Paul Bearer died of a heart attack caused by an untreated rapid heart rate, according to his son, Michael Moody.

Michael Moody told TMZ on Saturday that his father’s death certificate lists the cause of the heart attack as supraventricular tachycardia, or SVT.

SVT is an extremely rapid heart rhythm that occurs at the part of the heart’s control system which keeps the top of the organ properly functioning.

Wrestling legend Paul Bearer, real name William Alvin Moody, the pasty-faced, urn-carrying manager for performers The Undertaker and Kane, died on Tuesday, March 5. He was 58.

SVT is typically not life threatening, though it can decrease one’s heart functionality if prolonged without treatment, according to medical sources.

Paul Bearer died of a heart attack caused by an untreated rapid heart rate

SVT’s symptoms are similar to anxiety and heartburn, so it is not uncommon for people to wait out the discomfort instead of seeing a doctor.

Those who get treated for the fairly common heart condition without waiting too long more often than not survive, one cardiologist told TMZ.

Michael Moody said doctors believe Paul Bearer had been struggling with SVT for several weeks.

Three days before Paul Bearer died, he had reportedly complained to friends and family that he was suffering a blood clot.

The WWE released a statement at the time of his death saying: “WWE is saddened to learn of the passing of William Moody, aka Paul Bearer.

“Moody made his WWE debut in 1991 as the manager of The Undertaker and went on to become a memorable part of WWE over the course of the next 20 years. Our deepest condolences go out to Moody’s family, friends and fans.”