Two adult cases of Bland-White-Garland syndrome with lethal arrhythmia due to coronary steal phenomenon during physical or mental stress.

We experienced two adult cases of anomalous origin of the left coronary artery from the pulmonary artery, so-called Bland-White-Garland (BWG) syndrome, that presented with ventricular tachycardia (VT) and ventricular fibrillation during exertion in daily life. They presented to our hospital with syncope due to VT, and recovered following application of an automated external defibrillator with cardiopulmonary resuscitation. We diagnosed BWG syndrome by multi-detector computed tomography angiography and coronary angiography. We analyzed the mechanisms of lethal arrhythmias in relation to myocardial ischemia on exertion. Coronary flow modification and implantable cardioverter defibrillator implantation were performed in order to prevent future lethal arrhythmia due to myocardial ischemia. It is important to be aware of congenital heart disease in ordinary cases. <Learning objective: We experienced two rare cases of patients who were admitted with ventricular tachycardia and ventricular fibrillation who had adult type Bland-White-Garland syndrome during exertion in daily life. It is important to be aware of congenital heart disease in ordinary cases.>.