The 65-year-old underwent a coronary angioplasty--a procedure to open up arteries, allowing a greater flow of blood to and from the heart--late last year.
But the star has made a good recovery--he appeared onstage with singer Kylie Minogue for a televised concert on New Year's Eve.
A source tells British newspaper The Sun, "Paul had been complaining about not feeling well and saw a Harley Street specialist at The London Clinic.
"Tests were carried out and the decision was taken to operate. Paul had the angioplasty in a private hospital. It was all very routine, but any work on your heart is a big deal."
A spokesman for McCartney confirmed the surgery adding, "It was a routine medical operation."
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