Heart Patient Guide

Investigations of Coronary Artery Disease

(i) Electrocardiogram

ECG is EECG is useful to diagnose recent and old myocardial infarctions. It is also helpful to diagnose a large proportion of patients with angina, especially if ECG is performed when the patient is having chest pain. However normal ECG, performed at rest, can not rule out coronary artery disease.

(ii) Exercise test (tread mill test, TMT)

In this test, patient’s ECG is monitored while the patient is given graded exercise. If coronary artery disease is present and if it is causing reduction in blood flow to heart muscle, the ECG will show abnormalities and the patient may develop angina or breathlessness. This test shows the presence of coronary disease but it can not clearly show where and how severe the disease is.

(iii) Thallium scan

The principle of this test is same as that of TMT, but it is more sophisticated. Blood flow to the heart muscles is evaluated by injecting radioactive material into the circulation. The pictures are taken by a camera placed outside the body.

(iv) Angiography

In this a thin, long tube (catheter) is passed from groin or elbow of the patient to the heart. X-ray opaque dye is injected through this catheter and X-ray pictures are taken in a fast sequence. This test demonstrates the exact site and severity of coronary blockade.Though angiography requires entry into the body, it is quite safe in present times.

(v) Other investigations

Patients who had history of stroke or giddiness and fainting, will require evaluation of the arteries supplying blood to the brain (carotid arteries). A carotid duplex scan (ultrasound examination of the carotid arteries) or carotid angiography may be required. Similarly, some patients require evaluation of arteries supplying blood to the kidneys or lower limbs. Besides these tests, patients are evaluated for the presence of diabetes and also to know the levels of fats in the blood.