A prominent US cardiologist has questioned White House denials that President Donald Trump was treated for a heart attack on the weekend.

Mr Trump on Wednesday (Australian time) denied he suffered a heart attack or chest pains amid speculation over his sudden trip to hospital.

Dr Jonathan Reiner, former vice president Dick Cheney’s personal cardiologist, told CNN later Wednesday he was “skeptical” about White House claims the Saturday hospital visit was “routine”.

Speaking before a cabinet meeting at the White House, Mr Trump brought up the unscheduled trip without prompting.

He said that he had gone to hospital to do a portion of his yearly physical – and berated the media for worrying his wife, Melania.

“I went for a physical, and I came back,” Mr Trump said.

“My wife said ‘darling, are you Ok? What’s wrong? Oh, they’re reporting that you may have had a heart attack.’

“I said, ‘Why did I have a heart attack?’

“‘Because you went to Walter Reed Medical Centre’,” he said Mrs Trump replied.

“That’s where we go when we get the physical. I said I was only there for a very short period of time,” the President added.

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“I was called by our people in public relations: ‘Sir, are you OK?’. I said ‘OK for what?’. ‘The word is you had a heart attack. CNN said you may have had a heart attack. You had massive chest pains. You went to the hospital’.”

Dr Reiner maintained that the explanation for the visit didn’t add up.

“A spontaneous trip for a medical exam is distinctly uncommon, raising the question of whether there was something specifically at issue that required an evaluation on Saturday,” he said.

“Almost everything that is usually done in a presidential physical like this, can be done in the White House at the White House medical unit. So, it doesn’t really make a lot of sense why the President would travel up to Walter Reed on a Saturday afternoon for this kind of testing.”

Unlike Mr Trump’s last two visits to Walter Reed for physicals, Sunday’s trip was not published on his public schedule ahead of time.

Adding to the intrigue was the fact that journalists in the President’s press pool were told not to report on his movements until he arrived at the centre – a protocol generally used when the motorcade route has not been adequately secured.

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The theory the President fell unwell intensified in the days after as he stayed out of the public eye.

“Visited a great family of a young man under major surgery at the amazing Walter Reed Medical Centre,” the President tweeted early Sunday.

“Those are truly some of the best doctors anywhere in the world. Also began phase one of my yearly physical. Everything very good (great!). Will complete next year.”

On Monday, Mr Trump’s doctor said the President had not experienced any “chest pain” or “urgent or acute issues”.