Left Atrial Abnormality: Causes, Symptoms & Risk Factors

Left atrial (LA) abnormality encompasses enlargement, dysfunction, or structural anomalies. It is a marker of diastolic burden and atrial fibrillation (AF) substrate.

Major Etiologies

1. Pressure overload: Hypertension (most common), aortic stenosis, hypertrophic cardiomyopathy.
2. Volume overload: Mitral regurgitation, mitral stenosis, large VSD/PDA.
3. Atrial fibrillation: AF causes LA remodeling; LA enlargement perpetuates AF (vicious cycle).
4. Myocardial disease: Heart failure (HFrEF, HFpEF), myocarditis, infiltrative diseases (amyloid, sarcoid).
5. Congenital: ASD (ostium secundum), cor triatriatum, pulmonary venous obstruction.
6. Metabolic/systemic: Diabetes (diastolic dysfunction), obesity, sleep apnea, thyroid disease.
7. Aging: LA size increases with age; >40 mL/m² (BSA-indexed) defines enlargement.
8. Genetic: Familial AF, cardiomyopathy mutations.

Clinical Significance

• LA volume index (LAVI) > 34 mL/m² predicts: new-onset AF, stroke, HF hospitalization, mortality.
• LA mechanical dysfunction (reduced reservoir/conduit/booster function) precedes enlargement.
• ECG: "P mitrale" (broad, notched P wave in II, terminal negative in V1) suggests LA abnormality.

Management

Treat underlying cause (HTN control, valve intervention, rate/rhythm control for AF, HF GDMT). Anticoagulation if AF + CHA₂DS₂-VASc ≥2 (men) / ≥3 (women). Serial echocardiographic monitoring.