Unstable angina complicated with dynamic left ventricular outflow tract obstruction.

Left ventricular outflow tract obstruction (LVOTO) complicated with unstable angina (uAP) has not been described widely, but patients with these two conditions have several problems. Differentiation of the two conditions is also often difficult because the chest symptoms are similar. Moreover, nitrates are commonly used for ischemic heart disease, but have the effect of worsening LVOTO. We experienced three cases of dynamic LVOTO with a sigmoid-shaped septum, and without typical hypertrophic obstructive cardiomyopathy, that were complicated with uAP. In all cases, LVOTO was improved after initial percutaneous coronary intervention (PCI) for the left anterior descending artery lesion. Next, a dobutamine stress test was performed and LVOTO was provoked again in two cases, but not in a case with small acute myocardial infarction of the basal septum during PCI. All cases remained asymptomatic with beta-blocker therapy. Therefore, PCI and beta-blocker administration for LVOTO with uAP resulted in favorable clinical courses in all three cases. These outcomes suggest that revascularization including PCI should have priority in the therapeutic strategy for a case of acute coronary syndrome with LVOTO.