Empress Michiko has shown possible symptoms of heart disease in an electrocardiogram examination and will undergo a more detailed exam next month, the Imperial Household Agency said.
The 80-year-old Empress started complaining of chest pain around late June. Given her possible symptoms of coronary artery obstruction, she is scheduled to undergo a coronary computed tomography scan at University of Tokyo Hospital on Aug. 9.
The agency said the Empress could be suffering from myocardial ischemia, or insufficient blood flow to part of the heart muscle via the coronary arteries, which could lead to a heart attack.
There is no change so far to the schedule of her official duties. But she will be advised to refrain from any activities that could elevate her heart rate, including standing in a hot place for a long time, the agency said.
She will not be prescribed any medication for the time being.
The Empress experienced chest pain several times a week at first, but the frequency has increased recently to several times a day.
She took a 24-hour electrocardiogram by wearing a device around the clock and some abnormalities were found.
In myocardial ischemia, obstruction of a blood vessel could occur temporarily due to stress or simply advancing age. It is too early to conclude that she is in ill health and the agency has decided to ask her to undergo the more thorough examination next month, which is expected to take 10 minutes, the agency said.
Together with Emperor Akihito, the Empress visited Aichi Prefecture for three days starting Sunday. She did not experience chest pains during that trip, the agency said.
The Emperor underwent heart bypass surgery in February 2012 after being diagnosed from angina.