Definition of Hypertrophic Cardiomyopathy
Hypertrophic cardiomyopathy (HCM) is a disease of the heart muscle characterized by hypertrophy of cardiac muscle with misalignment of the cardiac fibers.
Hypertrophy may be generalized or localized to the interventricular septum (asymmetrical septal hypertrophy) or other regions (apical hypertrophic cardiomyopathy).
Types
• Asymmetrical septal hypertrophy (70%).
• Basal septal hyperatrophy (15–20%).
• Concentric (8–10%).
• Apical or lateral wall (<2%).
Clinical Features
Symptoms
• May be asymptomatic.
• Angina on exertion.
• Palpitation.
• Breathlessness on exertion.
• Presyncope or syncope on exertion.
• Sudden death.
Signs
• Pulse—Carotid pulse is jerky.
• BP—low systolic, normal diastolic, narrow pulse pressure.
Precordium Examination
Palpation
• Apex beat—heaving (may be double apical impulse).
• A systolic thrill may be palpable at apex.
Auscultation
• Ejection systolic murmur at the left lower sternal border.
• Pansystolic murmur at the apex due to mitral regurgitation.
Investigations
• Chest X-ray (may be normal).
• ECG (may be LVH, infarction, deep T—bizarre pattern).
• Echocardiogram (diagnostic)—shows asymmetrical septal hypertrophy (ASH), systolic anterior
motion (SAM) of anterior leaflet of mitral valve.
• Cardiac MR.
• Genetic analysis.
Treatment
1. In nonobstructive case—
–– Beta-blocker, rate-limiting calcium channel blocker (verapamil, diltiazem), and disopyramide for symptomatic
relief and prevention of syncope.
–– Amiodarone may be helpful in arrhythmia.
2. In significant left ventricular outflow obstruction—
–– Dual chamber pacing may be needed.
–– Outflow tract obstruction can be improved by partial surgical resection (myectomy).
–– Iatrogenic infarction of basal septum by injecting alcohol with cardiac catheter.
3. Other treatment—
–– ICD (Implantable Cardioverter Defibrillator) if there are clinical risk factors for sudden death (see below).
–– Cardiac transplantation may be needed in CHF not responding to treatment.
–– Infective endocarditis prophylaxis may be needed.
Advice to be Given in HCM
• Vigorous exercise and dehydration should be avoided.
• Genetic counseling, as in 50% of cases may be inherited as autosomal dominant.
• First-degree family members should be screened by echocardiogram.
Risk Factors for Sudden Cardiac Death in Hypertrophic Cardiomyopathy (HCM)
• History of previous cardiac arrest or sustained VT.
• Recurrent VT.
• Adverse genotype or family history of sudden cardiac death (<50 years old).
• Failure of blood pressure to rise during exercise (no change or hypotension).
• Nonsustained VT on 24 hours Holter monitoring.
• Marked increase in left ventricular wall thickness (>30 mm on echocardiography).
• Delayed gadolinium enhancement on cardiac MRI.
Drugs to be Avoided in Hypertrophic Cardiomyopathy (HCM)
• Digoxin.
• Vasodilators.
• Diuretics.
• Nitrates.
• Dihydropyridine calcium channel blockers.
• Alcohol (may cause vasodilatation).
Effect of Hypertrophic Cardiomyopathy (HCM) in Pregnancy
Pregnancy is not contraindicated in HCM. The patient usually tolerates pregnancy well if not severely symptomatic. There is no risk of sudden cardiac death in pregnancy.
Following precautions should be taken—
• Prenatal counseling regarding the risk of disease in offspring.
• The patient should have a regular follow-up in a well-equipped center with expertise in high-risk
pregnancies and cardiac disease.
• β-blockers or calcium blockers should be continued.