Taylor Swift's Dad Scott Recovering From Heart Surgery and Doing Great

Taylor Swift's dad had to go under the knife for a heart procedure ... and she was by his side in the hospital ... but now he's feeling fantastic, TMZ has learned.

The singer's spokesperson tells TMZ ... Scott Swift had quintuple bypass surgery over a month ago and his wife, Andrea, and their kids, Taylor and Austin, were with him through the entire surgery and recovery process. Taylor's rep also told us the procedure was NOT the result of a heart attack, and he's feeling just great.

Scott -- who's been married to Taylor's mom Andrea for 37 years -- originally went in for a check-up and his doctor saw something, which led to the surgery.

His surgery was a complex one ... quintuple bypass is a procedure used to treat patients who have blockages in the major arteries that feed the heart -- blood vessels are taken from another part of the body and transplanted to affected heart vessels to reroute blood flow and bypass the blockages.