AF Flashcards
What is AF?
Irregular/disorganised rhythm of atria
Disorganised firing of signals from atria
What are the causes?
• HTN
• T2DM
• Hyperthyroidism
How does AF increase the risk of stroke
There is a standstill of blood in the atria, which increases the risk of thrombosis (stroke)
What are the 3 classifications of AF?
• proximal
• persistent
• permanent
Describe Proximal AF
• lasts 30mins + BUT less than 7 days
• self terminating
• recurrent
Describe Persistent AF
• lasts -/+ 7 days
• requires chemical or physical Cardioversion
Describe Permanent AF
• does not terminate with Cardioversion
• or if terminates it returns within 25 hours
Detecting AF in people with irregular pulse, with or without:
• SOB
• palpitations
• chest pain
• stroke/TIA
Diagnosis/Investigations of AF
• Echo
• ECG
AF increases stroke risk by how many folds?
5 folds
List general ADRs of antiarythmics
Gi disturbances:
• nausea
• vomiting
• diarrhoea
CNS disturbances:
• hallucinations
• nightmares
• depression
• psychosis
• sezuires
Others:
• pro arrhythmic- TDP
• visual disturbances
List non drug therapy approaches in AF
• defibrillators
• cardioversion
• pacemakers
• interval Cardioversion defibrillators
Why may patients avoid antiarythmics?
• can cause new arrhythmia
• can increase the frequency of arrhythmia
• can cause ventricular tachycardia (TDP)
What is “Vaugh Williams classification” regarding antiarythmics?
These agents are classified based on their electrical activity towards myocardial cells
List the classes of agents
Class 1a = disopydramide
Class 1b = lidocaine
Class 1c = flecainide
Class 2 = beta blockers
Class 3 = amidarone
Class 4 = non-diydrophyradines - CCBs
Which phases of the action potential do they affect
Class 1 (all) - phase 0
Class 2 - phase 4
Class 3 - phase 3
Class 4 - phase 2
What is the MOA of class 1 agents?
Block na ions from entering voltage gated na channels - this slowing down electrical activity/AP - during phase 0
What is the MOA of class 2 agents?
Beta blockers
• inhibits effects of sympathetic nervous system
• negative inotrope
• negative chronotrope
- during phase 4
What is the MOA of class 3 agents
• blocks k channels, thus prolonging AP duration
What is the MOA of class 4 agents?
Blocks ca ions - during phase 2
What is the main reason behind managing arrhythmia?
Prevent/avoid stroke
^ asses stroke and bleeding risk
CHA2DS2-VASC is used to assess what? And in which patients?
Stroke risk (thrombotic) in patients with the following:
• asymptomatic/symptomatic AF
• atrial flutter
• risk of recurrent arrhythmia after Cardioversion
What does CHA2DS2-VASC stand for?
• congestive cardiac disease
• HTN (including history)
• Age: 75 and over
• Diabetes
• Stroke/TIA
• Vascular disease
• Age: 65-74
• Sex: female
Each score 1 point
Stroke and Age (75+) score 2 each
CHA2DS2-VASC - when to anticoagulant
•Score 2 or more (both genders) = offer anticoagulants
•Score 1 in men = consider anticoagulants
•Score 1 in women = NONE
•Score 0 (both genders) = NONE
ORBIT is used to assess what?
Bleeding risk when:
• starting new anticongulant OR
• review those already on it.
List MODIFIABLE risk factors for bleeding
• poor control of INR
• HTN
• concurrent use of: NSAID + SSRIs + antiplatlets
• anaemia
• renal and hepatic impairment
List NON- MODIFIABLE risk factors for bleeding
• older age
• hx of bleeding
• hx of stroke
• cancer
• liver disease
• dialysis
What is the Treatment for valvular AF
Warfarin
What is the Treatment for non-valvular AF
After calculating stroke risk with scoring system - DOACs
Which rate controlling drugs can be given?
Beta blocker (not sotalol)
OR
Non dihydropyradine CCB
• diltiazem (off label)
• verapamil
DOACs advantages and disadvantages
Advantages:
• quick onset of action
• therapeutic activity is predictable
• target enzyme specificity
• fewer drug-drug interactions
• as affective as warfarin, with less intercrainial haemorrhage
Disadvantage
• more frequent dosing than warfarin (reason for no compliance)
• lack of long term safety data
• expensive
• short half life
• no commercially available antidote
• no evidence for efficacy in valvular AF
Warfarin Advantages and disadvantages
Advantages;
• cheap
• gold standard- used for 50> years
• antidote - vitamin K
• prescriber familiar with management and ADRs
• once daily dosing (better compaince)
Disadvantages
• drug to drug interactions
• food to food interaction
• slow onset of action
• requiring INR testing
• narrow therapeutic windows
• unpredictable therapeutic response
