Atrial Fibrilation Flashcards
What is atrial fibrillation?
Supraventricular tachyarrhythmia resulting from irregular, disorganized electrical activity + ineffective contraction of the atria.
3 Patterns of AF
Paroxysmal AF
Persistent AF
Permanent AF
What is paroxysmal AF?
AF lasting >30s but <7 days (often <48h).
Self-terminating + recurrent.
What is persistent AF?
AF >7 days (spontaneous termination unlikely to occur after this time)
or <7 days but requiring cardioversion.
What is permanent AF?
AF that:
failed to terminate with cardioversion
OR
terminated but relapsed within 24h
OR
longstanding AF (>1y) in which cardioversion is CI or not been attempted
What 2 pathophysiological consequences may result due to loss of active ventricular filling?
Stagnation of blood in atria leading to thrombus formation + risk of embolism, increasing risk of stroke.
Reduction in CO: may lead to HF
Give 2 epidemiological facts on AF
VERY COMMON in elderly
M > F
What are the 4 most common causes of AF?
Coronary artery disease
HTN
Valvular heart disease
Thyrotoxicosis
What 3 lifestyle factors can cause AF?
Caffeine intake
Excessive alcohol intake
Obesity
What are 4 symptoms of AF?
Often ASYMPTOMATIC Palpitations Chest pain Dyspnoea Syncope (if low output)
List 3 possible signs of AF
Irregularly irregular pulse
Apical pulse rate > radial pulse rate
Signs of thyroid disease/ valvular disease
What investigation is required to confirm diagnosis of AF?
ECG
+/- ambulatory ECG for paroxysmal
Describe an ECG in AF
Chaotic baseline
Absent p waves
Irregular intervals between QRS complexes
List the 4 life-threatening features of tachycardias
Shock (Hypotension)
Syncope
Signs of myocardial ischaemia
Signs of Heart failure
What characterises Atrial flutter?
SVT
Similar symptoms as AF
Saw tooth pattern on ECG
Once AF is identified on ECG, what investigations are performed?
Bloods
Echo (TTE/ TOE)
What investigations can be performed to aid identification of underlying cause of AF?
FBC (Infection, Anaemia)
U+Es (Electrolyte imbalance)
TFTs (Thyrotoxicosis)
Cardiac enzymes
What 4 states may be seen on echocardiogram in AF?
Mitral valve disease
LA dilatation
LV dysfunction
Structural abnormalities
What are the 3 main components of management in AF?
Rhythm control
Rate control
Reduce stroke risk
When should rhythm control be tried first line in AF?
Haemodynamically unstable
New onset AF <48h
Heart failure (primarily caused by AF)
Reversible cause.
Describe management of haemodynamically unstable patient with AF
DC cardioversion
If rhythm control is indicated in a haemodynamically stable patient, describe management?
<48h: Heparinise + cardioversion
>48h: rate control + anti-coagulate for >,3w OR TOE to exclude a left atrial appendage thrombus then proceed
Describe ongoing management if AF is confirmed as being less than 48h and resolved with DC cardioversion
Further anticoagulation unnecessary
If onset of AF was more than 48 hours ago, why must a patient be anti-coagulated for at least 3 weeks prior to cardioversion?
High risk of cardioversion induced thromboembolism as clot likely to have formed in atria
What is used in pharmacological cardioversion?
Structural heart disease: Amiodarone
NO structural heart disease: Flecainide
Describe electrical cardioversion
Synchronised to R wave to prevent delivery of a shock during the vulnerable period of cardiac repolarisation when VF can be induced.
What indicates high risk of cardioversion failure? How can this be mitigated?
Previous failure or AF recurrence
Give at least 4w amiodarone or sotalol prior to DC cardioversion
Which drugs are used for rate control in AF?
B-blockers
Rate limiting CCB e.g. Diltiazem
Digoxin
List 3 b-blockers used in AF
Metoprolol
Atenolol
Propanolol
Name a common contraindication to B-blockers in AF. What should be used first line?
Asthma
Use CCB e.g. Diltiazem
In which patients with should nondihydropyridine CCBs be avoided?
Acute decompensated HF
Which drug is used second line for rate control in AF?
Digoxin
What non-pharmacological method can be used for rate control in AF?
Catheter ablation
(percutaneous, via groin)
ablates faulty electrical pathways resulting in AF
Give 3 indications for catheter ablation in AF
Recurrent AF
Refractory to medical rate control
If don’t tolerate drugs
Describe the use of anticoagulation with catheter ablation
Anticoagulate for 4w prior + during procedure
Catheter ablation controls rhythm but doesn’t reduce stroke risk
Continue anticoagulation as per CHADSVASc
Give 4 complications of catheter ablation for AF
Cardiac tamponade
Stroke
Pulmonary vein stenosis
Recurrence of AF
What tool is used to assess and manage stroke risk in AF?
CHA2DS2-Vasc Score
What are the elements of CHA2DS2VASc?
Congestive HF 1
HTN (inc. treated HTN) 1
Age >= 75y (2), 65-74y (1)
Diabetes 1
S2 Prior Stroke, TIA or thromboembolism 2
Vascular disease (inc. IHD + PAD) 1
Sex (F) 1
Describe the anticoagulation strategy based on CHA2DS2VASc score
0: No Tx
1: M: Consider anticoagulation
F: No Tx (because score 1 only due to their gender)
>,2: Offer anticoagulation
If CHA2DS2VASc score suggests no need for anticoagulation, what must be performed?
TTE
to exclude valvular heart disease
Vavular heart disease in combination with AF is an absolute indication for anticoagulation.
On what grounds should be NOT withold anticoagulation?
Solely on the grounds of age + falls risk
What scoring system is used to calculate risk of bleeding in patients with AF considering anticoagulants?
ORBIT
Age >75y
Anaemia: Hb <130 in M, <120 in F
Bleeding hx
Renal impairment: eGFR <60
Tx with antiplatelets
How can you remember the ORBIT parameters?
Old (age)
Red cells (anaemia)
Bleeding hx
Impairment (renal)
Treatment (anti platelet Tx)
What class of drug is used first line for anticoagulation in AF? Give 4 examples
DOACs
Apixaban
Dabigatran
Edoxaban
Rivaroxaban
What drug is used for anticoagulation in AF when DOACs are contraindicated?
Warfarin
What is are the main complications of AF?
THROMBOEMBOLISM
Worsening of existing heart failure
What mnemonic lists the causes of AF?
Dehydrated PIRATES Dehydration Pulmonary disease: PE Ischaemia: HTN, HF, IHD Rheumatic heart disease Anaemia, Atrial myxoma Thyrotoxicosis Ethanol abuse Sepsis
What sign may you see on ECG in a patient taking digoxin?
Normal QRS with ‘scooped’ ST depression
aka ‘revere tick sign’
What are the 4 categories of aetiologies of causes of ST depression with normal QRS?
Ischaemia
Hypokalemia
Digoxin
Normal variant
What should be used for long term stroke prevention in patients with AF once haemorrhage has been excluded?
Following TIA: DOAC (or warfarin) immediately
Following acute stroke: DOAC (or warfarin) after 2w (anti-platelet in the interim)
