Editing Atrial fibrillation


== Epidemiology ==

* Incidence
** <40yo <0.1%
** >80yo 2% in men, 1.5% women

== Risk factors ==

* Advanced age
* CCF
* Male
* Tall stature
* FHx at <50yo
* Left atrial enlargement
* HTN
* Obesity
* OSA

== Aetiology ==

* Most patients have HTN, usually with LVH, or some other form of structural heart disease
** Most commonly IHD, mitral valve disease, hypertrophic cardiomyopathy, and dilated cardiomyopathy
** Also restrictive cardiomyopathies, constrictive pericarditis, cardiac tumours
* Severe pulmonary hypertension
* OSA
* Obesity
* Tachycardia

== Presentation ==

* Symptoms - palpitations, fatigue, dyspnoea, effort intolerance, light-headedness
* 25% asymptomatic
* Syncope - either RVR with neurocardiogenic syncope, or long sinus pause in a patient with sick sinus syndrome
* Irregularly irregular pulse
* 'pulse deficit' - peripheral pulse not as rapid as the apical rate due to low stroke volume

== Classification (based on the predominant form of AF) ==

* Paroxysmal AF: terminates spontaneously within 7 days
** Vagotonic - occurs in the setting of high vagal tone
** Adrenergic - occurs with high sympathetic tone
* Persistent AF: present continuously for >7 days
* Longstanding AF: present for >1 year
* Permanent AF: all attempts to restore/maintain sinus rhythm have been abandoned (therapeutic attitude, not characteristic of the disease itself)
* Harder to classify if the disease path has been altered early in the course by cardioversion - don't know what would have happened
* Lone atrial fibrillation: patients <60yo without HTN or any evidence of structural heart disease. Old term, not meaningful. Essentially means low-risk AF.
* Valvular AF: moderate to severe mitral stenosis. Higher risk of stroke.


== ECG: ==

* Low-amplitude baseline oscillations (fibrillating atria) at 300-600bpm
** Contrast with atrial flutter waves which have a rate of 250-350 beats/min and are constant in timing and morphology
** Sometimes waves can be very small and not easily seen, and the diagnosis of AF is based on the irregularly irregular ventricular rhythm
* Irregularly irregular ventricular rhythm
** Typically 100-160bpm when untreated (can be up to 250 with WPW syndrome)
** Can look more regular when rate >170bpm, or when a junctional tachycardia independently controls the ventricles, or when there is high-degree AV block with a regular escape rhythm, or when the QRS complexes are paced

== Management strategy ==

* Rhythm control (restore sinus rhythm)
** Methods
*** Anti-arrhythmic drugs
*** Electrical cardioversion
*** RFA of left atrium
*** Surgical ablation
* Rate control
** Methods
*** Slow conduction through the AV node - beta-blockers, some CCBs, or digoxin
*** AV nodal ablation with ventricular pacing


== Complications ==

* AF with RVR
** Leads to severe palpitations, cardiac ischaemia, and global haemodynamic compromise
* Stroke
[[Category:Cardiology]]