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The number of patients with ischemic heart disease (myocardial infarction and angina pectoris) is estimated at more than 700,000, accounting for approximately 5% of all deaths in Japan. In myocardial infarction, the coronary arteries that supply blood to the heart muscle (myocardium) become completely blocked, which can lead to sudden death. We summarize the symptoms of ischemic heart disease, test methods for diagnosis, and measures for early detection.

Ischemic heart disease is a condition in which the coronary arteries that supply blood to the myocardium become narrowed or blocked, resulting in poor blood flow to the myocardium and oxygen deficiency in the myocardium. A narrowed coronary artery is angina pectoris, and a blocked coronary artery is a heart attack. According to a patient survey conducted by the Ministry of Health, Labor and Welfare, the number of patients with ischemic heart disease is about 720,000 (as of 2017), and the number of male patients is higher than that of males and females. It is also said to account for about 5% of all deaths in Japan. The main cause of ischemic heart disease is arteriosclerosis, which is said to be easily caused by lifestyle factors such as hypertension, dyslipidemia, diabetes, lack of exercise, and smoking.

In angina pectoris, although the coronary arteries are narrowed, they are not completely blocked, so myocardial cells do not die, and angina is not immediately life-threatening. When symptoms such as strong squeezing pain and a feeling of pressure appear, they are often precursors of myocardial infarction. Patients may not even be aware that they have symptoms. Especially in the case of the elderly, it seems that there are many cases where the symptoms are overlooked as a result of aging. In some cases, people with diabetes may not feel the pain of angina pectoris due to the effects of neuropathy, which is one of the complications. Most angina pectoris occurs during activity, but spasms of the coronary arteries can occur at rest, resulting in an angina attack.

Myocardial infarction is a condition in which the coronary arteries are blocked, depriving the heart muscle of oxygen, and can lead to sudden death. More than 30,000 people die from myocardial infarction each year, and it is one of the three major causes of death in Japan. When it develops, symptoms such as strong chest pain and pressure accompanied by cold sweat and nausea appear. Chest pain lasts more than 30 minutes. Once myocardial infarction occurs, the mortality rate is said to be as high as 30%.

Common symptoms of ischemic heart disease include chest pain and pressure, nausea, and shortness of breath, as well as pain in the side, arms, and shoulders. It is especially important to see a doctor as soon as possible if you experience chest pain or chest pain.
Tests for early detection of ischemic heart disease include the following:

(1) Treadmill exercise electrocardiogram:
There is no change even if you check the electrocardiogram when symptoms do not appear. Therefore, in order to reproduce the situation in which the symptoms appear, a load of exercise is applied to increase the oxygen demand of the myocardium to induce ischemia, and changes in the electrocardiogram at that time are observed. Stress is performed by walking on a moving belt conveyor, and the ECG and blood pressure during exercise are checked in conjunction with the ECG before and after the exercise load. If this test reveals an abnormal electrocardiogram, angina on exertion is suspected.

② Holter electrocardiogram test:
Since the symptoms of angina pectoris disappear in a few minutes, it is difficult to obtain an electrocardiogram when symptoms appear. Therefore, by wearing a portable electrocardiogram for 24 hours and observing it, we will investigate at what timing an abnormal electrocardiogram occurs. It is possible to determine whether an abnormal ECG is due to exertion or is occurring at rest.

③ Myocardial scintigram test:
A drug that generates a small amount of radiation is injected into the body and its uptake into the myocardium is measured. It is possible to assess how much the myocardium is ischemic and how weak it is. The drug used is so small that it disappears naturally in about half a day, so there is no harm to the body.

④Cardiac CT examination:
A contrast agent is injected into the body and photographed, and the stenosis of the coronary arteries is examined in 3D images. Compared to the conventional mainstream cardiac catheterization, it is a test that places less burden on the body. However, since the contrast medium is excreted through the kidneys as urine, caution should be exercised in patients with renal dysfunction.

⑤ Cardiac MRI examination:
A magnetic force is used to image the coronary arteries by computer analysis of the signals from the body's hydrogen atoms. There is no exposure to X-rays and the examination can be performed without using a contrast agent, making it suitable for patients with renal failure or contrast agent allergies.

⑥Echocardiography (echo):
Ultrasound waves are applied directly to the heart in the chest and an image is projected. The heart is cut into slices to examine the shape of the heart and blood vessels and the flow of blood. Heart movement abnormalities and changes in diastolic capacity may be observed. Ultrasound is harmless and painless.

⑦ Coronary angiography (cardiac catheterization) examination:
A thin, soft tube called a catheter with a diameter of 1 to 3 mm and a length of 1 m is inserted from the base of the foot or wrist, advanced to the coronary arteries of the heart, a contrast medium is injected, and moving images are taken with X-rays. Although an invasive technique, it allows direct visualization of vascular occlusions and narrowings that contribute to ischemic heart disease. In addition, if the examination reveals narrowed areas in the coronary arteries, treatment to widen the arteries may be performed.

If ischemic heart disease is suspected, electrocardiography, diagnostic imaging and examinations are performed, and coronary angiography is performed. The leading cause of death in Japan is malignant neoplasm <cancer>, followed by heart disease (heart failure, ischemic heart disease). The important thing is early detection at the stage of angina pectoris before myocardial infarction occurs. If you feel any discomfort in your body, we recommend that you see a doctor as soon as possible.