May 10, 2021

Background: Occlusion myocardial infarction (OMI) is defined as acute coronary occlusion or near occlusion with insufficient collateral circulation leading to downstream myocardial infarction. Currently, we use STEMI ECG criteria to identify acute coronary OMI in the clinical setting. The diagnosis of STEMI is based on millimeter criteria on the ECG (see below) and essentially acts as a surrogate marker for the presence of an OMI. Under the current STEMI vs NSTEMI paradigm, almost 1/3rd of NSTEMI patients have unrecognized acute total occlusion (OMI) discovered on delayed angiograms. The delay in diagnosis results in increased short and long-term mortality compared to NSTEMI patients without OMI (We have reviewed these trials before on REBEL EM). As ECG interpretation has improved it has become clear that there are other early ECG indicators of OMI that do not meet STEMI criteria (i.e. hyperacute T-waves) that would benefit from early percutaneous coronary intervention [2].  Additionally, there are other features such as hemodynamic instability and persistent symptoms, as well as adjunct modalities, like echocardiography, that can add useful information and increase the likelihood of OMI. Ultimately, the OMI paradigm emphasizes underlying pathology over surrogate test results (i.e. STEMI).

April 29, 2021

Background: Non-ST-elevation myocardial infarction (NSTEMI) is defined as acute coronary injury resulting in ischemia and myocardial infarction. The diagnosis is made based on clinical presentation and non-specific electrocardiogram (ECG) changes including ST-segment depression, T-wave inversions, or other nonspecific findings.1 Based on data from the NHS, most patients with NSTEMI are 70 years or older.2 This, coupled with an increasing aging population, raises the question, what is the best management in patients 80 years old or older with NSTEMI?

Previous studies have attempted to evaluate the best approach to elderly patients with NSTEMI, but the mean age of patients was 66 years old with few patients over 80 years old leaving few data to extrapolate these results to this specific population age.3 The best means of obtaining data to answer clinical questions is through prospective randomized trials and there is an upcoming trial to answer this question specifically, the SENIOR-RITA (cool name) will not be expected to complete enrolment prior to 2029. In the meantime, this trial (SENIOR-NSTEMI) was conducted to provide further data regarding the best management of patients older than 80 years old with a NSTEMI.

February 8, 2021

Background: What if we lived in a world where we didn’t call “STEMI alerts”, but instead paged out “OMI alerts”? In the Reperfusion Era of the late 20th century, many large trials showed the benefits of emergent reperfusion therapy, with even greater benefit in the subgroup of patients with undefined ST elevation. As the best idea available, the STEMI-NSTEMI paradigm replaced the Q-wave vs. non-Q-wave MI paradigm in 2000. STEMI-NSTEMI has been a primary determinant of cath lab activations, hospital metrics, and many other patient factors and outcomes. However, the STEMI criteria fail us frequently, missing upwards of 30% of acute coronary occlusion. Additionally, the STEMI/NSTEMI paradigm is dependent on ST segment elevation defined by millimeter criteria, however many occlusion myocardial infarctions (OMI), have no ST segment elevation at all.  To many of us, this idea is not new; we are often taught about STEMI equivalents and “subtle STEMI” that also deserve aggressive management. Over the last 15 years, there has been increased interest in identifying which patients would benefit most from emergent reperfusion therapy. Occlusion myocardial infarction (OMI) vs non-occlusion myocardial infarction (NOMI) is a new paradigm that emerged a few years ago (courtesy of Dr. Stephen Smith, Dr. Pendell Myers, and Dr. Scott Weingart) that might change the way we think about acute myocardial infarction. Their OMI Manifesto is an incredible document (which I highly recommend you read) outlining the historical, clinical, and academic perspectives of why the STEMI-NSTEMI paradigm should be replaced by the OMI-NOMI paradigm. OMI is defined as acute coronary occlusion or near occlusion with insufficient collateral circulation where without emergent catheterization and reperfusion myocardium will undergo necrosis. Patients with OMI are the only ones who benefit from emergent reperfusion therapy, and these patients can present with or without ST elevation on ECG.

October 8, 2020

Background: Prior to the discovery of thrombolytics, clinicians could only observe their patients completing their myocardial infarctions and then classify them according to whether their subsequent ECGs developed Q waves. When trials showed a clear survival benefit with thrombolytics (especially in STE) this shifted the paradigm from “Q-wave/ non Q-wave MI” to “STEMI / non-STEMI”. Eventually STEMI became synonymous with acute coronary occlusion (ACO) requiring reperfusion, except this connection was never studied in trials. Unfortunately, the STEMI criteria have limited diagnostic criteria for ACO, leading to false cath lab activation. And worse, missing ⅓ of ACO (NSTEMI), depriving them of emergent reperfusion therapy. This led many authors to shift from STEMI/ NSTEMI to ACO-MI/ non- ACO-MI. 

February 14, 2019

Background: The 2014 AHA guidelines for the management of NSTEMI, recommend unfractionated heparin with an initial loading dose of 60IU/KG (maximum 4,000 IU) with an initial infusion of 12 IU/kg/hr (maximum 1,000 IU/hr) adjusted per active partial thromboplastin time to maintain therapeutic anticoagulation according to the specific hospital protocol, continued for 48 hours or until PCI is performed (Level of Evidence B) [2]. With even a higher level of evidence the 2014 AHA guidelines for the management of NSTEMI, also recommend enoxaparin 1mg/kg subcutaneously every 12 hours with reduced dosing to 1mg/kg subcutaneously in patients with a creatinine clearance <30mL/min) (Level of Evidence A) [2].  The studies supporting this therapy were performed primarily on patients with a diagnosis of unstable angina and in the era before dual anti platelet therapy and early catheterization/revascularization. Therefore, the authors of this paper looked to evaluate the clinical outcomes associated with parenteral anticoagulation therapy (Heparin) in the era of dual anti-platelet therapy in patients with NSTEMI.

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