John Heard died of a heart attack.

The 'Home Alone' star - who played Peter McCallister in the film franchise - was found dead in a hotel in Palo Alto, California, last month aged 71, and his cause of death is confirmed to have been a heart attack brought on by heart disease.

According to TMZ, the Santa Clara County Medical Exmainer's Office discovered John died of a ''sudden cardiac death due to atheroscerotic and hypertensive heart disease'' after they carried out an autopsy.

John was staying at the hotel to recover from a minor back operation he had two days before at Stanford Medical Center, but the surgery ''did not play a role in his death''.

The star's toxicology results have not been made public.

The actor - who also starred in movies 'The Pelican Brief' and 'In the Line of Fire' - was found by a maid and pronounced dead at the scene when paramedics arrived.

John has been laid to rest in a plot at the Lady Of Hope Church in Massachusetts, beside his son Max, 22, who died following an overdose in December 2016.

His former wife Lana Pritchard recently said: ''John was laid to rest next to Max which was a sweet gesture. The funeral was arranged by his sister, Cordis, and only a very few family were in attendance.

''I co-operated with the family the best I could after his sudden death but we are totally in the dark about any will and testament John may have had.

''I'm sad because I would have liked to have paid my respects as I was very close to him right up until he died although there could be a service to commemorate him by his friends in Los Angeles later this month.''