Snapshot A 17-year-old boy is rushed to the emergency room after collapsing on the basketball court during a game. He is found to have a ventricular arrhythmia on electrocardiogram and died en route to the hospital. Prior to this event, he had a few episodes of syncope. His family history includes sudden cardiac death in 2 maternal uncles. Autopsy reveals markedly hypertrophic interventricular septum. Summary Hypertrophic Cardiomyopathy (HCM) is a prominent form of cardiomyopathy characterized by the thickening (hypertrophy) of the heart muscle, particularly the left ventricle. This condition is caused by genetic mutations affecting proteins that play a role in myocardial growth and contraction. HCM often presents in adolescents, young adults, and adults with diverse symptoms like chest pain, dyspnea, palpitations, and syncope. Diagnosis involves a comprehensive evaluation of clinical history, physical examination, electrocardiography (ECG), and echocardiography. Echocardiography is especially valuable for visualizing the hypertrophied heart muscle and assessing blood flow patterns. Treatment approaches for HCM aim to manage symptoms and reduce the risk of sudden cardiac death. Medications such as beta-blockers and calcium channel blockers are used. In severe cases, implantable cardioverter-defibrillators (ICDs) may be recommended. Surgical options like septal myectomy or alcohol septal ablation might be considered to relieve left ventricular outflow tract obstruction. Close monitoring and individualized treatment plans are crucial for optimal management of HCM patients. Epidemiology Incidence second most common cardiomyopathy two types of cases obstructive comprises 70% of cases non-obstructive comprises 30% of cases Demographics young adults Location cardiac chambers cardiac walls Risk factors family history of sudden cardiac death high-intensity athletes Etiology Pathogenesis concentric hypertrophy ventricular concentric hypertrophy (typically of the septum) from sarcomeres added in parallel ↓ left ventricular compliance results in diastolic dysfunction ventricles are hypercontractile and systole occurs rapidly hypertrophic obstructive cardiomyopathy this disease is obstructive in most patients (70%) left ventricular outflow tract obstruction caused by asymmetric septal hypertrophy systolic anterior motion of the mitral valve Genetics familial (most common) inheritance pattern autosomal dominant mutations chromosome 14 genes encoding sarcomere proteins myosin binding protein C and β-myosin heavy chain Associated conditions Friedreich ataxia Pompe disease (type II glycogen storage disease) Anatomy Cardiac walls are thickened and myocytes are stacked Presentation Symptoms syncope during exercise dyspnea on exertion angina palpitations sudden death from ventricular arrhythmia Physical exam auscultation S4 gallop (a sign of left ventricular hypertrophy) systolic murmur without radiation to carotids ↑ with valsalva and standing up (↓ preload) ↓ with hand grip (↑ afterload) and squatting (↑ afterload and ↑ preload) mitral regurgitation Imaging Radiography chest x-ray indications for all patients with clinical suspicion findings normal or enlarged heart potential pulmonary congestion Transthoracic echocardiography (TTE) indication for all patients as a diagnostic test findings may have normal ejection fraction hypertrophy of ventricular walls and interventricular septum systolic anterior motion of mitral valve with mitral regurgitation Exercise echocardiography indications confirm and quantify dynamic LVOT obstruction in patients with inconclusive TTE obligatory provocation rest if no obstruction seen at rest during echo findings LVOT obstruction and/or mitral regurgitation Cardiac MRI indications TTE ventricular morphology findings inconclusive patients with known HCM with additional findings seen on MRI findings visualization of segmental left ventricular hypertrophy located in anterolateral wall or apex compared to echo Studies Electrocardiogram indications for all patients findings left ventricular hypertrophy may have ventricular arrhythmias Labs CBC, CRP, ESR indications evaluate for signs of infection or inflammation findings elevated in cases of infection or pericarditis cardiac enzymes indications to assess for myocardial damage findings elevated in cases of myocardial infarction Histology tangled and disoriented myofibrils Diagnosis Based on clinical presentation and echocardiogram Differential Restrictive cardiomyopathy distinguishing factors Kussmaul sign on physical exam electrocardiogram with low voltages Dilated cardiomyopathy distinguishing factors echocardiogram with reduced ejection fraction progressive heart failure Treatment Goals typically managed with β-blockers and calcium channel blockers diuretics may be used cautiously in patients without left ventricular outflow tract obstruction digoxin and spironolactone do not provide any benefit Medical drugs that lower mortality avoidance of overexertion, especially athletic activities indication for all patients β-blockers indication for all patients non-dihydropyridine calcium channel blockers indication for patients who are are contraindicated or refractory to β-blockers drugs verapamil Operative surgical septal myectomy indication if significant heart failure symptoms persist despite maximal medical therapy, or patients have recurrent syncope judged to be related to hemodynamic compromise from LVOT obstruction implantable cardioverter defibrillator (ICD) indication patients with a history of syncope or events seen on a Holter monitor Techniques surgical septal myectomy approach careful patient selection, thorough preoperative assessment, and addressing the specific anatomic and functional issues technique remove a portion of the thickened septal muscle to relieve left ventricular outflow tract obstruction and improve blood flow dynamics complications bleeding infection arrhythmias residual obstruction ventricular dysfunction need for meticulous postoperative monitoring and care to ensure optimal outcomes implantable cardioverter defibrillator (ICD) approach careful patient assessment, identify those at risk of sudden cardiac death select suitable candidates technique position leads in the heart chambers connect them to the device placed under the skin program the ICD to detect and treat life-threatening arrhythmias complications infection lead-related issues bleeding pneumothorax inappropriate shocks device malfunction need for ongoing device management to ensure proper function and patient safety Complications Sudden cardiac death from ventricular arrhythmias Heart failure Prognosis Many have normal life expectancy However, there is a risk of sudden cardiac death in the young athletic population