GREAT, EMIP & MITI trials

The following trials have compared thrombolysis started before hospital admission with that started in hospital:

• European myocardial infarction project (EMIP)
• myocardial infarction triage and intervention (MITI)
• Grampian region early anistreplase trial (GREAT)

The GREAT trial showed that patients who were given immediate thrombolysis in the community had a lower mortality when compared to patients who received thrombolysis in hospital. The GREAT trial reveal that for patients who could receive thrombolysis two hours after the start of symptoms, each hour's delay increases the mortality risk by 21 lives per 1000 within 30 days and 69 lives per 1000 within 30 months.

EMIP and MITI found the benefits of community-initiated thrombolysis to be less marked. The discrepancy may stem from the short delays before starting in-hospital thrombolysis in these two trials which tends to reduce the advantages of therapy initiated in the community.

Such data prompted the British Heart Foundation to recommend that thrombolysis should not be delayed beyond 60 min after the onset of symptoms and certainly not beyond 90 min.

Reference:

• Rawles, J. (1994). Halving of mortality at 1 year by dimicilary thrombolysis in the Grampian region early anistreplase trial (GREAT). J. Am. Coll. Cardiol. 23, 1-5.
• Leizorovicz, A. et al. (1993). (The European Myocardial Infarction Project Group). Prehospital thrombolytic therapy in patients with suspected acute myocardial infarction. N. Engl. J. Med. 329, 383-9.
• Weaver, WD. er al. (1993). Prehospital-initiated vs. hospital-initiated thrombolytic therapy. (MITI). JAMA, 270, 1211-6.
• Weston, CFM. et al. (1994). Guidelines for the early management of patients with myocardial infarction. BMJ, 308, 767-71.
• Rawles J (1996). Magnitude of benefit from earlier thrombotic treatment in acute myocardial infarction: new evidence from the Grampian region early anistreplase trial (GREAT). BMJ, 312, 212-5.