A simple and inexpensive test that can spot a heart attack waiting to happen could be available next year, it was disclosed here Thursday. Scientists say they are very close to the \"holy grail of heart medicine\", a rapid blood test that will pick up if someone is on the verge of a heart attack. The US study was published in the \"journal Science Translational Medicine\". The US researchers developing the test believe it will be possible to predict heart attacks two to three weeks in advance. It is hoped the test will cost under 65 pounds per person. In the future, it might even be possible to use microchips implanted in the body to detect the danger signs. The study, by US scientists at the respected Scripps Research Institute in La Jolla, California, focuses on cells released when arteries crack in the lead-up to a heart attack. The test will serve as a welcome relief for the elderly who are more susceptible to such attacks. Most heart attacks begin with the gradual cracking of an artery that has been damaged by smoking, high blood pressure or other factors. After several weeks, a blood clot seals the damage, blocking the blood supply in the process and causing a heart attack. Current tests of heart health are unable to pick up this cracking. This means that many people who go to hospital with chest pains are sent home with a clean bill of health, only to suffer a heart attack days later. The new test would be added to those given to chest-pain patients. The researchers compared blood samples from heart attack patients and healthy people. This revealed differences in cells that lined the inside of the arteries before breaking off into the bloodstream. In the heart-attack patients, these circulating endothelial cells were much more numerous and abnormally large and mis-shapen. The researchers believe the difference should be noticeable when the artery is cracking, making it possible to predict a heart attack.