Pathological Q waves in anterior myocardial infarction: A marker of infarct extent rather than location

Pathological Q waves have traditionally been used to localize myocardial infarction (MI), although their anatomical specificity remains uncertain. We investigated the relationship between Q-wave distribution and cardiac magnetic resonance (CMR)-defined myocardial infarct burden after anterior MI.

We analyzed 102 patients with first anterior ST-elevation MI. Individual Q waves and established anterior Q wave patterns were compared with segmental late gadolinium enhancement (LGE).

Individual Q waves showed broad, overlapping relationships with LGE-defined infarct burden; after false-discovery-rate correction, only Q waves in V1 remained significantly associated with basal anteroseptal and apical septal LGE-defined infarct burden. Established Q wave patterns showed substantial anatomical overlap but a clear gradient in infarct burden. Across the four-level classification based on the most lateral precordial lead with a pathological Q wave (none, V1-V2 only, up to V3, or extending to V4-V6), infarct size increased from 6% to 14%, 17%, and 18% (P for trend<0.001), mid-ventricular LGE burden from 75 to 125, 150, and 175 percentage-points (P < 0.001), and apical LGE burden from 100 to 125, 200, and 200 percentage-points (P < 0.001). LVEF declined across categories (P for trend = 0.004).

In anterior MI, pathological Q wave distribution showed limited correspondence with discrete myocardial territories but was associated with increasing infarct size and greater mid-apical LGE-defined infarct burden, suggesting that Q-wave distribution may be better interpreted as a marker of infarct extent than as a geographical map of infarct location. External validation of this simplified extent-based classification is warranted.