Fibrinolytic therapy can be a lifesaving treatment for stroke. It can also decrease the lasting effects of strokes which can often lead to permanent disabilities. Fibrinolytic therapy works by dissolving clots which are obstructing blood flow to the brain. In order to be considered a suitable candidate for the therapy, patients must be over the age of 18 and have a firm diagnosis of ischemic stroke with deficits.
Although fibrinolytic therapy may be the recommended treatment, in some cases the risks outweigh the benefits and the therapy is contraindicated. A thorough assessment of the patient’s condition and medical history is an essential part of determining if fibrinolytic therapy is appropriate.
There are several absolute and relative contraindications for fibrinolytic therapy. For obvious reasons, one absolute contraindication for fibrinolytic therapy is evidence of intracranial hemorrhaging on the CT scan.
In addition, since intracranial hemorrhage is also a possible complication of fibrinolytic therapy, conditions that increase the risk of a hemorrhage are also viewed as fibrinolytic therapy contraindications. For example, if the patient has a history of a previous stroke within the past three months, it may increase their risk of a bleed and exclude them from treatment with fibrinolytics.
If a patient has a clinical presentation suggestive of a subarachnoid bleed, such as severe headache, orbital pain, vision loss, and dizziness, even with a normal CT scan, treatment with a fibrinolytic agent may not be advised. A previous subarachnoid bleed is also considered a contraindication.
Recent head trauma or brain or intraspinal surgery may also increase a person’s risk of suffering an intracranial hemorrhage and may exclude a patient from therapy. Additional contraindications include an arterial puncture at a non-compressible site within the previous week. Patients with evidence of active bleeding would also usually be excluded from fibrinolytic therapy.
Another risk of fibrinolytic therapy is systemic bleeding, so certain conditions that increase the risk of systemic bleeding are also relative contraindications. This includes an acute bleeding diathesis, such as a platelet count of less than 100,000.
Patients who have uncontrolled hypertension with a systolic blood pressure of greater than 180 mm Hg or a diastolic of greater than 110 mm Hg may also be excluded. Blood glucose levels are also taken into consideration. A glucose concentration of less than 50 mg/dL is considered a contraindication.
A relative contraindication means that the patient may have a certain condition that puts him or her at a higher risk of developing a complication, but the benefits of therapy may outweigh the risks. According to the American Heart Association, patients who have one or more relative contraindications may still be considered candidates for fibrinolytic therapy.
If relative contraindications for fibrinolytic therapy are present in a stroke patient, consideration should be given to the extent or severity of the stroke symptoms and the overall health of the patient.
One relative contraindication is rapidly improving stroke symptoms. It may be a judgment call if the patient’s stroke appears to be a minor one or symptoms are quickly resolving. The possible complications from therapy may not be worth the risk if symptoms are mild.
If the patient had a witnessed seizure when symptoms started and neurological impairments are evident following the seizure, the patient may not be considered to be a good candidate for fibrinolytic therapy. This is due to the fact that it can be hard to tell the difference between postictal Todd’s paralysis and an ischemic stroke, since clinical presentation may be similar.
Myocardial infarction within the previous three months may also exclude a patient from fibrinolytic therapy. Additional relative contraindications include major trauma or surgery within the previous two weeks or recent gastrointestinal hemorrhage. This is due to the increased risk of bleeding.
Although recommendations for fibrinolytic therapy include administration within three hours from the onset of symptoms, in some cases it may be given up to 4.5 hours from symptom onset. According to the AHA, carefully selected patients who receive fibrinolytic therapy within 3 to 4.5 hours of the start of symptoms also have good clinical outcomes. Because it is outside the window of the ideal time frame for therapy, there are additional (and more restrictive) exclusion criteria, including being over the age of 80, having a severe stroke, and having a history of diabetes prior to having a stroke. Taking oral anticoagulants is also a contraindication regardless of INR when treatment is being considered in the 3 to 4.5-hour range.