Inferior ST-segment elevation in anterior myocardial infarction: Coronary anatomy and CMR-defined injury distribution-A pilot study.

BACKGROUND: Inferior ST-segment elevation (STE) may accompany anterior myocardial infarction (MI) and is traditionally attributed to wraparound left anterior descending (LAD) anatomy with inferior-wall injury. Whether the spatial orientation of the resulting electrical field also contribute remains uncertain. We investigated the anatomical and cardiac magnetic resonance (CMR)-defined myocardial substrate of concomitant inferior STE. METHODS: This exploratory pilot analysis included patients with first anterior STEMI who underwent successful primary percutaneous coronary intervention and CMR within 1 week. Patients were classified by the presence of STE in all three inferior leads. LAD anatomy was categorized into four types according to distal extent, and CMR was used to assess regional edema, late gadolinium enhancement (LGE), and infarct size. RESULTS: Sixty-eight patients were included; seven (10.3%) had inferior STE. Basal/mid anterior edema was less frequent in patients with inferior STE (57.1% vs 90.2%; odds ratio, 0.15; 95% confidence interval, 0.03-0.81; P = 0.044). No patient with inferior STE had basal/mid inferior edema and LGE, whereas apical inferior involvement was common. LADs reaching or extending beyond the apex (types III-IV) were more frequent with inferior STE (85.7% vs 42.4%; P = 0.045), whereas type IV anatomy specifically supplying the basal/mid inferior wall was not (28.6% vs 20.3%; P = 0.634). CONCLUSIONS: In this small exploratory cohort, inferior STE accompanying anterior MI was associated with a regional injury pattern characterized by less basal/mid anterior involvement and without detectable basal/mid inferior extension. These findings are compatible with a contribution of spatial injury distribution to inferior‑lead STE but larger prospective studies are needed.