What are the contraindications to thrombolytic therapy for acute myocardial infarction? Is diabetic retinopathy a contraindication?

Haemorrhagic complications (particularly intracranial) are the most important risks associated with thrombolysis. The 1996 ACC/AHA guidelines for the management of acute myocardial infarction list four absolute contraindications to thrombolytic therapy:

• Previous haemorrhagic stroke or other stroke within one year
• Known intracranial neoplasm
• Active internal bleeding (excluding menses)
• Suspected aortic dissection.

In cases where the nature of the stroke (haemorrhagic or otherwise) is unknown, then the risk of not administering a thrombolytic agent should be considered. The majority of strokes are occlusive in origin, and thus lack of certain knowledge should probably not represent a contraindication to thrombolysis in those patients (such as those with extensive territories of myocardial infarction who present early) who have most to gain.

In addition, there are relative contraindications for which the potential risks need to be assessed against the anticipated benefits:

• Uncontrolled hypertension or history of chronic severe hypertension
• Known bleeding diathesis or anticoagulant therapy with INR
  
  • 2–3
• Trauma or internal bleeding (within 2–4 weeks), major surgery(<3>10 minutes), non-compressiblevascular puncture, active peptic ulcer
• Pregnancy
• For streptokinase/anistreplase – prior exposure (with 5 days to2 years) or prior allergic reaction.
  

Ocular haemorrhage after thrombolysis has been reported, and diabetic retinopathy was once considered a relative contraindication to thrombolytic therapy in AHA/ACC guidelines.

Although no systematic evaluation has been performed, the GUSTO-I trial observed no intraocular haemorrhages in 6011 patients with diabetes. Currently, therefore, diabetic retinopathy is only considered a contraindication to thrombolysis if there is clear evidence of recent retinal haemorrhage.