An autopsy on the body of Thomas Herrion shows the San Francisco offensive lineman died of heart disease and had a significant blockage in his right coronary artery.
The 23-year-old died after collapsing in a locker room following a preseason game against the Denver Broncos on August 20th.
Denver's coroner says the blockage in Herrion's artery caused the death of heart muscle, and that his heart was slightly enlarged. That's a condition that could be related to anything from heart disease and high blood pressure to heredity.
The findings confirmed the beliefs of Herrion's family and friends, who were certain drugs played no role in his death. Herrion's heart condition was caused by factors that are often nearly undetectable, though fairly rare in a young athlete in good physical condition.