Acute coronary syndrome (main)
(Redirected from MI)
For risk stratification see ACS - Risk Stratification
Background
- Abbreviation: ACS
- Refers to a spectrum of conditions compatible with acute myocardial ischemia and/or infarction that are usually due to an abrupt reduction in coronary blood flow.
Clinical ACS Categories
- ST-segment elevation myocardial infarction (30%)
- Non-ST-elevation myocardial infarction (25%)
- Unstable Angina (UA) (38%)
- The new title, “Non-ST-Elevation Acute Coronary Syndromes,” emphasizes the continuum between UA and NSTEMI[1]
- NSTEMI myocardium is damaged enough to increase biomarkers, UA is not.
MI Types by Causation[2]
- Type 1: Spontaneous Myocardial Infarction
- Atherosclerotic plaque rupture or intraluminal thrombus in one or more of the coronary arteries
- Type 2: Myocardial Infarction Secondary to an Ischemic Imbalance
- Condition other than CAD contributes to an imbalance between myocardial oxygen supply and/or demand (e.g. coronary spasm, embolism, low or high blood pressures, anemia, or arrhythmias)
- Type 3: Cardiac Death Due to Myocardial Infarction
- Sudden cardiac death with symptoms suggestive of myocardial ischaemia without elevated biomarkers
- Type 4: Myocardial Infarction Associated With Revascularization Procedure
- 4a: Related to PCI
- 4b: Related to Stent Thrombosis
- Type 5: Myocardial Infarction Related to CABG Procedure
Clinical Features
Risk of ACS
Clinical factors that increase likelihood of ACS/AMI:[3][4]
- Chest pain radiating to both arms > R arm > L arm
- Chest pain associated with diaphoresis
- Chest pain associated with nausea/vomiting
- Chest pain with exertion
Clinical factors that decrease likelihood of ACS/AMI:[5]
- Pleuritic chest pain
- Positional chest pain
- Sharp, stabbing chest pain
- Chest pain reproducible with palpation
Gender differences in ACS
- Women with ACS:
- Less likely to be treated with guideline-directed medical therapies[6]
- Less likely to undergo cardiac catheterization[6]
- Less likely to receive timely reperfusion therapy[6]
- More likely to report fatigue, dyspnea, indigestion, nausea or vomiting, palpitations, or weakness,[6] although some studies have found fewer differences in presentation[7]
- More likely to delay presentation[6]
- Men with ACS:
- More likely to report central chest pain
Factors associated with delayed presentation[6]
- Female sex
- Older age
- Black or Hispanic race
- Low educational achievement
- Low socioeconomic status
Differential Diagnosis
Chest pain
Critical
- Acute coronary syndromes (ACS)
- Aortic dissection
- Cardiac tamponade
- Coronary artery dissection
- Esophageal perforation (Boerhhaave's syndrome)
- Pulmonary embolism
- Tension pneumothorax
Emergent
- Cholecystitis
- Cocaine-associated chest pain
- Mediastinitis
- Myocardial rupture
- Myocarditis
- Pancreatitis
- Pericarditis
- Pneumothorax
Nonemergent
- Aortic stenosis
- Arthritis
- Asthma exacerbation
- Biliary colic
- Costochondritis
- Esophageal spasm
- Gastroesophageal reflux disease
- Herpes zoster / Postherpetic Neuralgia
- Hypertrophic cardiomyopathy
- Hyperventilation
- Mitral valve prolapse
- Panic attack
- Peptic ulcer disease
- Pleuritis
- Pneumomediastinum
- Pneumonia
- Rib fracture
- Stable angina
- Thoracic outlet syndrome
- Valvular heart disease
- Muscle sprain
- Psychologic / Somatic Chest Pain
- Spinal Root Compression
- Tumor
Elevated Troponin
True Positive
False (Non-CAD) Positives
- Pericarditis
- Myocarditis
- PE
- CHF
- Sepsis
- Dissection
- Arrhythmias
- CVA
- SAH
- Burns
- Renal failure
- Assume true positive until proven otherwise
