Atrial Fibrillation

A rapid irregular atrial rhythm at 300-600 bpm. The AV node blocks most of these impulses and only responds intermittently (hence irregular QRS). Cardiac output is reduced by 10-20% as ventricles are not primed properly by atria

Main risk is from clots forming from pooling blood in atria leading to ischaemic Stroke

Causes/Factors

SMITH pneumonic:

• Sepsis - pneumonia
• Mitral valve pathology
• Ischaemia - Coronary Artery Disease
• Thyrotoxicosis
• Hypertension

Lifestyle:

• Alcohol
• Caffeine

Symptoms

• Chest pain
• Palpitations
• Dyspnoea
• Syncope/pre-syncope
• May be asymptomatic

Signs

• Irregularly irregular pulse
• 1st heart sound is of variable intensity
• Signs of underlying cause

Diagnostic Tests

• ECG
• Blood: Thyroid function test
• Echo: look at valvular (mitral/aortic) and LV function

Paroxysmal	Persistent	Permanent
Episodes lasting >30 seconds but <7 days (often less than 48 hours)	Episodes lasting >7 days	Longstanding >1 year
Self-terminating	Not self-terminating
Recurrent

Management

Adverse features

Atrial fibrillation in patients with the follow should be defibrillated using synchronised DC cardioversion:

• Heart failure
• Myocardial ischaemia
• Shock
• Syncope

Paroxysmal AF

For intermittent short duration AF, “pill-in-the-pocket” strategy can be used. Patient can take a pharmacological cardioversion only when they feel symptoms of AF begin.

Rate control - slows down the heart rate to prevent symptom of palpitations and improve heart beat efficiency

• $\beta$ blocker
• Calcium channel blockers (diltiazem, verapamil)
• Digoxin

Rhythm control - convert the hearth rhythm back into sinus rhythm

• Amiodarone
• Electric (DC) cardioversion

Info

Most common combination of drugs in AF is bisoprolol + apixaban

No real difference in prognosis between rate or rhythm control but rate is more common as better symptomatic improvement

Anticoagulation - CHA${}_2$DS${}_2$-VASc score to determine whether to anticoagulate in AF. Do not withhold anticoagulation just on the basis of falls risk.

Congestive cardiac failure (1 point) Hypertension (1) Age 65-74 (1) Age 74+ (2) Diabetes (1) Stroke/TIA/thromboembolism (2) Vascular disease (1) Sex Category (1 if female)

A score of 2 = annual stroke risk of ~2-4% 3 = 3-6% risk

Increased chance of bleeding but bleeding is a better outcome than a stroke

ORBIT score used to predict risk of bleeding in AF

Variable	Points
Haemoglobin <130 g/L (M) <120g/L for females	2
Age >74 years	1
Bleeding history	2
Renal impairment (eGFR <60)	1
Treatment with antiplatelet agents	1
No formal rules on how to act on the ORBIT score but should be taken into account.

ORBIT score	Risk group	Bleeds per 100 patient-years
0-2	Low	2.4
3	Medium	4.7
4-7	High	8.1