Patient presents with complaints consistent with unspecified atrial fibrillation (AFib).  Symptoms include palpitations, intermittent shortness of breath, and occasional lightheadedness.  Onset is reported as gradual over the past few weeks.  Patient denies chest pain, syncope, or history of stroke.  Physical examination reveals an irregularly irregular pulse.  Electrocardiogram (ECG, EKG) confirms atrial fibrillation with an uncontrolled ventricular rate.  No evidence of pre-excitation or other arrhythmias noted.  Echocardiogram ordered to assess cardiac function and rule out underlying structural heart disease.  Blood work including thyroid stimulating hormone (TSH) and complete blood count (CBC) ordered to evaluate potential contributing factors.  Initial treatment plan includes rate control with beta-blocker therapy (metoprolol) and anticoagulation with apixaban for stroke prevention based on CHA2DS2-VASc score.  Patient education provided on atrial fibrillation management, medication adherence, and signs and symptoms of stroke.  Follow-up scheduled in two weeks to assess response to therapy and adjust medication as needed.  Differential diagnoses considered include sinus tachycardia, atrial flutter, and other supraventricular tachycardias.  Medical coding for this encounter will include unspecified atrial fibrillation (I48.91).  Further evaluation and management will be based on patient response to therapy and evolving clinical presentation.