Antithrombotic Therapy for Cerebrovascular Disorders: Completed Stroke
The use of aspirin following completed stroke failed to show a significant benefit in a level I study using 1.5 g/day of aspirin. Ticlopidine, another platelet-antiaggregating agent, has been demonstrated to reduce stroke recurrence following completed stroke.
Fibrinolytic therapy offers a new, potentially important approach to the acute treatment of cardioembolic stroke. Clot-specific fibrinolytic therapy with tissue plasminogen activator (TPA) is currently being employed widely in AMI, and preservation of myocardial function has been observed. Experiments with TPA and animal embolic stroke models have demonstrated that intracranial arterial thrombi can be dissolved rapidly and safely. Additionally, functional outcome can also be improved, if the fibrinolytic therapy is initiated early after the embolic event. Preliminary human trials of TPA have begun in patients with cardioembolic and atherothrombotic stroke. So far, this agent appears to be relatively safe in acute stroke patients, but the doses employed have been conservative. The safety and therapeutic efficacy of higher TPA doses in acute stroke remain uncertain, but large clinical trials to address these questions are planned. further
Primary Stroke Prevention
The United States and British physicians’ studies of aspirin in the prevention of cardiovascular disease have raised questions regarding the use of aspirin by individuals free of cardiac and cerebrovascular disease. The US Physicians Health Study compared altemate-day aspirin and placebo in 22,071 male physicians aged 40-84 years during a mean follow-up of 4.8 years. Of293 Mis, only 23 (7.8%) were fatal. Nonfatal MI was reduced by 43%, but the absolute magnitude of reduction was only 0.14%/year due to the low prevalence of MI in this population. Death from all cardiovascular causes was identical and extraordinarily low (only 0.08%/year). Strokes were about half as common as Mis, and only 5% were fatal. Disabling and fatal strokes increased by 64% in the aspirin arm, and disabling and fatal hemorrhagic strokes were increased 5-fold (10 vs 2), with an absolute risk increase of 0.02%/year. In this population of22,000 male physicians there were 13 fewer fatal Mis and 9 more disabling or fatal strokes in the aspirin-treated patients. While concern has been expressed over the routine use of aspirin in light of a potentially increased risk for hemorrhagic stroke, the risk is small, as suggested by the calculation that over 5,000 individuals would be required to take aspirin for a year before one would suffer a disabling stroke.
Category: Antithrombotic Therapy
Tags: antithrombotic therapy, cardioembolic source, cerebrovascular disorders