"Deteriorating or clogged heart valves in seriously ill elderly people can be successfully replaced through minimally invasive surgery researchers said Sunday. The new procedure represents a development whose significance many cardiologists are comparing to balloon angioplasty to clear blocked arteries. At least  Americans a year develop aortic valve stenosis which dramatically impairs the ability of the heart to pump blood. A previous study had shown that the valves can be replaced with prosthetic valves through a catheter inserted through a vein in the groin in patients who are too sick for conventional surgery. New results presented Sunday at a New Orleans meeting of the American College of Cardiology indicate that the procedure is at least as effective as surgery in patients who are not quite so ill which would extend it to a much larger group of patients. Cardiologists expect that within a few years the procedure will be performed on tens of thousands of patients each year. This will be seen as one of the biggest steps in cardiovascular medicine in our lifetime trailing only the development of balloon angioplasty and the use of stents to keep cleared arteries open said Dr. David J. Moliterno a cardiologist at the University of Kentucky College of Medicine who was not involved in the research.   This is a game changer said Dr. Michael J. Mack of the Baylor Health Care System in Dallas president of the Society of Thoracic Surgeons. Aortic stenosis is a clogged valve in the artery that transports oxygenrich blood from the heart. It affects as many as  of people older than  in the U.S. with the incidence increasing with age. The only approved way to treat the condition in the United States now is with open chest surgery. Edwards Lifesciences Corp. of Irvine has developed a device using valve flaps from cows that can be implanted through a vein in the groin or chest. The device is approved in Europe but not in this country. A Food and Drug Administration advisory committee is expected to consider it this summer. Two clinical trials have been underway one in patients too sick for conventional surgery and the second in patients at high risk for complications from surgery  effectively those in the top  of risk. Results from the first trial reported last fall showed that the device gave a nearly twoyear increase in survival compared with medical therapy alone in those patients whose median age was . New data from this portion of the trial presented by Dr. Matthew R. Reynolds of the Harvard Clinical Research Institute indicated that the procedure was costeffective. The surgery costs about  which includes about  for the device. But patients receiving only medical treatment were three times as likely to be hospitalized in the year of the study at a cost of about . Reynolds concluded that the surgery provided two additional years of life at a cost of about  a year. In the new study a team led by Dr. Craig R. Smith of the Columbia University Medical Center studied  patients with a median age of  and severe aortic stenosis. Half received the new procedure and half conventional surgery. After  days the number of deaths in the minimally invasive group was about half the number of the surgery group but at one year the numbers were the same. Strokes and minor strokes were about twice as common in the minimally invasive group and vascular complications such as bleeding or need for repair were about three times as common. But the group receiving the minimally invasive procedure was only about half as likely to undergo severe bleeding or develop irregular heart rhythms. This opens up a new set of patients who may be benefited as much by minimally invasive procedures as by the conventional goldstandard therapy Smith said. The studies were funded by Edwards Lifesciences."