Vitamin K Antagonists. The Practice Guideline, “Newly Detected Atrial Fibrillation: AAFP Updates Guidelines on Pharmacologic Management” (September 1, 2017, p. 332), incorrectly identified vitamin K antagonists as vitamin K agonists in the first paragraph in the left column on page 333. The sentence should have read: “Vitamin K antagonists are the first-line option, with high-quality data indicating that they have a lower stroke risk and all-cause mortality vs. placebo.” The online version of the article has been corrected.