After a "robust" start to 2019, Merit Medical Systems is a mid-cap name that investors need to own, Piper Jaffray analyst Matt O'Brien writes in a research note. He believes the company can deliver some of the best top- and bottom-line growth in med tech in the coming years. Revenue from the recently completed Cianna acquisition helped deliver some of the revenue upside in Q1, but the organic growth in the business remains strong, says O'Brien. He reiterates an Overweight rating on Merit Medical with a $75 price target and says the stock remains his favorite mid-cap name.