RC Welsh, P Goldstein, WC Chang, L Wallentin, CB Granger, F Verheught, F Van de Werf, PW Armstrong, on behalf of the ASSENT

Time to treatment remains a fundamentally important determinant of outcome in patients (pts) with ST elevation myocardial infarction (STEMI). ASSENT 3 Plus (A3+) a multi-centre international trial of pre-hospital tenecteplase with either unfractionated heparin or enoxaparin provides a unique opportunity to examine this dynamic. Accordingly, we assessed the components of time to treatment from selected sites across 7 countries enrolling at least 50 pts (pt #’s listed by country in figure) in A3+ (92% of the total), and compared their time to treatment in the corresponding countries participating in the ASSENT 3 (A3) study of in-hospital fibrinolysis. The median time from symptom onset to fibrinolysis was 47 minutes earlier in A3+ than in A3 (2.8 h) and 52% of pts received treatment within 2 h of symptoms. The figure shows the 5 components of elapsed time from symptom onset to treatment in A3+ and demonstrates substantial inter-country heterogeneity especially in time from symptom onset to first call for medical assistance which was shortest in Canada and longest in the United Kingdom. Although times from randomization to treatment were relatively homogeneous, elapsed time from ambulance arrival to randomization was longest in Canada and Sweden and shortest in Germany. Logistic modeling of time to treatment revealed that younger age, male sex, anterior MI and prior angioplasty were predictive of shorter time to treatment, but the most influential factor modulating time to treatment was country of origin. Although the overall reduction in time to treatment in the A3+ pre-hospital trial was substantial, this new understanding of the components of treatment delay highlight future opportunities to further abbreviate time to treatment in patients with STEMI.

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