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 coronary vasospasm are focal and diffuse patterns in clinical setting. We attempted to clarify the differences in vessel wall morphologic appearance 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 luminal diameter reduction > or = 90% compared with baseline coronary artery diameter. Focal spasm was defined if the length of spastic narrowing was less than 10mm. By IVUS, we observed atheromatous plaques in 32 spasm segments with either focal or diffuse vasospasm. We measured maximal intimal thickness, luminal cross-sectional area(CSA), and external elastic membrane-CSA in spasm sites. RESULT: When comparing maximal intimal thickness between focal (n=15) and diffuse vasospasm segments(n=17), there was significantly greater thickness at focal spasm segments(1.21+/-0.36mm vs. 0.70+/-0.23mm, P<0.001). The maximal plaque area was similar between two groups but tended to be greater in focal spasm segments(6.03+/-2.06mm2 vs. 4.92+/-2.59mm2, P=NS). When circular shaped factor(CSF standardized index of eccentricity) was compared, focal spasm segments were greater than diffuse spasm segments(0.89+/-0.06 vs. 0.97+/-0.02, P<0.001). At the segments of focal spasm, remodeling index was greater compared to the segments of diffuse spasm(1.02+/-0.16 vs. 0.86+/-0.13, P<0.001). CONCLUSION: Focal spasm segments were more eccentric and had greater atheromatous plaque than diffuse spasm segments. Positive remodeling pattern was observed at the segments of focal spasm and negative remodeling pattern at the segments of diffuse spasm. There were morphologic differences of vessel wall appearance between focal and diffuse spasm sites.