Coronary artery spasm plays an important role in the pathogenesis of not only variant angina but also other forms of angina,acute myocardial infarction, and sudden death. However precise mechanisms by which coronary spasms occur remains unknown. The role of increased coronary artery tone as a part of pathogenesis of conary spasm and relation to the severity of coronary artery disease are still controversial.

Thus we underwent this study to investigate the role of increased coronary artery tone as a part of pathogenesis of conary spasm and realtion to the severity of coronary artery disease.

Intracoronary acetylcholine and isosorbide dintrate were used as a spasm-provocative agent and vasodilator respectively. We analyzed 176 vessels(69 right coronary artery, 58 left anterior descending coronary artery, 49 left circumflex coronary artery) of 75 patients admitted for evaluation of chest pain syndrome. Among the 176 vessels, spasm occurred in 39 vessels of 25 patients.

1)Coronary artery spasm occured in 30.4%(21/69), 17.2%(10/58), 16.3%(8/49) of right coronary artery, left anterior descending coronary artery, left circumflex coronary artery respectively.

2) There is no relationship between angiographically visible minimal coronary artery disease and occurrence of spasm provoked by acetylcholine.

3) There was no significant difference of coronary risk factor predicting coronary spasm between two groups.

4) There is more significant % vasodilation by isosorbide dintrate(ISDDN) occurred din both the spastic and nonspastic arterial segment of vasospastic angina group than no spasm group(30.2%, 28.4% vs 14.2%, p<0.05).

5) Degree of % vasodilation by ISDN was more significantly larger in vasospastic angina group than no spasm group despite the presence of same amount of angiographically visible minimal coronary artery disease(38.3% vs 12.5%, p<0.05).

These findings suggests that the occurrence of conronary artery spasm is not related to minimal coronary artery disease. Increased coronary artery tone observed only in vasospastic angina group may be part of pathogenesis of coronary spasm.