Cardiomyopathy, Hypertrophic

Key Features

Essentials of Diagnosis

• May present with dyspnea, chest pain, syncope

• Though LV outflow gradient is classic, symptoms are primarily related to diastolic dysfunction

• Echocardiogram is diagnostic; any area of left ventricle (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

• 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

• 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

Clinical Findings

Symptoms and Signs

• Dyspnea

• Chest pain

• Syncope

• Arrhythmias

• 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 right ventricular (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

• 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

  • Often unimpressive

  • Unlike with aortic stenosis, the ascending aorta is not dilated

• Doppler ultrasound

  • Reveals turbulent flow

  • Dynamic gradient in the LV outflow tract

  • Mitral regurgitation

  • Abnormalities in the diastolic filling pattern are present in 80% of patients

Diagnostic Studies

• ECG

  • LVH is nearly universal in symptomatic patients

  • However, normal ECGs are present in up to 25%, usually in those with localized hypertrophy

  • Exaggerated septal Q waves inferolaterally may mimic myocardial infarction

• Echocardiogram

  • Diagnostic; findings include

    • LVH (involving the septum more commonly than the posterior walls)

    • Systolic anterior motion of the mitral valve

    • Early closing followed by reopening of the aortic valve

    • Small and hypercontractile ...