**Core Concept**
Hypertrophic obstructive cardiomyopathy (HOCM) is a condition characterized by an abnormal thickening of the heart muscle that can obstruct blood flow out of the heart. The treatment aims to alleviate symptoms, prevent complications, and improve quality of life.

**Why the Correct Answer is Right**
The drug of choice in HOCM is beta-blockers, specifically metoprolol. Beta-blockers work by reducing the heart rate and the force of contraction, thereby decreasing the obstruction of blood flow. This leads to improved symptoms and reduced risk of complications such as arrhythmias and sudden cardiac death. The mechanism involves blocking the beta-1 receptors in the heart, which are responsible for increasing heart rate and contractility.

**Why Each Wrong Option is Incorrect**
**Option A:** Amiodarone is not the first-line treatment for HOCM, although it may be used in certain cases to manage arrhythmias.
**Option B:** Angiotensin-converting enzyme (ACE) inhibitors are not typically used as first-line therapy in HOCM, as they may worsen the obstruction.
**Option C:** Calcium channel blockers are not the preferred treatment for HOCM, as they may not adequately address the underlying pathophysiology.

**Clinical Pearl / High-Yield Fact**
Beta-blockers should be initiated at a low dose and gradually increased to avoid exacerbating the obstruction.

**Correct Answer:** B.