Intro to IHD: Diagnostic Approach

What is ischemia?

when oxygen supply does not equal demand

the umbrella of ischemic heart disease

- stable ischemic heart disease

- acute coronary syndromes

stable ischemic heart disease

chronic coronary disease (CCD)

acute coronary syndromes

- unstable angina (UA)

- non-ST elevation MI (NSTEMI)

- ST elevation MI (STEMI)

What contributes to oxygen supply?

- coronary artery patency

- collaterals

- oxygen carrying capacity of blood

- HR (coronary arteries perfuse during diastole)

What demands oxygen? (MVO2)

- HR

- contractility

- myocardial wall tension (preload and afterload)

plaque progression and diminishing coronary artery patency

stable IHD -> chronic stable angina

plaque instability, plaque rupture (partial occlusion of coronary artery)

unstable IHD -> unstable angina/NSTEMI

plaque instability, plaque rupture (complete occlusion of coronary artery)

unstable IHD -> STEMI

What does the build-up of plaque affect?

supply

What does plaque rupturing affect?

demand

diagnostic approach

1. history/chest pain differential

2. ECG/EKG

3. cardiac injury biomarkers

history/chest pain

1. description of pain

2. precipitating factors

3. relieving factors

description of pain

- quality: pressure-like, tightness, crushing, "like an elephant sitting on chest", "chest in vice"

- duration: 30sec to 30min

- location: substernal

- radiation: jaw, back, shoulder, arm

precipitating factors

exertion or stress (physical or emotional)

relieving factors

rest, NTG s/l

chest pain history

- typical angina

- atypical angina

- non-anginal chest pain

typical angina

(1) substernal chest discomfort with a characteristic quality and duration that is (2) provoked by exertion or emotional stress and (3) relieved by rest or NTG

atypical angina

2-3 criteria

non-angina chest pain

0-1 of the criteria

mimics anginal pain

- aortic dissection

- pulmonary embolism

- gall bladder pain

- pancreatic pain

- gastric ulcer

- GERD

- liver distention

- musculoskeletal

- anxiety

Why is unstable angina important?

its presence predicts a much higher short-term risk of an acute coronary event

stable angina

- predictable

- non changing in frequency, intensity, duration

unstable angina

presents in either:

- rest angina

- new onset (

What do 3 findings on ECG signify?

ongoing myocardial ischemia or injury/infarction

ECG findings

- T wave inversion

- ST-segment depression

- ST-segment elevation

What ECG finding would show ishcemia leading to acute injury?

ST-segment elevation

What does the presence of any ECG finding along with chest pain suggest?

unstable ischemic heart disease syndrome occurring

What kind of ECG finding suggests myocardial injury at any time of life?

Q waves

T wave inversion

- may represent active myocardial ischemia

- non-specific, more suspicious if deep and symmetric

ST segment depression

- may represent active myocardial ischemia

- more sensitive than T wave inversion

ST segment elevation

- diagnostic for acute injury/infarct

- must be >1mm in 2 contiguous leads

- reversible

pathologic Q wave

- indicates transmural infarct

- irreversible

- can be old or new

cardiac biomarkers

- troponin I or T

- AST

Why would AST be a biomarker?

myocytes contain AST which suggests myocardial injury

What is the standard to rule acute MI in or out?

tropinin I or T (cTnI, cTnT)

What are the new assays for troponin?

hs-cTn

peak sensitivity for hs-cTn

1-2h

abnormal hs-cTn

>14 ng/L

criteria for acute MI when interpreting hs-cTn

>20% increase at 2h

For patients presenting with chest pain, how many criteria must be met to RULE IN acute myocardial infarction?

at least 2 (with >1 indicating injury)

criteria to be met to RULE IN acute myocardial infarction

- angina

- ST-elevation

- elevated troponin

CCD/stable IHD

- CP history: meets criteria for typical or atypical angina, does not meet criteria for unstable symptoms history

- no acute changes for ECG or biomarkers

non-STE ACS (UA)

- CP history: meets criteria for typical or atypical angina, meets criteria for unstable symptoms history

- ECG: may have acute T wave inversion or ST segment depression

- biomarkers: no acute changes

non-STE ACS (NSTEMI)

- CP history: meets criteria for typical or atypical angina, meets criteria for unstable symptoms history

- ECG: may have acute T wave inversion or ST segment depression

- biomarkers: acute rise

STEMI

- CP history: meets criteria for typical or atypical angina, meets criteria for unstable symptoms history

- ECG: acute ST segment elevation

- biomarkers: acute rise

goals for treatment of CCD

- increase oxygen supply

- decrease oxygen demand

- slow progression of atherosclerosis

protect vs thrombosis

antiplatelets

balance O2 supply & demand

- beta blockers

- calcium channel blockers

- nitrates

- ranolazine

modify atherosclerotic progression

- ACEi/ARBs

- lipid lowering

- colchicine

- SGLT2i

acute coronary syndrome (ACS)

atherosclerotic plaque has been compromised which leads to a prothrombin and inflammatory process

Why does therapy have to be more aggressive to treat ACS?

to combat the thrombotic process and to restore normal blood flow

goals for treatment of ACS

- prevent further expansion of thrombus

- restore artery patency

- increase supply

- decrease demand