ISLAMABAD – Several young people appeared to be in perfect health but they collapse with a heart attack or stroke one day. It sounds like a tragic surprise, but scientists say it was not sudden at all but they ignore several symptoms. A groundbreaking study revealed that nearly every patient who suffers heart attack, stroke, or heart failure experiences warning signs years before the life-threatening event. The joint research, conducted by Northwestern University (USA) and Yonsei University (South Korea), tracked health data of more than 9.3 million South Koreans and 7,000 Americans over two decades. About 95percent of young women who later suffered stroke or heart failure already had at least one warning sign.