Significance of the Diagnostic Q Wave of Myocardial Infarction

Abstract

Correlation between the QRS complex and postmortem ventricular anatomy was made in 1184 instances of normal conduction: (1) Mechanical reliance on the sheer presence or absence of a Q wave greater than 0.03 sec in duration led to "correct" diagnosis of infarction or not in 79% of the series. (2)With normal conduction, abnormal Q waves isolated to either the anteroseptal (V_l-V₄) or inferior (II, III, _aV_F) electrocardiographic zones were frequently false (46%). However, abnormal Q waves restricted to the lateral zone (V₅-V₆) or in a combination of more than one electrocardiographic zone, were rarely false predictors of the presence of infarction (4%). (3) Classical localization of infarction with normal conduction was statistically relatively reliable as compared with bundle-branch block. The increased frequency of the anatomic pattern of lateral basal infarction in association with normal QRS complexes (but known infarction) suggests relative "electrical silence" of the laterobasal left ventricle in abnormal Q-wave genesis. (4) Lesions confined to a given anatomic location in the left ventricle tended to place particular emphasis and limits on the spectrum of electrocardiographic expression but did not yield a uniform single pattern of Q-wave distribution.