"A new study calls into question the value of removing blood clots from a patients heart arteries during angioplasty a procedure to open blocked arteries. Although manually removing clots has become common medical practice this study of more than  heart attack patients found no benefit in terms of reducing death heart attack or heart failure in the six months after the procedure. Removing clots appears to have increased the risk of stroke in the month after clots were removed the Canadian researchers report. There has been some controversy about removing blood clots during the treatment of heart attacks said lead researcher Dr. Sanjit Jolly an associate professor of cardiology at McMaster University in Hamilton Ontario. A study in  suggested that removing clots during an angioplasty might save lives he said. Guidelines changed based on this study Jolly noted. Another trial in  however suggested that removing clots was not beneficial he added.  In this latest trial researchers found that routinely removing clots was not beneficial Jolly said.  Jolly isnt sure why removing clots causes additional problems. It is possible that parts of the clot break off and travel elsewhere in the heart or brain he said. This is an unexpected finding and we want to confirm this in other studies Jolly said. Jolly said there are mechanical methods of removing clots which were not tested in this study. Whether these methods would have produced better results isnt clear. The jury is out on that. It needs to be tested in large trials he said. However preliminary results from small trials of mechanical clot removal have not been promising Jolly noted. Jolly said the lesson from his teams trial is that clot removal should be used only as a rescue treatment when an angioplasty fails to clear an artery.  As a routine therapy clot removal is not beneficial and could have some significant downsides he said. The results of the study were published online March  in the New England Journal of Medicine to coincide with a planned presentation of the findings at the American College of Cardiologys annual meeting in San Diego. For the study Jolly and colleagues randomly assigned  patients undergoing an angioplasty after a heart attack to have clots manually removed or to not have them removed. Among all the patients . percent who had clots removed and  percent of those who didnt died had another heart attack or developed heart failure in the  days after the procedure. In the  days after the procedure . percent of the patients who had clots removed suffered a stroke as did . percent of those who only had angioplasty Jollys team found. Dr. Gregg Fonarow a professor of cardiology at the University of California Los Angeles said This is a very important and eagerly awaited clinical trial. A number of studies have suggested a benefit from manually removing clots during an angioplasty but this trial found no clinical benefits for doing so he said. These findings will likely have important implications for clinical practice Fonarow said.  More information Visit the U.S. National Library of Medicine http for more on angioplasty. SOURCES Sanjit Jolly M.D. associate professor cardiology McMaster University Hamilton Ontario Canada Gregg Fonarow M.D. professor cardiology University of California Los Angeles March   presentation American College of Cardiology annual meeting San Diego March   New England Journal of Medicine online"