"Papworth has established targets for patient survival after heart surgery, based on patient profiles and the operations performed. It's these targets that would have been breached if the extra virtual deaths had actually occurred.
"There is nothing specific in our study that distinguishes excess death due to malicious intent from any other cause, such as systems failure or human error.
"But it does alert us when death rates fall outside the norm and that is an essential part of any clinical quality assurance programme."
The hospital carried out the study to test the theory - voiced by Professor Mike Harmer of Wales College of Medicine in an editorial in Anaesthesia - that what had happened in a single-handed GP practice couldn't happen in a large and accountable hospital.
This followed the publication of the fifth report of the Shipman Inquiry which looked at how lessons could be learnt and patients safeguarded in the future.
"Some patients would have died during the eight to ten months before the death rates became statistically different from the norm and clinical audit staff were alerted" says consultant anaesthetist Dr Joe Arrowsmith. "But it is sadly inevitable that some harm is done before harm is detected.
"The aim should be to identify and investigate the problem as soon as possible.
"We believe that detailed monitoring of this type is possible in all medical specialities, including general practice, and is preferable to the publication of crude outcome data.
"Universal adoption of robust local monitoring could ensure that terrible events like the Shipman deaths are never repeated."