The U.S. is likely to face a severe shortage of heart surgeons in the next 10 years, say representatives from medical schools and thoracic surgeons' groups.

Writing in the journal Circulation, Dr. Atul Grover of the Association of American Medical Colleges in Washington, DC and colleagues point out that the number of active cardiothoracic surgeons in the U.S. "has fallen for the first time in 20 years."

More than half of today's cardiothoracic surgeons are older than 50 years, and more than 15 percent are between the ages of 65 and 74 years, the researchers note.

Based on current population growth, aging, and patterns of health care use, the demand for cardiothoracic surgeons could rise by 46 percent by 2025, they predict, while the supply will likely fall by 21 percent over the same period as today's senior surgeons retire and newer surgeons increasingly opt for other specialties.

Their study analyzed data from the Society of Thoracic Surgeons and the American Association for Thoracic Surgery, as well as Medicare claims files and Census Bureau projections.

Interest has been waning in what was historically a very competitive field: Every year from 2004 to 2007, there were more openings than applicants for spots in cardiothoracic residency programs.

"The reasons for this declining interest appear to be multiple," according to the investigators. For one thing, they note, the number of coronary artery bypass graft operations, in which surgeons reroute blood flow around block arteries that supply the heart, and which account for a large part of the surgeons' income, fell by 28 percent between 1997 and 2004. Many of these operations were replaced by stents — mesh tubes that prop blocked arteries open — inserted by cardiologists, not heart surgeons.

Furthermore, Medicare reimbursements for bypass surgery have fallen by 38 percent. Finally, newly trained cardiothoracic surgeons have had trouble finding jobs.

For the supply of cardiothoracic surgeons to be adequate in the coming decade would require elimination of coronary artery bypass operations, and numbers of young surgeons entering the field must be as high as in the 1990s. Since these are both highly unlikely, the researchers continue, the number of surgeons entering training in cardiothoracic surgery will probably be "inadequate to care for the US population in the coming decades."

This is concerning, they conclude, because patients will likely have worse outcomes if heart operations are performed by surgeons without specialized training in the area, or patients have to delay treatment to be seen by a specialist.