Local fibrinolytic therapy in ischemic carotid pathology

Intra-arterial thrombolysis in acute ischemic stroke: a review of pharmacologic approaches

Ischemic stroke is a major public health problem worldwide. The potential to cure stroke patients with intravenous thrombolytic therapy has evolved to the use of intra-arterial thrombolytic agents. Fewer than 200 patients have been enrolled in randomized trials of intra-arterial therapy. In this article the authors have reviewed the literature listed in MEDLINE and EMBase, and searched relevant articles to examine the role of fibrinolytic agents in acute interventional stroke therapy. Only English language articles reporting five or more patients were included. Outcomes were defined at 90 days. Good outcome was defined on the modified Rankin Scale. Symtpomatic hemorrhage was defined as hemorrhage in the setting of clinical deterioration in the first 24 to 48 h. The search identified 57 studies of which 44 reported usable data. Only three randomized trials were reported. Of a total of 1140 patients, most (73%) were treated open-label with urokinase (Abbokinase, Abbott Laboratories). The best outcomes were reported in case series and slightly worse outcomes were reported in clinical trials. Overall, it was not possible to distinguish whether one agent was superior to the others. There is a paucity of published evidence on intra-arterial therapy for acute ischemic stroke. Alteplase (Activase, Genentech Inc.) is currently the drug of choice simply because it is available and it is the current intravenous standard. Further trials and developments are anticipated.

Internal carotid artery stent implantation in 25 patients with acute stroke: preliminary results

PURPOSE

To evaluate retrospectively the outcome for patients with acute ischemic stroke in the territory of the middle cerebral artery (MCA) who had undergone stent implantation in the proximal segment of the internal carotid artery (ICA) in addition to intraarterial thrombolysis (IAT).

MATERIALS AND METHODS

Stent implantation and retrospective analysis of clinical and radiologic data were approved by the institutional ethical committee. Endovascular treatment was performed after obtaining informed consent from patients or their closest relatives. Informed consent for retrospective review was not required. After pharmacologic and/or mechanical IAT, 25 consecutive patients (seven women, 18 men; mean age, 59 years +/- 14 [standard deviation]) underwent stent implantation in the proximal segment of the ICA (endovascular group). The clinical and radiologic characteristics (ie, interval from symptom onset to arrival at the emergency department, prevalence of vascular risk factors, causes of stroke, stroke severity, early signs of cerebral ischemia, duration of endovascular intervention, type of occlusion, and prevalence of leptomeningeal collateral vessels), recanalization rates, and clinical outcomes for patients in the endovascular group were compared with those for patients in the medical group (10 women, 21 men; mean age, 62 years +/- 12) who experienced ischemic stroke in the territory of the MCA as a result of ICA occlusion and who received antithrombotic treatment only. Differences between groups were assessed by using the chi2 test. A logistic regression analysis was performed to assess the effect of clinical and radiologic factors on recanalization rates and outcome.

RESULTS

ICA recanalization was successful in 21 patients. Good recanalization of the MCA was achieved in 11 patients. In nine of these patients, recanalization of the MCA was achieved by using mechanical IAT only. In the remaining 12 patients, administration of intraarterial urokinase was performed in addition to mechanical thrombolysis. Two patients from the endovascular group experienced symptomatic intracerebral hemorrhage. At 3 months, 56% of the endovascular group and 26% of the medical group had a favorable outcome. Mortality was 20% in the endovascular and 16% in the medical group.

CONCLUSION

IAT and stent implantation in the proximal segment of the ICA seem to improve the outcome for patients with ischemic stroke caused by occlusion of the cervical portion of the ICA.

Open trial of intravenous tissue plasminogen activator in acute carotid territory stroke. Correlations of outcome with clinical and radiological data

BACKGROUND AND PURPOSE

Pilot studies using early thrombolytic therapy in stroke have suggested that recombinant tissue plasminogen activator (rTPA) might be effective. While large, double-blind, randomized studies are needed, open trials could generate hypotheses concerning (1) the clinical correlations of outcome, (2) the significance of CT scan data during the first week, and (3) the use of adjunctive therapies.

METHODS

We performed an open trial of intravenous rTPA on patients referred to our emergency service with all types of ischemic stroke in the carotid territory. All patients between 20 and 81 years hospitalized during 1994 with completed stroke in the internal carotid artery territory and a baseline Scandinavian Stroke Scale score lower than 48, even with severe disturbances of consciousness, were included. The inclusion time was within 7 hours after stroke onset. A 0.8-mg/kg dose of rTPA was infused for 90 minutes. Intravenous heparin was given either immediately at efficient dosage or after 24 hours. Mannitol was used in patients with severe presentation. The Scandinavian Stroke Scale evaluation was done at baseline, 3 hours, and 1, 7, 30, and 90 days. The CT scan was performed before the treatment and at days 1 (24 +/- 6 hours) and 7.

RESULTS

Forty-three consecutive patients met the criteria of the protocol. The mean age at inclusion was 65 +/- 10.4 years, and the mean interval to treatment was 232 +/- 79 minutes. At day 90, 25 patients (58.1%) exhibited a complete regression of symptoms, and 3 had moderate neurological sequelae. Thirteen patients had severe neurological sequelae, 11 with infarcts and 2 with secondary parenchymal hematomas. Two patients died (4.6%), 1 with hematoma. The overall hematoma rate was 6.9%. Excellent outcome at day 90 was significantly correlated with major neurological improvement at day 1. Intravenous immediate heparin versus delayed heparin after 24 hours improved the ischemic outcome but not the overall outcome. Reinfarction syndromes after major neurological improvement, likely to be rethrombosis syndromes, were observed in 3 patients (6.9%). For the day 1 CT scan, poor outcome was associated with the presence of structured and homogeneous hypodensities likely to represent classic infarcts, as confirmed by day 7 CT scan. Conversely, total recovery was significantly associated with the absence of any image or with unstructured hypodensities, a particular type of image characterized by its heterogeneous darkness and often polylobar shape. This type of image disappeared at day 7 in 17.6% of the cases and is likely to represent reperfusion images and/or incomplete ischemic damage.

