C01: Acute Coronary Syndrome (and ECGs)

Question 1

How does management of pain, nausea, and limitation of patient exertion have a positive effect on morbidity/mortality in ACS?

Answer 1

Limits myocardial oxygen demand

Question 2

Describe preferred placement of the therapy electrodes if you suspect your patient will be seen urgently in the cath lab

Answer 2

Anterolateral pad position with wires travelling cephalad (toward the head)

Question 3

Which region should be avoided for IV cannulation if your patient is being transported/transferred for angiography (cath lab)

Answer 3

Avoid the distal third of the right forearm, this is frequently the insertion site for PCI
Placement in the proximal right forearm or antecubital fossa is not an issue

Question 4

Describe the role of nitroglycerin in management of ACS

Answer 4

• Given for pain relief
• Does NOT improve outcomes, and may worsen them in some cases
• If not effective after first few doses, further doses are unlikely to produce benefit

Question 5

What are the three sub-classifications of ACS?

Answer 5

• Unstable angina
• NSTEMI
• STEMI

Question 6

What ECG changes are typically seen in NSTEMI?

Answer 6

• non-specific ischemic findings including; T-wave inversions, ST depressions, transient ST elevations, or hyperacute T-waves

Question 7

A patient presents with signs/symptoms of ACS. They are on daily apixaban therapy and have been advised to avoid ASA while taking it. Should you give ASA anyways?

Answer 7

Yes!
“Patients on oral anticoagulant therapies are often told by their physician to avoid ASA. In the setting of suspected or known ACS, the antiplatelet activity of ASA is of more importance than the temporary rise in INR.”

Question 8

What is an appropriate oxygen target for a patient with signs of ACS?

Answer 8

target 94% or greater. Ideally, do not exceed 98%

Question 9

What are indications for NTG administration in ACS for PCP/EMR?

Answer 9

• SBP must be greater than 110 mmHg
• HR must be between 50-150bpm

Question 10

What is the classic “tetrad” of treatments for ACS?

Answer 10

• MONA/FONA
• Fentanyl (0.5-1mcg/kg IV q.5m)
• Oxygen (target SpO2 94% or greater)
• Nitroglycerin (0.4mg q.3-5m SL, SBP 110 or greater, HR 50-150)
• ASA (160mg PO, dispatch instructs to take 320mg)

Question 11

Summarize diagnostic ECG criteria for STEMI
* include criteria for age/sex
* do not include equivalents/mimics

Answer 11

• ST elevation in 2 or more anatomically contiguous leads, meeting the following criteria:
• Men 40 or greater: 2.5mm in V2/V3, 1mm in all other leads
• Men less than 40: 2.0mm in V2/V3, 1mm in all other leads
• Women: 1.5mm in V2/V3, 1mm in all other leads

Question 12

Can reciprocal ST depression be used to rule in or rule out ACS?

Answer 12

NO!
This is no longer best practice. Recpiprocal depression adds little specificity, at an unacceptable cost to sensitivity

Question 13

Which ECG leads require higher levels of ST elevation than others to be considered diagnostic of STEMI?

Answer 13

V2/V3
*Men 40 or greater: 2.5mm in V2/V3, 1mm in all other leads
* Men less than 40: 2.0mm in V2/V3, 1mm in all other leads
* Women: 1.5mm in V2/V3, 1mm in all other leads

Question 14

What five patterns are considered STEMI equivalents by BCEHS? Which one of these five is typically seen as an NSTEMI, rather than STEMI equivalent in the medical community-at-large?

Answer 14

• De Winter’s T-waves
• Positive Sgarbossa Criteria (LBBB or V-paced Rhythm)
• aVR STEMI pattern
• Posterior STEMI pattern
• Wellen’s syndrome (Generally considered to be a NSTEMI equivalent)

Question 15

Describe properties of De Winter’s T-waves, including:
* Which leads to be considered
* Characteristic morphology
* Quantitative findings (i.e. degree of elevation or depression)

Answer 15

• Should only be considered in the precordial leads
• Characteristic upsloping ST depression with tall, prominent T-waves in any or all of the precordial leads
• No ST elevation in the precordial leads
• 0.5-1mm STE in aVR
• ST depression must be 1mm or greater

Question 16

What is the clinical significance of De Winter T-waves?

