atrial fibrillation (AF)

Question 1

define AF

Answer 1

arrhythmia (disrupted rhythm of cardiac beat) originating from atrial tissue

common type of supraventricular arrhythmia - above ventricle - atria

always associated with irregular heartbeat - leads to disruption of circulation around the body

Question 2

describe a normal impulse

Answer 2

1) generated by SA node

2) propagated through atrial tissue

3) reaches AV node

4) travels through AV node slowly

5) travels through bundle of his

6) conducted simultaneously down 3 bundle branches

7) distributed through ventricular tissue by embedded purkinje fibres

Question 3

describe an impulse in atrial fibrillation

Answer 3

1) impulse generated in atrial tissues, SAN and other focal activation, through reentry pathways instead of passing down AVN and bundle of His

2) bombards AVN in rapid + chaotic fashion

3) results in irregular heartbeat + tachycardia

Question 4

why does AF lead to rhythm abnormality

Answer 4

disorganised electrical impulses in atria - cause atria to fibrillate at a rate of 300-600bpm

some impulses pass from AVN to ventricles - contract in an irregular manner

loss of coordination b/w atria & ventricles - leads to irregular contractions

less blood filled in atria - leads to reduced CO - risk of cardiac failure

Question 5

risk factors of AF

Answer 5

male gender
family history
alcohol
caffeine
sepsis
hyperthyroidism
hypertension
congenital heart disease
HF
ischaemic heart diseases

Question 6

symptoms of AF

Answer 6

could be asymptomatic
palpitations
dyspnoea - SOB
fatigue
chest discomfort
dizziness

Question 7

classification of AF

Answer 7

paroxysmal - recurrent from 48hours - 7 days, can revert back to sinus rhythm (normal) by itself

persistent - recurrent > 7 days, can revert back to sinus with medical intervention

permanent - longstanding - cannot revert back to sinus

AF - progressive disease from paroxysmal to permanent

Question 8

diagnosis of AF

Answer 8

normal ecg - p, qrs and t waves

AF ecg- no p wave, very irregular rhythm

rate may be fast or slow depending on rate of AVN conduction

confirmed by ECG or ILR - implantable loop recorder

Question 9

what are the further investigation tests?

Answer 9

if they have other conditions or comorbidities that are causing AF e.g. HF or hyperthyroidism or sepsis

echocardiogram
chest X-ray
thyroid function tests
blood tests - FBC etc.

Question 10

explain the pharmacological management of AF

Answer 10

rate vs rhythm control:
- always prefer rate control first

rate control to slow down ventricular rhythm to improve symptoms reduce O2 demand - supply mismatch - increase CO

drugs such beta blockers, CCB - titrate up until resting HR is <80bpm in symptomatic patients or more lenient <110bpm in asymptomatic patients

rhythm control:
- shock heart electrically or control rhythm pharmacologically to restore sinus rhythm
- pharmacological approach - anti-arrhythmic class 1 or 3 drugs
- direct current cardiovertion
- catheter ablation

Question 11

rate control strategy - guidelines

Answer 11

1st line offer a BB or rate-limiting CCB unless person is sedentary or cannot use rate-limiting options

2nd - digoxin for people who are sedentary

can use digoxin with BB or CCB

amiodarone has rate controlling properties but don’t use for long-term rate control

if patient is still symptomatic - rhythm control

avoid BB, CCB, digoxin in wolff-Parkinson-white syndrome

Question 12

cardioversion in AF

Answer 12

if patient has acute condition e.g. HF or is still symptomatic after rate-control - need cardioversion

can either cardiovert electrically or pharmacologically - DCC or amiodarone

but if using rhythm control - need to make sure their risk of stroke is very low
- absence of atrial thrombi needs to be ensured
- because thrombi present + cardioversion = 91% stroke rate
- in left atrium - there is an opening - if cardiovert - high risk that clot will go from heart to brain
- so need to use anticoagulant

Question 13

Rhythm control strategy for persistent AF

Answer 13

persistent AF - duration >48hrs

if not on anticoagulants
- then give anticoagulation for 3 weeks before cardioversion

if already on anticoagulants
- risk of stroke already low so can do cardioversion or amiodarone therapy - electrical or pharmacological

Question 14

rhythm control strategy for paroxysmal AF

Answer 14

paroxysmal AF:

offer BB - rate control

pill in the pocket strategy - no drug treatment as paroxysmal will go back to normal

for patients with HF or Left ventricular impairment
- can only give amiodarone
- do not give class 1c anti-arrhythmic drugs to people with heart disease

if rhythm control treatment fails - ablation strategy

Question 15

describe rhythm control pharmacotherapy?

Answer 15

3 weeks anti coagulation before starting these:

class III anti-arrhythmic amiodarone - safe in patients with structural heart disease, HF

class 1c anti-arrhythmic flecainide, c/i in patients with structural heart disease

other rhythm control drugs:
soltalol - BB with anti-arrhythmic properties
dronaderone - c/i in patients with HF

Question 16

what is catheter ablation?

Answer 16

catheter ablation - used for treatment of irregular heartbeats called arrhythmias

uses heat or cold energy to create tiny scars in the heart

these tiny scars block faulty heart signals - restoring typical heartbeat - sinus rhythm

Question 17

what is the link b/w AF and stroke?

Answer 17

it is important regardless of rate or rhythm control to assess every patient that has AF for risk of stroke
- approximately 1in5 stroke patients have AF as underlying score - often fatal

AF - inadequate blood flow to areas of heart - blood clot

blood clots can dislodge and travel to brain - result in stroke

Question 18

what assessments need to be done for stroke prevention and anticoagulation in AF patients?

Answer 18

chadvasc score - assesses risk of stroke in AF patients

ORBIT bleeding score - assesses potential risk of bleeding in patients on anticoagulants

need to weigh up these and decide with patient if anticoagulant will be given or not
most of the time - stroke risk outweighs bleeding risk as stroke is more fatal

Question 19

guidelines for giving anticoagulation

Answer 19

if chadvasc score > or equal to 2 - give anticoagulant

if chadvasc score = 1 in men - give anticoagulant

if chadvasc score < or equal 1 in women and =0 in men - do not give anticoagulant

Question 20

what are the anticoagulant drug options

Answer 20

1st line - DOAC - direct acting anticoagulant e.g. rivoroxaban, edoxaban
- if c/i or patients already on warfarin switch to warfarin
- take into account TTR - time in therapeutic range
- therapeutic range - 2-3 times

vitamin K antagonist - warfarin
- calculate TTR at each visit
- number of INR within therapeutic range over total number x 100
- tells you if patient is poorly controlled on warfarin - consider switching to DOAC
- poorly controlled - 2 INR values >5, 1INR value > 8 or TTR <65%

Question 21

what do you do if patient is at a high risk of stroke and high risk of bleeding or c/i to anticoagulation (DOACs & warfarin)

Answer 21

left atrial appendage occlusion
- non pharmacological way of removing clot if cant use anticoagulant

• small ear shaped sac in muscle wall of left atrium called LAA
• in AF - atria can’t effectively squeeze blood from atria to ventricle - can collect in LAA and cause clot - when clot is pumped out can cause stroke
• process is safe and effective
• stent blocks the pouch so clot cannot form

Question 22

common anticoagulation counselling

Answer 22

alert patients to report bleeding or bruising

explain dosage and monitoring

drug interactions

OTC medicines

alert cards/booklets

Question 23

summary of AF

Answer 23

irregular cardiac arrhythmias

risk of stroke - fatal

rate control and rhythm control

anticoagulation assessment

treatment aims to reduce symptoms and prevent stroke