Atrial fibrillation (AF) is the most common sustained heart rhythm disorder, affecting around 1.4 million people in the UK. It occurs when disorganised electrical impulses fire from multiple sites in the atria (the heart’s upper chambers), causing them to quiver rapidly and irregularly instead of contracting in a coordinated sequence. The result is an irregular, and often fast, heartbeat.
AF significantly increases the risk of stroke, because blood can pool and clot in the left atrial appendage when the atria are not contracting properly. Anticoagulation (blood-thinning medication) is recommended for most people with AF, based on individual stroke risk assessment using the CHA2DS2-VASc score.
While AF is not a common direct cause of sudden cardiac arrest, it is relevant to cardiac arrest in several ways. In Wolff-Parkinson-White syndrome, AF can conduct extremely rapidly via an accessory pathway and trigger ventricular fibrillation. AF can also worsen heart failure and precipitate cardiogenic shock in an already-compromised heart.
Treatment falls into two main approaches. Rate control slows the ventricular response using medications including beta-blockers and digoxin. Rhythm control aims to restore and maintain normal sinus rhythm using cardioversion (electrical or chemical shock) or catheter ablation. The best approach depends on symptoms, heart function, and individual preference. Some people with AF require both anticoagulation and rate or rhythm control long-term.
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