- ESRD
- 86% elevated predialysis in troponin-T
- 6% elevated predialysis in troponin-I
- no difference in post-MI troponin-I clearance rate in ESRD vs. normal GFR
- Cardioversion
- Cardiotoxic medications
- Amyloidosis
- Rheumatoid Factor
- Heterophilic antibodies
- Apical ballooning syndrome
- Cardiac procedures (surgery, ablation, pacing, stenting)
- Extreme exertion
Evaluation
Workup
- ECG (Diagnosis)
- ECG is normal in 8% of all confirmed MI's
- In LBBB see Sgarbossa's Criteria
- Cardiac Enzymes
Evaluation
- HEART Pathway: https://www.mdcalc.com/heart-pathway-early-discharge-acute-chest-pain
- ACS - Risk Stratification
ACS Anatomical Correlation Chart
Ischemic Changes | Location | Coronary Artery |
STE V1-V3, TWI Q waves in V1-V3 over time |
Septal | Septal branch |
STE V2-V4 | Anterior | LAD |
STE I, aVL, V5, V6 STD inf leads |
Lateral | Circumflex |
STE I, aVL, V2-6 | Anterolateral | LAD + circumflex = Left main or 2 critical lesions |
STE II, III, aVF STD in aVL (most common lead to see reciprocal change) |
Inferior | RCA |
STE V1 (only lead looking at RV)
|
Right ventricle | RCA |
STD in V1, V2, V3; |
Posterior aka Inferolateral | RCA (90%), LCA (10%) |
STE avR>V1 Doesn't apply in SVT |
Anterolateral | Left Main |
Management
Intensity of treatment should be based on ACS likelihood
- ST-Elevation Myocardial Infarction (STEMI)
- Non ST-Elevation Myocardial Infarction (NSTEMI)
- Unstable Angina
Disposition
- Admit
- Ischemic ECG changes
- Pacemakers
- LBBB
- Positive troponins
- Abnormal vital signs
- ACC/AHA rec need for provocative testing withing 72 hrs, consider admitting
- For low risk (HEART) pts, may be better off discharge home with follow up[8]
- Risk of MACE after neg ED work up 1/2422 vs Risk of preventable adverse event in hospital is 1/164
Prognosis
External Links
- MDCalc - HEART Pathway
- MDCalc - Framingham Coronary Heart Disease Risk Score
- MDCalc - Sgarbossa’s Criteria for MI in Left Bundle Branch Block
- MDCalc - TIMI Risk Score for UA/NSTEMI
- Heart Association
See Also
- ACS - Risk Stratification
- ACS - Anatomical Correlation
- ACS - Stress Testing
- ST-segment elevation myocardial infarction
- Non-ST-elevation myocardial infarction
- Unstable angina
- STEMI equivalents
- Myocardial infarction complications
References
- ↑ AHA ACA - NSTEMI ACS Guidelines 2014 View Online
- ↑ Third Universal Definition of Myocardial Infarction http://circ.ahajournals.org/content/126/16/2020.full.pdf
- ↑ Body R, Carley S, Wibberley C, et al. The value of symptoms and signs in the emergent diagnosis of acute coronary syndromes. Resuscitation. 2010;81(3):281–286. PMID: 20036454
- ↑ Panju AA, Hemmelgarn BR, Guyatt GH, et al. The rational clinical examination. Is this patient having a myocardial infarction? JAMA. 1998;280(14):1256–1263. PMID: 9786377
- ↑ Swap CJ, Nagurney JT. Value and limitations of chest pain history in the evaluation of patients with suspected acute coronary syndromes. JAMA. 2005;294(20):2623–2629. PMID: 16304077
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 Mehta LS, et al. Acute myocardial infarction in women: A scientific statement from the American Heart Association. Circulation. 2016; 133:916-947.
- ↑ Gimenez MR, et al. Sex-specific chest pain characteristics in the early diagnosis of acute myocardial infarction. JAMA Intern Med. 2014; 174(2):241-249.
- ↑ Weinstock MB, Weingart S, Orth F, VanFossen D, Kaide C, Anderson J, Newman DH. Risk for Clinically Relevant Adverse Cardiac Events in Patients With Chest Pain at Hospital Admission. JAMA Intern Med. 2015 Jul;175(7):1207-12.