BOOK

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BOOKamazon.com
38 chapters 375 pages 200 cases 300 12-lead ECGs
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60 yo male with chest pain
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Missed MIBig lawsuit
60 yo with stuttering CP, pain free at 2100
With 6-8/10 pain at 2140, read as no ST
elevation
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Missed MI, big lawsuit
60 yo with CP, pain free in ED. LBBB
With chest pain in CCU, read as LBBB
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Recognizing STE of STEMIThe Reperfusion Decision

• Few similarly important skills necessary for
  emergency physicians
• Airway, Cardiac Arrest, Golden Hour of Trauma
• ST elevation alone has very POOR SPECIFICITY
• 90 of men 17-24 have 1 mm ST Elevation in 2
  leads
• Only 15 of CP and ST Elevation have MI (Brady
  1998)
• Computer is NOT SENSITIVE for STEMI
• 79 compared to cardiologists (Kudenchuck 1991)
• 62 compared to cardiologists (Massel 2000)
• In our ED (gross estimates) 3000 patients per
  year with ischemic sxs
• 80 with coronary occlusion
• 40 are obvious
• We need to find the other 40 STEMI out of about
  3000 with symptoms, most with ST elevation

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STEMI vs. NSTEMI1mmSTE2cLeads 1mm STE in 2
consecutive leads

• STEMI
• The term is meant to identify patients with
  complete, persistent coronary occlusion without
  collateral flow
• Needs emergent reperfusion therapy
• Defined as MI associated with 1mm STE2consLeads
• However Many CP patients with subsequent
  positive troponin (MI) have, at baseline, 1mm
  STE2consLeads
• NSTEMI
• The term is meant to identify patients with
  positive troponin, but with intact flow to the
  affected coronary distribution
• Defined as CP patients without 1mm STE2consLeads
  who have positive troponin
• However 1mm STE2consLeads not always present
  with complete, persistent coronary occlusion
  without collateral flow

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ST Elevation45 sensitive for MI by
CK-MBSensitivity for coronary occlusion much
better
LAD Occlusion 35 lt 2mm 43-60 upward
concavity Smith SW JEM 3169, 2006

• 1 mm 2 cons limb leads
• 85 sensitive for RCA occlusion
• 1 mm limb, 2 mm V1-V6
• 85 LAD, 46 Circumflex
• 1 mm limb, 1 mm V1-V6
• 96 LAD, 61 Circumflex
• Schmitt C et al. Chest 120(5)1540, Nov 2001
• Most accurate subjective impression
• Massel D, Am Ht J 140221
• Next best (56 sens, 93 spec)
• 1 mm limb, 2 mm V1-V3, 1 mm V4-V6
• ESC/ACC Committee, JACC 36959, 2000

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Proportionality

• Normally
• T-wave is proportional to the QRS
• ST elevation is proportional to the QRS
• ST depression is proportional to the QRS
• Large QRS amplitude may, under normal conditions,
  result in remarkable
• ST elevation, ST depression, or T-wave amplitude
  that is not pathological
• Conversely, these ST-T findings in the absence of
  a large R-wave or QRS are worrisome

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Concordance/Discordance

• Various abnormal depolarizations (abnormal QRS)
  produce abnormal repolarization, leading to
  discordant ST elevation, depression, or T-waves
• LBBB ST elevation in V1-V3, but discordant to
  negative QRS
• LVH ST elevation in V1-V3, discordant to
  negative QRS
• RVH T-wave inversion in anterior precordial
  leads
• RBBB ST depression V1-V3, discordant to positive
  QRS

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Proportion-ality LBBB
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The T-wave

• At least as important as the ST segment
• Maybe more important?
• Does it tower over the R-wave?
• Is it bulky? (straightening of the ST segment)
• Is it proportional to the QRS, or especially to
  the R-wave?
• Is there any T-wave inversion in the leads with
  ST Elevation marker that there has already been
  reperfusion?
• Early Repol vs. STEMI, V2-V4
• Mean R-wave (V2-V4) 5 mm favors early repol
• Any lead (V2-V4) with TARA ratio 2.0 favors
  aAMI
• Smith SW. Acad Emerg Med 2005 12132, 2005
• Validation study done, publication pending

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Consider (in High Suspicion patients)

• Comparing with a previous ECG
• Obtaining serial ECGs at 15 minute intervals
• Use additional diagnostic tools
  (echocardiography, angiography, biomarkers)

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Prehospital ECGs

• Take 2-5 minutes to perform
• Increase diagnostic accuracy
• Improve time to treatment
• With lytics or PCI (from 10-40 minutes)
• Also improve diagnosis
• Prehospital Cath Lab Activation
• HCMC Activate cath lab based on computer reading
  of Acute MI and presence of Chest Pain,
  without transmission and without physician
  approval
• 40 STEMI before 86 minute mean time
• 55 STEMI after 56 minute mean time
• 100 lt 90 min
• 56 lt 60 min
• 29 lt 45 min
• 4 false positives

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Typical CP, resolvingED ECG
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Compare with prehospital
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62 yo M c/o burning epigastrium to throat. O/w
healthy. Relieved by Maalox/lidocaine
Normal V4-V6
T
QRS
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Normal or nonspecific can be diagnostic
32 yo cocaine user presented 3 times with severe
SSCP radiating to left arm, assoc with exertion,
4 x in 3 days, now resolved after 3 NTG. Trop 2
hours after onset 0.1 ng/ml
ECG Jan. 11 15 min after pain resolution
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2nd ED visit, 1/19, trop (-)
1/11, a t 45 min (initial)
2nd, 7 hours later 1/11
3rd ED visit for CP, February 11, 8 PM, now pain
free
Max trop 12 hours after onset 0.2 ng/ml (nl up
to 0.3 at the time)
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pseudonormalization
2/12, 300 AM, with pain
307, after NTG, no pain
ED, February 11, 8PM
99 ostial LAD lesion requiring CABG