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It’s a matter of time: contemporary pre-hospital management of acute ST elevation myocardial infarction
  1. R C Welsh,
  2. P W Armstrong
  1. University of Alberta, Edmonton, Alberta, Canada
  1. Correspondence to:
    Dr Robert C Welsh
    University of Alberta, 2C2.12, Walter Mackenzie Centre, 8440 - 112 Street, Edmonton, Alberta T6G 2B7, Canada; rwelshcha.ab.ca

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Substantial intellectual and financial resources have been invested in the quest to reduce outcomes in patients with ST elevation myocardial infarction (STEMI) through improved pharmacological and mechanical reperfusion therapies. By contrast, little emphasis has been placed on enhancing the medical systems whereby these treatments are delivered, especially as it relates to pre-hospital reperfusion. In this article we will review (1) the importance of timely reperfusion, (2) data supporting pre-hospital fibrinolysis, and (3) a novel contemporary systems based approach to improving outcomes in patients with acute cardiac events.

THE IMPORTANCE OF TIME

Delay in treatment is associated with a substantial reduction in the benefit of fibrinolysis as demonstrated in a meta-analysis of greater than 50 000 patients with STEMI.1 Treatment within the first hour of symptoms achieves twice the benefit of subsequent treatment (< 1 hour  =  65/1000 patients treated lives v 1–2 hours  =  37 lives/1000 patients treated). This validated experimental models of acute myocardial infarction, which demonstrated a continuous and progressive wave of myocardial necrosis dependent on the duration of coronary artery ligation.2 These and other data spearheaded a focus on reducing time to reperfusion and spawned the adages “golden hour of fibrinolysis” and “time is muscle”.

Although the negative impact of temporal delay has been a key feature of fibrinolysis research, substantial debate exists over whether this phenomenon applies equally to percutaneous coronary intervention (PCI). In the primary PCI arm of DANAMI-2 there was a threefold increase in events in patients randomised later compared to earlier (1.5 hours  =  4.7% v 4–12 hours  =  12.2% 30 day death, re-myocardial infarction (MI), stroke).3 In GUSTO-2B the in-hospital delay from randomisation until first balloon inflation was associated with a sixfold increase in death comparing patients treated within the first 60 minutes and those treated after 90 minutes (1% v 6.4%, 30 …

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