ST-segment elevation in the precordial (chest) leads. Anteroseptal (V1–V3): Shows ST elevation and potential development of Q-waves in the early leads, indicating damage to the septum. Strict Anterior (V3–V4): Characterized by ST elevation localized to the mid-precordial leads. Anterolateral (V1–V6, I, aVL): A "proximal" LAD occlusion often results in ST elevation across all chest leads and the high lateral leads (I and aVL). Evolution of an Anterior MI ECG changes typically follow a predictable timeline as the heart muscle progresses from injury to permanent scarring: Hyperacute phase: T-waves become tall and peaked (often the very first sign). Acute phase: ST-segments rise, often taking on a "tombstone" or concave downward shape. Subacute phase: Q-waves begin to form as muscle dies, and T-waves may flip (inversion). Chronic phase: ST-segments return to baseline, but
To understand the ECG findings, one must understand the anatomy. The anterior wall of the left ventricle is primarily supplied by the . anterior infarction ecg
The anterior leads are (sometimes extending to V5, V6, and I/aVL depending on the LAD occlusion site). ST-segment elevation in the precordial (chest) leads
A loss of the normal increase in R-wave height from V1 to V4, often suggesting a prior or evolving anterior wall injury. Localization and Occlusion Site Anterolateral (V1–V6, I, aVL): A "proximal" LAD occlusion
Normally, R waves grow taller from V1 to V5 (R wave progression). In an anterior MI, the electrical force is diminished as the muscle dies, leading to poor R wave progression or a sudden loss of R wave height in the anterior leads.
| | ECG Clue | | :--- | :--- | | Early Repolarization | ST elevation is concave (smiling), not convex. Notching at J point. Prominent T waves. Stable over time. | | Acute Pericarditis | Diffuse ST elevation (I, II, III, aVF, V2-V6) with PR depression. Concave morphology. No reciprocal changes. | | Left Ventricular Aneurysm | Persistent ST elevation with deep Q waves. No evolutionary changes (stable over months/years). | | Left Bundle Branch Block (LBBB) | Discordant ST elevation (elevation in leads with negative QRS). Use Smith-Modified Sgarbossa criteria. | | Hyperkalemia | Peaked T waves but ST elevation rare unless severe. Wide QRS. |