HeartWare International (NSDQ:HTWR) said its $8 million acquisition of onetime competitor World Heart Corp. (NSDQ:WHRT) is complete.

WHRT shares stopped trading on the NASDAQ exchange when the market closed yesterday afternoon.

The companies make implantable heart pumps called ventricular assist devices. World Heart’s exit leaves Thoratec (NSDQ:THOR) and Thoratec (NSDQ:THOR) as HeartWare’s remaining rivals in the cardiac assist market.

"We are pleased with the pace of this transaction and anticipate moving quickly to integrate World Heart," HeartWare CEO Doug Godshall said in prepared remarks. "Consistent with our goal to be a leader in the VAD market for years to come, we believe that bolstering our patent portfolio and adding World Heart’s technologies broadens our options for the future."

The complex deal, announced in March, took more than a year to complete, during which time World Heart hired and fired its investment banker, was turned down by more than 16 suitors and laid off nearly all its staff. At 1 point, World Heart officials contemplated selling off all of its assets in a fire sale to pursue a reverse merger.

The deal began in earnest in March, 2011, when World Heart hired Barclays Capital to assist in exploring a potential sale to a group of large-cap and mid-to-small-cap companies.

By that time, World Heart had already paused enrollment in clinical trials of its Levacor device, a magnetically levitated, bearingless, implantable centrifugal pump, in order to make refinements to the system based on initial clinical experience.

In conversations with the FDA "it became increasingly clear that as we went down, process time lines we were hoping for were not going to be achieved and we were going to be delayed significantly," World Heart CFO Morgan Brown told MassDevice.com last summer.

Barclays contacted more than 16 potential buyers, but just HeartWare and 2 other unnamed companies agreed to explore a potential sale.

By June 6, 2011, HeartWare was the only suitor left. That company’s senior vice president and general counsel Lawrence Knopf submitted a $25 million non-binding indication of interest, but the deal soured July 12 when HeartWare, citing concerns over the Levacor trial and the company’s other projects, decided not to move forward with a merger.

For the next several weeks, as World Heart was suspending its Levacor efforts and cutting staff, officials maintained ongoing dialogue with Godshall. Those talks continued for several months with each side looking for ways to create a partnership or joint venture.

At the same time, officials at World Heart looked for ways to sell off some of the company’s more than 100 patents or the rights to intellectual property for the PediaFlow VAD program. World Heart officials explored other ways to exit the company, including selling off its intellectual property to HeartWare for $3.5 million in stock and then executing a reverse merger to a private company looking to assume World Heart’s public listing on NASDAQ.

In February 2012 World Heart laid off 77% of its workforce as it negotiated a new letter of intent from HeartWare. Those negotiations continued until the end of March when the companies announced that they had agreed to a $8 million merger, to be paid in either cash or HeartWare stock.