2021 年 38 巻 3 号 p. 363-367
Around 30% of cases of spontaneous intracerebral hemorrhage (ICH) occur in patients taking antithrombotic drugs (i.e., oral antiplatelet drugs and oral anticoagulants). However, antithrombotic drugs themselves are not a direct cause of vascular structure disruption, and only promote and/or prolong bleeding from vulnerable arterioles with pathology such as microaneurysms or fibrinoid necrosis, which are characteristics of cerebral small vessel diseases (SVDs). Thus, to a substantial degree, SVD, which is caused by aging, hypertension, or cerebral amyloid angiopathy (CAA), is the true cause of spontaneous ICH. Cerebral microbleeds (CMBs) are prone to bleeding and cause most spontaneous ICH. CMBs may thus be a specific and promising neuroimaging biomarker of SVDs and a clinically useful predictor of antithrombotic drug–related ICH. Such a relationship raises concerns about the increased ICH risk due to administration of antithrombotic drugs in patients with CMBs. Since 2017, several studies suggested some answers to this issue, and at this time, no evidence shows that the presence or number of CMBs on MRI can determine the pros and cons of antithrombotic therapy. A remaining major issue is validation of the risks and benefits of antithrombotic therapies for patients with CAA–related ICH. As a local issue, determining whether antithrombotic therapy for patients with a large number of CMBs is beneficial in East Asians will be necessary. East Asians are considered to be prone to hypertensive SVDs. Some of these issues will be clarified by an ongoing Japanese prospective, multicenter, observational study called “The Bleeding with Antithrombotic Therapy Study 2”, which enrolled patients with cerebrovascular or cardiovascular diseases who were taking oral antithrombotic agents.
