Yellow markings on the eyelids are a sign of increased risk of heart attack and other illnesses, say researchers in Denmark.A study published on the BMJ website showed patients with xanthelasmata were 48% more likely to have a heart attack.Xanthelasmata, which are mostly made up of cholesterol, could be a sign of other fatty build-ups in the body.Cardiologists said the findings could be used by doctors to help diagnose at-risk patients.The research team at the Herlev Hospital in Denmark started following 12,745 people in the 1970s.At the start of the study, 4.4% of patients had xanthelasmata.Yellow alertThirty three years later, 1,872 had had a heart attack, 3,699 had developed heart disease and 8,507 had died - and the data showed that those with the yellow markings around the eyes were at greatest risk.Those with the markings were 48% more likely to have a heart attack, 39% more likely to have developed heart disease and 14% more likely to have died during the study.The authors believe patients with xanthelasmata may be more likely to deposit cholesterol around the body.A build up of fatty material in the walls of arteries - known as atherosclerosis - leads to stroke and heart attack.For both men and women in several age groups, the data said there was a one in five chance of developing heart disease in the next decade if the patient had xanthelasmata.The authors said such patients were "generally considered to be at high risk" and should have "lifestyle changes and treatment to reduce [bad] cholesterol."However they warned that: "Today, most people with xanthelasmata are seen by dermatologists, when they want their xanthelasmata removed for cosmetic reasons."Some of these people may not have been managed according to their increased risk of cardiovascular disease."A review of the study, by US cardiologists Antonio Fernandez and Paul Thompson, concluded that: "Xanthelasmata could be used by general clinicians to help identify people at higher risk of cardiovascular disease."Judy O'Sullivan, senior cardiac nurse at the British Heart Foundation, said: "There are many different techniques to predict someone's risk of developing heart disease in the future, none of which are perfect. The most important thing is that any one of these techniques is used in the first place."