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A New Paradigm for AMI Management

Meyers, H. Pendell MD; Smith, Stephen W. MD

doi: 10.1097/01.EEM.0000719060.56207.d7
    myocardial infarction, AMI
    myocardial infarction, AMI:
    Figure 1:The progression of ECG findings seen in occlusion MI and reperfusion.
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    Reperfusion of acute coronary artery occlusion causing myocardial infarction (occlusion MI or OMI) decreases morbidity and mortality. (Lancet. 1994; 343[8893]:311.) A 1994 meta-analysis of the reperfusion era trials demonstrated that using a rudimentary understanding of ECG interpretation (ST elevation, ST depression, or neither) was better than not using ECG at all in deciding whether to administer thrombolytics for suspected OMI. (Lancet. 1994;343[8893]:311.)

    Unfortunately, no additional interventional trials were ever done to investigate whether more sophisticated ECG interpretation could result in more accurate differentiation of patients with and without OMI, and the term STEMI became universally used as a surrogate for acute coronary occlusion and as the name for the entire paradigm of AMI management.

    Missed Opportunities

    Under the current STEMI paradigm, 25-30 percent of NSTEMI patients are found to have total occlusion on delayed cardiac catheterization, and these missed OMIs have approximately double short- and long-term mortality compared with NSTEMI patients without OMI (non-occlusion MI or NOMI). (Eur Heart J. 2017;38[41]:3082.)

    Hillinger, et al., studied 2486 consecutive ED patients with suspected ACS, and found a poor sensitivity of 49% for cardiologists using the STEMI criteria to predict OMI. (Int J Cardiol. 2019;292:1.)

    Meanwhile, Aslanger, et al., reported that cardiologists were able to successfully reclassify 28 percent of NSTEMI as OMI when they used expert ECG interpretation instead of STEMI criteria. (Int J Cardiol Heart Vasc. 2020;30:100603.)

    Conversely, 15-35 percent of cath lab activations due to perceived STEMI criteria were found to be false-positives without a culprit lesion. (Arch Intern Med. 2012;172[11]:864; JAMA. 2007;298[23]:2754; Ann Emerg Med. 2010;55[5]:423.)

    Failed Decision

    The name STEMI cognitively inspires us to fail at the reperfusion decision. Because we've named the entire AMI paradigm after the ST segment, it is no surprise that we have made little progress in implementing other ECG findings of OMI. The name STEMI makes clinicians believe that the ST segment is the only ECG finding predictive of OMI, and may explain the lack of understanding of the full occlusion and reperfusion sequences of ECG findings in OMI. (Figure 1.)

    There is no definition of STEMI in abnormal QRS complexes such as paced rhythms, so clinicians are left with the bizarre mentality that OMI cannot be diagnosed in these situations. Most importantly, the name STEMI may cause providers to believe that not only are ST elevation criteria necessary but that some ECG findings are required to diagnose and treat OMI.

    This paradigm explains why we have seen little meaningful progress in the understanding of OMI over the past 25 years. Meanwhile, the previously bleak stroke paradigm has undergone a renaissance in its understanding of the large vessel occlusion paradigm, which helps providers understand the most meaningful population in need of diagnosis and reperfusion. For these reasons and many more, it is past time for the AMI paradigm to evolve.

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    Figure 2: The ACS spectrum using the OMI vs. NOMI paradigm.

    The Solution

    In response to these issues, we propose using the occlusion MI v. non-occlusion MI paradigm as a replacement for the STEMI v. NSTEMI paradigm. (Figure 2.) (Int J Cardiol. 2019;293:48; Dr. Smith's ECG Blog. April 1, 2018; https://bit.ly/OMIManifesto.) OMI is defined conceptually as acute coronary occlusion or near occlusion with insufficient collateral circulation, such that downstream myocardium will undergo imminent infarction without timely reperfusion.

    The OMI paradigm emphasizes the underlying pathology rather than an insufficient surrogate finding for that pathology (ST elevation). While paradigms based on a single specific ECG feature will inevitably become obsolete as we become better at recognizing OMI (as the Q wave v. non-Q wave paradigm is now), a paradigm based on the actual event of OMI itself cannot become obsolete as long as we believe that acute coronary occlusion benefits from reperfusion.

    Regardless of the future method of identifying acute coronary occlusion (whether it is expert or artificial intelligence-based ECG interpretation, ultrasound, noninvasive real-time coronary imaging, etc.), OMI will always be an appropriate name for the paradigm because OMI is the patient-centered event we are actually looking for when we consider reperfusion therapy.

    A New Era

    In the same way that a 30-year era (the reperfusion era) was required to progress from the Q wave paradigm to the STEMI paradigm, it will likely take another era to progress beyond STEMI. We propose calling this era the occlusion-reperfusion era during which we begin to understand AMI as an acute occlusion or non-occlusion syndrome rather than a millimeters-on-an-ECG syndrome.

    What should we do in the meantime while we are still stuck in the STEMI paradigm in daily practice? First, start using the terminology that allows our understanding to progress. Start using the terms acute coronary occlusion and occlusion MI. Second, consider learning more about ECG in OMI, especially about features other than ST elevation that help to diagnose OMI.

    Learn the full progression of ECG findings of occlusion and reperfusion that have been hidden from your education due to the STEMI paradigm. Follow up your patient's cath results to learn which were false-positives or missed occlusions. Most importantly, while waiting for the paradigm to evolve, maintain focus on our true goal for our patients with ACS: to identify and reperfuse patients with acute occlusion MI. (See box.)

    THE OMI Manifesto

    The full text of the OMI Manifesto and more than 1000 cases with detailed ECG interpretation alongside angiographic findings and patient outcomes are available at https://bit.ly/OMI-Manifesto.

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    Dr. Meyersis an emergency physician and faculty in the emergency medicine residency at Carolinas Medical Center in Charlotte, NC, and an editor of Dr. Smith's ECG Blog. Dr. Smithis an emergency physician and faculty in the emergency medicine residency at Hennepin County Medical Center in Minneapolis and a professor of emergency medicine at the University of Minnesota. He is the creator of Dr. Smith's ECG Blog.

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