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Cardiology

Atrial Fibrillation

Most common sustained arrhythmia; irregular chaotic atrial activity causing irregularly irregular ventricular response with high stroke risk from atrial thrombus.

Last reviewed 1 Jun 2026 - MedicoMedics editorial team

Atrial fibrillation irregular rhythm

Pathophysiology

Ectopic pulmonary vein foci initiate; atrial fibrosis, hypertension, obesity, OSA sustain. Loss of atrial kick reduces cardiac output; stasis in LA appendage causes thrombus.

Sources: AHA/ACC AFib 2023 (Circulation 2024;149:e1); EAST-AFNET (NEJM 2020;383:1305)

Presentation

Palpitations, dyspnoea, fatigue, angina, dizziness or syncope; asymptomatic in ~30% (silent AF). Rapid ventricular rate can precipitate heart failure.

Diagnosis

ECG: irregularly irregular rhythm without discrete P waves. Assess CHA2DS2-VASc for stroke risk and HAS-BLED for bleeding risk; echocardiogram; TSH.

Management

Rate control: beta-blockers or non-dihydropyridine CCBs (or digoxin). Rhythm control: catheter ablation (pulmonary vein isolation) first-line if paroxysmal/symptomatic per 2023 AHA. Anticoagulation with DOAC if CHA2DS2-VASc >=2 (men) or >=3 (women). LAA occlusion (Watchman) if contraindicated to anticoagulation.

Sample USMLE-style MCQs

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Question 1

A 70-year-old with AF, HTN, DM, prior stroke. Best long-term stroke prevention?

Question 2

First-line rate-control agent in AF with HFrEF?

Related topics:HFrEF

Question 3

Which finding on ECG is diagnostic?

Question 4

Alternative to anticoagulation for high-risk non-valvular AF?

Question 5

Which is a first-line rhythm control approach per 2023 AHA?

References

Primary guidelines and peer-reviewed sources used for this entry. Reviewed 1 Jun 2026 by MedicoMedics editorial team.

  1. AHA/ACC AFib 2023 (Circulation 2024;149:e1)
  2. EAST-AFNET (NEJM 2020;383:1305)

Frequently asked

Why prefer DOACs?

Fewer intracranial bleeds vs warfarin; no INR monitoring.

When is ablation first-line?

Paroxysmal symptomatic AF - now Class I in select patients.

Watchman for whom?

Long-term anticoagulation contraindicated.

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