title: Parallel hierarchy of scientific studies in cardiovascular medicine.
authors.forename: Giuseppe G
authors.initials: GG
authors.lastname: Biondi-Zoccai
authors.forename: Pierfrancesco
authors.initials: P
authors.lastname: Agostoni
authors.forename: Antonio
authors.initials: A
authors.lastname: Abbate
mesh_terms: D002318:Cardiovascular Diseases; D015510:Clinical Medicine; D002986:Clinical Trials as Topic; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D012107:Research Design; D012586:Science