title: Controlled trials and escape clauses.
mesh_terms: D002986:Clinical Trials as Topic; D004311:Double-Blind Method; D006801:Humans; D009203:Myocardial Infarction / Q000188:drug therapy; D011433:Propranolol / Q000627:therapeutic use; D011897:Random Allocation
chemical_list: D011433:Propranolol