U.S. — Medical experts are absolutely stumped as to what could be causing the recent uptick in healthy, young people everywhere that are suddenly collapsing with heart failure. Despite their uncertainty, experts do feel confident that we can rule out that one thing as the culprit. "It's too early to say what could be causing this, but it's never too early to say what isn't causing this," said local expert, Dr. Scott Rufflinger. "This could be caused by anything. But the one thing we know for certain is that it's definitely not what we're all thinking that's behind this —...