Heparin still one of the most important reperfusion therapies for ST-elevation myocardial infarction in out-of-hospital settings

This editorial refers to ‘Pre-hospital heparin use for ST-elevation myocardial infarction is safe and improves angiographic outcomes’, by Jason E. Bloom et al. doi:10.1093/ehjacc/zuab032. Increasing survival for patients presenting with ST-elevation myocardial infarction (STEMI) is an ongoing major concern. Despite the improvement of the care, mortality is still high. Guidelines regularly evolve and address this issue in a global perspective, recommending to implement systems that will save more lives, depending on each country and its specificity. These systems are multiparametric and should be performant as early as the patient calls the Emergency Medical Services (EMS).1 It is now admitted that patient with STEMI should be directed to a primary percutaneous coronary intervention (PCI) in less than 2 h from the first medical contact (FMC). Out of hospital experienced teams in the management of STEMI are dispatched and bring the patient to the best facility to revascularize the culprit arteries, and not to the nearest hospital. Thus, from the dispatch to the admission to the PCI centre, there is a race against time. Emergency Medical Services should insure quality and safety processes throughout this time and deliver the best care as if the patient is already in the hospital. They should rapidly record and interpret the electrocardiogram (ECG), and continuously monitor it until arrival to the hospital.2,3 It is also recommended to start pre-hospital treatment medications to optimize the revascularization strategy that will be chosen by the cardiologist.4–6 Premedication, also called reperfusion therapy, has been debated over the years.7 Antiplatelets therapy is widely spread, but few protocols include heparin in pre-hospital settings.8 The study from Bloom and colleagues, published in this issue of the journal, outlines this problematic and shows that administrating heparin as early as possible is associated with an improved infarct-related artery (IRA) patency. It was strongly associated with the presence of anterograde flow in the IRA at the time of emergent angiography. This study also gives some answers regarding the safety of administration of heparin by paramedics in an out-of-hospital environment: in fact, it did not increase the rate of major bleeding. Heparin is well established as the ideal antithrombotic for primary PCI, with the randomized HEAT-PPCI trial demonstrating reduced major adverse ischemic events, expense, and similar bleeding rates to bivalirduin.9 Giralt et al.10 showed that vessel patency at presentation is sensitive to the timing of heparin administration relative to symptom onset. It may be that ischaemic preconditioning, preceding aspirin prescription, influence the apparent effect on coronary flow from heparin. It’s probably not the only factor, but it’s difficult to draw real conclusions on the effect of heparin.11 Some of the explanations given in various studies and reports could be that patients who contact the emergency services earlier in the clinical course of their myocardial infarction (MI) illustrate a tendency to interact more favourably with medical services throughout their lives. They might be more health literate, more concordant with prescribed therapy, more likely to stop smoking, and better engaged with cardiac rehabilitation services.11 McGinley et al.11 suggested to investigate this more, and to check whether there are differences between the groups regarding decision-making processes when confronted with the symptoms of myocardial infarction. The largest study to date was an analysis of outcomes in 7000 patients in the TASTE study from Sweden. This article described decreased visible thrombus and increased vessel patency in patients receiving pre-hospital heparin.8 Unfortunately, as Bloom and colleagues, this study have failed to show a clear reduction in 30-day mortality in the group receiving out-of-hospital heparin. Future well-sampled studies are needed to answer this question. New STEMI guidelines should clearly address this question. Meanwhile, we can safely recommend the use of pre-hospital heparin administration in STEMI patients addressed to primary PCI and advocate for a strong out-of-hospital system that can quickly identify and take care of those patients. Conflict of interest: none declared. The opinions expressed in this article are not necessarily those of the Editors of the European Heart Journal: Acute Cardiovascular Care or of the European Society of Cardiology.