Boston Scientific’s chief executive yesterday ripped a tax on medical devices slated for 2013 and anticipated major layoffs at the Natick company if the levy — part of President Obama’s health-care overhaul — isn’t repealed. “It’s an outrage. It is soaking one of the last remaining industries in this country that pays (higher-than-average wages),” CEO Ray Elliott said at an industry conference in New York. “We’ve been very clear: We will have a lot less employees, if somebody tags us with a hundred million dollars worth of taxes.”