In a patient with moderate mitral stenosis, which complication is associated with an increased risk of systemic embolization?

• A. Atrial Fibrillation
• B. Pulmonary Hypertension
• C. Increased Left Atrial Pressure
• D. Left Ventricular Dilatation

Answer: (A)

In mitral stenosis, the left atrium becomes enlarged and blood flow through the narrowed valve slows, creating stasis. This stasis, especially when atrial fibrillation develops, leads to clot formation in the left atrium (often in the left atrial appendage) because the absence of coordinated atrial contraction allows blood to pool. When a clot dislodges, it can travel via the aorta to systemic arteries, causing embolic events such as stroke or limb ischemia. Atrial fibrillation therefore markedly increases the risk of systemic embolization in patients with mitral stenosis. Pulmonary hypertension is a consequence of the elevated left atrial pressures and affects the lungs, not the systemic circulation, so it does not directly explain embolic risk. Increased left atrial pressure contributes to the hemodynamic stress but the principal embolic risk comes from the loss of organized atrial contraction in atrial fibrillation. Left ventricular dilatation is not a typical feature of mitral stenosis and does not primarily drive embolic risk.