冠微小血管レベルのspasmによる急性心筋梗塞が考えられた1例

A Case of Acute Myocardial Infarction Caused by Coronary Microvascular Spasm

　症例は61歳，男性．狭心症を疑われ冠動脈造影を施行したところ，右冠動脈近位部に75％狭窄病変を認めたため，同部にステント植込み術を施行し成功した．以後，狭心症は消失し6カ月後の追跡造影においても再狭窄を認めなかったため，Ca拮抗剤と亜硝酸剤の内服を中止した．しかし，同日夜間より狭心症が再発し翌日当院を緊急受診したところ，心電図上II,III,aV_F誘導のST上昇と異常Q波を認めた．緊急の冠動脈造影ではステント部位は良好に開存しており血栓像も認めなかったが，右冠動脈に造影遅延所見が確認された．アセチルコリン負荷試験を施行したところ，冠表在血管に有意なspasmは誘発されなかったが，造影遅延所見が明らかに悪化した．以上より，冠微小血管レベルに生じたspasmが急性心筋梗塞を生じた稀な1例と考え報告した．

We reported here a very rare case suggesting that microvascular spasm might cause acute myocardial infarction. The patient was 61-year-old man who under-went coronary stent implantation in the right coronary artery successfully. After this procedure, he received Ca channel blocker, nitrate and antiplatelet agents and his chest pain disappeared completely. Six months later, a coronary angiogram was performed and showed the stented lesion was less than 25% stenosis. Because there was no significant stenosis producing angina pectoris, the patient discontinued all medications except for aspirin. Next day he suffered from chest pain and this symptom continued intermittently. Next evening, chest pain increased and he came back to our hospital. Since ECG revealed ST segment elevation in II, III, aV_F, and cardiac enzyme level was also elevated, emergent coro-nary angiogram was carried out. Coronary angiogram showed that the stented lesion was well patent, but delayed filling of contrast medium in the distal segment of the right coronary artery was demonstrated despite there being no findings of coronary artery obstruction, suggesting microembolism. We explained this phenome-non as probably being caused by elevation of microvas-culature resistance due to microvascular spasm.