Entwistle was found dead in his room at a hotel in Las Vegas last June. He was 57.
The coroner says he didn't find a "huge amount" of coke in Entwistle's system, but he says it was enough to hurt someone with heart disease.
This ruling backs up a California coroner, who ruled earlier that Entwistle died from a combination of cocaine and heart disease.
In July, Clark County Coroner Ron Flud ruled the rock star's death accidental. According to a statement, Flud found the immediate cause of Entwistle's death to be "ischemic heart disease" due to "coronary atherosclerosis."
Other significant conditions included "cocaine intoxication" and "hypertensive cardiovascular disease," the statement said.
Flud determined that death occurred as a result of "lethal drug effect in setting of significant natural disease."
Dr. Jeff Greenlee, an emergency room physician at University Medical Center in Las Vegas, interpreted the statement to mean that Entwistle's death was caused when cocaine caused the contraction of the coronary arteries, "which in his case was lethal because he had underlying natural heart disease."
Entwistle, a co-founder of The Who, was on medication for a heart condition, according to Steve Luongo, the drummer in another Entwistle band for the past 15 years.
Entwistle died the day before The Who was scheduled to kick off a three-month nationwide tour at the hotel's concert hall.
The group, founded in London in the early 1960s, was part of the British rock invasion along with the Rolling Stones and the Beatles. Their parade of hits included "I Can See For Miles," "I Can't Explain," "Substitute," "Pinball Wizard," "Won't Get Fooled Again" and "Who Are You."
Entwistle was born Oct. 9, 1944, in London, and played piano and trumpet in his early years. He met Pete Townshend and Roger Daltrey in his high school years and by 1964 the band was born.
They were inducted into the Rock and Roll Hall of Fame in 1990. Entwistle was among the first in rock to experiment with the six- and eight-string bass, and he also played the French horn.