Hypertrophic cardiomyopathy (HCM - HOCM) 💔

Related Subjects: |Dilated Cardiomyopathy |Hypertrophic cardiomyopathy (HCM - HOCM) |Peripartum cardiomyopathy |Restrictive Cardiomyopathy |Takotsubo Cardiomyopathy

💔 Hypertrophic Cardiomyopathy (HCM) may present in adolescence with cardiac arrest or sudden death. Genetic in origin, but even when no mutation is found, first-degree relatives require ECG + echo screening.

📖 About

• Defined as LV hypertrophy (LVH) with wall thickness >15 mm.
• Causes diastolic dysfunction (stiff ventricle, impaired filling).
• Risk of SVT and VT — prevalence ~1 in 500 adults.
• Can mimic aortic stenosis clinically.

🧬 Aetiology & Genetics

• Mostly autosomal dominant, but can be sporadic or de novo.
• Mutations in sarcomere proteins:
  • 🟠 MYH7 (beta-myosin heavy chain)
  • 🔵 MYBPC3 (myosin-binding protein C)
  • Others: troponin T/I, α-tropomyosin, titin, actin.
• Pathology: myocyte disarray + fibrosis. Septal hypertrophy → LV outflow obstruction (LVOTO). Apical HCM more common in Japan 🇯🇵.

🧑‍⚕️ Associations

• Mitral valve prolapse
• Phaeochromocytoma
• Noonan’s syndrome
• WPW syndrome

🩺 Clinical Presentation

• Often asymptomatic (picked up on screening).
• Symptoms:
  • 💥 Exertional chest pain (angina)
  • ❤️ Palpitations (AF, VT)
  • 🌬️ Dyspnoea (diastolic dysfunction)
  • 😵 Syncope/pre-syncope (exercise-related)
  • ⚡ Sudden death (esp. young athletes)

⚠️ Risk Factors for Sudden Cardiac Death (SCD)

🔍 Examination

• Irregular pulse (if AF).
• JVP: prominent 'a' wave.
• Jerky/bisferiens pulse, triple apical impulse.
• 🎧 Murmurs:
  • Pan-systolic (mitral regurg)
  • Late systolic (LVOTO) — louder on standing/Valsalva, softer on squatting.

🧪 Investigations

• ECG: LVH, deep T inversion, pseudo-infarct Q waves, AF.
• Echo: Asymmetrical septal hypertrophy, SAM of MV, diastolic dysfunction.
• Cardiac MRI: Detailed anatomy + fibrosis (LGE).
• Coronary angiography: Exclude CAD if angina symptoms.

💊 Management

• Pharmacological: - 🥇 Beta-blockers = first-line - Verapamil if BB contraindicated - Disopyramide (negative inotrope) for LVOTO - ❌ Avoid vasodilators, diuretics, high-dose nitrates (worsen obstruction)
• Procedures: - 🔪 Septal myectomy (definitive for LVOTO) - 🍷 Alcohol septal ablation (less invasive) - ⚡ ICD for high SCD risk
• Lifestyle: - Avoid competitive sports 🏃‍♂️ - Regular follow-up echo/MRI - Family screening & genetic counselling 👨‍👩‍👧

👶 Family Screening

• If mutation identified → genetic test relatives.
• If not → ECG + echo:
  • Children: every 3 yrs until puberty, then annually until 20.
  • If normal in early adulthood → low risk of later development.

📦 Exam Red Flags: Syncope + LVH ≥30 mm + family history of SCD → ICD indicated.

📚 References

• ACC/AHA HCM Guidelines
• ESC HCM Guidelines

🩺 Case 1 — Young Athlete with Syncope

A 19-year-old male collapses during football practice. He had been experiencing exertional chest pain and palpitations for weeks. On exam: jerky carotid pulse, harsh ejection systolic murmur at the left sternal edge that increases with Valsalva. ECG shows LVH, echo reveals asymmetric septal hypertrophy with LV outflow tract obstruction. Management: 🏥 Start beta-blocker for symptom control, restrict intense competitive sport, genetic counselling and family screening. Consider ICD if high risk of sudden cardiac death (syncope, family history, massive LVH). Avoid: ❌ Avoid dehydration, vasodilators, nitrates, and digoxin — all can worsen obstruction.

🩺 Case 2 — Middle-Aged Man with Dyspnoea

A 48-year-old man presents with progressive exertional dyspnoea and palpitations. Exam: harsh systolic murmur at apex radiating to axilla, variable intensity with posture. Echo shows hypertrophic obstructive cardiomyopathy with moderate outflow tract obstruction. Management: 💊 Beta-blockers or verapamil for symptom relief, anticoagulation if atrial fibrillation develops. Septal reduction therapy (surgical myectomy or alcohol septal ablation) if severe symptoms despite medical therapy. Avoid: ❌ Avoid aggressive diuresis (reduces preload and worsens obstruction).

🩺 Case 3 — Family History of Sudden Cardiac Death

A 32-year-old woman attends for screening after her brother died suddenly at age 29. She is asymptomatic but ECG shows T-wave inversion in lateral leads. Echo reveals asymmetric septal hypertrophy (wall thickness 22 mm). Management: 🩺 Refer to cardiology for risk stratification; consider ICD due to family history and significant LVH. Offer genetic testing and cascade screening for relatives. Lifestyle advice including avoidance of high-intensity competitive sports. Avoid: ❌ Ignoring asymptomatic but high-risk individuals; avoid prescribing competitive sports clearance without cardiology input.