Heart disease and alcoholism are understood to have played a factor in Hollywood actor Michael Madsen's death, it is reported.

The Kill Bill and Reservoir Dogs actor, aged 67, was found unresponsive at home last week, which his manager has since stated was as a result of a cardiac arrest. The star's cardiologist has now revealed his official cause of death to be heart failure and said contributing factors to this include heart disease and alcoholism.

Madsen's lawyer said the actor - known for his roles in Quentin Tarantino's Reservoir Dogs and Kill Bill - was battling an alcohol addiction before he died. No autopsy will be conducted because the cardiologist who was treating Madsen signed the death certificate, it is understood.

The doctor, who has not been named, told NBC Los Angeles the new developments today. The publication also details poignant tributes for the star, who was in multiple Quentin Tarantino films during his 40-year career.

READ MORE: Michael Madsen's sister Virginia pays emotional tribute after actor's death

Madsen's sister Virginia had said last week: "My brother Michael has left the stage. He was thunder and velvet. Mischief wrapped in tenderness. A poet disguised as an outlaw. A father, a son, a brother - etched in contradiction, tempered by love that left its mark.

"We're not mourning a public figure. We're not mourning a myth - but flesh and blood and ferocious heart. Who stormed through life loud, brilliant, and half on fire. Who leaves us echoes - gruff, brilliant, unrepeatable - half legend, half lullaby."

Those who knew Madsen said that, in addition to his acting work, the star was preparing to release a new book. A statement from his representatives issued after the tragedy read: "In the last two years Michael Madsen has been doing some incredible work with independent film including upcoming feature films Resurrection Road, Concessions and Cookbook for Southern Housewives, and was really looking forward to this next chapter in his life.

"Madsen was also preparing to release a new book called Tears For My Father: Outlaw Thoughts and Poems. Michael Madsen was one of Hollywood’s most iconic actors, who will be missed by many."

The actor's film career spanned decades, beginning in the early 1980s with minor roles in the likes of WarGames and Racing With the Moon. His biggest early break came in 1992 when, aged 35, he played a central role in Reservoir Dogs. It sparked a long relationship with its director Tarantino, which saw the duo work together with Kill Bill: Volume 2, The Hateful Eight, and Once Upon a Time in Hollywood over the years.

But as well as his legacy, tragic Madsen, born in Chicago, Illnois, leaves behind his seven children, wife DeAnna Morgan, his two siblings, and mother.