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 login to view 2 more bullets hypertrophic obstructive cardiomyopathy login to view 4 more bullets Genetics familial (most common) inheritance pattern autosomal dominant mutations chromosome 14 genes encoding sarcomere proteins login to view 1 more bullet 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 login to view 2 more bullets mitral regurgitation Imaging Radiography chest x-ray indications login to view 1 more bullet findings login to view 2 more bullets 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 login to view 1 more bullet 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 login to view 1 more bullet Studies Electrocardiogram indications for all patients findings left ventricular hypertrophy may have ventricular arrhythmias Labs CBC, CRP, ESR indications login to view 1 more bullet findings login to view 1 more bullet cardiac enzymes indications login to view 1 more bullet findings login to view 1 more bullet 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 login to view 2 more bullets β-blockers login to view 2 more bullets non-dihydropyridine calcium channel blockers login to view 4 more bullets Operative surgical septal myectomy indication login to view 1 more bullet implantable cardioverter defibrillator (ICD) indication login to view 1 more bullet 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, login to view 1 more bullet 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