Trump tweeted the news shortly before his meeting with North Korea's Kim Jong Un was scheduled to begin in Singapore. "Larry is now in good condition at Walter Reed National Military Medical Center and his doctors expect he will make a full and speedy recovery", White House press secretary Sarah Huckabee Sanders said in a statement.
As a commentator, Kudlow had strongly backed Trump's moves to cut taxes and reduce business regulations but was openly critical toward the president's tariffs moves.
When he was a CNBC contributor before taking the White House job, Kudlow argued the metals tariffs Trump had announced would harm consumers.
"Earlier today", Kudlow "experienced what his doctors say was a very mild heart attack".
Kudlow accompanied Trump this weekend to the annual G7 meeting in Quebec, where the president traded barbs with the leaders of Canada, Germany and France over trade.
In an interview with CNN on Sunday, Kudlow said Trudeau "really kind of stabbed us in the back".
Kudlow, a wry and upbeat speaker, has also adopted some of Trump's hard-line rhetoric while working inside the West Wing.
After working in President Ronald Reagan's administration, Kudlow moved to Wall Street and, though he never completed a master's program in economics and policy at Princeton University, served as chief economist at Bear Stearns. His recovery was a great source of pride for him and for his friends, contributing to his upbeat manner.