Two members of staff have been suspended over claims an NHS board manipulated waiting times figures to meet targets.
The suspension comes after Nicola Sturgeon told parliament NHS Lothian "betrayed" patients by marking them as unavailable to artificially reduce the number in breach of statutory waiting times guarantees.
It emerged in October last year that NHS Lothian had asked patients to go to appointments in England. When they declined, they were not included on a list of patients waiting the target of 18 weeks for treatment.
An independent report given to Ms Sturgeon on Tuesday showed the health authority "masked" the true number of patients having to wait longer than they should.
On Thursday, the health board said the practice of sending patients to Northumberland to be treated had been stopped and all the patients affected had been treated.
NHS Lothian said an internal investigation was being carried out and two members of staff had been suspended as a result.
Alan Boyter, director of human resources said: "As we had always intended, we have been following up a number of issues raised by the Dr Farquharson review. We are currently carrying out a Critical Incident Review and based on its emergent themes, steps have been taken today to suspend two members of staff pending further investigation.
"We are actively reviewing our management arrangements and have already reduced these by 80, streamlining our management to improve communications.
"We pride ourselves as being an open and transparent organisation which deals with challenging situations as soon as they are brought to our attention."
The health board’s chairman apologised for the "unacceptable practices" and said they had invested £4.8m in tackling waiting times.
NHS Lothian Chairman Dr Charles Winstanley said: "I accept in full the recommendations from this review and the comments made by the Cabinet Secretary. I apologise unreservedly on behalf of the Board for these unacceptable practices.
"The Cabinet Secretary and I have spoken at length about the actions I have been asked to take and I can give an absolute assurance that these will be undertaken.
"It is essential that we now act on this extremely sobering report. It is vital that we do whatever it takes to reassure the people of Lothian that the Board has patients and patient care at its very centre."