Hypertrophic Cardiomyopathy — SAQ

Stem

A candidate is asked to manage a classic presentation of Hypertrophic Cardiomyopathy in an exam setting. Use precise definitions, scores, doses, and decision thresholds.

Core knowledge (model answer backbone)

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant sarcomere-protein mutation disease producing unexplained left ventricular hypertrophy, classically asymmetric septal. Histology shows myocyte disarray, interstitial fibrosis and intramural small-vessel disease. Dynamic left ventricular outflow tract (LVOT) obstruction with systolic anterior motion (SAM) of the mitral valve and secondary mitral regurgitation occurs in about two-thirds. The cardinal clinical threats are sudden cardiac death (SCD) in the young, diastolic heart failure, atrial fibrillation and angina from microvascular ischaemia. The bedside signature is an ejection systolic murmur at the left sternal edge that increases with Valsalva and standing and decreases with squatting — the opposite of fixed aortic stenosis. Diagnosis is by echocardiography (LV wall thickness 15 mm or more in adults, or a lower threshold in relatives), with cardiac MRI and genetic testing as core adjuncts. Beta-blockers are first-line; disopyramide or non-dihydropyridine calcium-channel blockers are second-line; septal reduction therapy (Morrow surgical myectomy or alcohol septal ablation) is reserved for drug-refractory obstructive dis

Red flags

• Young athlete with syncope on exertion, family history of SCD, or exertional chest pain — HCM until proven otherwise; restrict sport pending echo
• Syncope, pre-syncope, or seizures on exertion in any HCM patient — high SCD risk; risk-stratify and consider ICD
• Documented non-sustained VT on Holter, unexplained syncope, massive LVH (over 30 mm), or abnormal BP response to exercise — major SCD risk modifiers; ICD evaluation
• Haemodynamic collapse in HOCM — avoid nitrates, diuretics, vasodilators, digoxin and pure alpha-agonists; give volume, beta-blockade, pure alpha-agonists (phenylephrine) and vasoconstrictors; never intra-aortic balloon pump

High-yield structure examiners expect

Cover: Overview & Definition, Classification, Epidemiology & Risk Factors, Pathophysiology, Clinical Presentation, Differential Diagnosis.

Key doses / thresholds (from topic teaching)

• phenylephrine 100 to 200 micrograms intravenously, titrated** — raises
• or up to 320 mg/day), metoprolol succinate (100 to
• loading 500 micrograms/kg over 1 minute, then 50 to 200 mi
• controlled-release 250 mg twice daily where available), titrated
• pure alcohol 1 to 2 mL** into the first septal perforator
• amiodarone 200 mg orally daily** is the usual first-line

Questions

a) Define the condition and give the most important classification or severity framework used in exams. (3 marks)

• Clear one-line definition matching standard teaching.
• Named classification / stages / types with discriminating features.
• One sentence on why classification changes management.

b) Outline pathophysiology in a mechanism chain that explains the main clinical features. (3 marks)

• Initiating insult → intermediate pathway → end-organ effect.
• Link at least two symptoms/signs to mechanism.
• Mention one complication pathway (e.g. shock, perforation, herniation, arrhythmia).

c) List discriminating clinical features and bedside assessment. (3 marks)

• Classic presentation plus one atypical group (elderly, pregnancy, child, immunocompromised).
• Named signs/manoeuvres if relevant.
• What must never be missed on exam/bedside (pregnancy test, airway, glucose, etc.).

d) Investigations with thresholds and one named score if applicable. (3 marks)

• First-line tests and what positive findings mean.
• Gold-standard or definitive investigation when needed.
• Score components reproduced exactly if a named score is standard for this topic.

e) Immediate resuscitation and definitive management with doses where standard. (3 marks)

• ABC / time-critical steps first.
• First-line drug(s) with agent + dose + route (or procedure steps).
• Escalation triggers (theatre, ICU, thrombolysis window, antidote, etc.).
• Disposition and safety-netting.

Marking tips

Full marks require specificity (numbers, names, doses) not generic "give antibiotics/fluids." Regional practice (ICMR / NICE / AHA) may be cited as alternative where relevant.