Atrial fibrillation: a very basic introduction

Question 1

Atrial fibrillation (AF) ?

Answer 1

• is the most common sustained cardiac arrhythmia. It is very common, being present in around 5% of patients over aged 70-75 years and 10% of patients aged 80-85 years.
• Whilst uncontrolled atrial fibrillation can result in symptomatic palpitations and inefficient cardiac function probably the most important aspect of managing patients with AF is reducing the increased risk of stroke which is present in these patients.

Question 2

Types of atrial fibrillation?

Answer 2

AF may by classified as either: ​

• first detected episode,
• paroxysmal,
• persistent or
• permanent.

Question 3

First detected episode?

Answer 3

first detected episode (irrespective of whether it is symptomatic or self-terminating)

Question 4

Recurrent episodes?

Paroxysmal AF?

Persistant AF?

Answer 4

• recurrent episodes, when a patient has 2 or more episodes of AF.
• If episodes of AF terminate spontaneously then the term paroxysmal AF is used. Such episodes last less than 7 days (typically < 24 hours).
• If the arrhythmia is not self-terminating then the term persistent AF is used. Such episodes usually last greater than 7 days

Question 5

Permanent AF?

Answer 5

• permanent AF there is continuous atrial fibrillation which cannot be cardioverted or if attempts to do so are deemed inappropriate.
• Treatment goals are therefore rate control and anticoagulation if appropriate

Question 6

Symptoms and signs?

Answer 6

Symptoms:

• palpitations
• dyspnoea
• chest pain

Signs:

• an irregularly irregular pulse

Question 7

Investigations?

Answer 7

Investigations:

• An ECG is essential to make the diagnosis as other conditions can give an irregular pulse, such as ventricular ectopics or sinus arrhythmia.

Question 8

Management?

Answer 8

Management:

• There are two key parts of managing patients with AF:
  1. Rate/rhythm control
  2. Reducing stroke risk

Question 9

Rate vs. rhythm control?

Answer 9

Rate vs. rhythm control;

There are two main strategies employed in dealing with the arrhythmia element of atrial fibrillation:

1. rate control: accept that the pulse will be irregular, but slow the rate down to avoid negative effects on cardiac function
2. rhythm control: try to get the patient back into, and maintain, normal sinus rhythm. This is termed cardioversion. Drugs (pharmacological cardioversion) and synchronised DC electrical shocks (electrical cardioversion) may be used for this purpose

Question 10

Rate Vs Rhythm?

Answer 10

• For many years the predominant approach was to try and maintain a patient in sinus rhythm.
• This approach changed in the early 2000’s and now the majority of patients are managed with a rate control strategy.
• NICE advocate using a rate control strategy except in a number of specific situations such as coexistent heart failure, first onset AF or where there is an obvious reversible cause.

Question 11

Rate control?

Answer 11

• A beta-blocker or a rate-limiting calcium channel blocker (e.g. diltiazem) is used first-line to control the rate in AF.
• If one drug does not control the rate adequately NICE recommend combination therapy with any 2 of the following:

1. a betablocker
2. diltiazem
3. digoxin

Question 12

Rhythm control?

Answer 12

• As mentioned above there are a subgroup of patients for whom a rhythm control strategy should be tried first.
• Other patients may have had a rate control strategy initially but switch to rhythm control if symptoms/heart rate fails to settle.
• When considering cardioversion it is very important to remember that the moment a patient switches from AF to sinus rhythm presents the highest risk for embolism leading to stroke.
• Imagine the thrombus formed in the fibrillating atrium suddenly being pushed out when sinus rhythm is restored.
• For this reason patients must either of had a short duration of symptoms (less than 48 hours) or be anticoagulated for a period of time prior to attempting cardioversion.

Question 13

Reducing stroke risk?

Answer 13

• Some patients with AF are at a very low risk of stroke whilst others are at a very significant risk.
• Clinicians use risk stratifying tools such as the CHA2DS2-VASc score to determine the most appropriate anticoagulation strategy.

Question 14

Answer 14

Question 15

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Question 16

Answer 16