6.7 Drugs Used for Secondary Prevention

Question 1

What is secondary prevention post myocardial infarction (Mi)?

Answer 1

Patients who have had a ST elevation myocardial infarction (STEMI)

or non- ST elevation myocardial infarction (NSTEMI)

benefit from treatment to reduce the risk of further MI

or other manifestations of vascular disease.

This is known as secondary prevention.

NICE provides comprehensive guidelines to prevent further MI and
progression of vascular disease in patients who have had an MI either
recently or in the past (> 12 months ago).

Question 2

What drugs are used as secondary prevention after an MI?

Answer 2

1. Angiotensin-converting enzyme inhibitor (ACEi)
2. Dual platelet therapy (aspirin plus second antiplatelet agent)
3. Beta blocker
4. Statin

Question 3

Angiotensin-converting enzyme inhibitor (Ace-i)

Answer 3

• Offered to patients who present acutely with an MI
  as soon as they are haemodynamically stable
  and continued indefinitely.
• Titrate dose upwards at short intervals
  (e.g. 12–24 hours before discharge from hospital
  until maximum dose tolerated).
• If unable to titrate dose upwards during admission,
  this should be completed within 4 to 6 weeks of hospital discharge.
• ACE-i is not to be combined with angiotensin II receptor blocker (ARB).
• Monitor renal function, serum electrolytes, and blood pressure

Question 4

Dual platelet therapy (aspirin plus second antiplatelet agent)

Answer 4

• Aspirin is offered to all patients after an MI and
  to continue indefinitely unless aspirin intolerant
  or have indication for anticoagulation.
• Patients who have had an MI > 12 months ago
  should also be offered aspirin.
• Ticagrelor in combination with low-dose aspirin is recommended for up to
  12 months.
• Alternative is Clopidogrel for up to 12 months in patients who have had
  NSTEMI or STEMI with bare metal or drug-eluting stents.

Question 5

Beta blocker

Answer 5

• Offered as soon as possible after an MI,
  when patient is
  haemodynamically stable.
• Continue for at least 12 months in patients
  with and without left ventricular systolic dysfunction
  or heart failure.
• Continue indefinitely in patients with
  left ventricular systolic dysfunction.

Question 6

4. Statin

Answer 6

• Offered to all patients with clinical evidence of cardiovascular disease.

Question 7

Is calcium channel blocker routinely offered?

Answer 7

No, It is offered only if beta blockers
are contraindicated or need to be discontinued.

Commonly used drugs are diltiazem or verapamil

Question 8

What is Ace-i?

Answer 8

ACE-i inhibits the angiotensin-converting enzyme in the
renin—angiotensin— aldosterone system.

Angiotensinogen (from liver)
Renin (from juxtaglomerular apparatus in kidney)

↓

Angiotensin i
ACE (from surface of pulmonary and renal endothelium)

↓

Angiotensin ii

Question 9

Angiotensin ii effects

Answer 9

• Increase sympathetic activity.
• Increase tubular sodium and chloride reabsorption and water retention.
• Increase tubular potassium excretion.
• Increase aldosterone secretion in adrenal cortex.
• Arteriolar vasoconstriction—increase blood pressure.
• Increase antidiuretic hormone (ADH) in posterior pituitary to increase
  water absorption in the collecting duct

Question 10

Can you give some examples of Ace-i?

Answer 10

Ramipril
Lisinopril
Captopril
Enalapril

Question 11

What clinical situations require use of Ace-i?

Answer 11

• After an MI
• Hypertension–
  first-line treatment for patients < 55 years old or
  non-Afro-Caribbean origin
• Heart failure
• Diabetic nephropathy—renal protective
• Chronic kidney disease—slows the progress of kidney disease

Question 12

What are the common side effects of Ace-i?

Answer 12

1. Renal impairment

• Under normal circumstances,
  angiotensin II maintains renal perfusion by altering the caliber
  of the efferent glomerular arterioles.

ACE-i inhibits this causing drop in renal perfusion pressure,
which can lead to renal failure in patients
with pre-existing impaired renal circulation.

ACE-i is therefore contraindicated in patients with renal artery stenosis.

2. Dry cough
   * Due to increased bradykinin, which is normally degraded by ACE

3, Hypotension
* First-dose hypotension—test dose should be given at night.

• Can cause refractory hypotension with anaesthesia.
  ACE-i is usually omitted for 24 hours prior to surgery.

4. Angioedema
   * Swelling of lips, eyes, and tongue

• More common in Afro-Caribbean patients