A Senate investigation has found that Medicare spent millions of dollars for stents implanted by a Maryland doctor accused of putting them in patients who didn't need them.

The investigation also found that the doctor was treated to an elaborate crab feast and barbecue by Abbott Labs, the maker of the stents. The stents are tiny, metal-mesh tubes used to keep unclogged arteries open.

The report released Monday by the Senate Finance Committee said Dr. Mark Midei's questionable implantations cost the Medicare program $3.8 million between 2007 and 2009.

Midei's attorney, Stephen L. Snyder, says the committee's investigation was not thorough and relied on documents.

An Abbott spokesman says the company's consulting relationship with Midei ended earlier this year.