A 48-year-old woman with chronic aortic regurgitation due to endocarditis presents with severe dyspnea and a wide pulse pressure. She is awaiting aortic valve replacement. Which drug is contraindicated and should be avoided?

Explanation

## Aortic Regurgitation: Pharmacological Management **Key Point:** In chronic aortic regurgitation (AR), vasodilators and ACE inhibitors are first-line to reduce afterload and slow disease progression. Beta-blockers are **contraindicated** because they increase diastolic pressure, worsening regurgitant flow. ### Pathophysiology of AR In aortic regurgitation: - Blood regurgitates back into the left ventricle during diastole - LV dilates and hypertrophies to accommodate the increased volume load - Afterload reduction decreases the regurgitant fraction and LV wall stress - **High diastolic pressure worsens regurgitation** — beta-blockers increase diastolic pressure and are harmful ### Pharmacological Strategy in Chronic AR | Drug Class | Effect | Role in AR | |-----------|--------|----------| | **ACE inhibitors** | ↓ Afterload, ↓ LV remodeling | **First-line** — slow progression | | **Vasodilators (nifedipine)** | ↓ Afterload | Alternative/adjunctive | | **Beta-blockers** | ↑ Diastolic pressure | **CONTRAINDICATED** — worsen regurgitation | | **Diuretics** | ↓ Preload, ↓ congestion | Adjunctive for pulmonary edema | **High-Yield:** The **only major contraindication** in AR is beta-blockers. They increase diastolic pressure and regurgitant volume, hastening LV decompensation and the need for surgery. **Clinical Pearl:** In acute severe AR (e.g., aortic dissection, endocarditis with perforation), vasodilators + inotropes (dobutamine) are used as a bridge to emergency surgery. Beta-blockers are absolutely avoided. ### Mechanism: Why Beta-Blockers Harm AR ```mermaid flowchart TD A[Beta-blocker given]:::action --> B[↓ Heart rate]:::outcome B --> C[↑ Diastolic filling time]:::outcome C --> D[↑ Diastolic aortic pressure]:::urgent D --> E[↑ Regurgitant flow into LV]:::urgent E --> F[↑ LV volume load & wall stress]:::urgent F --> G[Accelerated LV decompensation]:::urgent ``` **Mnemonic: AVOID Beta-blockers in AR** — Afterload reduction is key, Vasodilators are first-line, Oppose beta-blockers, Increase ACE-I, Delay surgery with medical therapy.