In the first 2020 issue of the journal, there is a focus on acute coronary syndrome. Erlinge and co-workers from Sweden report data from the Swedeheart registry. Heparin is the preferred choice of anticoagulant in percutaneous coronary intervention (PCI) for acute myocardial infarction (MI); however, an established dosage of heparin has not yet been determined.(1,2) The aim of the study of Erlinge et al. was to determine the relationship between heparin dose or activating clotting time (ACT) with a composite outcome of death, MI, or bleeding using data from the registry-based, VALIDATE-SWEDEHEART-trial. The authors found no association between heparin dose or ACT levels and death, MI bleeding complications, or stent thrombosis. Therefore, according to this study, there is no strong support for a specific heparin dose or mandatory ACT monitoring in patients treated with a potent P2Y12 inhibitor with no planned glycoprotein IIb/IIIa inhibitors.