Which of the following is NOT a mechanical therapy option for hypertrophic obstructive cardiomyopathy?

• A. Dual-chamber pacing
• B. Alcohol septal ablation
• C. Beta-blocker therapy
• D. Open surgical myectomy

Answer: (C)

In hypertrophic obstructive cardiomyopathy, mechanical therapies are those that physically modify the outflow tract or septal anatomy. Dual-chamber pacing can alter the contraction sequence to reduce the LVOT gradient, alcohol septal ablation creates a controlled infarct to thin the septum, and open surgical myectomy surgically removes thickened septal tissue. Beta-blocker therapy is pharmacologic, aiming to reduce heart rate and contractility to lessen obstruction but it does not change the anatomy or physically relieve the obstruction. Therefore, beta-blocker therapy is not a mechanical treatment.