Immediate Ischemic Stroke Therapies

Fibrinolytic Therapy

Fibrinolytic therapy uses recombinant tissue plasminogen activator (rTPA). Alteplase is the only rTPA approved for treating ischemic stroke. Studies show alteplase is effective in acute ischemic stroke treatment if patients are treated within 3 hours of symptom onset.¹ Some patients are eligible for  fibrinolytic therapy with alteplase up to 4.5 hours from the onset of stroke symptoms. 

Clinicians observe the best results when alteplase is administered in an institution adhering strictly to the NINDS (National Institute of Neurological Disorders and Stroke) protocol. The earlier treatment is provided, the better the outcome. An expert physician generally administers alteplase. In some settings, trained nurses may administer alteplase under a physician’s supervision.

Alteplase, a type of rtPA, dissolves blood clots.

The following is the fibrinolytic therapy inclusion criteria when symptom onset is within 3 hours:

1. CT scan images do not show intracerebral bleeding.
2. The presence of identifiable acute ischemic stroke.
3. No rapid neurologic function improvement.
4. The patient is 18 years old or older.

A CT scan locates the stroke and determines if there is intracranial bleeding.

The exclusion criteria for fibrinolytic therapy are previous stroke or recent head trauma, current or past brain bleeding, hypertension, bleeding diathesis, multilobar infarction on CT, current use of an anticoagulant with an INR greater than 1.7, or arterial puncture to a noncompressible site within the past week.²

Relative exclusion criteria includes recent major surgery, pregnancy, seizure at the beginning of stroke symptoms with residual neurological impairment, recent MI (within past 3 months), recent urological or gastrointestinal hemorrhage within the previous 3 weeks, and minor/rapidly improving stroke symptoms.

Criteria for Alteplase Therapy

The most significant adverse effect of fibrinolytic therapy is intracranial hemorrhage.³ Minor and major bleeding complications may occur elsewhere in the body. Other adverse reactions are angioedema and transient hypotension.

After a clinician determines the patient is a fibrinolytic therapy candidate, the attending physician explains the risks and benefits to the patient and/or family members. After obtaining consent, the attending physician proceeds with therapy. 

Following fibrinolytic therapy, clinicians follow the hospital care path protocol. Anticoagulants or antiplatelet therapy are withheld for 24 hours after administering alteplase or until a 24-hour follow-up CT scan reveals no intracranial hemorrhage is present.

It is possible to extend the alteplase therapy window from 3 hours to 4.5 hours after acute stroke symptom onset. There’s an additional exclusion and inclusion criteria table for patients eligible to receive alteplase 3–4.5 hours after symptom onset.

The criteria for rTPA therapy 3–4.5 hours after symptom onset.

Read: Stroke: Assessment in the Emergency Department

Endovascular Therapy

Endovascular therapy may be used for select ischemic stroke patients.⁴ A clot may form in the intracerebral blood vessels, and endovascular therapy attempts to disrupt the clot integrity or remove it via a stent to restore brain blood flow. Patients who may be considered for endovascular therapy include:

1. Pre-stroke Modified Rankin Scale (mRS) score of 0–1.
2. Acute ischemic stroke receiving intravenous alteplase within 4.5 hours of onset.
3. Causative occlusion of the internal carotid artery and proximal middle cerebral artery (MCA) (M1).
4. Age 18 years and older.
5. NIHSS score of 6 or more.
6. Alberta Stroke Program Early CT Score (ASPECTS) of 6 or greater.

Treatment is initiated via groin puncture within 6 hours of symptom onset.

Endovascular therapy is recommended in addition to IV alteplase for patients who meet the above criteria. Caretakers should consider transferring eligible acute ischemic stroke patients to institutions with advanced stroke units offering endovascular therapies.

The Modified Rankin Scale measures the degree of disability in stroke patients.

To compute the ASPECTS, 1 point is subtracted from 10 for any evidence of early ischemic change for each of the defined regions.

The ASPECTS score determines stroke severity on a scale of 0 to 10.

A normal CT scan receives an ASPECTS of 10 points.

An ASPECTS of 7 points or less highly correlates with a negative functional outcome as determined by Modified Rankin Scale (mRS).⁵

An ASPECTS of 0 indicates diffuse involvement throughout the MCA territory.

Summary

Alteplase is the only approved fibrinolytic therapy for treating ischemic stroke patients. It is most effective when administered within 3 hours of the onset of symptoms, but some patients can be treated with alteplase 3–4.5 hours after symptom onset. There are several inclusion and exclusion criteria for fibrinolytic therapy, and clinicians should be sure their patients meet the relevant inclusion criteria.