Demchuk, Andrew M.

Limited data exist on clot composition and detailed characteristics of arterial thrombi associated with large vessel occlusion in acute ischemic stroke. Advances in endovascular thrombectomy and related imaging modalities have created a unique opportunity to analyze thrombi removed from cerebral arteries. Insights into thrombus composition, etiology, physical properties and neurovascular interactions may lead to future advancements in acute ischemic stroke treatment and improved clinical outcomes. Advances in imaging techniques may enhance clot characterization and inform therapeutic decision-making prior to treatment and reveal stroke etiology to guide secondary prevention. Current imaging techniques can provide some information about thrombi, but there remains much to evaluate about relationships that may exist among thrombus composition, occlusion characteristics and treatment outcomes. Improved pathophysiological characterization of clot types, their properties and how these properties change over time, together with clinical correlates from ongoing studies, may facilitate revascularization with thrombolysis and thrombectomy. Interdisciplinary approaches covering clinical, engineering and scientific aspects of thrombus research will be key to advancing the understanding of thrombi and improving acute ischemic stroke therapy. This consensus statement integrates recent research on clots and thrombi retrieved from cerebral arteries and provides a rationale for further analyses, including current opportunities and limitations.

Background and Purpose— Hemicraniectomy and Durotomy Upon Deterioration From Infarction-Related Swelling Trial (HeADDFIRST) was a randomized pilot study to obtain information necessary to design a Phase III trial to evaluate the benefit of surgical decompression for brain swelling from large supratentorial cerebral hemispheric infarction. Methods— All patients with stroke were screened for eligibility (age 18–75 years, National Institutes of Health Stroke Scale ≥18 with Item 1a<2 [responsive to minor stimulation], and CT demonstrating unilateral, complete middle cerebral artery territory infarction by specific imaging criteria). All enrolled patients were treated using a standardized medical treatment protocol. Those with both ≥4 mm of pineal shift and deterioration in level of arousal or ≥7.5 mm of anteroseptal shift within 96 hours of stroke onset were randomized to continued medical treatment only or medical treatment plus surgery. Death at 21 days was the primary outcome measure. Results— Among 4909 screened patients, only 66 (1.3%) patients were eligible for HeADDFIRST. Forty patients were enrolled, and 26 patients developed the requisite brain swelling for randomization. All who failed to meet randomization criteria were alive at 21 days. Mortality at 21 and 180 days was 40% (4/10) in the medical treatment only and 21% (3/14) and 36% (5/14) in the medical treatment plus surgery arms, respectively. Conclusions— HeADDFIRST randomization criteria effectively distinguished low from high risk of death from large supratentorial cerebral hemispheric infarction. Lower mortality in the medical treatment only group than in other published trials suggests a possible benefit to standardizing medical management. These results can inform the interpretation of recently completed European trials concerning patient selection and medical management. Clinical Trial Registration— This trial was not registered because enrollment began before July 1, 2005.

Background and Purpose— Previous studies of multiple-day dosing with the defibrinogenating agent, ancrod, in acute ischemic stroke yielded conflicting results but suggested that a brief dosing regimen might improve efficacy and safety. The Ancrod Stroke Program was designed to test this concept in subjects beginning ancrod or placebo within 6 hours of the onset of acute ischemic stroke. Methods— Five hundred subjects with acute ischemic stroke who could begin receiving study material within 6 hours of symptom onset were infused intravenously with either ancrod (0.167 IU/kg per hour) or placebo over 2 or 3 hours. The primary efficacy outcome was a dichotomized, modified Rankin score at 90 days with less stringent cut-points for higher prestroke modified Rankin score and pretreatment NIHSS total score (“responder analysis”). Safety variables included mortality, major bleeding, and intracranial hemorrhage. Results— Although the desired changes in fibrinogen level were seen in >90% of ancrod subjects, interim analysis for futility led to the study being halted for lack of efficacy. Positive responder status in the interim dataset was seen in 39.6% of ancrod subjects and 37.2% of placebo subjects ( P =0.47). Ninety-day mortality did not differ between the 2 groups (ancrod, 15.6%; placebo, 14.1%; P =0.32), and the incidence of symptomatic intracranial hemorrhage within the first 72 hours, although not significantly different in ancrod compared to placebo subjects ( P =0.19), was approximately twice as high (3.9% vs 2.0%; P =0.19). Conclusion— These results demonstrate that intravenous ancrod starting within 6 hours after symptom onset in a broad selection of subjects with ischemic stroke did not improve their outcome and revealed a trend to increased bleeding despite successful efforts to achieve rapid initial defibrinogenation and avoid prolonged hypofibrinogenemia.