White House press secretary Sarah Huckabee Sanders followed up with a statement on Kudlow describing "what his doctors say was a very mild heart attack".
Kudlow's friend Stephen Moore, of the Heritage Foundation, told Politico that he believes he will be okay.
Kudlow appeared on Jake Tapper's CNN Sunday Beltway show, State Of The Union, this past Sunday, accusing Canadian Prime Minister Justin Trudeau of undermining the U.S. and the G-7 confab with his comments.
Donald Trump Tweets: Larry Kudlow Has Had A Heart Attack
Kudlow, who is a wry and upbeat speaker, has adopted some of Trump's hard-line rhetoric while working inside the West Wing. His recovery was a great source of pride for him and for his friends, contributing to his upbeat manner.
Trump then headed to his summit with North Korean leader Kim Jong Un, whom Kudlow referred to as "the insane nuclear tyrant in North Korea".
A 70-year-old former financier, Mr. Kudlow left Wall Street in 2001 to work for the conservative magazine National Review and later appeared in a string of political and economic current affairs shows on the MSNBC news channel.
Trudeau, in a news conference on Saturday, reiterated his strong objections to steep tariffs on Canadian exports of steel and aluminum to the United States.
Trump's close friend was not travelling with the US President in Singapore.
Missing Air Force officer found 35 years later
OSI agents assigned to Travis AFB in northern California went to his home and arrested the fugitive captain without incident. In retrospect, William Howard Hughes, Jr . was maybe not the kind of guy you wanted to guard your national security.
Vice President Mike Pence also tweeted about Mr Kudlow's heart attack.
Trump's choice of Kudlow to be his top economic aide elevated the influence of a longtime fixture on the business news network CNBC.
Eruption of lava continues from vent in Hawaii neighborhood
Lava erupts in Leilani Estates during ongoing eruptions of the Kilauea Volcano in Hawaii, June 5, 2018. A live webcam stationed at the summit shows volcanic gas and ash pouring from the crater vent.