Atrial Fibrillation Flashcards
Define AF
Chaotic, irregular atrial rhythm, 300-600bpm to which the AV node responds intermittently
- thus produces an irregular ventricular rhythm
What are the causes of AF
Cardiac - heart failure, MI, HTN, mitral valve disease, congenital heart disease, endocarditis and constrictive pericarditis
Pulmonary - PE, pneumonia and bronchocarcinoma
Other - hyperthyroidism (fast AF), alcohol, post-op, sepsis, high caffeine, anti-arrhythmic drugs, hypokalaemia, sarcoidosis and haemachromatosis
What is lone AF
No other cause can be found
How does AF present
May be asymptomatic, especially in chronic AF Chest pain Palpitations Dyspnoea Dizziness/syncope
What do you find when examining a patient with AF?
Irregularly irregular pulse
- apical pulse rate is greater than the radial rate
- 1st heart sound is variable
- signs of LV dysfunction
Examine the whole patient because AF typically has a non-cardiac cause
What investigations are required in ?AF and what will they show
ECG - absent P waves and irregular QRS complexes (normal shape because AV node conduction is normal)
Bloods
- U&Es to check for renal dysfunction
- cardiac enzymes
- TFTs in case it is secondary to hyperthyroidism
Echo
- atrial enlargement, mitral valve disease and poor LV function may be visible
Briefly outline the management of acute AF (AF< 48h or patient is younger with an identifiable cause)
If patient has adverse signs
- ABCDE and senior input
- DC cardioversion
- amiodarone (chemical cardioversion) if unsuccessful
If patient is stable and AF started <48 hours ago
- start heparin (in case cardioversion is delayed)
- DC cardioversion for rhythm control
- OR amiodarone
Patient stable and AF started >48 hours ago
- rate control (beta-blocker)
- patient would have be anticoagulated for at least 3 weeks before rhythm control is attempted
Treat underlying cause
Briefly outline the management of chronic AF
Goals are rate control and anti-coagulation
- rhythm control is not needed as rate control is just as effective
Anticoagulation
- direct oral anti-coagulant
- warfarin
Rate control
- beta-blocker or rate limiting calcium channel blocker
(- digoxin or amiodarone can be added if ineffective)
What are the adverse signs in acute AF?
Shock
Myocardial ischaemia
Syncope
Heart failure
In chronic AF, when is rate control not as effective as rhythm control?
Symptomatic Heart failure Younger patients 1st time lone AF presentation AF is from a corrected precipitant
How is risk of embolic stroke assessed in AF patients?
CHA2DS2VASc score balance against HAS-BLED score
- if CHA2DS2VASc is >1 in women or >0 in men, anti-coagulation should be considered
Describe the components of the CHA2DS2VASc score.
Carciac failure - 1 Hypertension - 1 A2 - age > 75yrs - 2 Diabetes Mellitus - 1 S2 - stroke/TIA/VTE in past - 2 Vascular disease - 1 Age >65yrs - 1 Sc - sex (female) - 1
What are the components that should be assessed as part of the HAS-BLED score?
Labile INR Age >65 Medications causing bleeding (e.g. NSAIDs) Alcohol abuse Uncontrolled hypertension History/predisposition to major bleeding Renal disease Liver disease Stroke history 1 point for each
If rhythm control is deemed appropriate in chronic AF, how is it undertaken?
Elective DC cardioversion - TOE to check for thrombi in the atria - if there is increased risk of cadioversion failure, then given amiodarone to be taken 4 weeks before and 12 months after Elective chemical cardioversion - flecainide or amiodarone In refractory cases - AV node ablation with pacing - pulmonary vein ablation
How is paroxysmal AF managed?
‘pill in the pocket’ - satalol or flexainide PRN
- used in infrequent AF
Ablation can be used for recurrence
