P3123Enoxaparin versus unfractionated heparin in ST-elevation myocardial infarction patients undergoing primary percutaneous coronary intervention

Background The use of intravenous enoxaparin (LBWH) in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (pPCI) was upgraded in the latest European Guidelines to a class IIa recommendation. Purpose The authors aim to compare safety and prognostic impact of LMWH versus unfractionated heparin (UFH) use in STEMI patients undergoing primary PCI. Methods Retrospective study of 3875 STEMI patients who underwent pPCI between October 2010 and September 2017 and were included in a national multicenter registry. Group A consisted of patients managed only with LMWH, and Group B patients were treated with UFH regardless of eventual LMWH associated exposure. The groups were compared according to their demographic, clinical and laboratory characteristics. The primary endpoint (PE) results from a composite which included: procedural failure (pPCI failure or bailout use of GPIIb/IIIa inhibitors), in-hospital mortality, re-infarction or major bleeding (according to the registry criteria). The secondary endpoint (SE) included: in-hospital major bleeding, need for red blood cell transfusion, or haemoglobin drop ≥2g/dL. A 1:1 propensity score (PS) analysis was performed according to demographic variables, medical history and previous medication, physical examination, electrocardiogram characteristics and left ventricular function, matching 1558 of the 3875 patients for later comparison between groups. Results Overall, Group A included 1083 (27.9%) and Group B 2792 (72.1%) patients. The mean age was 63±14 years, and 33.5% of the cohort were female. Despite the baseline characteristics heterogeneity between groups, this phenomenon was not observed after PS matching. The PE was more frequent in Group A, without reaching statistical relevance (15.6% vs 13.3%, p=0.07). The SE was superior in Group A (34.4 vs 29.4%, p=0.01). According to the PS matching analysis, there were no differences beetween groups in terms of the PE (13.9% vs 12.0%, p=0.28), while the SE kept more frequent among Group A (34.9% vs 28.5%, p=0.02) [Figure]. Propensity score: group comparison Conclusion In this study based on a national multicentric registry of STEMI patients, the use of LMWH was not associated with better in-hospital prognosis in terms of major cardiovascular events and was related with higher rates of bleeding related events in the scenario of pPCI, compared to UFH. According to these results, further studies are required to support the widespread use of LMWH in this clinical scenario.