Atrial Fibrillation/Flutter Flashcards
What is atrial fibrillation? What happens to the cardiac output?
A supraventricular tachyarrhythmia with chaotic, irregular atrial rhythm of rate 300-600bpm. AV node response intermittently so there is an irregular ventricular rhythm. CO drops by 10-20% because the ventricles are not being properly primed by the atria.
How common is AF?
- AF - 9% of elderly >80yrs affected
What is shown here?
Atrial fibrillation
What is the main risk associated with atrial fibrillation? What is done to prevent this and how does this affect treatment regime?
Embolic stroke
Anticoagulation reduces the risk from 4% to 1% - DOACs are recommended by NICE e.g. apixaban, dabigatran, edoxaban, rivaroxaban. Warfarin is second line.
Cardioversion therapy can only be done if AF started <48h ago as left atrial appendage (LAA) thrombus may form so patient must have _>_3 weeks anticoagulation before DCC.
What are the causes of AF? What does “lone AF” mean?
- Age
- Coronary artery disease
- Cardiac disease e.g. heart failure, hypertension, ischaemic heart disease, valve disease, hx arrhythmias
- Stroke/TIA
- OSA
- Obesity
- Alcohol use
- Previous cardiothoracic intervention
- Diabetes
- Obesity
- Hyperthyroidism
- Athletic levels of physical activity (limited data)
Lone AF = no cause found
What are the presenting clinical features of AF?
- Asymptomatic in up to 87%
- Palpitations - on rest or activity
- Irregular pulse
- Dyspnoea
- Fatigue/lightheadedness
- Anxiety
- Polyuria - due to tachycardia induced diuresis and natriuresis
AF may present with complications of emboli e.g. stroke, or with heart failure signs.
What is the difference between atrial flutter and fibrillation in simple terms?
- In atrial fibrillation, the atria beat irregularly and the electrical impulses are chaotic. ECG shows fibrillatory waves of varying shapes, amplitudes, and timing associated with an irregularly irregular ventricular response when atrioventricular (AV) conduction is intact.
- In atrial flutter, the atria beat regularly, but faster than usual and more often than the ventricles, so you may have 2 /3/4 atrial beats to every one ventricular beat. The electrical impulses are organized.
How are atrial flutter and fibrillation related?
One may turn into the other
They are also treated similarly - but DC cardioversion is preferred over pharmacological cardioversion in atrial flutter.
- If rate control is difficult in atrial flutter then IV amiodarone may be used
- Recurrence in atrial flutter is also high so radiofrequency ablation may be used for long-term management.
How do you diagnose AF? What other investigations should be done?
New onset atrial fibrillation
- ECG - no discernable or distinct P wave activity, irregularly irregular ventricular rate
Other:
- FBC - for anaemia or infection trigger
- Clotting profile - baseline for anticoag tx
- Renal function - U&E, Cr, exclude hypo/hyper K, hypo Mg and CKD triggers
- TFTs
- CXR - lung pathology cause
- TTE - LV size and function, valvular disease
- Depending on PC: troponin, ABG, CRP, LFTs, ESR, TOE, Holter monitor, CT angio, brain CT/MRI, CTPA
- Serum electrolytes, cardiac biomarkers, TFTs, CXR, echo (transthoracic and transoesophageal)
- Other: exercise stress test
How do you manage new onset atrial fibrillation?
If haemodynamically unstable → ABCDE → DC cardioversion immediately as per per-arrest → follow with 4 weeks anticoagulation
For haemodynamically stable if:
- < 48 hours: rate* or rhythm** control
- ≥ 48 hours or uncertain (e.g. patient not sure when symptoms started): rate* control
- if considered for long‑term rhythm control, delay cardioversion until they have been maintained on therapeutic anticoagulation for a minimum of 3 weeks
- Catheter ablation - if no response to antiarrhythmics; done percutaneously via groin. Anticoagulate for 4 weeks before, during procedure and for 2 months after (or lifelong if CHA2DS2VASc _>_2)
*Rate: 1st line - use combination of 2 if one does not suffice
- BB (e.g. atenolol) OR
- CCB (e.g. diltiazem) OR
- Digoxin - not first line anymore as less effective; good if coexistent HF
**Rhythm: i.e. chemical cardioversion
- BB (e.g. sotalol) OR
- Dronedarone - 2nd line, following cardioversion
- Amiodarone - in coexisting HF
What are the signs of haemodynamic instability in AF?
