REGIONAL MYOCARDIA SYMPATHETIC DYSINNERVATION IN PATIENTS WITH CORONARY VASOSPASM

The purpose of this study was to assess the presence and location of impaired myocardial sympathetic innervation by using I-123 metaiodobenzylguanidine (I-123 MIBG) in 15 patients with coronary vasospasm induced by intracoronary acetylcholine. The results were compared with those using thallium-201 (Tl-201). We also examined 14 patients with severe coronary stenosis (>90%) and 8 control subjects without significant coronary stenosis (<50%) and provokable coronary vasospasm. Regional myocardial sympathetic dysinnervation was detected by I-123 MIBG single-photon emission computed tomography (SPECT) in all patients with coronary vasospasm, despite normal uptake during Tl-201 SPECT. This regional uptake-mismatch between I-123 MIBG and Tl-201 SPECT occurred specifically in the vasospasm group (p <0.001 vs stenosis and control groups). Moreover, regional myocardial sympathetic dysinnervation was located in the distribution of perfusion in 25 of the 27 vasospasm-induced vessels. Normal uptake of I-123 MIBG was observed in the perfused areas in 16 of the 18 non-vasospasm-induced vessels. The sensitivity and specificity of I-123 MIBG for detection of coronary vasospasm were 92% and 88%, respectively. In patients with coronary vasospasm, we found regional myocardial sympathetic dysinnervation to be present. Furthermore, we were able to distinguish these patients from patients with critical coronary stenosis by I-123 MIBG and Tl-201 SPECT.