José Alvarez-Sabín

Matrix Metalloproteinase-9 Pretreatment Level Predicts Intracranial Hemorrhagic Complications After Thrombolysis in Human Stroke

Background—Matrix metalloproteinase (MMP) expression is related to blood brain barrier disruption after cerebral ischemia. Moreover, MMP inhibitors reduce hemorrhagic transformation (HT) after embolic ischemia in tissue plasminogen activator (t-PA)–treated animals. We aimed to correlate plasmatic MMP levels with the appearance of intracranial bleeding complications in stroke patients treated with t-PA. Methods and Results—Serial MMP-2 and MMP-9 determinations were performed (ELISA, ng/mL) in 41 strokes involving the middle cerebral artery territory in patients who received t-PA within 3 hours of stroke onset. Blood samples were obtained at baseline (pretreatment) and at 12 and 24 hours after symptom onset. Hemorrhagic events were classified according to CT criteria (petechial hemorrhagic infarctions [HI, 1 to 2] and large parenchymal hemorrhages [PH, 1 to 2]). Brain CT scan was obtained at 48 hours or when a neurological worsening occurred. HT was present in 36.5% of the patients (24.4% HI and 12.1% PH). MMP-2 values were unrelated to any subtype of HT. The highest baseline MMP-9 level (normal range <97 ng/mL) corresponded to patients who later developed a PH (PH: 270.2±87.8, non-HT: 126.3±127.5, HI: 94.6±88.7;P =0.047). A graded response was found between mean baseline MMP-9 levels and the degree of bleeding (HI-1=37.4; HI-2=111.0; PH-1=202.5; PH-2=337.8). Baseline MMP-9 was the most powerful predictor of PH appearance in the multiple logistic regression model (OR= 9.62; CI 1.31 to 70.26;P =0.025). Conclusions—Baseline MMP-9 level predicts PH appearance after t-PA treatment. Therefore, we suggest that MMP determination may increase the safety profile for thrombolysis and, in the future, anti-MMP drugs might be combined with t-PA to prevent hemorrhagic complications.

Microbubble Administration Accelerates Clot Lysis During Continuous 2-MHz Ultrasound Monitoring in Stroke Patients Treated With Intravenous Tissue Plasminogen Activator

BACKGROUND AND PURPOSE We sought to evaluate the effects of administration of microbubbles (MBs) on the beginning, speed, and degree of middle cerebral artery (MCA) recanalization during systemic thrombolysis and continuous 2-MHz pulsed-wave transcranial Doppler (TCD) monitoring. METHODS We evaluated 111 patients with acute stroke attributable to MCA occlusion treated with intravenous tissue plasminogen activator (tPA). Thirty-eight patients were treated with tPA plus continuous 2-hour TCD monitoring plus 3 doses of 2.5 g (400 mg/mL) of galactose-based MBs given at 2, 20, and 40 minutes after tPA bolus (MB group). These patients were compared with 73 patients who were allocated to receive tPA plus continuous 2-hour TCD ultrasound (US) monitoring (tPA/US group) or tPA plus placebo monitoring (tPA group), most of whom were enrolled in a previous study of US-enhanced thrombolysis. The beginning, degree, and time to maximum completeness of recanalization during the first 2 hours of tPA bolus were recorded. RESULTS Median prebolus National Institutes of Health Stroke Scale (NIHSS) score was 18. Eighty patients (72%) had a proximal and 31 (28%) a distal MCA occlusion on TCD. Thirty-seven patients (33%) received tPA/US, 38 (34%) received tPA/US/MB, and 36 (32%) were treated with tPA alone. Stroke severity, time to treatment, location of MCA occlusion, and presence of carotid artery disease were similar among groups. Two-hour recanalization was seen in 14 (39%), 25 (68%), and 27 patients (71%) in the tPA, tPA/US, and tPA/US/MB groups, respectively (P=0.004). Two-hour complete recanalization rate was significantly (P=0.038) higher in the tPA/US/MB group (54.5%) compared with tPA/US (40.8%) and tPA (23.9%) groups. The time to beginning of recanalization after tPA bolus was 26+/-18 minutes in the tPA/US group and 19+/-12 minutes in the tPA/US/MB group (P=0.12). Four patients (3.6%) experienced symptomatic intracranial hemorrhage: 2 (5.5%), 1 (2.7%), and 1 patient (2.6%) who received tPA only, tPA/US, and tPA/US/MB, respectively, experienced symptomatic intracranial hemorrhage. At 24 hours, 31%, 41%, and 55% of tPA, tPA/US, and tPA/US/MB improved >4 points in the NIHSS score. CONCLUSIONS Administration of MBs induces further acceleration of US-enhanced thrombolysis in acute stroke, leading to a more complete recanalization and to a trend toward better short- and long-term outcome.

