What Are the Contraindications for Streptokinase in MI?

Research has shown that thrombolytic therapy with streptokinase can significantly reduce mortality in acute myocardial infarction (MI) but carries a substantial risk of serious bleeding events. Understanding what are the contraindications for streptokinase in MI is critical for clinicians to weigh the potential benefits against the risks for each patient.

Quick Summary

This article details the absolute and relative contraindications for streptokinase in myocardial infarction, emphasizing critical risks like bleeding, prior medical history, and allergies that must be assessed before treatment.

Key Points

• Absolute Contraindications are Critical: Active internal bleeding, recent intracranial or intraspinal surgery or trauma, prior intracranial hemorrhage, and known intracranial neoplasms are strict reasons to avoid streptokinase due to a high risk of life-threatening bleeding.

• Recent Medical Events are Major Risks: A recent ischemic stroke (within 3 months) or major surgery (within 3 weeks) represents a serious bleeding risk and is a contraindication for thrombolytic therapy with streptokinase.

• Hypertension Must Be Controlled: Severe, uncontrolled hypertension (SBP >180 mmHg or DBP >110 mmHg) is an absolute contraindication due to the high risk of hemorrhagic stroke.

• Allergy is a Concern: Due to its bacterial origin, streptokinase can cause severe allergic reactions, and prior exposure within the last 6 months makes it ineffective and risky due to neutralizing antibodies.

• Newer Alternatives Offer Better Safety: Fibrin-specific thrombolytics like tenecteplase and alteplase are generally preferred over streptokinase today due to lower rates of major bleeding and allergic reactions.

• Risk Assessment is Case-by-Case: For conditions like recent gastrointestinal bleeding, traumatic CPR, or pregnancy, a careful risk-benefit analysis must be performed before using streptokinase.

Understanding Streptokinase in Myocardial Infarction

Streptokinase is a thrombolytic drug derived from bacterial proteins, used to dissolve blood clots that block coronary arteries in acute myocardial infarction (MI). By activating plasminogen to plasmin, it breaks down the fibrin in clots, restoring blood flow. However, this action can also cause systemic fibrinolysis, increasing bleeding risk. Careful patient selection based on contraindications is vital.

Absolute Contraindications for Streptokinase

Absolute contraindications mean streptokinase should not be used due to a high risk of severe complications, particularly intracranial hemorrhage. These include:

• Prior intracranial hemorrhage.
• Known structural cerebral vascular lesions, like arteriovenous malformations or aneurysms.
• Intracranial neoplasm (brain tumor).
• Ischemic stroke within the previous 3 months.
• Active internal bleeding (excluding menses).
• Suspected aortic dissection.
• Significant head or facial trauma within the past 3 months.
• Intracranial or intraspinal surgery within the past 2 months.
• Severe uncontrolled hypertension (systolic >180 mm Hg or diastolic >110 mm Hg).
• Prior streptokinase treatment within the last 6 months due to allergy risk and potential neutralizing antibodies.

Relative Contraindications and Risk Assessment

Relative contraindications require a case-by-case assessment of risks versus benefits. These include:

• Recent internal bleeding (e.g., gastrointestinal or urinary tract hemorrhage within 2-4 weeks).
• Major surgery or trauma within the past three weeks.
• Recent prolonged (over 10 minutes) cardiopulmonary resuscitation.
• Active peptic ulcer.
• Pregnancy or peripartum status (especially within one week postpartum).
• Current use of oral anticoagulants.
• Advanced liver or renal disease.

Streptokinase vs. Newer Thrombolytics: A Comparison

Newer, fibrin-specific thrombolytic agents like tenecteplase (TNK) and alteplase (tPA) are often preferred over streptokinase due to lower bleeding and allergic reaction risks.

Feature	Streptokinase (SK)	Tenecteplase (TNK)	Alteplase (tPA)
Mechanism	Systemic fibrinolysis.	Fibrin-specific.	Fibrin-specific.
Antigenicity	High.	Low.	Low.
Bleeding Risk	Higher.	Lower.	Lower.
Administration	Infusion over 60 minutes.	Single bolus.	Infusion.
Hypotension Risk	High.	Low.	Moderate.

Managing Bleeding and Allergic Reactions

Bleeding is a primary risk. Minor bleeding can be managed with local pressure, but major bleeding is potentially fatal. Hospital protocols involve monitoring and readiness to administer blood products. Allergic reactions are also a concern, ranging from mild to severe anaphylaxis. Prior streptococcal infections or previous streptokinase use increase allergy risk and may render the drug ineffective. In cases requiring repeat thrombolysis, a different agent is typically used. Guidelines on assessing bleeding risk are available from the American Heart Association.

Conclusion

Streptokinase was important for MI treatment, but its use is now limited by high antigenicity and bleeding risks, especially intracranial hemorrhage. Strict adherence to contraindications is vital. Newer thrombolytics and the increasing use of percutaneous coronary intervention (PCI) offer better safety profiles. Clinical decisions must prioritize patient safety through thorough risk evaluation and adherence to guidelines.

Frequently Asked Questions

What is the primary danger of using streptokinase in MI?

The primary danger is the risk of serious bleeding, especially intracranial hemorrhage, because streptokinase induces a systemic fibrinolytic state, breaking down clots throughout the body, not just the one causing the heart attack.

Can streptokinase be given if a patient had a stroke in the past?

No, a history of any prior intracranial hemorrhage is an absolute contraindication. A recent ischemic stroke within the last 3 months is also an absolute contraindication due to the risk of converting to a hemorrhagic stroke.

Why is streptokinase contraindicated in patients with high blood pressure?

Severe, uncontrolled hypertension is a contraindication because the high pressure increases the risk of a hemorrhagic stroke during the systemic fibrinolysis caused by streptokinase.

Is it safe to give streptokinase to a pregnant woman with an MI?

No, pregnancy is considered a relative contraindication for streptokinase and other thrombolytics due to the risks it poses to both the mother and the fetus.

Can streptokinase be given if a patient has recently had major surgery?

No, major surgery within the preceding 3 weeks is a relative contraindication, while recent intracranial or intraspinal surgery (within 2 months) is an absolute contraindication. The risk of bleeding at the surgical site is too high.

Why is prior exposure to streptokinase a contraindication?

Prior exposure to streptokinase, particularly within the last 6 to 12 months, can cause the body to develop neutralizing antibodies, rendering the drug ineffective and increasing the likelihood of severe allergic reactions.

Are newer thrombolytics like tenecteplase also contraindicated under the same conditions?

While newer agents like tenecteplase have better safety profiles and lower bleeding rates than streptokinase, many of the same high-risk contraindications, especially related to intracranial bleeding, still apply.