A large-scale clinical trial of AstraZeneca's Brilinta tablets for patients with a history of heart attack has been successful in proving its effectiveness, the drug developer said.The Pegasus-TIM 54 study, which involved over 21,000 patients, "successfully met its primary efficacy endpoint", with the treatment resulting in a significant reduction in major cardiovascular thrombotic events.The study assessed Brilinta, otherwise known as ticagrelor, at either 60mg twice daily of 90mg twice daily plus low-dose aspirin for the secondary prevention of atherothrombotic events in patients who have had a heart attack in the past one to three years.These patients are at high risk of major thrombotic events and the study was designed to better under how to manage their needs.Elisabeth Björk, the vice president and head of cardiovascular and metabolic diseases at Astra's global medicines development division, said she was "very pleased" with the results."The results build on existing understanding of the benefits of Brilinta for patients with acute coronary syndrome and offer important clinical insights into its potential role for the longer-term prevention of cardiovascular events. We look forward to presenting the data later this year," she said.Astra's shares were up 1.4% at 4,783p by 08:19 on Wednesday.