Left anterior fascicular block concealing anteroseptal infarction.

: Fascicular blocks may modify electro-cardiographic morphologies and signs of necrosis may be masked. This report concerns the case of a patient with an anteroseptal myocardial infarction who developed a transient left anterior fascicular block. An explanation for the concealment of the signs of necrosis is proposed, based on an analysis of the modified activation process by means of a vectorial representation.