Coronary Artery Spasm in Unstable Angina Pectoris; Assessment of Plaque Morphology and Dynamic State of Vasoconstriction by Optical Coherence Tomography
Wakayama Medical University, Wakayama, Japan
N. Maniwa, M. Mizukoshi, T. Kubo, H. Kitabata, T. Tanimoto, K. Komukai, K. Iashibashi, Y. Ino, K. Kimura, A. Kuroi, H. Ikejima, H. Tsujioka, K. Okochi, M. Kashiwagi, K. Satogami, A. Shimokado, T. Nishiguchi, T. Masuno, I. Teraguchi, T. Imanishi, T. Akasaka
Background: Intravascular ultrasound studies have suggested that the plaque morphology of spasm coronary arteries might be related to the pathogenesis of variant angina. However, the influence on unstable angina pectoris (UAP) remains unclear. Optical coherence tomography (OCT) is a high-resolution imaging modality and allows us to analyze tissue characteristics in detail. In this study, we assessed dynamic state of vasoconstriction and plaque morphology at the spasm sites in patients with UAP by OCT.
Methods: Fifty patients with UAP were enrolled. Nine of these patients had coronary spasm. OCT examinations were performed at the spasm sites during coronary spasm and after intracoronary injection of nitroglycerin.
Results: OCT findings were as follows: mild intimal thicknening (0.130~0.180mm) with erosion, 3 patients (33.3%); lipid-rich plaque with rupture, 1 patient (11.1%); and eccentric fibro-fatty plaque, 5 patients (55.5%). In 5 patients with fibro-fatty plaque, there were more intensity-attenuated areas in the plaques, which correspond to necrotic core or hemorrhage. More, accumulation of erythrocytes and macrophages was observed in the specimen of the plaque obtained by directional coronary atherectomy. Oct examinations revealed dynamic state of spasm. Circumferential vasoconstriction occurred equally regardless of the plaque burden. The constriction changed the morphology of the intima. The surface of the intima was folded, whereas the media got thick without making folds.
Conclusion: Tissue characteristics at coronary spasm sites had the potential for the progression of plaque vulnerability. Furthermore, the dynamic state of coronary spasm could lead to intimal injury. Coronary spasm might play an important role on the onset and/or progression of acute coronary syndrome.