Increased Brain Expression of Matrix Metalloproteinase-9 After Ischemic and Hemorrhagic Human Stroke

Background and Purpose— Abnormal expression of some matrix metalloproteinases (MMP) has shown to play a deleterious role in brain injury in experimental models of cerebral ischemia. We aimed to investigate MMP-2 (gelatinase A) and MMP-9 (gelatinase B) in brain parenchyma in both ischemic and hemorrhagic strokes. Methods— Postmortem fresh brain tissue from 6 ischemic and 8 hemorrhagic stroke patients was obtained within the first 6 hours after death. Finally, 78 brain tissue samples from different areas (infarct, peri-infarct, perihematoma and contralateral hemisphere) were studied. To quantify gelatinase content we performed gelatin zymograms that were confirmed by Western Blot Analysis, immunohistochemistry to localize MMP source, and in situ zymography to detect gelatinase activity. Results— Among ischemic cases, gelatin zymography showed increased MMP-9 content in infarct core although peri-infarct tissue presented also higher levels than contralateral hemisphere (P<0.0001 and P=0.042, respectively). Within infarct core, MMP-9 was mainly located around blood vessels, associated to neutrophil infiltration and activated microglial cells. In peri-infarct areas the major source of MMP-9 were microglial cells. Tissue around intracranial hemorrhage also displayed higher MMP-9 levels than contralateral hemisphere (P=0.008) in close relationship with glial cells. MMP-2 was constitutively expressed and remained invariable in different brain areas. Conclusions— Our results demonstrate in situ higher levels of MMP-9 in human brain tissue after ischemic and hemorrhagic stroke, suggesting a contribution of MMP-9 to ischemic brain injury and perihematoma edema.

Matrix Metalloproteinase Expression After Human Cardioembolic Stroke Temporal Profile and Relation to Neurological Impairment

Background and Purpose— Uncontrolled expression of matrix metalloproteinases (MMPs) can result in tissue injury and inflammation. In animal models of cerebral ischemia, the expression of MMP-2 and MMP-9 was significantly increased. However, their role in human stroke in vivo remains unknown. Therefore, we sought to determine the temporal profile of MMP expression in patients with acute ischemic stroke and to investigate its relationship to stroke severity, location of arterial occlusion, and total infarct volume. Methods— Serial MMP-2 and MMP-9 determinations were made in 39 patients with cardioembolic strokes that involved the middle cerebral artery territory by means of enzyme-linked immunosorbent assay. Blood samples, transcranial Doppler recordings, and National Institutes of Health Stroke Scale (NIHSS) scores were obtained at baseline and at 12, 24, and 48 hours after stroke onset. Infarct volume was measured with CT scanning at 48 hours. Results— No correlation was found between MMP-2 and NIHSS score at any time point, although a close relation appeared between mean MMP-9 and final NIHSS score (r =0.486, P =0.002). MMP-9 value was the only factor associated with the final NIHSS score in the multiple logistic regression model (OR 4.54, 95% CI 1.5 to 13.75). A cut-point of MMP-9 142.18 ng/mL had a positive predictive value of 94.4% to assess a patient’s NIHSS (<8 or ≥8) by the end of the study. Final MMP-2 and MMP-9 levels were significantly lower when recanalization occurred (528±144.3 versus 681.4±239.2 ng/mL, P =0.031 for MMP-2; 110.2±100.9 versus 244.8±130 ng/mL, P =0.004 for MMP-9). A positive correlation was found between mean MMP-9 and infarct volume (r =0.385, P =0.022). Conclusions— MMPs are involved in the acute phase of human ischemic stroke. MMP-9 levels are associated with neurological deficit, middle cerebral artery occlusion, and infarct volume.

