In the Excel trial, the four main investigators all declared conflicts of interest.
Lead investigator Prof Gregg Stone declared he had received personal fees or held equity in 20 private medical companies, several of which made tools that helped with putting in stents.
He's also the course director for TCT, an annual medical conference where the results were presented.
TCT makes money from exhibitors including some of the biggest stent makers - Abbott, who sponsored the trial, Boston Scientific and Medtronic.
Prof Pieter Kappetein, who worked on the trial and on the body that worked on the guidelines, declared that he had left the guidelines body to go and work for Medtronic, a medical device manufacturer that makes stents.
Newsnight found that he'd become chief medical officer of Medtronic Structural Heart.
By Newsnight's count, around half of the investigators on the trial had declared personal fees from companies that made stents, and around a third of those on the taskforce writing the guidelines.
