Myocardial ischemia due to vasospasm of small coronary arteries detected by methylergometrine maleate stress myocardial scintigraphy

BACKGROUND: Recently, several case reports have implicated vasospasm of small coronary arteries in vasospastic angina pectoris. Vasospasm of small coronary arteries was also considered from angiographic findings in patients with atypical chest pain. In Syrian hamster, vasospasm in small coronary arteries was considered to be the cause of dilated cardiomyopathy. HYPOTHESIS: This study was undertaken to determine whether vasospasm in small coronary arteries can be induced by methylergometrine maleate stress thallium-201 (201Tl) myocardial scintigraphy. METHODS: Twenty-five patients with chest pain, all of whom had intact coronary arteries, were studied. After intracoronary methylergometrine maleate injection, coronary arteriograms also looked normal in all cases. Thallium-201 myocardial scintigraphy was carried out immediately after intracoronary methylergometrine maleate injection in four patients with chest pain. In the remaining 21 patients with chest pain, methylergometrine maleate was given intravenously within up to 2 weeks before 201Tl myocardial scintigraphy. RESULTS: In the intracoronary injection study, one patient had chest discomfort after methylergometrine maleate injection, and ST-segment elevation was observed on electrocardiogram (ECG). Of the 21 patients with chest pain, 11 patients felt angina-like chest pain after intravenous injection of methylergometrine maleate, but their ECGs showed no ischemic changes. Stress 201Tl myocardial scintigrams showed methylergometrine maleate-induced perfusion defects with complete redistribution in 3 of 4 patients in the intracoronary injection study and in 12 of 21 patients in the intravenous injection study. These findings suggest that vasospasm in small coronary arteries caused myocardial ischemia in 15 of 25 patients (60%) with chest pain. CONCLUSION: Vasospasm in small coronary arteries may be involved in the myocardial ischemia of some patients with chest pain who do not show any large coronary artery vasospasm.