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)
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 to keep in mind, in addition to typical HEART score criteria:
- HEART score:
- 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
- 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.
- 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.
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.
- Jung J, Bord S. Emergency department management of non-ST-segment elevation myocardial infarction. Emerg Med Pract. 2020;22(1):1-24. Issue , PubMed
- 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
- 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
- Borges N. Radiation-Induced CAD: Incidence, Diagnosis, and Management Outcomes. American College of Cardiology; 2018, May Article
- 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