## Most Common Structural Cause of Atrial Fibrillation **Key Point:** Left ventricular hypertrophy (LVH) secondary to hypertension is the single most common structural cardiac abnormality predisposing to atrial fibrillation in developed countries. ### Pathophysiology of LVH-Induced AF LVH leads to: 1. Increased left atrial pressure and stretch 2. Atrial fibrosis and electrical remodeling 3. Shortened atrial refractory period 4. Substrate for re-entrant circuits ### Epidemiology in the Indian Context | Structural Cause | Prevalence in AF | Geographic Notes | |---|---|---| | LVH (hypertension) | 40–50% | Most common in urban India | | Mitral stenosis | 20–30% | Still significant due to rheumatic heart disease | | Dilated cardiomyopathy | 10–15% | Ischemic or idiopathic | | Atrial septal defect | 5–10% | Congenital, less common | **High-Yield:** In hypertensive patients with AF, LVH is present in >60% of cases. The combination of hypertension + diabetes (as in this case) accelerates LV remodeling. **Clinical Pearl:** Echocardiography showing LV wall thickness ≥11 mm (women) or ≥12 mm (men) with normal cavity size confirms LVH. This is the most frequent finding in AF patients presenting to Indian tertiary centers. ### Why LVH Dominates in Modern AF - Hypertension is the leading modifiable risk factor for AF globally - Rheumatic mitral stenosis (historically the #1 cause) is declining due to improved streptococcal prophylaxis - LVH-induced atrial stretch and fibrosis create the ideal substrate for ectopic foci and re-entry [cite:Harrison 21e Ch 297]
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