JPMorgan Chief Executive Jamie Dimon Has Emergency Heart Surgery

Jamie Dimon, the longtime chairman and chief executive of JPMorgan Chase, had an emergency medical procedure on his heart on Thursday, according to a memo sent to bank employees.

Mr. Dimon, 63, underwent successful heart surgery for an “acute aortic dissection,” and he is recovering, said the memo, which was reviewed by The New York Times.

While Mr. Dimon is out of work, the bank will be run by two senior JPMorgan executives, Daniel Pinto and Gordon Smith, the memo said.

Mr. Dimon, who previously overcame a bout of cancer, is the longest-serving leader of a major American bank, having run the company since 2005.

“The good news is that it was caught early and the surgery was successful,” the memo said. “He is awake, alert and recovering well.”

Mr. Dimon has kept an iron grip on the job, weathering the 2008 financial crisis and a 2012 scandal in which a trader nicknamed the London Whale lost the bank more than $6 billion.

Under Mr. Dimon, the bank has grown to be the largest in the United States, with $2.6 trillion in assets and a habit of dominating its competitors, both in consumer banking and on Wall Street. Its profits have set records. Its customers make up a sizable chunk of the American population. It has also paid tens of billions of dollars in fines for transgressions like mortgage lending abuses and weak anti-money-laundering controls, and because of its booming business lending to the fossil fuel industry, it has become the foremost target for climate activists.

This isn’t Mr. Dimon’s first bout of ill health. In the summer of 2014, he announced that he had a “curable” form of throat cancer. He underwent chemotherapy, and did not step away from his duties during that time. At the end of that year, he disclosed that a checkup had found no trace of the cancer.

The aorta is the biggest artery in the body, and has three layers. An aortic dissection occurs when blood forces its way into a tear in the aorta, separating the layers or peeling them apart. The symptoms can be similar to those of a heart attack.

This is a developing story. Check back for updates.