However, an ECG taken in the presence of pain may yield a great deal more information because it may document the presence of transient ST segments depression, a characteristic sign of subendocardial ischemia. Several studies have correlated findings from the exercise ECG with the presence or absence of significant obstruction of the coronary arteries with findings with angiography. Variant angina is due to coronary artery spasm. The spasm usually occurs very close to the obstruction. The ergonovine test is the most sensitive test for coronary artery spasm.
Ergonovine is introduced to induce coronary spasm.
Hyperventilation and coronary injections of acetylcholine are other means used to induce variant angina. Radioisotope imaging is a viable procedure for diagnosing coronary artery disease. Presently thallium-201 is the isotope most frequently used for myocardial imaging. A clear indication for angiography is a patient with unacceptable incapacitating angina who is on maximal medical therapy or in young and vigorous patients who have a great deal of cardiac muscle at ischemic risk. Medical Therapy Angina can be treated medically with drugs which purpose is to reduce myocardial oxygen consumption, improve coronary artery blood flow and prevent disease progression.