New Q waves do not always a new infarct spell: right bundle branch block-dependent Q waves simulating infarct extension.

: We present the electrocardiograms of three patients, representative of 14, with acute anterior wall infarction in whom, in contrast to current understanding, the appearance of right bundle branch block was associated with a shift of the initial vector of depolarization that resulted in 'new' Q waves in V1-V2 that mimicked extension of necrosis. This little-known electrocardiographic phenomenon should be kept in mind when consideration is given to attempts at reperfusion.