[Unstable angina pectoris in intermittent left bundle branch block]

We present a case report of a 57 year old woman with recurrent chest pain, initially exclusively at exercise and later also at rest. This led to an emergency hospitalization for suspected myocardial infarction. As there were no enzymatic and electrocardiographic signs of acute infarction she was treated, as unstable angina pectoris. Coronary angiography revealed but a modest coronary atheromatosis without significant coronary stenosis. Therefore her symptoms were interpreted as primary manifestation of an intermittant Left Bundle Branch Block (LBBB) with changing heart-rate dependency. A majority of patients with LBBB and chest pain have a relevant Coronary Artery Disease (CAD). There is a small number of reports in literature about patients with intermittant LBBB without significant CAD but with both typical (exercise-induced) and atypical (at rest) chest pain. Special features of our case are presentation of LBBB as unstable angina, documentation of an intermittant LBBB with changing heart-rate dependency and heart-rate-dependent supranormal conduction in the left bundle branch. We review some important aspects of LBBB with regard to this case.