Maricopa County spokeswoman Cari Gerchick says that's the finding from an autopsy conducted Thursday by the county Medical Examiner's Office.
The 54-year-old wrestler's given name was James Hellwig. He collapsed April 8 while walking with his wife to their car at a Scottsdale hotel and was pronounced dead at a hospital.
Scottsdale police have said there were no signs of foul play. The Ultimate Warrior was one of pro wrestling's biggest stars in the late 1980s.
The Ultimate Warrior began his WWE career in 1987 and quickly went on to become one of the biggest stars in WWE history. Ultimate Warrior became WWE Champion at WrestleMania VI, defeating Hulk Hogan in an epic encounter.
"We are grateful that just days ago, Warrior had the opportunity to take his rightful place in the WWE Hall of Fame and was also able to appear at WrestleMania 30 and Monday Night Raw to address his legions of fans," a WWE statement April 9 said.
The WWE offered its sincere condolences to Warrior's family, friends and fans. The Ultimate Warrior is survived by his wife Dana and his two daughters, the WWE said.
The Ultimate Warrior was known for his neon mask and energetic ring entrances, when he would run full speed down the entrance ramp and run circles around the ring before shaking the ropes "like a man possessed," the WWE said.
At SummerSlam in 1988, the powerful competitor famously defeated The Honky Tonk Man for the Intercontinental Championship in 30 seconds, the WWE said. In the early '90s, the intense superstar then entered into a rivalry with "Macho Man" Randy Savage, culminating in a legendary Retirement Match at WrestleMania VII, which Ultimate Warrior won. In the months that followed, he battled superstars like Undertaker, Papa Shango and Sid, but disappeared from the ring suddenly, the WWE said.
The WWE said throughout the '90s, Ultimate Warrior made sporadic returns to the WWE, including a smashing of a young Triple H at WrestleMania XII, and finally popped up in World Championship Wrestling for a rematch with Hogan at Halloween Havoc in 1998. This contest would be his last major ring appearance, bringing an anticlimactic end to the career of one of sports-entertainment's most unique competitors, the WWE said.
He was inducted into the WWE Hall of Fame April 13.
The Associated Press contributed to this report.