Eleven(13.4%, mean age 48+13, male 11) out of 82 consecutive patients with acute myocardial infarction showed angiographically normal or near normal coronary arteries at 7~10 in-hospital days. Ten(91%) had history of heavy smoking and 7 patients(64%) had no history of previous angina. Anterior myocardial infarction was in 8 and inferior in 3 patients.

After intracoronary administration of acetylcholine(incremental dose of 20, 50ug for the right and 20, 50, 100ug for the left), 9(82) of 11 infarct related arteries showed total or subtotal occlusion, but only in 3(17%) out of 18 non-infarct related arteries of 10 patients. Multivessel spasm was noticed in 3. Ergonovine test(graded doses of 0.05, 0.1 and 0.2 mg intravenously) was performed 30 minutes after completion of acetylcholine test in 5 patients. In 1 patients, acetylcholine test was positive and but ergonovine test was negative.

Conclusion : 1) Eleven(13.4%) out of 82 patients with acute myocardial infarction had angiographically normal coronary arteries.

2) Ach positive responses of infarct-related arteries are more frequent(82%) than that of non-infarct related arteries(17%), suggesting that the infarction might be related to coronary artery spasm.

3) Positive Ach responses of non-infarct related arteries occurred in 30% of Patients.

4) Ach and Erg induced vasospasm developed at the same site in 5, which suggests that local hyperreactivity might be related to spasm.