Atrial Fibrillation

Question 1

Mechanism of AF

Answer 1

Dilatation (progressive) and fibrosis of atria
-Activate ventricle very fast
-Multiple wavelets, some, AV node filters some out

Question 2

Types of AF

Answer 2

1. Paroxysmal – intermittent, sporadic, unpredictable, spontaneous termination
2. Persistent – lasting longer than 7 days but where the initial and primary plan is to restore sinus rhythm
3. Permanent – lasting longer than 7 days with no plans to restore sinus rhythm

Question 3

Fibrillation vs flutter

Answer 3

A fib= fibrillatory waves
A Flutter= sawtooth pattern, increased electrical activity arises in R atrium only, 300 cycles per second- AV node filters out most usually 150 or lower bpm

Question 4

Causes of AF

Answer 4

-Idiopathic
-Hypertension
-CHD
-Alcohol
-Thyroid
-Mitral valve disease
-LVSD
-Cardiomyopathy
-Pulmonary disease
-Pneumonia
-Post cardiac surgery
-Congenital Heart Disease
-Veteran athletes

Question 5

Epidemiology of AF

Answer 5

-Men affected more than women (coronary heart disease)
-Increase frequency with age

Question 6

Complications of AF

Answer 6

-Stroke (embolism L atrium)
-Peripheral embolism (legs, arms, kidney, spleen, gut, coronary artery)
-Heart failure (poor response- prolonged tachycardia)
-Mitral and tricuspid regurgitation (long term, remodelling of atria and dilatation of valvular rings)

Question 7

Presenting symptoms and signs of AF

Answer 7

-Asymptomatic - is not uncommonly detected incidentally at routine health screening check for BP or diabetes for example
-Breathlessness/ dyspnoea
-Palpitations
-Syncope/dizziness
-Chest discomfort
-Stroke/transient ischaemic attack
-Sign – irregular pulse

Question 8

Clinical investigations of AF

Answer 8

-Routine bloods= U&E, glucose, FBC, thyroid function tests

-Electrocardiogram (ECG), irregular pulse has been detected, can see ectopic beats

-Ambulatory ECG monitor (24-hour tape) =If the 12 lead is ECG shows sinus rhythm and you suspect paroxysmal AF or if you want to assess the ventricular rate

-Transthoracic echocardiography (TTE) to assess for underlying structural heart disease

-Transoesophageal echocardiography is occasionally used to exclude thrombus in the left atrium/ appendage

Question 9

Two strategies of AF

Answer 9

-Rhythm control= restore SR
-Rate control= leave in AF

Question 10

Rhythm control

Answer 10

-Cardioversion
-Short-medium term use of antiarrhythmic drugs
-Short term-medium anticoagulation
-Restores AV synchrony
-Improves cardiac output
-Allows the atria to remodel favourably

Question 11

Rate control

Answer 11

-Control rate with drugs
-Long term anticoagulation (risk of bleeding)
-Avoids need for general anaesthetic
-Loss of AV synchrony may affect cardiac function
-Atria may adversely remodel
-Leading to MR and TR

Question 12

Which patients have rhythm control?

Answer 12

-Younger patients (<60)
-Athletic/fit
-Symptomatic – palps, SOB
-Normal heart structure
-Normal left atrium size
=Able to maintain sinus rhythm
-Heart failure linked to AF
-First episode
-Short duration of AF (<6 months)
-Never had DCCV before
-Euthyroid
-Patient preference

Question 13

Which patients have rate control treatment?

Answer 13

-Older patients (>65)
-Structurally abnormal heart- valves, LVSD, LVH
-Dilated left atrium- unlikely to restore long-term
-Asymptomatic
-Long duration of AF (>12 months)
-Multiple previous attempts at DCCV
-Thyrotoxic (may attempt DCCV once treated)
-Contra-indication to GA (general anaesthetic)

Question 14

Types of rhythm control treatment

Answer 14

1. Pharmacological cardioversion: using intravenous flecainide or amiodarone in people with no evidence of structural or ischaemic heart diseaseor use amiodarone in people with evidence of structural heart disease, no general anaesthesia (GA) required
2. Direct current cardioversion (DCCV): synchronised transthoracic electric shock using direct current from a standard defibrillator at 100-200 Joules under light GA.

Question 15

Risk of embolism in rhythm control

Answer 15

<48 hours in AF -low risk of embolism
>48 hours in AF -high risk of embolism

Do not cardiovert a patient that has been in AF for longer than 48 hours unless anticoagulated for >4 weeks beforehand

Exception: AF with haemodynamic instability requires urgent electrical cardioversion

Question 16

AF<48hr duration- drug therapy and cardioversion in rhythm control

Answer 16

-Short term anticoagulation with IV or SC heparin during hospital stay

-Pharmacological/ electrical cardioversion

-After cardioversion: start a drug that reduces risk of AF recurrence for short-medium term duration (<12 weeks) e.g. betablockers or verapamil or diltiazem or amiodarone (in people with LVSD). NO need for longer term anticoagulation.

Question 17

AF>48hr duration- drug therapy and cardioversion in rhythm control

Answer 17

-Delay cardioversion until maintained on therapeutic oral anticoagulation for > 4 weeks with warfarin or NOAC,

-Add rate control while waiting to cardiovert: *digoxin, beta blocker, or rate limiting calcium antagonist (diltiazem or verapamil)

-After cardioversion: continue anticoagulation and continue a drug that reduces the risk of recurrent AF for 6-12 weeks e.g. betablockers or verapamil or diltiazem or amiodarone (in people with LVSD).

Question 18

Rate control drug therapy

Answer 18

NO planned cardioversion: (permanent AF)- 90/80 bpm at rest aim

-Assess the need for longer term oral anticoagulation using an appropriate stroke risk-assessment tool (e.g. cha2ds2-vasc score)

-Assess long term bleeding risk (HASBLED score) –

-Add rate limiting medication tailored to underlying clinical conditions e.g. betablocker, digoxin, verapamil (not with beta blocker), diltiazem (hypotension), amiodarone

-Long term oral anticoagulants: warfarin (weekly then 4-6 weekly INR), NOAC – apixaban, rivaroxaban, dabigatran (No INR required, more expensive, lower risk of bleeding/haemorrhage)

Question 19

Stroke Risk Assessment Criteria

Answer 19

-Age= <65 (0), 65-74 (1), >75 (2)
-Sex: male (0), female (1)
-Congestive heart failure (1)
-Hypertension (1)
-Stroke/TIA/thromboembolism (2)
-Vascular disease history (prior MI, peripheral artery disease, aortic plaque) (1)
-DM (1)

0.2-12%

Question 20

Bleeding risk assessment criteria

Answer 20

-Hypertension
-Renal disease
-Liver disease
-Stroke
-Prior major bleeding or predisposition to bleeding
-Labile INR (up and down)
-Age>65
-Medication usage predisposing to bleeding
-Alcohol

Question 21

Advanced treatment of AF

Answer 21

-Pulmonary vein isolation (PVI): percutaneous
-PVI: surgical cryo-ablation
-Left atrial appendage isolation or removal (for anticoagulant contraindication)

Question 22

PVI percutaneous

Answer 22

Cryo- or Radiofrequency Ablation therapy to isolate the pulmonary veins from the left atrium, reserved for patients with ongoing symptoms of palpitation, breathlessness, chest discomfort with or without signs of heart failure despite optimal medical management with appropriate rate limiting drugs and anticoagulation

Question 23

AF screening strategies

Answer 23

-Check pulse manually during routine health checks in primary care
-Use smart phone based single lead ECG technologies
-Smart-watch based technologies (Apple series 4 & 5)