II. Epidemiology
- Prevalence: 5% of general population
- Most common in healthy young patients under age 50 years old
III. Risk Factors
- Young men
- African american
- Athletes
- Bradycardia
IV. Signs
- Characteristics
- ST Segment Elevation with a concave upwards appearance (Smiley appearance) in V2-V5
- ST Elevation < 2 mm in precordial leads (may be up to 5 mm in atypical cases)
- May be accompanied by concave upward inferior lead ST Elevation
- ST Elevation <0.5 mm in limb leads
- Inferior ST Elevation should not be isolated (precordial leads should also be involved)
- ST Elevation should be greater in lead II than lead III
- Contrast with acute coronary events
- Convex upwards appearance (Tombstone, Frown appearance) of an acute coronary event
- No reciprocal ST depression (V1 and aVR are the exceptions)
- ST Segment Elevation with a concave upwards appearance (Smiley appearance) in V2-V5
- Distribution
- Widespread across precordial leads (especially V2 to V5) with or without inferior lead involvement
- Asociated findings
- J Wave (deep J Waves are associated with worse prognosis)
- Notch or slurring at the end of the QRS Complex
- T Waves
- Prominent T Waves that are concordant with the QRS
- ST Segment Elevation is <25% the height of the T Wave (leads V4-6, lead I)
- J Wave (deep J Waves are associated with worse prognosis)
V. Precautions: Red Flags NOT consistent with Early Repolarization
- Convex upwards ST Elevation (Tombstone)
- ST Elevation Myocardial Infarction until proven otherwise
- Reciprocal ST depression
- Reciprocal ST depression (aside from aVR or V1) is a ST Elevation Myocardial Infarction until proven otherwise
-
ST Elevation in the Inferior Leads
- Suspect STEMI if ST Elevation is greater in lead III than lead II
- Suspect STEMI if isolated inferior lead ST Elevation (but no ST Elevation in the precordial leads)
-
ST Elevation >5 mm
- Early Repolarization is usually <5 mm
VI. Interpretation: Studies with mixed results on prognosis
- Early Repolarization has been long considered a benign finding until 2008
- Brugada Syndrome and Early Repolarization Syndrome are both J Wave Syndromes
- Studies in 2008 suggested possible connection between Early Repolarization and sudden Cardiac Arrest
- If risk is increased it appears to manifest in the longterm (5-30 years of follow-up)
- Haissaguerre (2008) N Engl J Med 358(19): 2016-23 [PubMed]
- Large study in 2011 showed no increased risk of Sudden Cardiac Death
- However, study sample was skewed to older, white patients
- More typical cohort of concern would be younger african american patients described above under risk factors
- Uberoi (2011) Circulation 124(20): 2208-14 [PubMed]
VII. Prognosis
- If Early Repolarization increases Sudden Cardiac Death, the risk is a longterm risk (over as much as 30 years)
- Manage emergency department patients based on their presenting symptoms (e.g. Syncope)
- Asymptomatic Early Repolarization incidently found on EKG can be addressed on a routine basis
- Aggressive measures (e.g. AICD) are not indicated in asymptomatic patients
- Early Repolarization associated risk of idiopathic Ventricular Fibrillation or early cardiac death
- Associated with 4-10 fold increased risk of Sudden Cardiac Death (10 year risk)
- Incidence overall: 3.4 per 100,000
- Incidence if J Wave present (esp. >2mm in inferior leads): 11 per 100,000
- Benito (2010) J Am Coll Cardiol 56(15): 1177-86 [PubMed]
VIII. Resources
- Early Repolarization vs STEMI (Amal Mattu, UMEM)
IX. References
- Krishnan (2018) Cardiac Arrhythmias Conference, UMN, Minneapolis
- Mattu and Herbert in Herbert (2012) EM:RAP 12(3): 4
- Grauer (2001) 12 Lead EKGs, 2nd ed, KG/EKG Press, Gainesville, Florida