Answer 16

• Considered a STEMI equivalent!
• Early finding in evolving STEMI
• Transmit early and treat as STEMI

Question 17

You respond to a patient with cardiac-suggestive chest pain and the following 12-lead ECG is acquired.
* What are the relevant findings?
* Should you notify/bypass?
* How will you treat?

Answer 17

• De Winter T-waves are seen in V2-V4, as well as widespread ST depression with STE greater than 1mm in aVR
• This is a STEMI equivalent (x2)
• YES! You should immediately transmit and advocate for PCI bypass
• Treat per standard ACS package: MONA/FONA, treat shock, prepare for resuscitation

Question 18

You respond to a patient with cardiac-suggestive chest pain and the following 12-lead ECG is acquired.
* What are the relevant findings?
* Should you notify/bypass?
* How will you treat?

Answer 18

• De Winter T-waves are seen in V3-V5, as well as STE greater than 1mm in aVR (an expected finding with De Winter’s T-waves)
• This is a STEMI equivalent
• YES! You should immediately transmit and advocate for PCI bypass
• Treat per standard ACS package: MONA/FONA, treat shock, prepare for resuscitation

Question 19

Describe the original, and Smith’s-modified Sgarbossa criteria, including;
* Indications for using the Sgarbossa criteria
* The original point-based scoring system for clinical significance
* How Smith’s rule impacts clinical scoring

Answer 19

• Used to identify AMI in the presence of LBBB or a paced rhythm
• The original criteria are as follows:
  1. Concordant STE of 1mm or greater in ANY lead (5 points)
  2. Discordant ST depression in V1-V3 (3 points)
  3. Excessively discordant ST elevation (more than 5mm) in any lead (2 points)
• 3 points or more were required for clinical significance
• Smith’s-modified rule replaces the third Sgarbossa criteria. Excessive discordance is redefined as ST/S ratio greater than 0.25
• Smith’s-modified does away with the points system, any finding is clinically significant

Question 20

Compare sensitivity and specificity of Sgarbossa’s original criteria and the Smith-modified rule

Answer 20

• Both are essentially equally specific (91% vs. 90%). Smith’s-modified is substantially more sensitive (91% vs. 36%)

Question 21

You are responding to a patient with “chest pressure” and diaphoresis. You acquire the following 12-lead ECG.
* What are the relevant findings?
* Should you notify/bypass?
* How will you treat?

Answer 21

• This is a LBBB with positive Smith-modified Sgarbossa criteria
• There is excessive discordance in V3-V4 (ST/S greater than 0.25) and concordant STE in the inferior leads
• This is a STEMI equivalent!
• YES! You should immediately transmit and advocate for PCI bypass
• Treat per standard ACS package: MONA/FONA, treat shock, prepare for resuscitation

Question 22

Describe ECG findings in aVR STEMI pattern

Answer 22

• ST elevation in aVR ≥ 1mm
• ST elevation in aVR ≥ V1
• Widespread horizontal ST depression (often I, II, aVL, and V4-6)
• aVR elevation in the presence of a tachycardia is often rate related and not suggestive of LMCA occlusion

Question 23

Which leads are MOST likely to show ST depression in aVR STEMI pattern?

Answer 23

The anterolateral leads; I, II, aVL, and V4-6

Question 24

What is the clinical significance of an aVR STEMI pattern?

Answer 24

In the context of widespread ST depression + symptoms of myocardial ischemia:
* STE in aVR ≥ 1mm indicates proximal LAD / LMCA occlusion or severe 3VD
* STE in aVR ≥ 1mm predicts the need for CABG
* STE in aVR ≥ V1 differentiates LMCA from proximal LAD occlusion
* Absence of ST elevation in aVR almost entirely excludes a significant LMCA lesion

Question 25

With regards to aVR STEMI pattern, is the degree of ST elevation in aVR correlated to the degree of morbidity/mortality?

Answer 25

YES!!! * STE in aVR ≥ 0.5mm is associated with a 4-fold increase in mortality * STE in aVR ≥ 1mm is associated with a 6- to 7-fold increase in mortality * STE in aVR ≥ 1.5mm has been associated with mortalities ranging from 20-75%

Question 26

What two non-ecg conditions should be met prior to considering a provisional Dx of AMI in aVR STEMI pattern?

