A new study offers some advice for doctors poking around the heart to reopen a clogged artery that has caused one type of heart attack: Come back again to finish the job. The study found that when doctors also open other arteries that are dangerously narrow — either while the patient is still hospitalized or after a month or so — those patients are half as likely to die from heart problems, have a heart attack or need repeat surgery due to chest pain than patients given conventional medical therapy. The results of the study, known as COMPLETE, are likely to transform the way some heart attack patients are treated, specifically when doctors stumble upon other narrowed heart arteries likely to cause a future heart attack, chief author Dr. Shamir Mehta, director of interventional cardiology at McMaster University in Ontario, told Reuters Health in a telephone interview. The benefit “is very clear,” he said. The will result in “a sweeping change in practice across the world. It helps us solidify how patients with multi-vessel disease should be treated.” The findings also show that doctors don’t have to do the second procedure immediately; patients can be brought back to the hospital up to 45 days later to have the remaining narrowed arteries reopened with stents. “When the patient is in the throes of a major heart attack, there’s no need to rush in and do a second procedure and put the patient at risk,” said Dr. Mehta. “You can do it the next day if the patient is stabilized and there are no other medical issues. But if they’re frail or have kidney disease, you may want to give them time to recover.” The team, which reported its findings Sunday at the European Society of Cardiology Congress in Paris and online in The New England Journal of Medicine, calculated that for every 13 patients given the more-aggressive therapy, one heart-related death, heart attack or repeat surgery would be prevented over the course of three years. The question of whether doctors should also open up the narrowed arteries they find while unclogging an artery that is causing a heart attack has been debated for years. In the COMPLETE study, when doctors only fixed the clogged artery, the incidence of bad outcomes at the three-year mark was 16.7% among 2,025 volunteers. But when doctors returned and reopened narrowed arteries that might cause problems in the future, the rate dropped to 8.9% for the 2,016 patients in that group. Both groups of patients had roughly the same risk of major bleeding, stroke, kidney injury or having a clot appear in a stent. “This is really a compelling result,” said Dr. Gregg Fonarow of the David Geffen School of Medicine at UCLA, who was not involved in the research. “I think this will be embraced and taken into clinical practice across the world.” The study showed that the follow-up procedure is safe and works if done within the 45-day window , which “opens the door to maximal flexibility,” he said. The findings only apply to a type of heart attack known as an ST-segment elevation myocardial infarction, which accounts for about 30% of heart attacks, said Dr. Fonarow. In those patients, another narrowed artery is discovered in about half the cases, which would make them eligible for the follow-up stenting. The volunteers were treated at 140 centers in 31 countries. All received standard non-surgical therapy.