Boston Scientific Corp.’s up to $664 million acquisition of Bolt Medical Inc. closed just days after Bolt secured U.S. FDA 520(k) clearance for its intravascular lithotripsy (IVL) system, positioning Boston Sci to challenge Johnson & Johnson’s Shockwave IVL system, which has been the only player in the market.

In early validation of widespread predictions of a robust year for M&A activity, Boston Scientific Corp. signed a definitive agreement to acquire the 74% of Bolt Medical Inc. it doesn’t already own for $443 million up front and up to $221 million in contingent milestone payments.