Myocardial Infarction and Angina Tutorial

Question 1

64M - presents to GP complaining of increasing breathlessness, with chest pain on exertion

Smokes 20 cigarettes/day and drinks moderately

Father died of a heart attack at 50 y/o
Mother still alive at 95

Breathlessness started 12 months ago, increased over time

Cannot walk more than 20m without rest, has chest pain when hurrying

On examination: HR = 98 b/min, BP = 160/110 mmHg and ECG shows no significant changes

What is the differential diagnosis of the chest pain?

Answer 1

Consider all areas: Pulmonary, CVD, GI, musculoskeletal

MI
Pulmonary embolism / oedema
Pneumothorax
Congestive heart failure
Pericarditis 
Stable angina 
Ischaemic heart disease
GORD - heartburn 
Muscular pain

Question 2

What type of angina is he presenting with?

Answer 2

Typical angina = precipitated by physical exertion, constriction discomfort, relieved by rest

Atypical angina = 2 of the features of typical angina
Though atypical angina may also present with GI discomfort, breathlessness and/or nausea

The patient is presenting with typical angina

Question 3

What are the classifications of Angina?

Answer 3

3 classifications of angina:

Stable = pain or discomfort onset when the heart must work harder i.e. physical exertion; usually lasts for a short time (< 5min); is relieved by rest or medicine

Unstable = can occur while resting, lasts longer than stable angina, rest or medicine does not help relieve it; gets worse over time. May lead to MI

Prinzmetal (AKA variant) = spasm in coronary arteries triggered by stress, smoking, cold etc.

Question 4

What factors make a stable angina diagnosis less likely?

Answer 4

Pain that is:

Continuous or prolonged
Unrelated to activity
Brought on by breathing
Associated with dizziness, palpitations, tingling, or difficulty swallowing

Question 5

What risk factors can you identify which can lead to IHD / angina in this patient?

Answer 5

Family history
Smoking
Hypertension
Alcohol
Age - 64 y/o
Male

Question 6

Which tests would you like to perform and why?

Answer 6

ECG
Coronary angiography
Exercise tolerance test

Lab tests:
Complete blood profile
Lipid profile
Renal tests
Liver function tests
Cardiac enzymes
Cardiac biomarkers - troponin, myoglobin, BNP, CK-MB

Question 7

Why is looking at troponin important?

Answer 7

Blood levels of troponin = elevated within a few hours of heart damage and remain elevated for up to two weeks

Normal levels = less likely the symptoms and chest pain are due to heart muscle damage and more likely due to stable angina

A rise and/or fall in the series of troponin results indicates a heart attack

Question 8

How will you manage this patient? What is done for all patients?

Answer 8

Initiate patient education

Implement lifestyle modifications (e.g. diet, exercise, smoking cessation, weightloss)

Control risk factors with acetylsalacylic acid (or clopidogrel) and/or a statin

Consider ACEi or ARB (angiotensin receptor blocker) therapy

Question 9

What are the first line options for this patient for their management?

Answer 9

First line:

Pain management - short-acting nitrate (e.g. sublingual nitrogen)
Beta blockers
Calcium channel blockers (CCBs)
Dihydropyridine (DHP) CCB - for low heart rate
Symptoms remain uncontrolled = beta blocker and DHP CCB

Question 10

What is the second line of options for the patient’s management?

Answer 10

Long-acting nitrate
Ivabradine
Nicorandil
Ranolazine
Trimetazidine

Question 11

What is the next step in management if the patient does not respond to second line treatment?

Answer 11

Revascularisation options

Question 12

34M - presents at hospital with severe chest pain lasting for 24 hours

History of hypertension and was a smoking

No prior symptoms, sudden severe chest pain with nausea and diaphoresis

An ECG is performed

Explain the findings on the ECG. What is your diagnosis based on the ECG?

Answer 12

MI, more specifically a lateral STEMI

Leads aVR, I and V6 = ST elevation
III, aVF - ST depression (Reciprocal changes)

Inferior myocardial infarction = left circumflex artery MI

STEMI = ST segment elevation

Question 13

What are the different types of MI based upon the areas of infarct and how are they diagnosed by looking at the ECG?

Answer 13

ST Segment Elevation in Leads:

1. V1, V2, V3, V4 = left coronary artery and left anterior descending artery (LAD) affected = anterior MI
2. I, aVL, V5, V6 = reciprocal changes in III and aVF = (left) circumflex artery affected = lateral MI
3. II, III, aVF = reciprocal changes in I, aVL = right coronary artery affected = inferior MI
4. V7, V8, V9 = right coronary and (left) circumflex artery affected = posterior MI
5. V1, V2 = left anterior descending (LAD) affected = septal MI

Question 14

What is the first line of management?

Answer 14

1. Painkillers, antiplatelet, anti-ischaemic / anti-coagulant treatment, PCI (percutaneous coronary intervention AKA angioplasty with stent)
2. Reperfusion therapy, PCI, thrombolysis, rescue PCI if thrombolysis fails, coronary artery bypass graft (CABG)
3. Long-term management (antiplatelet therapy, statins, beta bloackers, ACE inhibitors, cardiac rehabilitation, lifestyle changes, etc.)

Question 15

52F - presents with episodes of chest pain not relieved by rest

History of illicit drug use and family history of premature heart disease

ECG performed

What is the most likely diagnosis based upon the ECG?

Answer 15

Leads II, III = ST depression
T wave inversions

Patient has non-STEMI / unstable angina

Question 16

What are the pathophysiological differences between STEMI, NSTEMI and unstable angina?

Answer 16

STEMI = (almost always) coronary plaque rupture resulting in thrombosis formation occluding a coronary artery

NSTEMI = incomplete thrombus formation = not complete stop of blood and oxygen supply, but restriction = rapid use up of oxygen content = tissue death near distal arteries and arterioles due to oxygen starvation. Small area affected = not enough to cause ST elevation, but enough to cause minor ST/T wave changes and Troponin elevation

Unstable Angina = unstable plaque, disrupted fibrous cap and thrombus is formed but still enough lumen to meet the demand during rest

Question 17

What is the difference between NSTEMI and Unstable Angina (pathologically)?

Answer 17

Pathologically = how much of the blood flow in obstructed i.e. amount of occlusion

NSTEMI = more blockage = reduced flow = not enough to keep the tissue going = sudden onset = raised troponin

Unstable = normal troponin, enough blood flow to meet oxygen demands of cardiac muscle at rest

Question 18

What is the difference between NSTEMI and Unstable Angina (clinically)?

Answer 18

Troponin not elevated in unstable angina

Elevation in cardiac biomarkers in NSTEMI - i.e. raised troponin

Chest pain associated w/ no ST elevation on ECG in either

Question 19

How do you treat NSTEMI and unstable angina?

Answer 19

For both:
Risk assessment
Aspirin, clopidogeral, heparin, nitrates, beta blockers

For low risk - conservative management and stress test

Negative stress test = discharge and long-term management
Positive stress test = coronary angiography, PCI, CABG, medical treatment

For high risk - positive troponin, ST changes, unstable patient = invasive management i.e. CA, CABG, PCI, and long-term management

Question 20

How will you manage the patient?

Answer 20

Depends on urgency of treatment needed

And whether the patient has self-medicated (e.g. opioid use)