Objective This study investigated the policies of cardiac and cardiovascular system journals concerning clinical trial registration and guideline adoption to understand how frequently journals use these mechanisms to improve transparency, trial reporting and overall study quality.

Methods We selected the top 20 (by impact factor) journals cited in the subcategory ‘Cardiac and Cardiovascular Systems’ of the Expanded Science Citation Index of the 2014 Journal Citation Reports to extract journal policies concerning the 17 guidelines we identified. In addition, trial and systematic review registration adherence statements were extracted. 300 randomised controlled trials published in 2016 in the top 20 journals were searched for clinical trial registry numbers and CONSORT diagrams.

Results Of the 19 cardiac and cardiovascular system journals included in our analysis, eight journals (42%) did not require or recommend trial or review registration. Seven (37%) did not recommend or require a single guideline within their instructions to authors. Consolidated Standards for Reporting Trials guidelines (10/19, 53%) were recommended or required most often. Of the trials surveyed, 122/285 (42.8%) published a CONSORT diagram in their manuscript, while 236/292 (80.8%) published a trial registry number.

Discussion Cardiac and cardiovascular system journals infrequently require, recommend or enforce the use of reporting guidelines. Furthermore, too few require or enforce the use of clinical trial registration. Cardiology journal editors should consider guideline adoption due to their potential to limit bias and increase transparency.