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Cardiology

Atrial Fibrillation: The Basics

Classification, the rate-versus-rhythm decision, and how stroke and bleeding risk scores guide anticoagulation.

Classification

TypeDefinition
ParoxysmalSelf-terminates within 7 days
PersistentContinuous, lasting longer than 7 days
PermanentSustained AF where rhythm control is no longer pursued

Rate vs. Rhythm Control

Rate control (beta-blockers or rate-limiting calcium channel blockers) is first-line for most patients and focuses on symptom control without necessarily restoring sinus rhythm. Rhythm control (antiarrhythmics or cardioversion) is considered for persistently symptomatic patients or new-onset AF, particularly in younger patients or those with heart failure.

Stroke Risk: CHA₂DS₂-VASc

Use the CHA₂DS₂-VASc calculator to estimate stroke risk and guide whether anticoagulation is warranted. It does not apply to valvular AF (rheumatic mitral stenosis or mechanical valves), which follows its own approach.

Bleeding Risk: HAS-BLED

The HAS-BLED score flags bleeding risk and modifiable factors to address — it should not, by itself, be used to withhold anticoagulation when stroke risk is significant.

Cardioversion

Emergency synchronized cardioversion is indicated for hemodynamic instability. For elective cardioversion in stable patients, anticoagulation status and AF duration (commonly the 48-hour rule, or transesophageal echocardiography to exclude a left atrial thrombus) determine timing and safety.

Frequently Asked Questions

Does CHA2DS2-VASc apply to all AF patients?

No — it doesn't apply to valvular AF (rheumatic mitral stenosis or mechanical heart valves), which has its own anticoagulation approach regardless of score.

Why is the 48-hour rule important for cardioversion?

AF lasting longer than 48 hours carries a meaningfully higher risk of atrial thrombus formation, so cardioversion without prior anticoagulation or excluding a thrombus (e.g. via TEE) carries a higher embolic stroke risk.

Is rate control always preferred over rhythm control?

Not always — younger patients, those with heart failure that improves with sinus rhythm, or those who remain symptomatic despite rate control may benefit more from a rhythm-control strategy.