Thrombolysis in myocardial infarction in general practice

Thrombolytic treatment of acute myocardial infarction should be instituted at the earliest opportunity. Evidence from the GREAT trial (see menu) revealed 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.

Comparing pre-hospital and in-hospital thrombolysis (1)

• the randomised controlled trials found that, on average, pre-hospital thrombolysis was administered 58 minutes earlier than hospital thrombolysis; the differences ranged from 33 minutes in the MITI study to 130 minutes in the GREAT study. Individually, the trials failed to show statistically significant reductions in in-hospital mortality, although findings in all of the studies favoured pre-hospital administration. However, a meta-analysis of six of the trials found a statistically significant absolute reduction in mortality of 1.6% (95% CI 0.2% to 3%), and a relative risk reduction of 17% (95% CI 2% to 30%, p = 0.03) favouring pre-hospital administration of thrombolysis. This analysis is heavily influenced by the results of the GREAT study (in which thrombolysis was administered by general practitioners in rural Scotland) and therefore does not directly relate to the potential for paramedic based pre-hospital thrombolysis

Reference:

1. NICE guidance (October 2002) on the use of drugs for early thrombolysis in the treatment of acute myocardial infarction
2. Drug and Therapeutic Bulletin 2005; 43(7):49-52.