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Hypertrophic Cardiomyopathy

Practice Essentials

Hypertrophic cardiomyopathy (HCM) is a genetic cardiovascular disease. It is defined by an increase in left ventricular wall thickness that is not solely explained by abnormal loading conditions. This disorder is caused by a mutation in cardiac sarcomere protein genes and is most frequently transmitted as an autosomal dominant trait. HCM has a variable presentation.

Signs and symptoms

Signs and symptoms of HCM can include the following:

Sudden cardiac death (the most devastating presenting manifestation)

Dyspnea (the most common presenting symptom)

Syncope and presyncope

Angina

Palpitations

Orthopnea and paroxysmal nocturnal dyspnea (early signs of congestive heart failure [CHF])

CHF (relatively uncommon but sometimes seen)

Dizziness

Physical findings may include the following:

Double apical impulse or triple apical impulse (less common)

Normal first heart sound; second heart sound usually is normally split but is paradoxically split in some patients with severe outflow gradients; S3 gallop is common in children but signifies decompensated CHF in adults; S4 is frequently heard

Jugular venous pulse revealing a prominent a wave

Double carotid arterial pulse

Apical precordial impulse that is displaced laterally and usually is abnormally forceful and enlarged

Systolic ejection crescendo-decrescendo murmur

Holosystolic murmur at the apex and axilla of mitral regurgitation

Diastolic decrescendo murmur of aortic regurgitation (10% of patients)

See Clinical Presentation for more detail.

Diagnosis

No specific laboratory blood tests are required in the workup. Genetic testing is not yet widely available but is becoming increasingly so.

Two-dimensional (2-D) echocardiography may be diagnostic for HCM. Findings may be summarized as follows:

Abnormal systolic anterior leaflet motion of the mitral valve

Left ventricular hypertrophy (LVH)

Left atrial enlargement

Small ventricular chamber size

Septal hypertrophy with septal-to-free wall ratio greater than 1.4:1

Mitral valve prolapse and mitral regurgitation

Decreased midaortic flow

Partial systolic closure of the aortic valve in midsystole

Other imaging modalities that may be useful include the following:

Chest radiography

Radionuclide imaging

Cardiac magnetic resonance imaging: Particularly useful when echocardiography is questionable, particularly with apical hypertrophy

Electrocardiographic findings may include the following:

ST-T wave abnormalities and LVH (common)

Axis deviation (right or left)

Conduction abnormalities (P-R prolongation, bundle-branch block)

Sinus bradycardia with ectopic atrial rhythm

Atrial enlargement

Abnormal and prominent Q wave in the anterior precordial and lateral limb leads, short P-R interval with QRS suggestive of preexcitation, atrial fibrillation (poor prognostic sign), and a P-wave abnormality (all uncommon)

The following diagnostic modalities may also be useful:

Cardiac catheterization (to determine the degree of outflow obstruction, cardiac hemodynamics, the anatomy and diastolic characteristics of the left ventricle, and the coronary anatomy)   

Electrophysiologic studies

See Workup for more detail.

Management

Pharmacologic therapy for HCM may include the following:

Beta blockers

Calcium channel blockers

Diltiazem, amiodarone, and disopyramide (rarely)

Antitussives to prevent coughing

The following caveats are warranted:

Avoid inotropic drugs if possible

Avoid nitrates and sympathomimetic amines, except in concomitant coronary artery disease

Avoid digitalis

Use diuretics with caution

Surgical and catheter-based therapeutic options include the following:

Left ventricular myomectomy

Mitral valve replacement

Permanent pacemaker implantation

Catheter septal ablation

Placement of an implantable cardioverter defibrillator

Heart transplantation

See Treatment and Medication for more detail.

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