6. Stable Angina

Question 1

Define angina.

What is the most commonly occluded coronary artery?

Distinguish between stable and unstable angina.

Answer 1

Clinical syndrome characterised by discomfort in chest, jaw, shoulder, back or arm. Typically aggravated by exertion or emotional stress and relieved by nitroglycerin. Usually occurs in pts with CAD involving at least 1 major epicardial artery.

LAD (pic)

Unstable: angina that presents in 1 of 3 principle ways: rest angina, severe new-onset angina, or worsening angina. It predicts a much higher short-term risk of acute coronary event.
Stable: absence of these features i.e. occuring for several weeks in a reasonably predictable manner, without deterioration.

Question 2

How does plaque rupture and treatment differ between stable and unstable angina?

What is angina caused by?

Why does angina not occur during exercise in a normal heart?

Answer 2

Stable: event rate low, tx - medical, PCI or CABG for symptom relief
Unstable: event rate high, tx - combination antiplatelet rx, PCI or CABG carries prognostic benefit

Myocardial ischaemia, which occurs when myocardial O₂ demand exceeds myocardial O₂ supply.

Increased myocardial O₂ demand is met by an increased O₂ supply delivered by an increase in coronary blood flow.

Question 3

What pathophysiologies can affect O₂ supply and O₂ demand?

Case Study
65 yo male, smokes 20/day for 40 yrs, 1 yr history of chest tightness on walking 400 yds, symptoms on most days. His history is typical of stable angina. List the features (SOCRATE).

What is the next most important issue to establish from the history?

Answer 3

O₂ supply: CAD, anaemia, hypoxia
O₂ demand: LVH 2^o AS, HCM (hypertrophic cardiomyopathy), HT, thyrotoxicosis,

• *Site** - central
• *Onset** - exertion/emotion
• *Character** - heavy/pressure/tight
• *Radiation** - arm(s)/neck/jaw/teeth
• *Associated factors** - SoB
• *Timing** - duration = minutes
• Exacerbating factor** - cold weather (due to peripheral vasoconstriction -> increased afterload -> increased myocardial O₂ consumption*), hills. Relieving - rest, SL GTN

The modifiable risk factors

Question 4

65 yo male, smokes 20/day for 40 yrs, 1 yr history of chest tightness on walking 400 yds, symptoms on most days. His history is typical of stable angina.

What are the modifiable risk factors for CAD in this case?

What should you look for when examining this patient?

Answer 4

• *1. Smoking** - must stop
• *2. ?Hypertension** - measure BP. Target <130/80 mmHg for pts with CVD
• *3. ?Hypercholesterolaemia** - measure blood (chol) and treat with statin irrespective of result
• *4. ?Diabetes** - measure blood (glu) and treat if raised

1. Measure BP
2. Listen for murmurs of AS or HCM (in small number of cases it’s not coronary disease causing stable angina - could be 2 others: Aortic stenosis: hear ejection systolic murmur radiating up to carotid. OR Hypertrophic cardiomyopathy: causing LV output obstruction but can mimic AS).
3. (Look for xanthelasma - yellowish plaques occuring most commonly near inner canthus of eyelid, more often on upper lid than lower)

Question 5

What 2 types of diagnostic tests will be done for the case pt with suspected angina?

Answer 5

1) Tests which look for evidence of myocardial ischaemia:
Exercise ECG. Non-invasive tests: nuclear and MRI myocardial perfusion imaging, stress echo. Compare images at rest with those taken during ‘stress’.
2) Tests which look for coronary artery disease itself:
CT calcium score and CT coronary angiography. Invasive coronary angiogram.

Question 6

What are the following diagnostic tests for angina?

Answer 6

• *A:** Exercise ECG (resting on L, exercise on R. ST depression could = coronary disease)
• *B:** Nuclear perfusion scan (see resting perfusion defect in LAD that supplies apex)
• *C:** Cardiac MRI perfusion scan

Question 7

What are the following diagnostic tests for angina?

What test is now recommended first and formost for any suspected coronary artery disease?

Answer 7

• *A:** Conventional/invasive coronary angiography (can see severe stenosis in proximal RCA (left) and stenosis in bifurcation of LAD (right))
• *B:** stress echocardiography
• *C:** CT Ca scoring and CT angiography

CT scan (v. accurate for excluding coronary artery disease, low dose radiation, safe, non-invasive, cost-effective).

Question 8

65 yo male, smokes 20/day for 40 yrs, 1 yr history of chest tightness on walking 400 yds, symptoms on most days. His history is typical of stable angina.

Treatment falls under to categories: to improve prognosis, and to treat symptoms. List the treatements in both categories.

Answer 8

Tx to improve prognosis:
1) Aspirin - antiplatelet blood thinner - in pts with CVD, reduces MI and stroke by 1/3 and CV death by 1/6. If can’t take aspirin give clopidogrel.
2) Statin - reduces death or MI by 25-30% in pts with CVD. Atorvastatin.
3) ACE-I - reduces death, MI, or stroke by 20% in pts with CVD
4) (β-blocker if post MI)
AND address modifiable risk factors - STOP SMOKING!
ACE-I and β-blocker for diabetics and/OR poor LV function OR previous MI.

Tx for symptoms:

1) Sublingual GTN or long acting nitrite e.g. isosorbide mononitrate.
2) β-blocker - 1^st line anti-anginal therapy. Bisoprolol. OR CCB e.g. amlodapine (vasculature-selective) /verapamil (heart-selective - blocks AVN)

Question 9

65 yo male, smokes 20/day for 40 yrs, 1 yr history of chest tightness on walking 400 yds, symptoms on most days. His history is typical of stable angina.

The patient failed to tolerate β-blocker because of wheeze. What is the next step? (Give examples)

What would you also add to investigate/treat further?

Answer 9

Replace symptomatic β-blocker treatment with 2^nd line anti-anginal therapy.

Angiogram with a view to PCI or CABG. (stent/bypass).
Stent: no prognostic benefit. Non invasive. Lower proceedural risk, but higher chance of repeat proceedures. Bypass: may have prognostic benefit, open chest, 2m recovery, less likely to need repeat work.

Question 10

What are the 2^nd line anti-anginal agents? (4 examples)

What proceedures do the following images show?

What are the 3 different types of coronary artery stents?

Answer 10

1) CCB e.g. amlodipine
2) Long acting nitrate
3) K⁺ channel opener e.g. nicorandil (causes hyperpolarisation)
4) I_f channel blocker e.g. ivabradine (reduces cardiac pacemaker activity - slows heart) BUT NEED TO BE IN SINUS RHYTHM FOR THIS!

PCI (percutaneous coronary intervention)

Metal lattice structures, balloon-mounted, scaffold. (pic)