Introduction: According to current guidelines, for pa-tients with acute ST-elevation myocardial infarction (STEMI), primary percutaneous coronary intervention (PPCI) is the standard treatment for coronary reperfu-sion. It is recommended that ischaemia interval should be as short as possible. However, there is a delay due to particularities in every healthcare system. During this interval, antiplatelet agents are recommended to be ad-ministered as soon as STEMI diagnosis is established. There is a strong indication for efficient anticoagulant therapy during PPCI, however, its efficacy and safety of early administration at diagnosis are not well esta-blished.

Methods: Our study is an observational, retrospecti-ve, nonrandomized study in patients with STEMI, ad-mitted in our clinic in 2017, with PPCI in the first 24 hours from symptoms onset. Patients with thromboly-tic treatment were excluded. We evaluated the impact of early anticoagulation treatment on invasive (angiogra-phic appearance) and non-invasive reperfusion criteria (pain and >50% of ST-segment elevation resolution). Early treatment was defined as anticoagulant adminis-tration (unfractioned heparin or low molecular weight heparin) before arriving at the PCI center (group A), while group B consists in patients who recieved antico-agulant at the PCI center.

Results: There were 216 patients included in the study, among which 119 were in group A and 97 in group B. According to pre-procedural non-invasive signs of reperfusion criteria, there were statistically significant more patients in the early treatment group: 42 (35.3%) compared to 14 (14.4%), p<0.01. Regarding the invasi-ve signs of reperfusion, there was a trend towards more patients in the early group: 56 (47.1%) group A vs. 40 (41.2%) group B, p=NS. Considering the two hours post-PCI electrocardiogram, there are more patients with successful tissue reperfusion criteria in group A 89 (74.8%) vs. group B 59 (60.8%), p=0.028.

Conclusions: Early anticoagulation in patients trans-ferred for PPCI results in an increased rate of non-in-vasive reperfusion prior to PCI. This translates in a de-crease in total ischemia time and an improved quality of reperfusion evaluated two hours after intervention. However, this was not associated with a significantly improved angiographic reperfusion of the infarct re-lated artery, probably because of low patient num-ber. This may also be due to the complex relationship between epicardial and myocardial tissue reperfusion. Additional studies in a larger population with rando-mized allocation of anticoagulants prior to interventi-on may shed light on this important issue.