ACE and atrial fibrillation: For example, in one guideline summary, “For patients with systolic dysfunction (EF <40 %) who have no contraindications: Angiotensin-converting enzyme (ACE) inhibitors for all patients...Digoxin only for patients who remain symptomatic despite diuretics, ACE inhibitors and beta blockers or for those in atrial fibrillation needing rate control,” [19] the concepts Angiotensin-converting enzyme (ACE) inhibitors and ACE inhibitors were annotated drug classes and considered synonymous, digoxin was a drug name, and diuretics and beta blockers were drug class names.