- Hypotension (systolic <90mmHg)
- Chest pain or MI on ECG
- Reduced GCS or syncope
- Heart failure signs
If using warfarin as anticoagulation in AF, what is the target INR range?
INR 2-3
What are the complications of catheter ablation in AF?
- cardiac tamponade
- stroke
- pulmonary vein stenosis
How successful is catheter ablation at getting rid of AF?
50% experience recurrence within 3 months but this often resolves spontaneously
After 3yrs 55% remain in sinus rhythm
If multiple procedures 80% remain in sinus rhythm
What can palpitations post-op signify?
Post-operative atrial fibrillation - common
May be self-limiting but increases risk of :
- haemodynamic derangements
- postoperative stroke
- perioperative MI
- ventricular arrhythmias
- heart failure
The AF may be new, post-MI which was silent, or long standing but now no longer rate controlled.
Which rate controlling medication should be used with caution in certain conditions?
- Beta blcokers - use with caution in COPD
- CCB - preferred if chronic lung disease is present but contra indicated in HF
- Digoxin is a cardiac glycoside - improves cardiac output so used in HF, contraindicated in those who exercise a lot
What is the difference between paroxysmal and persistent AF?
Paroxysmal - terminates spontaneously within 7 days of onset
Persistent - sustained beyond 7 days
Which score should be calculated to work out need for anticoagulation in AF?
CHADS2Vasc
ORBIT is used to calculate bleeding risk
What is the acronym for assessing embolic stroke risk/need for anticoagulation?
CHA2DS2-VASc
- C- congestive heart failure/LV dysfunction
- H- hypertension
- A - Age 65-74y (1) Age >74y (2)
- D - Diabetes
- S - previous Stroke/TIA/thromboembolism(2)
- VA- Vascular disease (MI, PVD, atherosclerosis)
- S C - Sex Category (1 if female with one of above)
Anticoagulate if score is 2 or more (2.2% stroke rate per year). Consider if score is 1.
What do CHA2DS2VASc scores indicate in terms of risk?
What are the components of the ORBIT score for bleeding risk?
- Older age - _>_75yrs → 1 point
- Reduced Hb (<12g/dL F, <13mg/dL M), Hct (<36% F, <40% M) or anaemia→ 2 points
- Bleeding history → 2 points
- Insufficient renal function eGFR <60mg/dL → 1 point
- Treatment with antiplatelets → 1 point
Low risk 0-2
Intermediate risk = 3
High risk = _>_4
NB: HASBLED is less commonly used now but consists of (1 point for each):
- HTN
- Abnormal renal+/- liver function
- Stroke
- Bleeding history
- Labile INR
- Elderly _>_65yrs
- Drugs or alcohol concomitant
Low risk 0-1
Intermediate risk 2
High risk _>_3
In the instance of stroke being the first sign of AF, when should you start anticoagulation?
Exclude haemorrhage first
Commence anticoagulation (DOAC or warfarin) 2 weeks after - give antiplatelets in the intervening period; delay anticoag if the cerebral infarction was large
What are DOACs? Give examples and precautions that should be taken.
NOACs = direct oral anticoagulants e.g. rivaroxaban, dabigatran, apixaban, edoxaban.
- NOACS - don’t require monitoring of anticoagulant activity
- NOACS - must be used with caution in patients with renal impairment and a dose adjustment may be necessary.
How is DC cardioversion carried out?
- Start anticoagulation with LMWH (e.g. enoxaparin) pre-cardioversion; later transition to DOAC
- Make sure patient is fasted state to avoid aspiration
- Call anaesthetics to sedate patient with short-acting general anaesthetic
- Senior support
- Record ECG rhythm strip during and immediately after the shock is delivered
- Monitor BP and oximetry during the procedure
- If initial attempts fail then ensure good skin-to-electrode contact with the pads in the anteroposterior position
