Morphologic Differences of Vessel Wall at Sites of Focal and Diffuse Coronary Vasospasm by Intravascular Ultrasound(IVUS)

Abstract

Background and Objectives:The coronary vasospasm has been shown to play an important role in the pathogenesis of not only variant angina but also ischemic heart disease in general, including other forms of angina pectoris, acute myocardial infarct, and sudden death. The angiographic features of a coronary vasospasm are focal and diffuse patterns in the clinical setting. We attempted to clarify the differences in the morphologic appearance of the vessel wall between the sites of focal and diffuse vasospasm by intravascular ultrasound (IVUS). Material and Methods:We studied 23 patients (32 segments) with variant angina in whom coronary angiograms were normal and coronary spasm was documented by intracoronary injection of acetylcholine. Coronary spasm was defined as a luminal diameter reduction of at least 90% of the baseline coronary artery diameter. Focal spasm was defined if the length of spastic narrowing was less than 10 mm. Using IVUS, we observed atheromatous plaques in 32 spasm segments with either focal or diffuse vasospasm. We measured the maximal intimal thickness, luminal cross-sectional area (CSA), and external elastic membrane-CSA in the spasm sites. Results:When comparing the maximal intimal thickness between the focal (n=15) and diffuse (n=17) vasospasm segments, the focal spasm segments were significantly thicker (1.21±0.36 mm vs. 0.70± 0.23 mm, p<0.001). The maximal plaque areas of the two groups were similar but tended to be greater in the focal spasm segments (6.03±2.06 mm vs. 4.92±2.59 mm, p=NS). When the circular shaped factor (CSF: standardized index of eccentricity) was compared, the focal spasm segments were greater than the diffuse spasm segments (0.89±0.06 vs. 0.97±0.02, p<0.001). The remodeling index was greater at the focal spasm segments than at the diffuse spasm segments (1.02±0.16 vs. 0.86±0.13, p<0.001). Conclusion:The focal spasm segments were more eccentric and had greater atheromatous plaque than the diffuse spasm segments. A positive remodeling pattern was observed at the segments of focal spasm, and a negative remodeling pattern was observed at the segments of diffuse spasm. There were morphologic differences in the vessel wall appearance between the focal and diffuse spasm sites.(Korean Circulation J 2001;31(8):749-756)