Atrial fibrillation (AF) is a supraventricular tachyarrhythmia characterized by disorganized atrial electrical activity (350–600 impulses/min), loss of coordinated atrial contraction, and an irregularly irregular ventricular response. In rate control strategy, the goal is NOT to restore sinus rhythm but to reduce ventricular rate to ≤110 bpm at rest (lenient) or ≤80 bpm (strict, per ACC/AHA), allowing adequate diastolic filling and reducing hemodynamic compromise. AF is the most common sustained cardiac arrhythmia in Canada; without anticoagulation, it carries a 5-fold increase in ischemic stroke risk. Missing AF or failing to anticoagulate appropriately is the single highest-stakes clinical error in this condition. Top 3 nursing priorities: 1. Identify ventricular rate on cardiac monitor and establish hemodynamic stability (BP, LOC, perfusion) 2. Initiate or verify therapeutic anticoagulation to prevent thromboembolic stroke (CHA₂DS₂-VASc score ≥2 in men, ≥3 in women = anticoagulation indicated) 3. Monitor for rate control medication toxicity (hypotension, bradycardia, AV block) Common NCLEX trap: Choosing cardioversion or antiarrhythmics for a patient in AF >48 hours who has not been adequately anticoagulated — this risks dislodging an atrial thrombus and causing embolic...