Answer 26

* There should be other clinical findings of ACS (ex: cardiac-suggestive chest pain) * The patient can not have a clinically-significant tachycardia

Question 27

Describe ECG findings in posterior STEMI pattern, including * relevant leads * quantitative criteria (i.e. how much STE is required)

Answer 27

* Precordial ST Depression V1-4 > 1mm (sensitive). As always, 2 or mroe contiguous leads are required * ST Elevation in V7/8/9 > 0.5mm adds specificity

Question 28

Are posterior leads required to diagnose posterior STEMI?

Answer 28

NO! posterior leads add specificity, but are not required and should not delay treatment/transport

Question 29

Describe both clinical **and** ECG findings in Wellen's syndrome, including: * characterisitic physical findings * ECG findings for both type A and type B patterns * Which leads are involved in both cases

Answer 29

* Following an ischemic event suggestive of unstable angina. ECG findings are generally only visible once patient is **pain free**. Note that the presenting complaint may be resolved syncope! * TYPE A: Biphasic T waves, most commonly in leads V2 and V3. Presents with upstroke/down-stroke. * TYPE B: 76% of the time, deep inversion of the T-wave segment in the precordial leads, V1-V4.

Question 30

Describe the clinical significance of Wellen's syndrome

Answer 30

* Pre-infarction stage of coronary artery disease suggesting 80-90% LAD occlusion that often progresses to a devastating anterior wall MI. * Most sources consider this to be a NSTEMI equivalent rather than a STEMI equivalent * When in doubt; transmit, call, and advocate

Question 31

You respond to a patient who initially complained of ischemic chest pain, but now states their pain has spontaneously resolved. Their 12-lead ECG shows deep T-wave inversions in V1-V4. What is the significance of this finding?

Answer 31

* This is characterisitic of a Wellen's syndrome with TYPE B pattern * Suggests 80-90% LAD occlusion that often progresses to a devastating anterior wall MI * Treat as NSTEMI/STEMI equivalent

Question 32

What four ECG patterns are recognized as STEMI mimics by BCEHS? Which one of these four may ALSO be considered a STEMI equivalent if certain criteria are met?

Answer 32

* Benign early repolarization (BER) * Pericarditis * Left Ventricular Hypertrophy (LVH) * Left bundle branch block (LBBB); may be a STEMI equivalent if Sgarbossa/Smith's-modified criteria are met

Question 33

Describe characteristic ECG features of benign early repolarization (BER), including; * Key features of morphology * Which leads are affected * which patients should **not** be considered for a provisional Dx of BER

Answer 33

* Widespread concave ST elevation with J point elevation * May have 'fish-hooked' Osborne wave * No reciprocal ST depression to suggest STEMI (except in aVR) * ST changes are relatively stable over time (no progression on serial ECG tracings) * BER should only be considered in younger patients, typically males. Use extreme caution for patients 50 or older, and NEVER consider BER for patients over 70!

Question 34

What is the clinical significance of BER?

Answer 34

* None! It is a benign ECG finding, typically in younger, healthy males. * Thought to be caused by highly excitable ion channels (particularly due to presence of testosterone) leading to rapid depolarization and, consequently, simultaneous depolarization and repolarization * BER should only be considered in younger patients, typically males. Use extreme caution for patients 50 or older, and NEVER consider BER for patients over 70!

Question 35

Describe characteristic physical and ECG findings in pericarditis

Answer 35

* Sharp, pleuritic sub-sternal pain worsening when supine. May have a pleural friction rub. May demonstrate Beck's triad - hypotension, muffled heart sounds, and JVD. Investigate for recent myocardial insult (ttraumatic or infectious) * Widespread concave ST elevation and PR depression * Reciprocal ST depression and PR elevation in lead aVR * Sinus tachycardia is also common in acute pericarditis due to pain and/or pericardial effusion

Question 36

How should ST elevation be measured in pericarditis?

