unwilling to take effective contraceptive measures; * Life expectancy \< 1 year; * Mental or emotional disorders preventing cooperation with follow - up; * Participating in other clinical trials within 30 days before enrollment; * Unable to complete blood concentration detection (such as difficulty in establishing venous access).