Arrhythmias: Atrial fibrillation Flashcards
Define atrial fibrillation
Irregular uncoordinated contraction of the atria
Commonly originates near the pulmonary veins.
Name five causes of atrial fibrillation
- Ischaemic heart disease
- HTN
- Valve disease
- MI
- Heart failure
- Cardiothoracic surgery: occurs in 1/3
- Rheumatic heart disease causing mitral stenosis
- Non cardiac: infection; hyperthyroidism; electrolyte depletion; PE
- Lifestyle: excess caffeine; smoking; alcohol
Name 2 significant risk factors for atrial fibrillation
Increased BMI Sleep apnoea
What ECG changes are seen with atrial fibrillation?
- Absent P waves
- Wavy baseline/f waves
- Irregular-irregular R-R intervals
- Narrow QRS complex
- Variable R waves
Name four presenting features of atrial fibrillation
Asymptomatic: incidental finding (30%)
Suspect AF if irregular pulse with ot without:
- Dyspnoea
- Palpitations
- Chest pain or discomfort
- Syncope; dizziness
- Stroke/TIA
How is atrial fibrillation classified?
-
Paroxysmal: <7d duration, commoner in younger
- Acute: onset within previous 48h
- Persistent: >7d duration
-
Permanent:
- Fails to terminate using cardioversion; or
- Longstanding with no further attempts to restore sinus rhythm
Name two complications of atrial fibrillation
- Stroke/TIA
- Heart failure
- Tachycardia-induced cardiomyopathy
- Critical cardiac ischaemia
- Reduced QOL
What is the CHADS2-VASc score? Outline the score
Stroke risk score: Need for anticoagulation in non-valvular AF.
- Congestive heart failure - 1
- Hypertension - 1
- Age 65 to 74 - 1
- Diabetes mellitus -1
- Stroke/TIA - 2
- Vascular disease - 1
- Age 75+ - 2
- Sex category (female) - 1
0: Do not offer anticoagulation
1: Consider (male); do not offer (female)
2+: Offer anticoagulation
What is the HAS-BLED score?
Risk of bleeding assessment for patients on anticoagulation.
- Hypertension - 1
- Abnormal liver or renal function - 1 or 2
- Stroke - 1
- Bleeding - 1
- Labile INR - 1
- Elderly (>65) - 1
- Medication predisposing bleeding or alcohol - 1 or 2
What determines the use of anticoagulants in atrial fibrillation?
Anticoagulation therapy is indicated when the risk of stroke > risk of bleeding
CHADS2-VASc and HAS-BLED scores are used to assess this
Which atrial fibrillation patients are indicated for anticoagulation?
Warfarin for all patients with:
- Rheumatic mitral stenosis
- Prosthetic heart valves
Offered to AF with CHADS2-VASc score 2+
Summarise the immediate management of atrial fibrillation
-
Haemodynamic instability: emergency electrical cardioversion
- If >48h: TOE to assess atrial clots
-
No haemodynamic instablility:
- Onset within 48h: Rate or rhythm control
- Onset after 48h: Rate control
- If for DC cardioversion: needs 3/52 anticoagulation before
- Treat any underlying causes
Rate control: Beta-blockes, Diltiazem, Digoxin
Rhythm control: Flecainide or amiodarone; DC cardioversion
Give two indications for DC cardioversion as management of atrial fibrillation?
- Emergency: haemodynamic instability or shock
- >48h requires TOE to assess atrial thrombus
- Continuous AF with >48hr duration
- Will require 3wk warfarin or dabigatran prior
Outline Singh-Vaughan Williams classification of antiarrhythmic drugs
- Ia: Intermediate Na channel blockers - Quinidine, procainamide
- Ib: Fast Na channel blockers - Lidocaine, phenytoin
- Ic: Slow Na channel blockers - Flecainide, Prepafenone
- II: Beta-blockers - Propranolol, metoprolol, bisoprolol etc.
- III: K channel blockers - Amiodarone, sotalol
- IV: CCBs - Verapamil, diltiazem
- Other: Adenosine, digoxin
Name two contraindications for both Flecainide and Amiodarone
- Structural heart disease
- Ischaemic heart disease
Outline the long-term management of atrial fibrillation
Stroke prevention: Oral anticoagulant
Symptom management
- Rate control
- Beta-blocker or CCB (diltiazem)
- Digoxin: consider if sedentary
- Combination therapy of 2 of the above
- Rhythm control
- Beta-blockers
- Flecainide
- Dronedarone: used after successful cardioversion
- Amiodarone: heart failure; LV impairment
- AVN ‘Pace and ablate’; Implantable cardioverter defibrillator
- Electrical cardioversion: consider for persistent AF
- Consider adding amiodarone to maintain sinus rhythm afterwards
Name three side effects and three absolute contraindications of beta-blockers
Side-effects:
- GI upset
- Bradycardia
- Heart failure; hypotension
- Bronchospasm
- Cold peripheries
Absolute contraindications: Asthma; Marked bradycardia; Heart block
- Avoid non-dihydropyridine CCB due to risk of severe hypotension
Name three side-effects and three contraindications of CCBs
Verapamil SEs:
- Constipation, N+V
- Flushing
- Headaches; dizziness; fatigue
Contraindications: Heart failure, 2nd or 3rd heart block, cardiogenic shock
- Avoid B-blockers due to risk of severe hypotension
What monitoring is required whilst taking digoxin?
Renal function due to its narrow therapeutic index
Reduced in impaired renal function to minimise risk of digoxin toxicity.
Describe digoxin toxicity
Chronic digoxin toxicity is associated with one-week-mortality of 15-30%
Characterised by GI distress; Hyperkalaemia; Life-threatening arrhythmias
Treatment: Digibind
Name three common and three significant side-effects of amiodarone
- Common: Photosensitivity, thyroid dysfunction, impaired night vision, bradycardia, raised serum transaminases
- Rare but significant: Pulmonary fibrosis, cirrhosis, optic neuritis, blue-grey skin pigmentation
Differentiate between the different anticoagulation therapies used in atrial fibrillation
- Warfarin: Vitamin K reductase inhibitor
- Dose adjusted to maintain INR 2.0-3.0 in AF
- Requires regular INR blood monitoring
- Antidote: Vitamin K
- Well known drug profile
- Significant drug interactions
- NOACs: Apixaban; rivaroxaban; Dabigatran
- Rapid onset; shorter half-life
- Does not require blood monitoring
- Fewer drug interactions
- Unlicensed for valvular heart disease or mechanical heart valves
- Avoid in liver or renal impairment
