Atrial Fibrillation/ Flutter Flashcards
What is the definition of AF?
Characterised by rapid, chaotic and ineffective atrial electrical conduction. Often subdivided into:
Permanent
Persistent
Paroxysmal
What is the aetiology of AF?
There may be no identifiable cause
Secondary causes lead to an abnormal atrial electrical pathway that results in AF
Systemic Causes
- Thyrotoxicosis
- Hypertension
- Pneumonia
- Alcohol
Heart Causes
- Mitral valve disease
- Ischaemic heart disease
- Rheumatic heart disease
- Cardiomyopathy
- Pericarditis
- Sick sinus syndrome
- Atrial myxoma
Lung Causes
- Bronchial carcinoma
- PE
What is the epidemiology of AF?
VERY COMMON in the elderly
Present in 5% of those > 65 years
May be paroxysmal
What are the presenting symptoms of AF?
Often ASYMPTOMATIC
Palpitations
Syncope (if low output)
Symptoms of the cause of AF
What are the signs of AF upon physical examination?
Irregularly irregular pulse
Difference in apical beat and radial pulse
Check for signs of thyroid disease and valvular disease
What are the appropriate investigations for AF?
ECG
- Uneven baseline with absent p waves
- Irregular intervals between QRS complexes
- Atrial flutter = saw-tooth
Bloods
- Cardiac enzymes
- TFT
- Lipid profile
- U&Es, Mg2+ and Ca2+ = Because there is increased risk of digoxin toxicity with hypokalaemia, hypomagnesaemia and hypercalcaemia
Echocardiogram May show: - Mitral valve disease - Left atrial dilatation - Left ventricular dysfunction - Structural abnormalities
What is the management plan for AF?
First and foremost, try to treat any reversible causes (e.g. thyrotoxicosis, chest infection)
Then after there are two main components:
- Rate control
- Rhythym control
Stroke risk stratification:
- LOW RISK patients can be managed with aspirin
- HIGH RISK patients require anticoagulation with warfarin
- This is based on the CHADS-Vasc Score
How is rhythym control achieved in patients with AF?
If > 48 hrs since onset of AF
- Anticoagulate for 3-4 weeks before attempting cardioversion
If < 48 hrs since onset of AF
- DC cardioversion (2 x 100 J, 1 x 200 J)
- Chemical cardioversion: flecainide or amiodarone
NOTE: flecainide is contraindicated if there is a history of ischaemic heart disease
Prophylaxis against AF
- Sotalol
- Amiodarone
- Flecainide
- Consider pill-in-the-pocket (single dose of a cardioverting drug (e.g. flecainide) for patients with paroxysmal AF) strategy for suitable patients
How is rate control achieved in patients with AF?
Chronic (Permanent) AF
Control ventricular rate with:
- Digoxin
- Verapamil
- Beta-blockers
Aim for ventricular rate ~ 90 bpm
How does the CHADS-Vasc score stratify stroke risk
Based of these risk factors:
Previous thromboembolic event
Age > 75 yrs
Hypertension
Diabetes
Vascular disease
Valvular disease
Heart failure
Impaired left ventricular function
What are the potential complications of AF?
THROMBOEMBOLISM
- Embolic stroke risk of 4% per year
- Risk is increased with left atrial enlargement or left ventricular dysfunction
Worsening of existing heart failure
What is the prognosis for patients with AF?
Chronic AF in a disease heart doesnt usually return to sinus rhythm
