Contact Us

Occlusion MI Paradigm

STEMI Paradigm: A Problem 🏴‍☠️

  • Clinicians are taught:
    • STEMI = 100%, complete coronary occlusion
    • NSTEMI = incomplete coronary occlusion

  • The Reality: ~25-30% of NSTEMIs are found to have complete coronary occlusion, & ~15-33% of STEMIs are false positives

  • The Consequence: ~25-30% of NSTEMIs who should go immediately for PCI have highly delayed care

  • Note: guidelines suggest a few highly specific situations where NSTEMI patients should go for immediate PCI: hemodynamic instability, cardiogenic shock, & refractory angina. Guidelines suggest high risk patients (eg GRACE score > 140) should also undergo an "early invasive strategy" within 24 hours (based on TIMACS trial, which showed high-risk patients were a subgroup that had ↓ death, MI, & refractory ischemia with "early invasive strategy" vs. "delayed strategy" occurring >36hr)

  • Note 2: despite the guidelines for high-risk NSTEMIs above, adherence to these guidelines is extremely poor. One study of 1,793 NSTEMI patients found only 6.4% of very high-risk NSTEMIs underwent immediate PCI (<2 hours), & only 32.1% underwent early PCI (<24 hours). Additionally, of the high-risk NSTEMIs, only 43.9% underwent early PCI (<24 hours)

Why Care? 🏴‍☠️

  • Remind yourself why STEMIs should go immediately to the cath lab: here is a figure showing 30-day mortality vs. time to PCI in a landmark study.

image

  • With that in mind, you can imagine how the ~25-30% of NSTEMIs with complete occlusion can suffer. This risk isn't theoretical, though! This has been studied! A meta-analysis of 40,777 NSTEMIs showed that 25.5% of cases had complete occlusion, & these patients had ↑ short-term mortality (RR 1.67) & ↑ major adverse cardiac events (RR 1.41)

A New Hope: The Occlusive MI Paradigm 🏴‍☠️

  • A group of physicians developed & published a new approach coined the "OMI Paradigm," which essentially brings back the art of intense ECG scrutiny–particularly, of the entire QRST segment–to identify patients with complete occlusive MIs ("OMIs") who should undergo immediate PCI

  • The OMI Paradigm emphasizes that in addition to ECG findings that meet current STEMI criteria, a host of other patterns, including subtle findings, should be learned by clinicians as highly specific for OMIs. These have in fact been studied w/ high specifities noted below & w/ JACC recognition of these patterns in the 2022 Acute Chest Pain Decision Pathway (in the form of "STEMI equivalents")

image

  • STEMI Paradigm vs. OMI Paradigm, Head-to-Head: in patients with confirmed OMIs, the median time to PCI was 41 minutes for STEMI ⊕ cases vs. 437 minutes for OMI ⊕ STEMI ⊖ cases

OMIs 🏴‍☠️

  • There is a decent number of OMI patterns I won't include in this page, but that are available here in the page referenced at bottom of this note. The best way to learn the OMI patterns is to save this pocket guide & reference it often. Additionally, it is worth reviewing & memorizing the expected changes seen in OMI, which explains the morphology of 2 major OMIs (hyperacute T-waves, Wellens' pattern)

image

Getting Your Patient to Cath Lab 🏴‍☠️

  • Your OMI ⊕ STEMI ⊖ patients may be brushed off by cardiologists who aren’t aware of the paradigm shift. The following are counterpoints/rebuttals:

1. Your patient is unstable: Don't forget guidelines recommend NSTEMI patients w/ hemodynamic instability, cardiogenic shock, & refractory angina should undergo immediate PCI.

2. The initial troponin is ⊖: DO NOT RELY ON THE INITIAL TROPONIN! It takes several hours for the troponin to rise. While troponins are being serially collected, instead focus on highly frequent q15 minute serial ECGs to prove developing ischemia. Waiting for a ⊕ troponin in a patient with an ECG diagnostic of OMI is essentially a “hospital-supervised infarction.”

OMI ⊕ Angiography ⊖ 🏴‍☠️

  • What if you get the patient to the cath. lab & angiography is ⊖ for 100% occlusion? Think MINOCA (MI with non-obstructive coronary arteries)! There is a ~5-15% incidence of MINOCA in patients initially diagnosed as having a (N)STEMI, which is most commonly (~2/3) due to spontaneous lysis of thrombus, but can also be due to non-atherosclerotic causes (e.g. vasospasm, embolism, microvascular dysfunction)

References 📚

☠️OMIs