[Thrombolysis by intravenous tissue plasminogen activator (t-PA)--current status and future direction].
In Japan, the intravenous tissue plasminogen activator (t-PA) Alteplase (0.6 mg/kg) administration of the within 3 h of the onset of acute ischemic stroke was approved for therapeutic use in the year 2006. t-PA induces thrombolysis in patients with acute ischemic stroke, and this method has gradually gained recognition among physicians and the general population. However, the number of patients who were treated using Alteplase is low (4,000-5,000 patients/year), and this figure accounts for only 2-3% of the annual number of cases of ischemic stroke. There is little doubt that Alteplase treatment is a potentially effective modality for some patients with acute ischemic stroke. The post-marketing surveillance of 4,749 Japanese patients treated using Alteplase showed that 33% of the patients had modified Rankin scale (mRS) scores of 0-1, 17% of patiens died and 4.5% presented with symptomatic intracerebral hemorrhage (ICH); these results were comparable to those from other countries. The expansion of the therapeutic time window has been a matter of concern. The investigators of the European Cooperative Acute Stroke Study (ECASS) have reported that there was significant improvement in the clinical outcomes of patients with acute ischemie stroke when Alteplase was administered 3-4.5 h after the onset of the symptoms. Mismatches in perfusion- and diffusion-weighted (DW) magnetic resonance imaging (MRI) images have been used for selecting patients 3 h after the onset of symptoms, and the findings from MRI, dwimages (DWI) and MR angiography are practical predictors of t-PA therapy within 3 h of onset. The Middle Cerebral Artery Embolism Local Fibrinolytic Intervention Trial (MELT) Japan study showed that local intra-arterial fibrinolysis is effective in patients with embolic MCA occlusion within 6 h of the onset of symptoms. Combining the initiation of intravenous t-PA administration with further intra-arterial fibrinolysis or mechanical thrombolectomy may improve the recanalization rate. Thrombolysis in combination with ultrasound-enhanced clot lysis is another attractive therapy. In Japan the neuroprotective agent edaravone (radical scavenger) is commonly used in combination with t-PA, and it is expected to decrease the hemorrhagic transformation after t-PA administration. Acute cerebral ischemic symptoms may occasionally precede thoracic aortic dissection. Thoracic aortic dissection after t-PA administration may prove to be fatal, and it is an important disorder that must be differentially diagnosed.
Tanahashi
Norio
N
Department of Neurology, International Medical Center, Saitama Medical University, 1397-1 Yamane, Hidaka-shi, Saitama 350-1298, Japan.
D000784:Aortic Dissection / Q000209:etiology; D000983:Antipyrine / Q000008:administration & dosage / Q000031:analogs & derivatives; D017545:Aortic Aneurysm, Thoracic; D000077553:Edaravone; D016166:Free Radical Scavengers / Q000008:administration & dosage; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000188:drug therapy; D008279:Magnetic Resonance Imaging; D018696:Neuroprotective Agents / Q000008:administration & dosage; D020521:Stroke / Q000150:complications / Q000175:diagnosis / Q000188:drug therapy*; D015912:Thrombolytic Therapy; D013997:Time Factors; D010959:Tissue Plasminogen Activator / Q000008:administration & dosage* / Q000009:adverse effects; D014057:Tomography, X-Ray Computed
D016166:Free Radical Scavengers; D018696:Neuroprotective Agents; D010959:Tissue Plasminogen Activator; D000077553:Edaravone; D000983:Antipyrine