1. Atrial Fibrillation

2. Definition • Chaotic, irregular atrial rhythm at 300-600 bpm • Maintained by continuous, rapid activation of the atria by multiple meandering re-entry wavelets • Atria respond electrically, but there is no coordinated mechanical action and only a proportion of the impulses are conducted to the ventricles. • AV node responds intermittently, hence irregular ventricular rate • Cardiac output can drop by 10-20%

3. Common in elderly (<9%) • Main risk is embolic stroke • Warfarin reduces this to 1%/yr

4. Causes • Heart failure/ischaemia; HT; MI (22%); mitral valve disease; coronary artery disease • PE; Pneumonia; Hyperthyroidism; post-op hypokalaemia; Mg2+ decrease; Phaeochromocytoma • Caffeine; alcohol

5. Symptoms • May be asymptomatic or cause- • Chest pain • Palpitation • Dyspnoea • Faintness

6. Signs • Irregularly irregular pulse • Apical pulse rate greater than the radial rate • 1st heart sound of variable intensity • Should examine whole pt as AF often assoc with non-cardiac disease

7. Investigations • ECG: • Shows fine oscillations of the baseline (fibrillation/f-waves) and absent P waves • QRS rhythm is rapid & irregular • ‘Irregularly irregular’ • DO an ECG on anyone with irregular pulse (+ 24 hr ECG if dizzy, faints, palpitations etc) • Blood tests: U & E, cardiac enzymes, TFTs • (Echo) • Look for left atrial enlargement, mitral valve disease, poor LV function & other abnormalities

8. Management • Acute: Treat assoc illness, control ventricular rate • 1st choice: diltiazem or verapamil or metoprolol • 2nd rate: digoxin, amiodarone • Start full coag with LMWH • 2nd choice: rate control & anticoagulation • Beta-blocker or rate-limiting Ca-blocker • If fails, consider digoxin (as monotherapy) or amiodarone