ROME (CNN) -- Official autopsy results are expected Friday for "Sopranos" star James Gandolfini, who died of an apparent heart attack while vacationing in Italy.
Doctors analyzed samples from his body and will provide a final report later in the day, Dr. Claudio Modini said.
Initial indications suggest the actor died of a heart attack, according to Modini, who heads the emergency department he was taken to in Rome.
"During the autopsy, it appeared clear the presence of an important miocardio arrest," he said.
Its unclear whether Gandolfini's family will release the full autopsy results to the public.
The actor was hospitalized Wednesday after falling ill at his hotel in the Italian capital. After failed resuscitation attempts, his body was transferred to the morgue early Thursday.
By law, medical examiners in Italy are required to conduct a postmortem 24 hours after the body's arrival in the morgue, a hospital spokesman said.
Doctors had not noted any suspicious factors, such as alcohol, on his medical report, Modini said.
Ambulance staff tried to resuscitate the actor at the hotel, and further efforts were made when he reached the emergency room, Modini said.
Though the cause of death is not confirmed, his managers also believe that a heart attack killed the man who portrayed a mob boss battling panic attacks in the HBO show, "The Sopranos."
Gandolfini was scheduled to receive an award at the Taormina Film Festival.
He was to arrive Friday in Taormina in Sicily, a quaint town packed with historical architecture and nestled between lush green hills and the azure waters of the Mediterranean Sea.
Before Italian authorities can release his remains for transport back to the United States, the U.S. Embassy in Rome must issue a death certificate.
The U.S. Embassy said it was "deeply upset" by the news of the actor's death, but had not received any official confirmation from local authorities.
It said the family will get assistance from the embassy when it requests it.
Gandolfini experienced a medical emergency about 10 p.m. Wednesday in his room, said Michael Kobold, who described himself as a close family friend of the actor.
He gave more details of his final moments in a news conference Thursday at the Boscolo Exedra Rome Hotel, where the actor was staying.
"The hotel notified emergency crews who responded, and first aid was administered before Mr. Gandolfini was taken to the hospital, where he died of an apparent heart attack," he said.
Kobold said he'd known the actor from New Jersey for more than a decade and lived with him years ago.
CNN's Hada Messia reported from Rome, and Faith Karimi wrote from Atlanta