9. Which of the following is considered the most common cause of atrial fibrillation?

A. Post-operative

B. Hypertension

C. Valvular heart disease

D. Hyperthyroidism

Hypertension is the most common cause of atrial fibrillation, likely followed by obstructive sleep apnea, which causes hypertension.

Remember the mnemonic “PIRATES” to recall the causes of atrial fibrillation:

Pulmonary embolus, pulmonary disease, post-operative, pericarditis
Ischemic heart disease, idiopathic (“lone AF”), intravenous central line (in right atrium)
Rheumatic valvular disease (specifically mitral stenosis or mitral regurgitation)
Anemia, alcohol (“holiday heart”), advanced age, autonomic tone (vagally-mediated AF)
Thyroid disease (hyperthyroidism)
Elevated blood pressure (hypertension), electrocution
Sleep apnea, sepsis, surgery