Conservative MP Jim Hillyer died of a heart attack at his desk in his Ottawa office in the early morning hours of March 23, according to the Ontario's coroner's office.

In a statement, Hillyer’s chief of staff Colleen Valin said that autopsy results showed the representative for Medicine Hat-Cardtson-Warner in Alberta died “instantly” of cardiomyopathy, a heart muscle disease that reduces the organ's ability to pump blood.

The condition may have been related to an undiagnosed pre-existing heart condition or the intense regimen of chemotherapy that Hillyer underwent in 2003 to treat his leukemia, the coroner said.

Hillyer, 41, also underwent a bone marrow transplant that same year.

"The coroner has advised that in the coming weeks further test results will confirm which of the two identifiable factors is the cause of death," Valin said.

The autopsy also ruled out any current health issues as playing a factor in Hillyer’s death.

Hillyer had been dealing with a bone infection following surgery on his leg. The MP had been granted a medical leave in February as a result of the complication, but his doctor gave him special permission to return to Ottawa for the release of the federal budget last week.

In the statement, Hillyer's wife Olivia also expressed her grief over her husband's death and thanked the public for their well-wishes.

"More than words can express, I am moved deeply and comforted by the outpouring of love, support and prayers my family has received since Jim's sudden and tragic death," said Olivia Hillyer.

The MP's wife described her husband as her "high school sweetheart" and said her heart is "broken to lose him."

"He loved me so much in our 25 years together that I know I will feel it for the rest of my life," she said.

Hillyer leaves behind four children: London, Taylor, Nation and Asia.

"He has cheered for them, counselled with them and cuddled them. London, Taylor, Nation and Asia are faithful and strong because of his example and love," said Olivia Hillyer.

She also said it was her husband's "lifelong dream" to serve as a member of parliament, and that his heart swelled with "humility and gratitude" when he would see the Canadian flag atop the Peace Tower on the way to work.

"He believes Canada is the greatest country on earth. He believes Southern Alberta is the best place to live and raise a family," she said.

"The golden prairies, vast enough to see the Sweet Grass Hills on the east and Old Chief Mountain on the west, are a delight to his soul."

Hillyer first won a seat in the House of Commons in the 2011 election.

The shock of Hillyer's death reverberated across Parliament Hill last week, as the leaders of all three major federal parties expressed their grief.

Interim Conservative leader Rona Ambrose fought back tears as she described Hillyer's hobbies, sense of humour and dedication to the public service.

"It was clear that he loved life, he loved his wife, he loved his community and he loved his job," Ambrose said in the House of Commons last Wednesday.

Prime Minister Justin Trudeau credited Hillyer for his hard work in Parliament, and offered his condolences to his family.

"His youth and the suddenness of his passing have blanketed the Hill with a weighty sadness," he said.

NDP Leader Thomas Mulcair also said Hillyer was "taken from us far too soon."

Hillyer's funeral is set to take place at the Church of Jesus Christ of Latter-day Saints Stake Centre in Raymond, Alta., on April 1. Raymond is about 250 kilometres southeast of Calgary.