CUH ACS guidleine 2018

• Non-ischaemic ST elevation is seen in 15% population, especially young men
• abnormal ST elevation:
  • Leads V2,3 >0.2mV in men >40y and >0.25mV in men <40y (>0.1mV in all other leads)
  • Leads V2,3 >0.15mV in women (>0.1mV in all other leads)
  • usually convex or straight

Croydon ACS protocol

• ST elevation reflects transmural ischaemia
• criteria for STEMI in patients with LBBB = modified Sgarbossa criteria (≥3 points 90% specificity for STEMI)
  • 5 points: ≥1 lead with ST elevation ≥1mm, concordant with the vector of the QRS complex
  • 3 points: ≥1 lead of V1-V3 concordant ST depression ≥1 mm
  • 2 points: ≥1 lead with discordant ST elevation ≥25% of depth of preceding S wave (Leads V1-3)

Modified Sgargossa Criteria for MI in LBBB: ≥3 points

• patients determined to have symptoms consistent with ACS and troponin elevation but without ECG changes consistent with STEMI
• may have transient ST elevation, ST depression, or new T wave inversion
• differs from Unstable angina in that cardiac markers are elevated
• *de Winter T waves are associated with LAD occlusion and sometimes considered STEMI equivalent

https://www.icrjournal.com/articles/what-interventionalist-needs-know-about-mi-non-obstructive-coronary-arteries

• not a benign diagnosis: outcomes similar to those of patients with acute MI and obstructive coronary disease up to 1 year

• SCAD may be a cause of up to 1% to 4% of ACS cases overall
• occurs overwhelmingly in women and may be the cause of ACS in up to 35% of MIs in women ≤50 years of age
• most common cause of pregnancy-associated MI (43%)

Circulation 2018 - SCAD review

usually concave pattern

• associated with LVH
• secondary to conduction defect eg LBBB, non-specific intracardiac conduction delay, WPW
• Early repolarization pattern
• Spontaneously reperfused STEMI
• Aneurysm/old myocardial infarction
• Pericarditis/myocarditis
• Brugada pattern
• Takotsuboclose A sudden, transient cardiac syndrome that involves dramatic LV apical akinesis and mimics acute coronary syndrome (ACS)
  Requires all 4 of the following:
  ♦ Transient hypokinesis, dyskinesis, or akinesis of the LV midsegments, +/- apical involvement; the regional wall-motion abnormalities extend beyond a single epicardial vascular distribution, and a stressful trigger is often, but not always, present
  ♦ Absence of obstructive CAD or angiographic evidence of acute plaque rupture
  ♦ New ECG abnormalities (either ST-segment elevation and/or T-wave inversion) or modest elevation in troponin
  ♦ Absence of phaeochromocytoma or myocarditis (apical ballooning) syndrome, AKA 'broken heart syndrome'
• Hyperkalaemia, Hypercalcaemia

• especially young, athletic afro-Caribbean males and Hispanics
  • often disappears with hyperventilation & tachycardia
• usually early V leads

The different infarct patterns are named according to the leads with maximal ST elevation:

• Septal = V1-2
• Anterior = V2-5
• Anteroseptal = V1-4

localisation	ST elevation	Reciprocal ST depression	coronary artery
Anterior MI	V1-V6 but especially V2-5 +/- high lateral leads I & aVL	None	LAD
Lateral MI	I, aVL, V5, V6 • uncommonly isolated • usually as anterolateral	II,III, aVF	LCX or obt marginal
Anterolateral MI	V3-V6, I + aVL extensive includes V1,2
Septal MI	V1-V2, loss of septum Q in leads V5,V6	none	LAD-septal branches
Anteroseptal MI	V1-V4
Inferior MI	II, III, aVF	I, aVL	RCA (80%) or RCX (20%)
Posterior MI	V7, V8, V9	high R & ST depression V1-V3 > 2mm (mirror view)	RCX
Right Ventricle MI	V1, V4R	I, aVL	RCA
Atrial MI	PTa in I,V5,V6	PTa in I,II, or III	RCA

• Major criteria
  • PR elevation >0.5 mm in V5 & V6 with reciprocal PR depression in V1 & V2
  • PR elevation >0.5 mm in lead I with reciprocal PR depression in leads II & III
  • PR depression >1.5 mm in the precordial leads
  • PR depression >1.2 mm in leads I, II, & III
• Minor criteria:
  • Abnormal P wave morphology: eg M-shaped, W-shaped, irregular or notched

1. ST depression (not elevation) in the septal & anterior precordial leads (V1-V4)*. This occurs because these ECG leads will see the MI backwards; the leads are placed anteriorly, but the myocardial injury is posterior.
2. A R/S wave ratio greater than 1 in leads V1 or V2.
3. ST elevation in the posterior leads of a posterior ECG (leads V7-V9). Suspicion for a posterior MI must remain high, especially if inferior ST segment elevation is also present.
4. ST elevation in the inferior leads (II, III and aVF) if an inferior MI is also present.

• a scoring system used to determine intervention strategies - PCI vs CABG

• The SYNTAX score is the sum of the points assigned to each individual lesion identified in the coronary tree with >50% diameter narrowing in vessels >1.5mm diameter.
• The coronary tree is divided into 16 segments according to AHA classification, with scores of 1 or 2 attributed to each relevant lesion and then weighted for calculation.
• Higher scores represent greater risk for PCI and therefore more indicative of need for CABG

https://www.cathlabdigest.com/articles/What-SYNTAX-Score-and-How-Should-We-Use-It

St elevation - ischaemia vs non-ischaemia 2014
Takotsubo cardiomyopathy
https://the-breach.com/introducing-the-modified-sgarbossa-criteria/
https://epmonthly.com/article/stemi-in-the-presence-of-lbbb/
NSTEMI 2020
global T inversion review
4th universal definition of Myocardial infarction 2018
Circulation: Localisation of MI's - New terminology 2006