LOS ANGELES - The exact reason why rapper Kanye West's mother died shortly after undergoing plastic surgery could not be determined but there was no sign of "surgical or anesthetic misadventure," according to a coroner's report released Thursday.

Donda West, 58, died Nov. 10 at a Los Angeles-area hospital, a day after she had breast reduction, tummy tuck and liposuction procedures.

"It is my opinion Ms. West died from some pre-existing coronary artery disease and multiple post-operative factors following surgery," Dr. Louis A. Pena, a deputy medical examiner, stated in West's lengthy autopsy report.

"Based on the history and available information, as currently known, the manner of death could not be determined," Pena said.

Donda West was found unresponsive at her home a day after her surgery. In emergency tapes released earlier this month, two unidentified women told a police dispatcher that West suffered a heart attack and that they unsuccessfully tried to revive her.

Los Angeles County coroner's official Ed Winter said West's family was told of the findings earlier Thursday.

"They were appreciative of our efforts," he said.

A representative for Kanye West declined to comment.

Asked if Donda West would still be alive if she had not undergone the surgery, Winter said: "She could, possibly. But she could have also died because of pre-existing cardiac issues."

The coroner's office had said early indications suggested Donda West died from surgical complications.

Studies have shown serious complications from plastic surgery are rare, with death occurring in one in 58,810 procedures.

Dr. Jan Adams, who operated on Donda West, has denied any wrongdoing. Adams has repeatedly suggested other causes of death including heart attack, pulmonary embolism or accidental overdose of painkillers prescribed after the cosmetic surgery.

The coroner's investigation found "therapeutic levels of medication" but no unusually high levels, and no internal bleeding.

Adams' spokesman, Kevin Williams, did not immediately respond to phone and e-mail requests for comment Thursday.

Adams has appeared as a plastic surgery expert on such shows as "Oprah," "Entertainment Tonight," "E!" and "Extra." He is the author of "Everything Women of Color Should Know About Plastic Surgery."

The state medical board is investigating whether Adams' licence should be revoked or suspended after two alcohol-related arrests in the past four years.

Five months before her death, Donda West had approached Beverly Hills plastic surgeon Dr. Andre Aboolian, who was concerned about a pre-existing condition that may cause a heart attack during surgery. Aboolian did not operate on her.

Donda West was the inspiration for the song, "Hey Mama," on her son's 2005 album "Late Registration." She taught at the University of Chicago and raised Kanye by herself after her husband left when he was a toddler. She often accompanied him to parties and award shows.

She left academia in 2004 to manage Kanye's career and was chief executive of West Brands LLC and chairwoman of the Kanye West Foundation, an educational nonprofit that works to decrease dropout rates and improve literacy.

In May, she published a memoir titled "Raising Kanye: Life Lessons from the Mother of a Hip-Hop Star."