Wellens' syndrome can indicate high-grade LAD stenosis in case of left bundle branch block.

Diagnosing acute myocardial infarction (AMI) in left bundle branch block (LBBB) is challenging. Modified Sgarbossa criteria are known to help detect AMI in LBBB. This is a report about an electrocardiogram (ECG) with Wellens' signs in combination with a pre-existing LBBB. The ECG of a patient with fluctuating chest pain showed very subtle and one day later more obvious Wellens'signs. A left anterior descending artery (LAD) stenosis was diagnosed and successfully treated. Wellens' syndrome can be diagnosed in a case of LBBB and help detect a high-grade LAD stenosis even if modified Sgarbossa criteria are not met.