Effects of Admission Hyperglycemia on Stroke Outcome in Reperfused Tissue Plasminogen Activator-Treated Patients

Background and Purpose— We sought to investigate the impact of hyperglycemia before reperfusion on long-term outcome in patients treated with intravenous tissue plasminogen activator (tPA). Methods— Of 268 consecutive patients with a nonlacunar middle cerebral artery (MCA) stroke evaluated at <3 hours after onset, 73 (27.2%) received intravenous tPA. Serum glucose was determined at baseline before tPA administration. Hyperglycemia was defined as a glucose level >140 mg/dL. National Institutes of Health Stroke Scale (NIHSS) scores were obtained at baseline and 24 hours. Transcranial Doppler monitoring of recanalization and reocclusion was conducted during the first 24 hours. Total infarct volume was measured on CT at day 5 to 7. Modified Rankin Scale was used to assess outcome at 3 months. Results— Median NIHSS score was 17. At baseline, 31 patients (42.5%) were hyperglycemic and 42 (57.5%) normoglycemic. Early reperfusion (<6 hours) occurred in 43 patients (58.9%). Admission blood glucose correlated negatively with the degree of neurological improvement at 24 hours in reperfused (r =−0.43;P =0.019) but not in nonreperfused (r =−0.20;P =0.21) tPA-treated patients. Increased age (P =0.014), history of diabetes mellitus (P =0.043), admission glucose >140 mg/dL (P =0.002), and early reocclusion (P =0.004) were factors associated with poor outcome among reperfused patients. A logistic regression modeling revealed that only admission glucose value >140 mg/dL (odds ratio, 8.4; 95% CI, 1.76 to 40.02;P =0.005) emerged as an independent predictor of poor outcome despite tPA-induced recanalization. In patients with 6-hour persistent MCA occlusion, baseline NIHSS score >15 points (P =0.011) and proximal MCA occlusion (P =0.039) were variables associated with poor outcome on univariate analysis. In a logistic regression model, only NIHSS score >15 points (odds ratio, 11.9; 95% CI, 1.48 to 97.1;P =0.032) remained as an independent predictor of poor outcome and functional dependence at 3 months in nonreperfused tPA-treated patients. Conclusions— Hyperglycemia before reperfusion may in part counterbalance the beneficial effect of early restoration of blood flow, which translates into a worse outcome in hyperglycemic patients despite tPA-induced recanalization.

Molecular signatures of brain injury after intracerebral hemorrhage.

BackgroundThe mechanisms of cellular death in the tissue surrounding an intracerebral hemorrhage (ICH) are not defined. ObjectiveTo investigate the relationship of markers of excitotoxicity and inflammation to brain injury after ICH. MethodsA total of 124 consecutive patients with spontaneous ICH admitted within 24 hours of stroke onset were prospectively investigated. The volumes of the initial ICH, peripheral edema on days 3 to 4, and the residual cavity at 3 months were measured on CT scan. Glutamate, cytokines, and adhesion molecules were measured in blood samples obtained on admission. Stroke severity and neurologic outcome were evaluated with the Canadian Stroke Scale. ResultsPoor neurologic outcome at 3 months (Canadian Stroke Scale < 7) was observed in 53 patients (43%). Stroke severity and glutamate concentrations (by each increment of 10 &mgr;mol/L, odds ratio 1.23; 95% CI 1.09 to 1.41), but not the initial volume of ICH, were independent predictors of poor outcome. In the multiple linear regression analyses, tumor necrosis factor-&agr; concentration was correlated (r = 0.83, p < 0.0001) with the volume of perihematoma edema, and glutamate concentrations were correlated (r = 0.78, p < 0.0001) with the volume of the residual cavity. These same results were observed when lobar (n = 58) and deep (n = 66) ICH were analyzed separately. ConclusionsHigh plasma levels of proinflammatory molecules within 24 hours of intracerebral hemorrhage onset are correlated with the magnitude of the subsequent perihematoma brain edema, whereas poor neurologic outcome and the volume of the residual cavity are related to increased plasma glutamate concentrations.

