View source for STEMI mimics

==Background==
*ST segment elevation is myocardial injury until proven otherwise
**1mm in two contiguous leads or Left Bundle Branch Block (LBBB) configuration meeting Sgarbossa criteria
*When STEMI is unlikely based on symptoms and demographics, consider other etiologies of ST elevation
**Serial EKGs helpful in observing evolution of STEMI pattern
***Only 72% of patients with STEMI receive diagnosis in first 1.5h <ref>Riley RF, Newby LK, Don CW, et al. Diagnostic time course, treatment, and in-hospital outcomes for STEMI patients presenting with non-diagnostic initial ECG: A report from the Aheadache mission: lifeline program. Am Heart J. 2013; 165(1):50–56.</ref>

==Mnemonic==
The mnemonic “ELEVATION”, can help you remember STEMI mimics
*'''E'''lectrolytes (Hyperkalemia)
*'''L'''eft Bundle Branch Block
*'''E'''arly Repolarization 
*'''V'''entricular Hypertrophy (Left)
*'''A'''neurysm (Ventricular)
*'''T'''hailand (Brugada Syndrome)
*'''I'''nflammation (Pericarditis)
*'''O'''sborne (J) Waves
*'''N'''on-Ischemic Vasospasm

==ELEVATION==
===[[Hyperkalemia|Electrolytes (Hyperkalemia)]]===
*T waves are peaked without any concave-down (tombstone) ST elevation
*T waves of hyperkalemia should be tall, symmetrical, pointed, and narrow
*Untreated hyperkalemia will progress to a [http://download.e-bookshelf.de/download/0000/7529/01/L-X-0000752901-0001831435.XHTML/images/c2f005.jpg sinuventricular] rhythm or a sine wave

===[[Left Bundle Branch Block]]===
*LBBB as well as any LBBB configuration (ex: RV pacing) can result in ST segment elevation, usually < 5mm
*Use [[Sgarbossa Criteria]] to determine if there is a concurrent infarct  
*In addition, may look for [http://www.learntheheart.com/cardiology-review/cabreras-sign/ Cabrera’s sign] or [http://www.learntheheart.com/cardiology-review/chapmans-sign/ Chapman’s sign] if infarct is suspected, though both are specific but poorly sensitive
*RBBB does not typically give ST elevation, therefore in cases of RBBB, the usual STEMI rules apply

===Early Repolarization===
*Normal variant often seen in young athletes
*Synonymous with J-point elevation (though not to be confused with a J-wave) i.e. elevation of the point where the QRS usually meets the isoelectric line
*Some studies suggest an increased risk of VF in these patients, though the lifetime risk remains unclear
*Elevation in this case should be concave and greatest in precordial leads

===[[Left ventricular hypertrophy (LVH)|Ventricular Hypertrophy (Left Ventricular Hypertrophy)]]===
*LVH typically with ‘strain’ pattern: in these cases, the ST elevation should only be in V1-3, be concave-up (i.e. not a tombstone morphology), be discordant with the deep S wave, and not be elevated >2mm

===[[Left ventricular aneurysm|Aneurysm (Ventricular Aneurysm)]]===
*After an MI, the walls of the ventricles can become aneurysmal and manifest on the surface 12 lead as persistent ST elevation in the territory of the old infarct
*Q waves (from the previous MI) should be present in the leads with persistent ST elevation  
*An echo is required for the final confirmation
*[[Takotsubo cardiomyopathy]] (broken heart syndrome) will present similarly.

===[[Brugada syndrome|Thailand (Brugada Syndrome)]]===
*Cause by a mutation in a cardiac sodium channel (mostly SCN5A), was first described in Thailand in 1992
*May be responsible for 4-5% of all sudden cardiac deaths
*3 described ECG types - Types 1 and 2 more commonly give ST elevation while type 3 has a “saddle back” appearance without ST elevation
*Brugada pattern can be pharmacologically induced (ex: antiarrhythmics such as sodium channel blockers), precipitated by illness or fever, or be intermittent (will commonly see an incomplete RBBB pattern)

===[[Pericarditis|Inflammation (Pericarditis)]]===
*Look for diffuse ST elevation
*PR depression is typically only seen in viral pericarditis, though the teaching is that this is a classic electrocardiographic sign of pericarditis  
*In acute pericarditis, there might be PR elevation and ST depression in aVR only, but this is poorly sensitive
*Consider the diagnosis of STEMI in favor of pericarditis when: there is ST depression anywhere (except for V1, aVR), ST elevation height in III>II, there is a convex/horizontal ST elevation morphology, or when there are new Q waves
*If predominantly inferior elevation, depression in aVL is very sensitive for STEMI<ref>Bischof JE, Worrall C, Thompson P, et al. ST depression in lead aVL differentiates inferior ST-elevation myocardial infarction from pericarditis. Am J Emerg Med. 2016; 34(2):149-154.</ref>

===[[Hypothermia|Osborn (J) wave]]===
*Hypothermia, usually <30 C is associated with the presence of Osborn J waves
*Positive deflections at the J point.  
*Bradycardia (including AV block) and atrial fibrillation are also common in moderate and severe hypothermia
*Hypothermic patients are at risk for VF

===[[Cocaine chest pain|Non-Ischemic Vasospasm]]===
*True ST elevation, in the sense that the ST elevation pattern is that of an injury current, but has a different mechanism and a different management
*Cocaine-induced ST elevation secondary to vasospasm should be treated with benzodiazepines and nitrates as needed 
*While it is possible to have a STEMI from a ruptured plaque and subsequent clot formation in a patient with cocaine toxicity, it is helpful to risk stratify patients with a suspected STEMI by age, risk-factors, etc
*It may be impossible to tell by surface ECG (and therefore without a left heart catheterization) if the ST elevation is due to cocaine toxicity or due to plaque rupture

==See Also==
*[[ST-Elevation Myocardial Infarction (STEMI)]]
*[[ST segment elevation]]
*[[STEMI equivalents]]

==References==
<references/>

[[Category:Cardiology]]