Hypertrophic Cardiomyopathy Quiz

Understanding Hypertrophic Cardiomyopathy (HCM)

Hypertrophic Cardiomyopathy (HCM) is the most common inherited cardiovascular disease, characterized by unexplained thickening (hypertrophy) of the heart muscle, particularly the left ventricle. This thickening can obstruct blood flow out of the heart and lead to various symptoms and complications. Understanding its genetic basis, diagnostic criteria, and management strategies is crucial for healthcare professionals.

Genetic Basis and Pathophysiology

HCM is primarily an autosomal dominant genetic disorder caused by mutations in genes that encode for sarcomeric proteins—the fundamental contractile units of heart muscle cells. The most commonly implicated genes are:

• MYH7: Encodes for the β-myosin heavy chain.
• MYBPC3: Encodes for the myosin-binding protein C.

These mutations lead to disorganized myocardial architecture (myofiber disarray), fibrosis, and small vessel disease, contributing to the clinical manifestations of HCM, including diastolic dysfunction, myocardial ischemia, and arrhythmias.

Diagnosis and Evaluation

The diagnosis of HCM is typically established through imaging, primarily echocardiography. The key diagnostic finding is a left ventricular wall thickness of ≥15 mm in any segment that is not explained by other causes like hypertension or aortic stenosis. Key components of the evaluation include:

• Echocardiography: To assess wall thickness, left ventricular outflow tract (LVOT) obstruction, systolic anterior motion (SAM) of the mitral valve, and diastolic function.
• Electrocardiogram (ECG): Often shows abnormalities like left ventricular hypertrophy (LVH), deep T-wave inversions, and ST-segment changes, though a normal ECG does not exclude HCM.
• Cardiac MRI (CMR): Provides detailed anatomical assessment and is the gold standard for measuring myocardial mass. Late gadolinium enhancement (LGE) on CMR can identify myocardial fibrosis, which is a risk marker for sudden cardiac death.

Management of Obstructive HCM

In patients with obstructive HCM (LVOT gradient ≥30 mmHg at rest or with provocation), management focuses on alleviating symptoms. First-line therapy involves medications that reduce heart rate and contractility, thereby decreasing the LVOT gradient. These include beta-blockers and non-dihydropyridine calcium channel blockers (verapamil, diltiazem). For patients who remain symptomatic despite medical therapy, more invasive options like septal reduction therapy (surgical myectomy or alcohol septal ablation) may be considered.

Risk Stratification for Sudden Cardiac Death (SCD)

A critical aspect of HCM management is identifying patients at high risk for SCD. An implantable cardioverter-defibrillator (ICD) is recommended for primary prevention in patients with one or more major risk factors. These factors include a history of cardiac arrest, spontaneous sustained ventricular tachycardia, a family history of SCD due to HCM, unexplained syncope, and massive LVH (wall thickness ≥30 mm).

Non-obstructive HCM

Patients without significant LVOT obstruction are managed based on their symptoms, which are often related to diastolic dysfunction. Treatment focuses on managing heart failure symptoms with diuretics and addressing atrial fibrillation if it occurs. Vasodilators should generally be avoided as they can worsen a potential latent gradient.

This content is for informational and educational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional for diagnosis and treatment.