Timing of Spontaneous Recanalization and Risk of Hemorrhagic Transformation in Acute Cardioembolic Stroke

Background and Purpose The relationship between reperfusion and hemorrhagic transformation (HT) remains uncertain. Therefore, we aimed to clarify the relationship between the time course of recanalization and the risk of HT in patients with cardioembolic stroke studied within 6 hours of symptom onset. Methods Fifty-three patients with atrial fibrillation and nonlacunar stroke in the middle cerebral artery (MCA) territory admitted within the first 6 hours after symptom onset were prospectively studied. Serial TCD examinations were performed on admission and at 6, 12, 24, and 48 hours. CT was performed within 6 hours after stroke onset and again at 36 to 48 hours. Results Proximal and distal MCA occlusions were detected in 32 patients (60.4%) and 18 patients (34%), respectively. Early spontaneous recanalization occurring within 6 hours was identified in 10 patients (18.8%). Delayed recanalization (>6 hours) occurred in 28 patients (52.8%). HT on CT scan was detected in 17 patients (32%) within the first 48 hours. Only large parenchymal hemorrhage (PH2) was significantly associated with an increase (P =0.038, Kruskal-Wallis test) in the National Institutes of Health Stroke Scale (NIHSS) score compared with the other subtypes of HT. Univariate analysis revealed that an NIHSS score of >14 on baseline (P =0.001), proximal MCA occlusion (P =0.004), hypodensity >33% of the MCA territory (P =0.012), and delayed recanalization occurring >6 hours of stroke onset (P =0.003) were significantly associated with HT. With a multiple logistic regression model, delayed recanalization (OR 8.9; 95% CI 2.1 to 33.3) emerged as independent predictor of HT. Conclusions Delayed recanalization occurring >6 hours after acute cardioembolic stroke is an independent predictor of HT.

Tandem internal carotid artery/middle cerebral artery occlusion : An independent predictor of poor outcome after systemic thrombolysis

Background and Purpose— Although tandem internal carotid artery/middle cerebral artery (MCA; TIM) occlusion has been associated with low recanalization rate after IV tissue plasminogen activator (tPA), its independent contribution on stroke outcome remains unknown. Moreover, whether the relative resistance to thrombolysis in tandem lesions varies depending on the location of MCA clot remains uncertain. Methods— Two hundred and twenty-one consecutive stroke patients with an acute MCA occlusion treated with IV tPA were studied. Emergent carotid artery ultrasound and transcranial Doppler (TCD) examinations were performed in all patients before treatment. Recanalization was assessed on TCD at 2 hours of tPA bolus. National Institutes of Health Stroke Scale (NIHSS) scores were obtained at baseline and after 24 hours. Modifed Rankin Scale score was used to assess outcome at 3 months. Results— Median prebolus NIHSS score was 16 points. On TCD, 156 (71.6%) patients had a proximal and 65 (29.4%) a distal MCA occlusion. TIM occlusion was identified in 44 (19.9%) patients. Eighteen (41.9%) patients with and 123 (69.5%) without TIM lesions achieved an MCA recanalization (P=0.01). In a logistic regression model, hyperglycemia >140 mg/dL (odds ratio [OR] 3.3, 95% CI, 1.6 to 6.8) and the presence of TIM occlusion (OR 2.8, 95% CI, 1.1 to 6.9) emerged as independent predictors of absence of recanalization. However, the independent contribution of TIM lesions on poor response to thrombolysis varied depending on the location of MCA occlusion. TIM occlusion independently predicted resistance to thrombolysis in patients with proximal (OR 4.63, 95% CI, 1.79 to 11.96), but not in those with distal MCA occlusion. Patients with TIM occlusion had worse short- (P<0.0001) and long-term (P<0.0001) clinical outcome. Conclusions— TIM occlusion independently predicts poor outcome after IV thrombolysis. However, its impact varies depending on the location of MCA clot. Therefore, emergent carotid ultrasound plus TCD examinations may improve the selection of patients for more aggressive reperfusion strategies.

