Atrial Fibrillation

Question 1

Suggest some possible causes of atrial fibrillation.

Answer 1

Most commonly hypertension or heart failure, however also:

• Rheumatic fever
• Alcohol
• Hyperthyroid - mandatory testing when AF is shown up
• Mitral stenosis
• Lung disease (pneumonia, PE, malignancy)

Question 2

Suggest how a patient with undiagnosed atrial fibrillation may present.

Answer 2

• Palpitations
• Shortness of breath (dyspnoea)
• Chest pain
• Tachycardia
• Syncope

Question 3

What signs may be elicited on examination (not just physical) of a patient with atrial fibrillation.

Answer 3

• Irregularly, irregular pulse

- Absent P waves on ECG

Question 4

Why do we use non-dihydropyridines (ditalazem, verapamil etc.) as opposed to dihydropyridines in the treatment of atrial fibrillation?

Answer 4

Dihydropyridines have very little effect on the heart rate, their primary action is via arteriolar dilatation, the non-dihydropyridines are much more balanced.

Question 5

Describe the mechanism of action of flecanide. What is it used for in atrial fibrillation?

Answer 5

It is a Class 1c anti-arrythmic (Vaughan-williams classification) which means it blocks Na+ channels however doesn’t alter the length of action potential. This therefore slows the upstroke of the action potential and reduces the premature contraction of cells of the heart.

Question 6

Describe the mechanism of action of digoxin. What ADRs are associated with digoxin?

Answer 6

Digoxin inhibits the Na+/K+ ATPase in cardiac myocytes, resulting in reduced sodium excretion. This build of sodium leads to reversal of the Na+/Ca2+ exchanger, leading to large amount of Ca2+ accumulating in the myocytes.

Question 7

Suggest some possible ADRs of flecanide. In which groups of patient should it NEVER be prescribed in?

Answer 7

• Can cause arrythmias
• Cardiac toxicity
• Respiratory toxicity

It should never be prescribed to patients with structural or ischaemic heart problems.

Question 8

Outline a treatment plan that focuses on the rate control for a patient presenting with atrial fibrillation.

Answer 8

• Initiate treatment with Beta blockers or CCBs (non-dihydropyridines)

If ineffective:
- Combine BB/CCB with the other one OR digoxin

Question 9

Which score should be calculated to determine whether anticoagulation treatment needs to be started in a patient with AF?

Answer 9

CHADS2Vasc Score (Normally a score of 1+ in men, 2+ in women indicates treatment needs to be initiated)

Question 10

Why is amiodarone commonly reserved until after class 1 anti-arrythmics in rhythm control of AF?

Answer 10

Significant side-effect (ADR) profile:

• Interstitial lung disease
• Hyperthyroidism (more common) OR Hypothyroidism
• Blue-grey skin discolouration

N.b. amiodarone is used in AF instead of anti-arrythmics if the patient has HF and LVH

Question 11

Suggest TWO possible complications of atrial fibrillation.

Answer 11

• Stroke

- Heart failure

Question 12

Suggest TWO possible differentials (other than AF) which may cause palpitations.

Answer 12

• Other arrythmias
• Vasovagal
• Anaemia, hypovolaemia
• Electrolyte disturbances

Question 13

Suggest TWO possible differentials (other than AF) which may cause syncope.

Answer 13

• Vasovagal
• Other arrythmias
• Hypovolaemia
• Psychogenic

Question 14

Suggest TWO possible differentials (other than AF) which may cause dyspnoea.

Answer 14

• Respiratory conditions (PE, lung cancer)
• Heart failure
• Anxiety

Question 15

Suggest TWO possible differentials (other than AF) which may cause chest pain.

Answer 15

• Cardiac - aortic dissection, MI, pericarditis, chest wall
• GI - GORD
• Respiratory - PE, pleural effusion, infection