Atrial Fibrillation (Chronic) Flashcards
What is atrial fibrillation (AF)?
Atrial fibrillation (AF) is a supraventricular tachyarrhythmia.
Electrocardiographic characteristics include:
- Irregularly irregular R-R intervals (where atrioventricular conduction is not impaired)
- Absence of distinct repeating P waves
- Irregular atrial activations
What are the risk factors for AF?
- Coronary artery disease (CAD)
- Hyperthyroidism
- Valvular disease
- Hypertension
- Heart failure
- Diabetes
- Thyroid disorders
- COPD
- Obstructive sleep apnoea
- Advanced age
Damage to which heart valve is most commonly the cause of AF?
Mitral valve
Differentiate between paroxymal, persistent, long-standing and permanent AF
- Paroxysmal AF: recurrent AF that terminates spontaneously within 7 days.
- Persistent AF: lasts longer than 7 days.
- Long-standing persistent AF: continuous AF >1 year in duration.
- Permanent AF: refractory to cardioversion and sinus rhythm cannot be restored or maintained, such that AF is accepted as a final rhythm. A decision has been made by the patient and physician not to pursue restoration of sinus rhythm by any means, including catheter or surgical ablation.
What are the symptoms of AF?
- Palpitations
- Dizziness
- Sycope
- Fatigue
- Dyspnoea
What are the signs of AF?
- Tachycardia
- Irregularly irregular pulse
- Hypotension
- Elevated JVP
- Murmur or gallop rhythm
What investigations should be ordered for AF?
- ECG
- Serum urea and electrolytes
- Echocardiogram
- Cardiac biomarkers
- Thyroid function tests
- CXR
- Transthoracic echocardiogram
- Transoeophageal echocardiagram
What ECG changes are seen in AF?
- Absent P waves
- Presence of fibrillatory waves that vary in size, shape and timing
- Irregularly irregular QRS complexes
- Variable QRS heights
Why investigate serum urea and electrolytes (including serum magnesium)? And what may this show?
- Routine biochemistry should be done to assess for the presence of other co-morbid conditions, and to assess electrolyte and metabolic status.
- May be normal; may be abnormal with renal dysfunction.
Why investigate using echocardiogram? And what may this show?
- Echocardiogram is important to exclude important cardiac pathologies and risk factors for persistent AF such as valvular and pericardial disease, and cardiomyopathies.
- May have valvular regurgitation or stenosis, left ventricular or atrial enlargement, peak right ventricular pressure (pulmonary hypertension), left ventricular wall thickness and dysfunction.
Why investigate thyroid function? And what may this show?
- Thyrotoxicosis may present with AF.
- Suppressed thyroid-stimulating hormone (TSH) with elevated free T4 and/or T3.
What criteria scoring systems are used to assessment of AF? And why?
- CHAD-VASc: risk of thromboembolism
- HAS-BLED: risk of bleeding
Briefly describe the CHA2DS2-VASc scoring
CHA2DS2-VASc score
- 2 points:
- For history of stroke or transient ischaemic attack
- Age ≥75 years
- 1 point:
- Age 65-74 years
- History of hypertension
- Diabetes mellitus
- Recent cardiac failure
- Vascular disease (myocardial infarction, complex aortic plaque, peripheral arterial diseas)
- Female sex
What are the 3 elements in the management of AF?
- Rate control
- Rhythm control
- Prevention of thromboembolic events
When is direct current (DC) cardioversion indicated?
Used immediately if the patient is haemodynamically unstable with chest pain, shortness of breath, dizziness or sycope, hypotension and rapid heart rate.
Briefly describe DC cardioversion
DC cardioversion is performed under adequate short-acting general anaesthesia and involves delivery of an electrical shock synchronised with the intrinsic activity of the heart by sensing the R wave of the ECG.
What drugs are used in rate control of AF?
Rate control with beta-blocker and/ or calcium-channel blocker:
- Beta-blocker: esmolol, metoprolol, propanolol or bisprolol
- Calcium-channel blocker: diltiazem or verapamil
Why are beta-blockers and calcium-channel blockers used for rate control in AF?
Beta-blockers and calcium-channel blockers slow atrioventricular nodal conduction of cardiac impulses and subsequently reduce ventricular rate.
What drugs are used in pharmacologial cardioversion?
Flecainide, propafenone, amiodarone or dronedarone
Which drugs cannot be used for rhythm control in AF patients with coronary artery disease (CAD)?
- Class IC agents (flecainide and propafenone) have a higher mortality in patients with coronary artery disease (CAD) and are contraindicated in patients with CAD and cardiac dysfunction.
Briefly describe the anticoagulation regime used to treat chronic AF
Once sinus rhythm has been restored, direct oral anticoagulants (DOACs) should be started. Anticoagulation may be with apixaban, dabigatran, rivaroxaban
If DOACs are not suitable warfarin, avitamin K antagonist, can be used.
In which group of patients should the use of DOACs be cautioned?
Renal impairment
In which group of patients is catheter ablation the first line treatment?
Paroxysmal AF
In which group of patients shoud DOACs not be used?
DOACs should not be used in patients with mechanical prosthetic valves or moderate to severe mitral stenosis
What complications are associated with chronic AF?
- Death
- Bradycardia
- Stroke
- Hypotension
- Heart failure
What differentials should be considered for chronic AF?
- Atrial flutter with variable atrioventricular (AV) conduction
- Multifocal atrial tachycardia
- Sinus rhythm with premature atrial or ventricular contractions
How does chronic AF and atrial flutter with variable atrioventricular (AV) conduction differ?
- Differentiating signs and symptoms: history and physical examination may be similar to AF patients.
- Differentiating investigations: ECG tracing to examine all leads for flutter waves: ECG shows more discrete, uniform atrial activity, such as the typical saw tooth pattern described for typical atrial flutter.
How does chronic AF and multifocal atrial tachycardia differ?
- Differentiating signs and symptoms: often seen in severely ill patients with pulmonary disease.
- Differentiating investigations: ECG tracing: more than 3 different but distinct P-wave morphologies associated with varying PR intervals and RR intervals.
How does chronic AF and sinus rhythm with premature atrial or ventricular contractions differ?
- Differentiating signs and symptoms: there may be no difference in signs and symptoms.
- Differentiating investigations: ECG tracing: sinus with premature atrial or ventricular complexes.
