Pre-hospital heparin is not associated with infarct vessel patency and mortality in ST-segment elevation myocardial infarction patients with out-of-hospital cardiac arrest.
Phillip Scholz, Tim Friede, Karl Heinrich Scholz et al.
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In 30 seconds
This analysis examined whether pre-hospital heparin was associated with infarct-artery patency and mortality among patients with ST-segment elevation myocardial infarction (STEMI) and out-of-hospital cardiac arrest (OHCA). It used data from 394 OHCA participants in a prospective, multicentre trial cohort; 272 (69%) received heparin from emergency medical services. Although univariate in-hospital mortality was lower with heparin (26.8% vs. 42.6%, p = 0.002), heparin was not a significant mortality predictor after regression adjustment (OR = 0.992; p = 0.981), and was not associated with pre-revascularization TIMI flow grade (OR = 0.840; p = 0.724).
Key findings
- Pre-hospital heparin was given to 272 (69%) of 394 STEMI patients with OHCA.
- Univariate in-hospital mortality was 26.8% vs. 42.6% with and without pre-hospital heparin, respectively (p = 0.002).
- After regression adjustment, heparin was not a significant mortality predictor (OR = 0.992; p = 0.981).
- Heparin was not associated with infarct-artery TIMI flow before revascularization (OR = 0.840; p = 0.724).
Why it matters
The lower unadjusted mortality among heparin recipients did not persist in the regression model, and no association with early infarct-artery patency was observed. This distinction is clinically important when interpreting apparent benefits in non-randomised treatment comparisons, where differences in who receives treatment may influence crude outcome estimates.
What to keep in mind
This was an analysis of trial-cohort data rather than a reported randomised comparison of pre-hospital heparin; treatment allocation may therefore be subject to confounding.