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.