Diagnosis of Stable Angina & Unstable Angina
Stable angina is diagnosed primarily on symptoms, such as chest pain. A diagnosis of unstable angina is made when
- a person develops new onset angina that is severe and/or frequent;
- a patient with chronic stable angina develops more frequent, severe, prolonged, or more easily triggered episodes;
- angina occurs at rest.
A diagnosis of variant angina is suspected when there are symptoms of recurrent prolonged angina attacks.
Laboratory Tests to Diagnose Angina
Laboratory tests can help the physician identify underlying ischemic heart disease and conditions that may contribute to the development of angina. For example, urinalysis may reveal diabetes mellitus or renal disease, both of which are associated with atherosclerosis.
Blood tests may show elevated lipid (fats) levels that indicate atherosclerosis and an elevated CPK (creatine phosphokinase) level. CPK is an enzyme released into the blood when heart tissue dies. Testing CPK blood levels in the emergency room and during the following 6 to 24 hours after a chest pain episode can determine with some certainty whether heart attack has occurred.
A chest x-ray may show an enlarged heart or other structural signs of possible heart failure.
A stress test helps the physician diagnose ischemic heart disease. Typically, this test involves taking an electrocardiogram (ECG or EKG) before, during, and after exercise on a treadmill or stationary bicycle. Patients who are at risk for a coronary event with exercise are, instead, given a drug to increase the heart rate instead.
Ten to twelve electrodes are attached to various areas of the patient's skin and to the ECG machine. The machine traces the heart's activity as peaks and troughs onto a strip of graph paper. Certain changes in activity may indicate heart disease or that a person is actually having a heart attack.
A "normal" ECG may indicate a patient's chest pain is caused by something other than a blocked coronary artery, but it does not conclusively rule out blockage as a cause.
A coronary angiogram is obtained by injecting contrast material into the bloodstream and taking x-rays of the coronary arteries. This enables the physician to see blockages, malformations, and stenosis in the vessels.
In variant angina, spasm of an artery may occur spontaneously or may be induced during angiography, which would help confirm a diagnosis of that form of angina.
Echocardiography is an ultrasound procedure used to evaluate the valves, function, and size of the heart.