Hypertrophic Cardiomyopathy

On physical examination, patients with LVOT obstruction may show a triple apical impulse and a systolic murmur along the left sternal border, which changes in intensity with posture, the Valsalva maneuver, or exercise. A pansystolic murmur at the apex may indicate associated mitral regurgitation. In obstructive HCM, the carotid pulse may appear bifid.

Electrocardiographic abnormalities are present in about 95% of patients, including left ventricular hypertrophy, ST-T changes, left atrial enlargement, deep narrow Q waves, or decreased R wave amplitude in lateral leads. However, ECG findings do not reliably predict outcomes.

Echocardiography is the most useful diagnostic tool, revealing asymmetric septal hypertrophy, apical hypertrophy, systolic anterior motion of the mitral valve, LVOT obstruction, and mitral regurgitation. It also allows assessment of diastolic function.

Cardiac MRI and CT provide additional detail, especially in cases where echocardiography is inconclusive.

Sudden Cardiac Death Prevention

• Implantable cardioverter-defibrillator (ICD): Highly effective for both secondary prevention (in patients with prior cardiac arrest or sustained ventricular tachycardia) and primary prevention in high-risk individuals. ICDs reduce the annual risk of sudden death by up to 11% in secondary prevention and 4% in primary prevention settings.
• Antiarrhythmic drugs such as amiodarone or beta-blockers have been used but do not provide the same protection as ICDs.

Symptom Management

• Beta-blockers: Commonly used in obstructive HCM to reduce heart rate, improve symptoms, and decrease outflow tract gradients.
• Verapamil: Improves diastolic function and exercise tolerance, particularly in non-obstructive HCM.

Septal Reduction Therapy

• Surgical septal myectomy: Recommended for patients with severe symptoms refractory to medical therapy and resting or provoked LVOT gradients ≥50 mmHg. Myectomy improves symptoms in up to 95% of patients and has shown long-term survival benefits, including reduced risk of sudden death.
• Alcohol septal ablation: A less invasive alternative that induces localized myocardial necrosis by injecting alcohol into a septal branch artery, thereby thinning the septum and relieving obstruction. While effective, its long-term outcomes continue to be studied.