Emperor Emeritus Akihito will be admitted to the University of Tokyo Hospital in the capital's Bunkyo Ward from Tuesday for heart tests, the Imperial Household Agency said Monday.

The 91-year-old former emperor has been diagnosed with a high probability of myocardial ischemia, which occurs when blood flow to the heart is insufficient, according to the agency.

It will be the first time for the emperor emeritus to be hospitalized since February to March in 2012, when he underwent coronary bypass surgery at the age of 78.

According to his aides, the emperor emeritus had regular health checks in mid-April, during which signs of possible myocardial ischemia were observed on an electrocardiogram. After a reexamination at his residence in Tokyo's Minato Ward, it was learned on Sunday that he likely has myocardial ischemia.

With no symptoms, the emperor emeritus had continued his routine morning and evening walks until Sunday, but skipped the morning walk on Monday. He also decided to postpone a plan to stay at the Hayama Imperial Villa with Empress Emerita Michiko from Thursday.

In July 2022, the emperor emeritus was diagnosed with right heart failure due to a problem with the tricuspid valve between the right atrium and ventricle. Since then, he has been receiving medical therapy, including drug administration and water restriction.