The infarct Q wave: foretaste and aftertaste; presentiment and recall.

Since acute myocardial infarction involves a progressive disturbance of intramyocardial propagation the process might be regarded as a conduction disturbance: incomplete in the evolving phase; complete with Q wave inscription. Premature atrial excitation (PAE) can induce fascicular or bundle branch conduction delay, or complete functional block. Considered here are the concepts of foretaste: in which PAE reveals the infarct Q before it has appeared in regular sinus beats, and aftertaste: in which, following the healing of the myocardial infarction, the Q wave is recalled by PAE after it has disappeared from regular beats. Foretaste was observed in a small number of acutely infarcted dogs. Aftertaste is substantially more problematic since Q wave inscription is known to occur, however uncommonly, in a small minority of noninfarcted aberration morphologies. Only lateral infarct Q waves appear to be recallable by PAE.