2.2 Acute Coronary Syndrome Flashcards
Which is more common: plaque rupture or plaque erosion? In what percentage of cases does it occur?
Plaque rupture (60-75%)
How do plaques that undergo erosion differ from plaques that undergo rupture?
- Thicker fibrous cap
- No necrotic core
- Fewer macrophages or other inflammatory immune cells (e.g. lymphocytes)
What is a vulnerable plaque?
Plaque that is prone to rupture (not erosion, but rupture)
What are three characteristics of vulnerable plaques? Which predisposes most importantly?
- Thin fibrous cap
- Large lipid pool
- Activated macrophages
Most predictive: fibrous cap
Clinically, what differentiates unstable angina from myocardial infarction?
UA: no troponin elevation
MI: troponin elevation
STEMI vs NSTEMI
STEMI: Full occlusion, transmural infarct
NSTEMI: Partial occlusion, subendocardial infarct
Which demographics are more likely to present with no chest pain (but other symptoms) during MI?
- Women
- Older
- Diabetic
What are the three possible outcomes of a suspected MI following ECG?
- STEMI
- NSTEMI
- Undifferentiated chest pain
What conditions (other than STEMI) can cause ST elevation?
- Myocarditis
- Acute pericarditis
- Benign variant
Other than chest pain, what are some other clinical features of MI?
- Dyspnoea
- Diaphoresis
- Nausea/vomiting
- Palpitations
- Rarely, weakness
ECG presentation in NSTEMI
ST depression and/or T-wave inversions without subsequent ST-segment elevations
What is troponin? What is it important for?
[Enzyme] Complex of three regulatory proteins (C, I and T) integral to skeletal and cardiac muscle contraction
Which troponin proteins are indicators of cardiac injury?
I and T
What precentile troponin is considered to be abnormal?
> =99th percentile
Is troponin elevation specific to MI?
NO. IT IS NOT; must be taken in context with symptoms and ECG
How many hours for MI exclusion for negative troponin levels using sensitive and hs assay?
Sensitive: 6-8 hours
Hs: 3 hours
What are some common causes of chest pain other than ACS?
- Costochondritis
- Reflux oesophagitis
- Chest wall pain
What percentage of chest pain is ACS?
2-4%
List some life-threatening conditions associated with chest pain
- ACS
- Stress cardiomyopathy
- Aoritc dissection
- Pulmonary embolism
- Tension pneumothorax
- Esophageal rupture, perforation
List some non-life-threatening cardiac conditions associated with chest pain
- Stable myocardial ischaemia/angina pectoris
- Peri(myo)carditis
- Aortic stenosis
List some non-life-threatening pulmonary conditions associated with chest pain
- Pneumothorax
- Pneumonia
- Asthma/COPD exacerbation
- Pleuritis
List some non-life-threatening gastrointestinal conditions associated with chest pain
- Reflux
- Peptic ulcer
- Oesophageal motility disorders
- Oesophagitis
Mechanism of how ACS causes dyspnoea when lying down (orthopnea and PND)
- Oxygen supply to myocardium is decreased/removed
- Heart cannot pump blood as effectively as it normally does (heart failure)
- Blood is “backed up”, causing regurgitation into pulmonary circulation
- Pulmonary oedema
- Fluid is pushed into alveoli
- Decreased efficiency of oxygen transport
- Dyspnoea
Orthopnea vs PND
Orthopnea: Shortness of breath on lying down
PND: Comes about 1-2 hours after patient falls asleep
List two substances that are thought to be released that cause pain during myocardial ischaemia
- Adenosine
- Bradykinin