Etiologic Diagnosis of Ischemic Stroke Subtypes With Plasma Biomarkers

Background and Purpose— Because there is no biologic marker offering precise information about stroke etiology, many patients receive a diagnosis of undetermined stroke even after all available diagnostic tests are done, precluding correct treatment. Methods— To examine the diagnostic value of a panel of biochemical markers to differentiate stroke etiologies, consecutive acute stroke patients were prospectively evaluated. Brain computed tomography, ultrasonography, cardiac evaluations, and other tests were done to identify an etiologic diagnosis according to TOAST classification. Blood samples were drawn on Emergency Department arrival (<24 hours) to test selected biomarkers: C-reactive protein, D-dimer, soluble receptor for advanced glycation end products, matrix metalloproteinase-9, S-100b, brain natriuretic peptide (BNP), neurotrophin-3, caspase-3, chimerin, and secretagogin (assayed by ELISA). Results— Of 707 ischemic stroke patients included, 36.6% were cardioembolic, 21.4% atherothrombotic, 18.1% lacunar, and 23.9% of undetermined origin. High levels of BNP, soluble receptor for advanced glycation end products, and D-dimer (P<0.0001) were observed in patients with cardioembolic stroke. Independent predictors (odds ratios with CIs are given) of cardioembolic stroke were as follows: atrial fibrillation 15.3 (8.4–27.7, P<0.001); other embolic cardiopathies 14.7 (4.7–46, P<0.001); total anterior circulation infarction 4 (2.3–6.8, P<0.001); BNP >76 pg/mL 2.3 (1.4–3.7, P=0.001); and D-dimer >0.96 &mgr;g/mL 2.2 (1.4–3.7, P=0.001). Even among patients with transient symptoms (n=155), a high BNP level identified cardioembolic etiology (6.7, 2.4–18.9; P<0.001). A model combining clinical and biochemical data had a sensitivity of 66.5% and a specificity of 91.3% for predicting cardioembolism. Conclusions— Using a combination of biomarkers may be a feasible strategy to improve the diagnosis of cardioembolic stroke in the acute phase, thus rapidly guiding other diagnostic tests and accelerating the start of optimal secondary prevention.

Higher Risk of Further Vascular Events Among Transient Ischemic Attack Patients With Diffusion-Weighted Imaging Acute Ischemic Lesions

Background and Purpose— Recently, a new definition of transient ischemic attack (TIA) has been proposed based on the duration of symptoms and diffusion-weighted imaging (DWI) findings. We investigate the value of temporal and neuroimaging data on the prognoses of TIA patients. Methods— Clinical data, symptom duration, DWI, and ultrasonographic findings were collected in 83 consecutive classical TIA patients attended in the emergency department. Stroke recurrence, myocardial infarction, or any vascular event was recorded at follow-up (mean of 389 days). Results— A total of 27 (32.5%) patients revealed focal abnormalities on DWI, whereas 37(44.6%) had symptoms lasting >1 hour. Large-artery disease was detected in 37 (44.6%) patients. Twenty (24.1%) patients experienced an endpoint: 2 (2.4%) myocardial infarctions, 16 (19.3%) cerebral ischemic events, and 2 cases (2.4%) of peripheral arterial disease. Cox proportional hazards multivariate analyses identified the association of symptoms >1 hour with DWI abnormalities as independent predictors of further cerebral ischemic events or any vascular event (hazard ratio [HR], 5.02; CI, 1.37 to 18.30; P=0.015; and HR, 3.77; CI, 1.09 to 13.00; P=0.029). Large-artery occlusive disease also remained an independent predictor of both endpoints (HR, 4.22; CI, 1.17 to 15.22; P=0.028; and HR, 3.60; CI, 1.14 to 11.39; P=0.0293). Conclusions— TIA patients with DWI abnormalities associated with duration of symptoms >1 hour and those with large-artery occlusive disease have a higher risk of further vascular events. Routine use of DWI and Doppler ultrasonographic examinations will be useful for identifying TIA patients at high risk to plan aggressive prevention therapies.