ISCHEMIC STROKES AND TREATMENT OPTIMIZATION

Identifying Stroke?

With more than 140,000 people dying from a stroke in the United States each year, as reported by the US Centers for Disease Control and Prevention, who is the most at risk for a stroke? People who suffer from a predominant heart condition, cerebrovascular events, coronary artery disease, chronic pulmonary disease, or high blood pressure are at higher risk for a stroke; however, age, gender, family history, ethnicity and lifestyle choices are also contributing factors. Thus, being able to identify a stroke (ischemic or hemorrhagic) is critical for patient care. Stroke symptoms include weakness, paralysis of the face, arms or legs, difficulty speaking, blurred vision, and/ or a severe headache. Global healthcare providers developed the FAST method to easily identify a stroke and spread awareness amongst the public.

FAST stands for:

• F: Face drooping
• A: Arm weakness
• S: Speech difficulty
• T: Time to call (Ambulance)

Stroke Diagnosis Pathway

Once stroke symptoms are recognized, the patient pathway begins. It starts with the patient being admitted to a primary hospital capable of scanning him/her and diagnosing the condition. This process is time sensitive as the stroke type will guide further treatment. The sooner the stroke is diagnosed, the greater the likelihood of improved clinical outcomes and patient recovery increases. Doctors will perform a series of tests to determine the patient’s risk. The first step, according to the Mayo Clinic, is that the doctor should complete a physical examination of the patient and ask a family member about the symptoms they witnessed, along with any previous signs of injury or disease. Blood tests are also essential, as they can help evaluate sugar levels, the time of blood clotting, and the balance of other critical blood chemicals. Finally, for stroke diagnosis, various imaging studies can be taken into consideration, such as computerized tomography and magnetic resonance imaging. These tests are determined by the doctor, according to the patient’s situation, and can be any of the following:

• Computerized Tomography (CT) scans are used to recognize a hemorrhage, tumor, ischemic stroke, and other conditions.
• Magnetic Resonance Imaging (MRI) can detect tissue(s) damaged by an ischemic stroke or hemorrhage.
• Carotid ultrasound can show blood flow and the build-up of fatty deposits in the carotid arteries.
• A cerebral angiogram gets a detailed view of the brain and neck arteries by injecting a dye into the blood vessels
• An echocardiogram can be used to look for clots that may have travelled from the heart to the brain, causing a stroke.

By combining the patient’s history, symptoms, blood work, and imaging studies the doctor can accurately determine the stroke type and develop a treatment plan. The possible conclusions are (1) no transient ischemic attack or stroke, (2) transient ischemic attack, or (3) acute stroke (ischemic or hemorrhagic).

Ischemic Stroke Treatment

If an ischemic stroke is diagnosed, then the direct goal of treatment is to restore blood flow to the brain. Treatment can include medications such as clot busting drugs and/ or endovascular procedures. Globally, the gold standard for treating ischemic stroke is using tissue plasminogen activator (tPA) also known as alteplase, primarily through intravenous injection. This clot busting drug is injected through the vein within 3 to 4.5 hours after stroke symptoms appear and helps dissolve the clot that caused the stroke and restore blood flow. The aim of this approach is “the quicker, the better.” Important to note is that the time window is considered the door-to-needle time, with less passing time meaning a reduced risk of complication and increased rate of survival.

On the other hand, endovascular procedures are performed directly inside the blocked vessel and have larger time windows than the intravenous approaches. One such procedure, known as intra-arterial thrombolysis, delivers tPA to the affected brain area through a long catheter that is inserted via a small incision in the groin artery. However, today’s focus is on another endovascular treatment, mechanical thrombectomy (MT), since its time window quadrupled from 6 hours to up to 24 hours. It is particularly beneficial to patients who suffer a large clot, as these clots are difficult to dissolve completely with tPA.

Mechanical Thrombectomy

Mechanical thrombectomy (MT) uses a catheter to maneuver a stent retriever through the cerebral arteries to the blocked brain blood vessel to trap and remove the clot. This interventional neuroradiological procedure is performed by trained personnel under general anesthesia or conscious sedation in an angiographic suite, commonly used for large vessel occlusion. Additionally, it can be performed in combination with intravenous tPA for effective results.

The most important aspect of mechanical thrombectomy (MT) is the time window evolution. The DAWN and Defuse 3 trials challenged the assumption of providing an interventional procedure within 6 hours of initial symptom onset, and suggest patient benefits for up to 24 hours. These studies proved a decreased degree of disability among patients who received mechanical thrombectomy (MT) treatment. This evolution, of up to 24 hours from door-to-puncture time, is a result of various trials which demonstrated massive patient benefits to those arriving late to the medical facility after symptom onset. Recent studies have suggested that this form of treatment may be the most effective for ischemic stroke, and several hospitals, including facilities like Mayo Clinic, have proven through clinical studies that decreased door-to-puncture time reflects decreased rehabilitation time and ultimately cost and resource savings for the hospital during the post-treatment phase. Furthermore, endovascular treatment research has confirmed that time is critical for patient recovery and reducing the degree of possible disability after a stroke. Now, various cases allow a door-to-puncture time as late as 24 hours after symptom onset, if the large artery occlusion is in posterior circulation.

Despite the challenges and investment to start endovascular procedures, such as an angiographic suite and a trained interventionist to perform the procedure, there has been a significant increase in the number of patients receiving these procedures.