Making good on a pledge it made nearly four years ago, St. Jude Medical said Wednesday it spent $375 million to acquire the remaining 81 percent of CardioMEMS, an Atlanta maker of heart failure monitors.

The acquisition came just after CardioMEMS received Food and Drug Administration approval for its remotely monitored miniature sensor, which is implanted in the pulmonary artery during a minimally invasive surgical procedure. If a problem is detected, doctors can adjust medication or pursue other treatment options, often while keeping the patient out of the hospital.

The approval was a major victory for CardioMEMS, because its heart-failure monitor had been rejected by the FDA in 2011. At the time, the FDA Circulatory Systems Devices advisory panel said the product was safe, but questioned whether it was effective and whether the product’s benefits outweighed its risks.

St. Jude, based in St. Paul, had paid $60 million in 2010 for a 19 percent interest in CardioMEMS, and agreed at that time to buy the remaining 81 percent for $375 million if certain milestones were met.

The CardioMEMS monitoring system should generate $15 million to $20 million in sales in 2014, St. Jude CEO Dan Starks said following the company’s fourth-quarter earnings report in January.