Answer 36

* Using the TP segment! * Comparing to the PR segment will often lead to false findings due to characteristic ST depression in pericarditis * Spodick's sign (a down-sloping TP and PR) is often present

Question 37

Describe ECG findings in LVH, including; * Voltage criteria * Strain criteria

Answer 37

* Voltage criteria: BCEHS uses the following: S(V1 or V2) + R(V5 or V6) > 35mm * This is a modification of the Sokolov-Lyon criteria (normally V2 not included) * Strain Criteria: 1. ST Elevation V1-4 1. ST Depression / Inverted T waves V5 and V6 1. Generally proceeds from most elevated V1/2 to most depressed V6

Question 38

Describe characteristic ECG findings in LBBB

Answer 38

* QRS > 120ms * Prominent S (V1-3) / prominent R (V5/6, I/aVL) * ST Elevation common in V1-4

Question 39

Is a new LBBB considered a STEMI equivalent?

Answer 39

No! This is old practice! Check for the presence of Sgarbossa/Smith's-modified criteria

Question 40

You respond to a patient with chest pain and the following 12-lead ECG is acquired: * What are the relevant findings? * Should you transmit/bypass? * How should you treat?

Answer 40

* This is a LBBB which is **negative** for Sgarbossa/Smith criteria * LBBB is not considered a STEMI equivalent. You are **not** required to transmit/bypass, but this could be appropriate if other clinical findings are present; always advocate for your patient. * Investigate for other causes of chest pain. Treat per ACS guidelines if findings are supportive.

Question 41

Which leads are considered "anatomically contiguous" for purposes of STEMI recognition? (i.e. what are the groupings of anatomical regions of the heart by leads?)

Answer 41

* Inferior: II, III, aVF * Septal: V1, V2 * Anterior: V3-V4 * Lateral: V5, V6, I, aVL * Note that any contiguous grouping of V1-V6 is considered significant (ex: V2+V3)

Question 42

You respond to a patient with chest pain and the following 12-lead ECG is acquired: * What are the relevant findings? * Should you transmit/bypass? * How should you treat?

Answer 42

* This is a paced rhythm which is **positive** for Sgarbossa/Smith criteria (concordant ST depression in precordial leads) * This is a STEMI equivalent. Transmit early and bypass to a PCI center * Treat as ACS; MONA/FONA, treat for shock, prepare to resuscitate

Question 43

You respond to a patient with chest pain and the following 12-lead ECG is acquired: * What are the relevant findings? * Should you transmit/bypass? * How should you treat?

Answer 43

* This is a LBBB which is **negative** for Sgarbossa/Smith criteria * LBBB is not considered a STEMI equivalent. You are **not** required to transmit/bypass, but this could be appropriate if other clinical findings are present; always advocate for your patient. * Investigate for other causes of chest pain. Treat per ACS guidelines if findings are supportive.

Question 44

You respond to a patient with chest pain and the following 12-lead ECG is acquired. The patient is a fit, 55M who complains of chest pain since their usual workout this morning: * What are the relevant findings? * Should you transmit/bypass? * How should you treat?

Answer 44

* This is likely BER (upsloping STE with osborne waves and high QRS voltages in a fit male). BER should be considered with caution in patients over 50, but this case fits the clinical picture. * This is a STEMI mimic. Do not transmit or bypass unless other evidence of ACS exists * Investigate for other causes of chest pain (likely MSK). Continue to monitor with serial 12-lead ECGs; dynamic ST changes are NOT characterisitic of BER and point to ACS!

Question 45

You respond to a patient with chest pain and the following 12-lead ECG is acquired: * What are the relevant findings? * Should you transmit/bypass? * How should you treat?

Answer 45

* ST-depression in V2-V4 suggests posterior STEMI * This is a STEMI equivalent! Transmit and bypass to a PCI center * Treat as ACS: MONA/FONA, treat for shock, prepare to resuscitate. * You may consider acquiring posterior leads V7-V9 to add specificity, but only if it does not delay transport

Question 46

You respond to a patient with chest pain and the following 12-lead ECG is acquired: * What are the relevant findings? * Should you transmit/bypass? * How should you treat?

Answer 46

* If you don't know, you're in trouble..... * This is an **obvious** inferior STEMI with posterior extension * Transmit and bypass immediately * Treat as ACS: MONA/FONA, treat for shock, prepare to resuscitate.