Sir Paul McCartney was diagnosed with a heart problem for which his doctors reportedly ordered him to stop boozing.
However, the former Beatle, who recently underwent heart surgery, allegedly ignored the instruction.
A source has revealed that Macca's heart problems were a major source of conflict between him and estranged wife Heather Mills.
He further said that the 65-year-old legendary singer had electric shock treatment since to ease the problem.
"It's not a threatening condition, he just needs to take better care of himself. This was a major source of problems between him and Heather Mills," The Sun quoted the source, as saying.
"He was receiving electrical shocks over the two years on his chest to help with his heart and was under strict instructions to stop drinking completely, which he didn't do," the source added.