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For further information, see CMDT Part 11-07: Hypertrophic Cardiomyopathy

KEY FEATURES

Essentials of Diagnosis

  • May present with dyspnea, chest pain, syncope

  • Though left ventricular (LV) outflow gradient is classic, symptoms are primarily related to diastolic dysfunction

  • Echocardiogram is diagnostic; any area of LV wall thickness > 1.5 cm defines the disease

  • Increased risk of sudden death

General Considerations

  • Hypertrophic cardiomyopathy (HCM) is noted when there is LV hypertrophy (LVH) unrelated to any pressure or volume overload

  • The LV is usually more involved than the right ventricle (RV), and the atria are frequently significantly enlarged

  • Increased wall thickness

    • Reduces LV systolic stress

    • Increases the ejection fraction (EF)

    • Can result in an "empty ventricle" at end-systole

    • The consequence of the hypertrophy is elevated LV diastolic pressures rather than systolic dysfunction

  • The interventricular septum may be disproportionately involved (asymmetric septal hypertrophy)

  • However, in some cases, the hypertrophy is localized to the mid-ventricle or to the apex

  • LV outflow obstruction is worsened by

    • Increased myocardial contractility (sympathetic stimulation, digoxin, and postextrasystolic beat)

    • Decreased LV filling (Valsalva maneuver, peripheral vasodilators)

  • LV outflow obstruction, however, may not be present

  • Patients usually present in early adulthood

  • HCM in older adults

    • Usually associated with hypertension

    • Has been defined as a distinct entity (often a sigmoid interventricular septum is noted with a knob of cardiac muscle below the aortic valve)

  • Elite athletes may demonstrate hypertrophy that can be confused with HCM, but generally diastolic dysfunction is not present in the athlete and this finding helps separate pathologic disease from athletic hypertrophy

  • Pregnancy results in an increased risk in patients with symptoms or outflow tract gradients of > 50 mm Hg

CLINICAL FINDINGS

Symptoms and Signs

  • Dyspnea

  • Chest pain

  • Syncope, typically postexertional

  • Arrhythmias

    • Atrial fibrillation

    • Ventricular arrhythmias and sudden death, often after extraordinary exertion

  • Features on physical examination include

    • A bisferiens carotid pulse

    • Triple apical impulse (due to the prominent atrial filling wave and early and late systolic impulses)

    • A loud S4

  • The jugular venous pressure may reveal a prominent a wave due to reduced RV compliance

  • In cases with LV outflow obstruction, a loud systolic murmur is present along the left sternal border that increases with upright posture or Valsalva maneuver and decreases with squatting; these maneuvers help differentiate HCM from aortic stenosis

    • In HCM, reducing the LV volume increases the outflow obstruction and the murmur intensity

    • In valvular aortic stenosis, reducing the stroke volume across the valve decreases the murmur

  • Mitral regurgitation is frequently present

  • HCM in older adults

    • Mitral annular calcification is often present

    • Mitral regurgitation is variable and often dynamic, depending on the degree of outflow tract obstruction

  • The LV is usually more involved than the RV

  • The atria are frequently significantly enlarged

DIAGNOSIS

Imaging

  • Chest radiograph

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