NSTEMI

Why Do We Care? 

In-hospital mortality rates are about the same for STEMI and NSTEMI, approximately 10%. However, 1-year fatality rate in NSTEMI is more than double that of STEMI, at about 25% 5. (See comment section)


ECG

Some important patterns to keep in mind. These are best reviewed in the EM Practice issue1.

  • ST depression >0.5mm in 2 contiguous leads is a common finding in NSTEMI
  • ST depression > 1 mm in V1-V3 may represent posterior MI, especially with reciprocal ST-elevation in aVR. Consider posterior lead placement.
  • ST elevation should prompt consideration of STEMI
  • Wellens Syndrome – deep symmetric T wave inversion or biphasic T waves in the precordial leads (V1-V6), associated with proximal LAD occlusion. Impending MI, not NSTEMI
  • Sgarbossa Criteria for the diagnosis of MI in the setting of known LBBB.
  • de Winter Pattern: 2% of LAD occlusions had ST depression at the J point with tall peaked T waves.
  • Left Main Pattern:
    • ST elevation > 1mm in aVR and
    • ST elevation in V1 of lower amplitude and
    • ST depressions diffusely

Risk Factors

Risk factors to keep in mind, in addition to typical HEART score criteria:

  • HEART score:
    • HTN
    • Hypercholesterolemia
    • Diabetes mellitus
    • Obesity (BMI >30 kg/m²)
    • Smoking (current, or smoking cessation ≤3 mo)
    • Family history (parent or sibling with CVD before age 65)
    • Atherosclerotic disease: prior MI, PCI/CABG, CVA/TIA, or peripheral arterial disease
  • Illicit substance abuse
  • Age (CAD prevalence in age<40 is 1%, age >80 is 25%)
  • HIV 2,3
  • Cancer with history of radiation to the chest 4

Special Populations

Women:

  • Men are twice as likely to have ACS. 
  • Woman who have ACS have higher short term mortality. 
  • AHA/ACC guidelines DO NOT recommend differences in management of NSTEMI based on gender. 
  • AHA/ACC guidelines DO note that revascularization is not beneficial in low-risk troponin -negative patients, particularly women. 

Black Patients:

  • Higher incidence of MI compared to white patients. 
  • Same male predominance. 
  • Black men 35-44 age, suffer 2.4 MI’s/1000 vs 0.8 for white men.
  • Black men 75-84 age, suffer 15.9 MI’s/1000 vs 9.1 for white men.
  • Risk for black women is lower than black men, but still higher than all gender white patients. 
  • Interestingly, mortality is higher following MI for blacks than whites. Black patients are less likely to undergo invasive management in NSTEMI, but this difference goes away when we look at STEMI. This suggests that “unambiguous standards of care and protocolized management” may help mitigate the issue of racial bias.

Young Patients: One study found 10% of MIs occur in patients <45 old.  Risk factor reduction is a big focus, with up to 90% being smokers. Other risks include family history of high cholesterol, obesity, and cocaine use.  But, long term they have lower risk of MACE and heart failure. 

Diabetics have higher incidence of MACE and mortality due to atypical presentations and delay in diagnosis. This is worse for insulin dependent patients.

Cocaine using patients with NSTEMI are treated as any other NSTEMI with one exception. Benzodiazepines become first line treatment. 


Further Reading

Emergency Department Management of Non–ST-Segment Elevation Myocardial Infarction Date Release: Jan 2020 When patients present to the ED with suspected myocardial infarction, it is critical to differentiate NSTEMI from other cardiac causes and initiate swift, evidence-based management. Review the latest evidence on diagnosis and treatment of NSTEMI.


References

  1. Jung J, Bord S. Emergency department management of non-ST-segment elevation myocardial infarction. Emerg Med Pract. 2020;22(1):1-24. Issue , PubMed
  2. Grunfeld C, Delaney JA, Wanke C, et al. Preclinical atherosclerosis due to HIV infection: carotid intima-medial thickness measurements from the FRAM study. AIDS (London, England). 2009;23(14):1841–9. PubMed
  3. Holloway CJ, Ntusi N, Suttie J, et al. Comprehensive cardiac magnetic resonance imaging and spectroscopy reveal a high burden of myocardial disease in HIV patients. Circulation. 2013;128(8):814–22. PubMed
  4. Borges N. Radiation-Induced CAD: Incidence, Diagnosis, and Management Outcomes. American College of Cardiology; 2018, May Article
  5. McManus DD, Gore J, Yarzebski J, et al. Recent trends in the incidence, treatment, and outcomes of patients with STEMI and NSTEMI. Am J Med. 2011;124(1):40-47. PubMED

3 thoughts on “NSTEMI

  1. I received a note asking about the mortality rate for NSTEMI quoted above and in the EB Medicine article. I thought the subsequent conversation might be helpful to others:

    The citation above (#5) is a 2011 study examining medical records of over 5000 patients with STEMI and NSTEMI in Worchester, MA. They examined case fattily rates in hospital, at 30 days, and 1 year for both sets of patients. They found an improvement in STEMI mortality but inconsistent improvement in NSTEMI mortality from 1997-2005. Also, they included ” all-case death rates” as the 1 year outcome measure.

    A more recent study appeared in JAMA Cardiology in 2016 by Hess et al, titled “Sudden Cardiac Death After Non–ST-Segment Elevation Acute Coronary Syndrome”. It examined the combined databases of 4 drug trials across multiple countries, totaling over 40,000 patients with NSTEMI. They used a different standard, sudden cardiac death (SCD) instead of all-cause death, and found that “At 6, 18, and 30 months, the cumulative incidence estimates of SCD were 0.79%, 1.65%, and 2.37%, respectively”.

    Given the improvement year after year form 1997-2005 noted in the older McManus study, the differences in study populations, and the more focused definition of death used in the Hess study, it is accurate to say that sudden cardiac death in NSTEMI patients appears to occur in 2.3% of NSTEMI patients by 30 months. This may be a more helpful statistic when speaking with patients than the number in the McManus study. The study differences in population and definition make further comparison difficult without access to the original trial data.

    Thanks again to a friend and reader, Dr. Mike Weinstock, for the engaging conversation and passing along the Hess study.

    Sam

    Reference: Hess PL, Wojdyla DM, Al-Khatib SM, et al. Sudden Cardiac Death After Non–ST-Segment Elevation Acute Coronary Syndrome. JAMA Cardiol. 2016;1(1):73–79. doi:10.1001/jamacardio.2015.0359

  2. A problem with NSTEMIs is that many are actually acute coronary occlusions (“STEMIs”) that have simply gone unrecognized: no serial ECGs, one normal troponin, no right-sided or posterior leads or the failure to understand that in some cases ST depression indicates an acute occlusion (ST depression in V1 – V3 indicating an RCA or LCx occlusion, deWinter’s T waves indicating a proximal LAD occlusion). It has been estimated that about 90% of the voltage occurring during one myocardial depolarization is not inscribed on the 12-lead ECG due to cancellation of forces which can make recognition of an acute epicardial ischemia very difficult.

    Thanks for a very good article and great comments.

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