Pretreatment of patients with ST-segment elevation myocardial infarction with heparin: a systematic review and meta-analysis

Background: Unfractionated heparin (UFH) is frequently administered before percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI). However, current guidelines do not provide clear recommendations for UFH pretreatment before arrival at the coronary catheterisation laboratory. Methods: Between June and July 2023, we systematically searched PubMed, Embase and Cochrane databases for studies comparing UFH pretreatments in patients with STEMI. A random-effects meta-analysis and meta-regression analyses were performed. Results: Fourteen studies were included, of which four were randomised clinical trials (RCTs). A total of 76446 patients were included: 31238 in the pretreatment group and 39208 in the control group. Our meta-analysis revealed a lower all-cause mortality for the pretreatment strategy when compared with the control group, albeit with high heterogeneity (pooled odds ratio (OR) = 0.61, 95% confidence interval (CI) [0.49 - 0.76], P < 0.01; I2 = 77%); lower in-hospital cardiogenic shock (pooled OR = 0.68, 95% CI [0.58, 0.78], P < 0.21; I2 = 27%) and a higher rate of spontaneous reperfusion events (pooled OR = 1.68, 95% CI [1.47, 1.91], P < 0.01; I2 = 79%). In terms of major bleeding, the UFH pretreatment strategy further revealed a decreased rate of events (pooled OR = 0.85, 95% CI [0.73, 0.99], P = 0.40; I2 = 4%). Conclusions: Our study suggests that UFH pretreatment in patients with STEMI undergoing primary PCI was associated to reduced all-cause mortality, cardiogenic shock, enhancing reperfusion rates, whilst diminishing major bleeding events. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement No funding was received ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Our systematic review protocol was published in PROSPERO database I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All included studies are publicaly available