Intracranial Hemorrhage From Thrombolytic Therapy Calculator

How does this intracranial hemorrhage from thrombolytic therapy calculator work?

This health tool evaluates risk of cerebral hemorrhage in patients who undergo treatment with thrombolytic therapy for myocardial infarction.

The intracranial hemorrhage risk calculator consists of 8 items with questions related to bleeding risk factors:

■ Age – presents a cut off of 75 years old for increased risk as evidenced in the original study.

■ Gender – although females are more protected than males against heart disease before menopause, after that risk of developing heart treatment complications is higher for them.

■ Race – black race has a greater intracranial hemorrhage risk. These populations also have higher rates of both hemorrhagic and ischemic stroke.

■ Prior history of stroke – prior cerebrovascular events were associated with an increased risk of thrombolysis-related intracranial hemorrhage.

■ Systolic blood pressure – equal to or higher than 160 mmHg (consistent with hypertension) is another risk factor.

■ Body weight – less than 65 kg (143.3 lbs) for females and 80 kg (176.36 lbs) for males, poses a greater risk for cerebral bleeding.

■ INR >4 or prothrombin time >24 seconds – excessive anticoagulation in the setting of MI with agents such as heparin or hirudin increases cerebral bleeding risk.

■ TPA as thrombolytic therapy – tissue plasminogen activator is one of the thrombolytic agents with higher risks (associated with a higher rate: 3 per 1000 treated patients with intracranial hemorrhage compared to streptokinase).

Score interpretation

Each of the 8 items in the above hemorrhage score has two answer choices, one awarded 1 point and the other 0 points.

Choices that evidence the presence of a bleeding risk factor i.e. TPA as thrombolytic therapy are given 1 point, therefore the maximum score, correlated with the highest risk percentage is 8 points.

These are the intermediary intracranial hemorrhage risk percentages:

■ 0 - 1 points: 0.69%;

■ 2 points: 1.02%;

■ 3 points: 1.63%;

■ 4 points: 2.49%;

■ 5 - 8 points: 4.11%.

By using the above calculator, clinicians are able to stratify bleeding risk based on individual patient data and are helped with the decision making of the right thrombolytic therapy for MI.

The bleeding risk stratification scale has yet to be externally validated and compared with similar scales in other studies.

Hemorrhage and thrombolytic therapy

The rate of intracranial hemorrhage associated with thrombolytic therapy is quoted as 50% in clinical trials. However, the number changes in the case of elderly populations.

At the same time, some medical professionals might withhold useful thrombolytic therapy because of the significant hemorrhage and stroke risks involved, without any risk stratification being performed on the patient.

Low risk patients would be able to benefit from tPA or other thrombolytic agents in acute myocardial infarction and the other conditions such as:

■ Pulmonary embolism (PE);

■ Deep vein thrombosis (DVT);

■ Acute ischemic stroke (AIS);

■ Ischemic limb injury.

Thrombolytic therapy for MI lyses infarct artery thrombi with the aim to achieve reperfusion and reduce infarct size while preserving left ventricular function.

High risk patients may be directed towards alternate therapies such as primary percutaneous transluminal coronary angioplasty for acute reperfusion which has lower rates of intracranial hemorrhage.

The score doesn’t include other contraindications for thrombolytic therapy because of low frequency reporting, however some are:

■ History of dementia, or central nervous system damage within 1 year;

■ Major surgery, trauma, or bleeding within 3 weeks;

■ Suspected aortic dissection;

■ Internal bleeding within 6 weeks;

■ Known intracranial neoplasm.

References

1) Brass LM, Lichtman JH, Wang Y, Gurwitz JH, Radford MJ, Krumholz HM. (2000) Intracranial hemorrhage associated with thrombolytic therapy for elderly patients with acute myocardial infarction: results from the Cooperative Cardiovascular Project. Stroke; 31(8):1802-11.

2) Gebel JM, Sila CA, Sloan MA et al. (1998) Thrombolysis-Related Intracranial Hemorrhage. A Radiographic Analysis of 244 Cases From the GUSTO-1 Trial With Clinical Correlation. Stroke; 29: 563-569

3) Goldstein JN, Marrero M, MD; Masrur S et al. (2010) Management of Thrombolysis-Associated Symptomatic Intracerebral Hemorrhage. JAMA Neurology; 67(8)

4) Alpert JS. (1992) Intracranial Hemorrhage After Thrombolytic Therapy: A Therapeutic Conflict. JACC, 19(2):295- 6.