Which of the following is the most common cause of acute severe aortic regurgitation in a previously asymptomatic patient?

Explanation

## Acute Severe Aortic Regurgitation: Etiology ### Pathophysiology of Acute vs Chronic AR Acute severe aortic regurgitation presents with sudden haemodynamic collapse because the left ventricle has not had time to dilate and compensate. The sudden volume overload causes acute pulmonary oedema and cardiogenic shock. ### Common Causes of Acute Severe AR | Cause | Mechanism | Presentation | |-------|-----------|-------------| | **Infective endocarditis** | Vegetation erodes valve leaflet or perforates cusp | Acute onset, septic picture, new murmur | | Aortic dissection | Dissection extends to aortic root, disrupts valve support | Sudden chest pain, haemodynamic collapse | | Prosthetic valve dehiscence | Surgical complication or paravalvular leak | Post-operative or late dehiscence | | Trauma | Blunt chest injury, iatrogenic (catheterization) | Clear history of trauma | **Key Point:** Infective endocarditis is the **most common cause of acute severe AR in previously asymptomatic patients** because it can rapidly destroy valve tissue without prior structural abnormality. **High-Yield:** Chronic causes (hypertension, rheumatic disease, Marfan syndrome) develop gradually over years and allow LV compensation; they do not typically present as acute severe AR. **Clinical Pearl:** Acute severe AR presents with **early diastolic decrescendo murmur** + signs of acute heart failure (pulmonary oedema, hypotension) ± fever/stigmata of endocarditis. The absence of a wide pulse pressure (unlike chronic AR) is a clue to acuity. **Mnemonic:** **ICED** — Infective endocarditis, Catheter/trauma, Endocarditis, Dissection — causes of acute severe AR.