Severe coronary spasm occasionally detected by coronary computed tomography

Abstract

Coronary spasm not only plays an important role in coronary spastic angina but also in ischae- mic heart diseases in general, and the incidence is quite high among Japanese. Coronary spasm can be reliably detected by an intracoronary injection of acetylcholine (ACh) during cardiac catheterization, but not by coronary computed tomography (CT) because coronary spasm is transient, occurs mostly between midnight and the early morning and rarely during the daytime. When a patient undergoes coronary CT at our institution, we routinely administer sublingual nitroglycerine to maximally dilate cor- onary arteries. Thus, we were totally unaware of the possibility of coronary spasm occurring during coronary CT, which did occur in a 41-year-old man and is described herein. Cardiac catheterization as an examination for chest pain at rest did not reveal any significant changes in coronary arteriograms. The patient's symptoms were mild and atypical for angina pec- toris, and only nitroglycerin was prescribed. Six months later, electrocardiography in a regular outpatient clinic revealed abnormal QS mor- phology in leads V1-V4 indicating severe anterior myocardial ischaemia without specific symptoms. A second CAG was a provocative test for coronary spasm using ACh which revealed coronary spasm. Organic stenosis was also identified at Segment 6 of the left anterior descending artery (LAD). Per- cutaneous coronary intervention (PCI) using balloon angioplasty was performed. Thereafter, the patient was prescribed with medi- cation for angina pectoris. Five years later, the patient developed chest pain during exertion and was examined by coronary dual-source CT (DSCT). The results showed almost total occlusion of Segment 1 of the right coronary artery (RCA) (Panels A and B). A third CAG was planned considering PCI for the most recently identified region. No significant stenosis was evident in the LAD, but collateral arteries to the RCA via the septal branches indicated total or subtotal chronic occlusion of the RCA (Panel C). We injected nitroglycerine into the LAD to arrange PCI and then infused the RCA with contrast dye. Surprisingly, only 25% stenosis of Segment 1 was evident (Panel D) and immediate angiography of the LAD showed that the collateral arteries had dis- appeared, indicating that a severe and spontaneous coronary spasm had occurred immediately before PCI and that the total occlusion identified by DSCT was due to coronary spasm. Calcium channel blockers were then administered, which effectively treated his con- dition for now. Silent spasm frequently occurs among patients with coronary spasm, and this should be considered when analysing coronary CT images. This report is the first description of severe coronary spasm being detected by coronary CT. Panels (A and B) Arrows show significant coronary stenosis in Segment 1 of the right coronary artery detected by coronary com- puted tomography.