League tables showing the fate of heart specialists' patients - being introduced in the wake of the Bristol babies report - could lead to fewer operations on those with the most serious conditions.
A study shows this is what happened in the US where cardiologists became more risk averse and "selected out" patients likely to depress their performance, a move which also pushed up costs.
The study examined the patient records of cardiac surgeons in New York and Pennsylvania, where they have had to compile individual "report cards" since the early 1990s. Knowing their patients' results would be published apparently led surgeons to refuse to operate on the most ill where they could avoid it.
Doctors working for the NHS might find it harder to cherry-pick patients - but the study does have implications for the decision announced by Alan Milburn, the health secretary, last month to publish figures on the death rates of heart doctors' patients.
John Appleby of the King's Fund, the health thinktank, said regulators might have to intervene to ensure consultants took their share of the most difficult cases to avoid the cherry-picking of patients.
The American data seems to confirm a prediction made by Bruce Keogh, secretary of the Society of Cardiothoracic Surgeons and adviser to the government's commission on health improvement. "Publishing results will lead to surgeons avoiding difficult, high risk cases where the only hope is an operation, but the patient is likely to die," he said.
In the report, entitled Is more information better?, published by the National Bureau for Economic Research, academics from Northwestern and Stanford universities compared surgical records from one state where doctors had to publish their outcomes against another state where there was no such obligation. They found bypass operations reserved for less ill heart patients even though they produced no appreciable benefit to their long term health.
Performance data for surgeons had the effect of pushing up total spending on care of heart patients - because the sicker patients, denied surgery, had heart attacks and needed further treatment.
"Doctors and hospitals avoided performing both bypass and angioplasty [where a small balloon is used to open blocked arteries] and took longer to deliver the intensive cardiac treatment they ultimately administered," the report said.
In Britain, in the wake of Ian Kennedy's report on children's deaths at the Bristol royal infirmary, information on death rates within 30 days of surgery is soon to be published for every cardiac surgeon in England.
Mr Milburn said such data would be a "milestone in the development of a more open, responsive and patient-centred NHS".
Data on death rates after or during surgery has been collected for several years but not published.
The American academics said that report cards could be beneficial "if designed in a way to minimise the incentives and opportunities for [patient] selection".
