Amarin Corp. (NASDAQ:AMRN) announced Tuesday that it was granted a key U.S. patent for its heart-drug candidate AMER-101, a treatment for high triglyceride levels.The product is currently waiting for approval by the FDA and should have a decision by late July.Share of the company were up 6% in midday trading.Amarin (NASDAQ:AMRN) has potential upside of 98.9% based on a current price of $11.23 and an average consensus analyst price target of $22.33.