STEMI / NSTEMI

Question 2

List the ECG changes in posterior MI and the likely site of occlusion.

Answer 2

1. Horizontal ST depression in V1-V3
2. Tall, broad R waves V1-3
3. Upright T-waves
4. Dominant R wave in V2 (R:S >1)
5. STE >0.5mm in V7-9
6. Q-wave formation in V7-9

Posterior MI can be caused by either:

• Occlusion of the (L)Cx, or
• RCA/PDA

Question 3

Which artery supplies the AV + SA nodes?

Answer 3

The RCA supplies:

• The SA node (60% of the time), and
• The AV node

Question 4

List the site of occlusion in the following STEs:

• V1-2
• V3-4
• V5-6
• II, II and aVF
• STD in V2 - V3

Answer 4

• LAD
• LAD/Diagonal branch (D1)
• LCx/D1
• RCA/PDA
• Sub-endocardial ischaemia OR Wellens OR reciprocal change from posterior MI (Is there peaked T-waves (Wellens) or R/S ratio > 1 in V2 (Post MI)?

Question 5

List the ECG findings seen in atrial infarction.

Answer 5

PT wave elevation w/ reciprocal PT depression.

Question 6

List differential for PT depression or elevation.

Answer 6

1. Pericarditis - PR depression (with reciprocal PR elevation in aVR and I) -> look for widespread STE with no reciprocal STE (other than STD in aVR +I)
2. Atrial ischaemia - PR elevation w/ PR depression in reciprocal leads

Question 7

What are the non-STE criteria for early re-perfusion?

Answer 7

• New LBBB or as per Sgarbossa
• New RBBB with LAFB
• Inferior wall MI - any STE in two contiguous inferior leads with any STD in aVL
• RV infarction
• Posterior MI
• High lateral MI - STE in aVL w/ STD in III
• De Winters T-waves
• Ongoing pain w/ NSTEMI
• Wellens
• Hyper-acute T waves

Question 8

List the 4 criteria to define Q-waves as pathological.

Answer 8

1. >40mm wide, or
2. >2mm deep, or
3. >25% QRS height, or
4. Any in V1-3

Question 9

List the 4 differentials for pathological q-waves.

Answer 9

1. Old MI
2. Evolving MI
3. Cardiomyopathies - HOCM (NB in HOCM - Q-waves usually lateral or inf’r and <40ms -> “dagger-like”
4. Rotation of the heart - extreme clockwise or counterclockwise rotation
5. Lead placement errors

Question 10

What are the ECG findings in acute Q-wave MI?

Answer 10

• Pathologic q-waves +/- STE in leads corresponding to the territory of infarct.
• Upright T-waves

Question 11

What are the ECG findings in old/recent Q-wave MI?

Answer 11

• Pathologic Q-waves with normal ST in territory corresponding to MI.
• Inverted T-waves in region corresponding to the infarcted territory.

Question 12

What is the prevalence of isolated, posterior MI (ie the % of all STEMIs)?

Answer 12

3-11%

Question 13

What are the ECG indications of isolated posterior MI?

Answer 13

• ST depression in V1-3
• Lack of STE elsewhere on the normal ECG
• R:S > 1 in V1 -> these are effectively reciprocal Q-waves
• Peaked and/or upright Twaves in V2-3

Question 14

What are the ECG findings of LMCA occlusion?

Answer 14

• Widespread ST depression
• STE in aVR

Question 15

List 5 causes of ST depression in the (R) precordial leads. How can each be differentiated?

Answer 15

• Posterior infarct / reciprocal change - also look for:
  
  • look for R:S >1 (reciprocal q-waves)
  • upright T-waves
  • No other STE (in isolated posterior MI)
  • STE in V7-9
• Myocardial ischaemia
  
  • Contiguous leads V1-3
  • Absence of post’r infarct signs
  • May be widespread STD (and STE in aVR) in LMCA occlusion
• deWinters T-waves
  
  • ​Upsloping precordial STD
  • Accompanied by tall, peaked, upright T-waves
• Hypokalaemia
  
  • ​Not confined to precordium - widespread
  • Presence of U-waves -> long T-U interval
• RVH - RV strain pattern -> ST dep + TWI in V1-4 (+/- inf’r leads)
  
  • ​Accompanied by RAD >+150 deg
  • R:S > 1 in V1 - opposite of normal
  • R:S < 1 in V6 - opposite of normal​
• ​RBBB
  
  • ​RBBB pattern: QR > 120ms + RsR’ + slurred rS in lateral leads
  • STD and TWI common in V1-3
• SVT
  
  • ​Widespread STD -> rate related - not indciative of ischaemia
• Digoxin effect
  
  • ​Sagging ST segments (“Dali’s mo”)

Question 16

List the criteria for LBBB.

Answer 16

• QRS >=120ms
• Predominantly -ve QRS in V1
• Predominantly +ve QRS in v6
• Intrinsicoid deflection >=50ms in V6
• Small r-wave (ie lack of q-waves in V1-V3

Question 17

List the modified Sgarbossa Criteria.

Answer 17

• >=1mm concordant STE in any lead
• >=1mm concordant STD in V1-V3
• >=1mm discordant STE that is proportionally excesive (>25% preceding Swave) in any lead

Question 18

List ten causes of STE on the ECG.

Answer 18

Categorise the cuases!

1. Ischaemic/infarct:
   
   1. STEMI
   2. Coronary artery vasospasm (Prinzmetal’s angina)
   3. Reciprocal STD in myocardial ischaemia (eg STE in aVR duirng (L)MCA occlusion)
2. Other cardiac
   
   1. Inflammatory -> Pericarditis
   2. Benign -> Benign Early Repolarisation
   3. Conduction -> LBBB
   4. Conduction -> Paced rhythyms
   5. Sturctural -> LVH
   6. Structural -> Ventricular aneurysm
   7. Structural -> Aortic dissection
   8. Channelopathies -> Brugada syndrome
   9. Stunning -> Post DC reversion
3. Non-cardiac
   
   1. Rasied ICP - eg SAH, other ICH
   2. PE
   3. HyperK
   4. Na channel blockers
   5. J-waves of hypothermia or hyperCa

Question 19

What ECG changes may be seen in patients w/ raised ICP?

Answer 19

1. Widespread STE or STD
2. Widespread deeply inverted T-waves -> cerebral T-waves