Thrombolysis for Acute Ischemic Stroke--Is There Evidence of Benefit in Older People?

Dr. Ruth Hubbard
Lecturer

Dr. M. Sinead O'Mahony
Senior Lecturer,
University Department of Geriatric Medicine,
University of Wales,
College of Medicine, Wales, UK.

Introduction
Stroke is the second most common cause of mortality in much of the developed world and leads to an estimated 4.4 milllion deaths per year, worldwide.¹ It also causes significant morbidity. Thirty percent of patients with a stroke will die within the first three months and half of the remaining patients will have significant long-term disability.

Stroke is particularly a problem of older people. The risk of stroke doubles with each decade of life after 35 years, such that two thirds of all strokes occur in patients over the age of 65 years. People over 75 years are the fastest growing population in North America. Any treatment that improves outcomes in elderly patients with stroke is potentially of huge importance.

Until recently, there was no effective therapy or management strategy to reduce stroke mortality and disability. Two interventions have been shown to result in some benefit--stroke units and aspirin therapy. Stroke Unit care is associated with 70 fewer deaths or dependencies per 1000 patients treated.

Is There a Role for Thrombolytic Therapy in the Management of Acute Ischemic Stroke?

Joyce So, BSc

While thrombolytic therapy has become an established part of treatment for acute ischemic heart disease, the controversy continues regarding its potential and practical use in acute ischemic stroke. In a situation where time is of the essence, is thrombolysis the best available solution?

Acute ischemic stroke (AIS), or "brain infarction", is most commonly a result of intracerebral artery occlusion due to embolism from proximal sites such as the internal carotid arteries, heart or aorta. Unlike cardiac arrest, where brain viability is measured in minutes, AIS presents with a mixture of salvageable tissue, allowing for a therapeutic window that can last several hours. While the definitive time frame has yet to be pinned down, the generally accepted mantra "Time is Brain" reflects the notion that prognosis is improved by early intervention. The question now is whether there is a role for thrombolytic therapy in the management of AIS.

The two most prominent candidates for use in thrombolytic AIS therapy are streptokinase and recombinant tissue plasminogen activator (rtPA), both serine proteases that catalyze the conversion of plasminogen to plasmin, which digests fibrin clots.