CONCLUSIONS

The results obtained in this open, small study suggest safety and effectiveness of rTPA thrombolysis at the dose of 0.8 mg/kg within 7 hours in acute strokes of the carotid territory, including highly serious baseline neurological presentations, until age 81 years and under special therapeutic conditions. Complete recovery is significantly associated with major neurological improvement during the first 24 hours and the presence of a particular type of image at day 1 CT scan characterized by an unstructured hypodensity, often polylobar and heterogeneous, which is likely to correspond to reperfusion images.

Thrombolytic therapy. From myocardial to cerebral infarction. The MAST-I Group. Multicentre Acute Stroke Trial

Thrombolysis is proposed for the acute treatment of cerebral infarction as it is able to recanalize occluded arteries and thus potentially restore normal perfusion of the cerebral parenchyma, but the results concerning the efficacy of this treatment are still inconclusive. However, it has been fully demonstrated that thrombolytic treatment, leads to a significant reduction in mortality, in patients with acute myocardial infarction. Data from all of the pilot studies using SK or tPA treatment in acute stroke are described in this review, which underlines the incidence of hemorrhagic transformation (hemorrhagic infart and parenchymal hematoma) and its possible correlation to clinical worsening. Pharmacological, experimental and clinical studies encourage the carrying out of large-scale clinical trials using thrombolytics in patients with acute cerebral infarction. Significant data relating to ongoing controlled clinical trials will be available in the near future; only after the analysis of these results will it be possible to confirm the efficacy of thrombolytics in acute stroke.

Interventional neuroradiology

Images

Thrombolysis in acute ischemic stroke: does it work?

BACKGROUND

This article is presented to provoke further discussion regarding the use of thrombolytic drugs to treat acute ischemic stroke.

SUMMARY OF REVIEW

Overview analysis of the six randomized trials of thrombolysis in acute ischemic stroke available in the world literature shows a 20% increase in the odds of death and a 30% reduction in the odds of death or deterioration (both with wide confidence intervals, neither result significant) after thrombolytic treatment for acute ischemic stroke. Exclusion of the two trials conducted without the benefit of computed tomographic scanning shows a 37% reduction in the odds of death (95% confidence interval, 74% reduction to 40% excess) and a significant reduction of 56% in the odds of death or deterioration after thrombolytic treatment (95% confidence interval, 20-76% reduction; 2p = 0.007). Analysis of all published studies (randomized and nonrandomized) shows that there does not appear to be an excess risk of hemorrhagic transformation of the cerebral infarct or of severe edema formation.

CONCLUSIONS

We believe the present evidence is sufficiently encouraging to warrant proper testing of thrombolysis in sufficiently large and well-designed randomized clinical trials to influence clinical practice.

Therapeutic interventions in acute stroke

1. Potential therapies for ischaemic stroke include agents to reduce oedema, to improve cerebral perfusion, to reduce excitotoxic damage, to minimise free-radical induced injury and to reduce complications such as deep venous thrombosis. 2. Of the anti-oedema drugs, steroids are ineffective and possibly dangerous; intravenous glycerol is unproven. 3. Haemodilution to reduce whole blood viscosity and improve perfusion is ineffective. Thrombolytic drugs have not been adequately tested but several randomised multicentre trials are now commencing. Early treatment and CT scanning are essential. 4. Anticoagulants and antiplatelet drugs may have wide applicability but have not been tested in the acute phase of stroke. A multi-centre trial will address this issue. 5. Neuronal cytoprotection offers exciting prospects for acute stroke treatment. Antagonists of glutamate at the NMDA receptor, calcium and sodium channel blocking agents and free radical scavenging drugs have potent effects experimentally. Several agents are now reaching clinical trials. The calcium antagonist nimodipine has been disappointing in large scale trials but some studies were flawed by late treatment. 6. Successful treatment of acute stroke is likely to combine several approaches. 7. Therapeutic trials in stroke must include CT scanning, early treatment and a multicentre approach to achieve large numbers of patients.

Free-floating thrombus of the extracranial internal carotid artery

Free-floating clots of the extracranial internal carotid artery are generally considered as surgical emergencies. This retrospective study analyzes six free-floating clots diagnosed by arteriography. Three of these patients had a fixed stroke while the other three had an evolving stroke. Three patients had antecedent ocular or hemispheric transient ischemic attacks. The causes of free-floating clots in the internal carotid artery were atheromatous stenosis in two cases, ulcerated plaque in three cases, and carotid artery dissection in one. All six patients were seen late, approximately 15 hours after their neurologic accident. They were treated with intravenous heparin over a two to five week period. Repeat arteriograms demonstrated complete clot lysis in four instances, while partial lysis was seen in one case. Moderate extension of thrombus occurred in one case only. No further neurologic complications were noted during the treatment by heparin. As indicated by follow-up arteriographic findings, secondary surgery was performed for major carotid lesions and residual clots in five cases. The free-floating thrombus syndrome of the carotid artery should not be considered as a surgical emergency when discovered late in the wake of an acute neurologic accident.