The former first lady Barbara Bush, who died in April, blamed what she thought was a heart attack in June 2016 on President Donald Trump, according to a new book.

Bush was apparently filled with "angst" over the state of American politics and her son Jeb's battle against Trump in the 2016 Republican primary.

The book says the former first lady was so disillusioned by Republican politics by early 2018 that she no longer considered herself a Republican.

The former first lady Barbara Bush, who died in April, blamed what she thought was a heart attack in June 2016 on President Donald Trump, according to a new book.

While the episode was not technically a heart attack, Bush, whose son Jeb ran against Trump in the 2016 Republican primary, was filled with "angst" over Trump and the state of American politics at the time, according to an excerpt from a new biography of the former first lady, "The Matriarch: Barbara Bush and the Making of an American Dynasty," by Susan Page.

According to Page, Bush's episode "hit her like a sledgehammer," and the former first lady was taken to a hospital.

Bush died in April, two years after the episode, at the age of 92. She had both lung disease and congestive heart failure.

"I'm trying not to think about it," Bush told Page in an interview a year into Trump's presidency. "We're a strong country, and I think it will all work out."

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In February 2018, Bush — one of the best-known faces of the Republican party — told Page that she no longer considered herself a Republican.

Read more: Inside the 'storybook' marriage of Barbara and George HW Bush — who were been married longer than any first couple, and still said 'I love you' every night

Bush's husband, President George H.W. Bush, died in December. The two were married for 73 years and are survived by their five children, 17 grandchildren, and eight great grandchildren.