MMP9 Variation After Thrombolysis Is Associated With Hemorrhagic Transformation of Lesion and Death

Background and Purpose Experimentally, matrix metalloproteinases (MMPs) play a detrimental role related to hemorrhagic transformation and severity of an ischemic brain lesion. Tissue-type plasminogen activator (tPA) enhances such effects. This study aimed to expand clinical evidence in this connection. Methods We measured MMPs 1, 2, 3, 7, 8, 9, and tissue inhibitors of metalloproteinases 1, 2, 4 circulating level in blood taken before and 24 hours after tPA from 327 patients (mean age, 68.912.1 years; median National Institutes of Health Stroke Scale, 11) with acute ischemic stroke. Delta median values ([24 hours post tPA-pre tPA]/pre tPA) of each MMP or tissue inhibitors of metalloproteinase were analyzed across subgroups of patients undergoing symptomatic intracerebral hemorrhage, 3-month death, or 3-month modified Rankin Scale score 3 to 6. Results Adjusting for major clinical determinants, only matrix metalloproteinase-9 variation proved independently associated with death (odds ratio [95% confidence interval], 1.58 [1.11-2.26]; P=0.045) or symptomatic intracerebral hemorrhage (odds ratio [95% confidence interval], 1.40 [1.02-1.92]; P=0.049). Both matrix metalloproteinase-9 and tissue inhibitors of metalloproteinase-4 changes were correlated with baseline, 24 hours, and 7 days National Institutes of Health Stroke Scale (Spearman P from <0.001 to 0.040). Conclusions Our clinical evidence corroborates the detrimental role of matrix metalloproteinase-9 during ischemic stroke treated with thrombolysis, and prompts clinical trials testing agents antagonizing its effects.