ROME, June 21, 2013— -- An autopsy has confirmed that James Gandolfini, 51, died of a heart attack.
The actor "died of a heart attack of natural causes" and "nothing else was found in his system," Michael Kobold, a family friend and spokesman for the Gandolfinis, told a news conference in Rome this morning.
Gandolfini's body has been turned over to a funeral director and, contingent upon Italian authorities, will be flown back to the United States where a funeral will occur in New York Thursday, Friday or Saturday of next week, he said.
"We are looking forward to working with the Italian government to shorten the process so that we can get Jim's body back sooner," Kobold said. "And once we have the clearance, we will put him on a flight to America. We expect that to be Wednesday, maybe Thursday, but we will keep you informed."
The full statement provided by the family reads: "James came here on vacation, leaving his family. He had a wonderful day. He visited the Vatican. He had dinner at the hotel with his son, awaiting the arrival of his sister.
"Today we received the results of the autopsy, which stated he died of a heart attack of natural causes. The autopsy further states that nothing else was found in his system. We are all devastated by this loss. James was a devoted husband, the loving father of two children, and a brother and cousin we could always count on.
"We thank you for giving us the privacy that you have given us and afforded us at this difficult time. Our expressed thanks."
Kobold last spoke to Gandolfini June 16, Father's Day, and said, "Jim was happy, he was healthy, he was doing really fine."
The actor was in his room Wednesday at Hotel Exedra when he became ill around 10 p.m. local time, officials said. His son Michael, 13, called the reception desk begging for help, according to the hotel. An ambulance brought Gandolfini to Policlinico Umberto I hospital in central Rome, where he arrived in cardiac arrest.
Dr. Claudio Modini, who was in charge of the emergency room the night Gandolfini arrived, said emergency personnel spent 40 minutes trying to revive him.
"It was more than critical, practically dead," Modini said of Gandolfini's condition upon arriving at the hospital.
Modini said he believes the three-time Emmy winner died of a heart attack.
Modini says he does not believe drugs or alcohol played a role in the star's death. Gandolfini was known to be a smoker.
"Increased weight and regular smoking extraordinarily increase the risk of heart disease in anyone," said Dr. Holly Andersen, who specializes in cardiovascular disease at New York-Presbyterian-Weill Cornell.
Gandolfini talked openly about his inability to lose weight, especially while playing the role of Tony Soprano.
"When I do get thin, which isn't often, I don't feel the same. I don't walk the same. He doesn't walk the same. You know, with that lumber," Gandolfini told "Inside the Actors Studio" host James Lipton.
VIDEO: New Jersey Diner Pays Tribute to James Gandolfini
Gandolfini was set to receive an award this weekend at the Taormina Film Festival in Sicily.
Gandolfini is survived by his wife, Deborah Lin, their daughter, Liliana, 8 months old, and his son, Michael, from a previous marriage.
ABC News' Eliza Murphy and Anthony Castellano contributed to this report.