## Most Common Site of Ventricular Arrhythmias in Structural Heart Disease ### Anatomical Origin Patterns In patients with structural heart disease (hypertension, cardiomyopathy, prior MI), the **left ventricular apex and anteroapical wall** is the most frequent site of origin for ventricular arrhythmias, particularly sustained ventricular tachycardia. This region corresponds to areas of scar formation and heterogeneous conduction that develop secondary to chronic pressure overload or ischemic injury. ### Site-Specific Distribution | Site | Clinical Context | Frequency | |------|------------------|----------| | **LV apex/anteroapical wall** | Structural heart disease, prior MI, LVH | Most common (40–50%) | | Right ventricular outflow tract | Idiopathic VT (no structural disease) | 70% of idiopathic cases | | Left ventricular outflow tract | Idiopathic VT, catecholaminergic | Less common | | RV inflow tract | Arrhythmogenic RV cardiomyopathy | Specific substrate | ### Key Point: **In structural heart disease, reentrant VT arises from scar-related circuits in the LV apex.** In contrast, idiopathic VT (normal heart) typically originates from the RVOT due to triggered activity or abnormal automaticity. ### Clinical Pearl: The location of VT origin can be inferred from the 12-lead ECG morphology. **Inferior axis deviation with positive concordance in precordial leads** suggests LV apical origin, which is typical in post-MI or hypertensive remodeling. ### High-Yield: Remember the dichotomy: - **Structural disease** → LV apex (reentrant, scar-based) - **No structural disease** → RVOT (idiopathic, triggered) [cite:Harrison 21e Ch 226]
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