Cardiomyopathies in children — structured clinical encounter

Station brief (candidate)

You are the paediatric registrar in the emergency department. A 14-year-old competitive runner collapsed briefly during a 1500-metre race and recovered fully within seconds. His father died suddenly at 38 of an unspecified "heart attack". On examination he is well, with a soft ejection systolic murmur at the left sternal border that grows louder on standing. The team asks you to establish the diagnosis, order and interpret the investigations, perform the sudden-death risk stratification, and proceed to the management and family-counselling plan. You have 12 minutes with the team and 5 minutes for examiner discussion. [4] [6]

Information available on request

• 14-year-old competitive runner; collapsed briefly mid-race, recovered fully in seconds; no seizure activity, no incontinence, no tongue-biting. [4]
• Father died suddenly at 38 of an unspecified "heart attack"; paternal uncle has a pacemaker. [6]
• Examination well, soft ejection systolic murmur at the left sternal border that grows louder on standing; no heart failure signs. [4]
• 12-lead ECG (on request): voltage criteria for left ventricular hypertrophy with deep lateral T-wave inversions and borderline pathological Q waves. [4]
• Echocardiogram (on request): asymmetric septal hypertrophy (max wall thickness 22 mm), systolic anterior motion of the mitral valve, a resting left ventricular outflow tract gradient of 40 mmHg rising to 90 mmHg on Valsalva, hyperdynamic systolic function. [9]
• Holter monitor (on request): infrequent ventricular ectopy, one run of non-sustained ventricular tachycardia of six beats. [5]
• Cardiac MRI (on request): extensive late gadolinium enhancement at the right ventricular insertion points and mid-wall septum. [9]

Tasks

1. Give the diagnosis and explain the bedside sign that supports it, and state why the family history is central. [4] [6]
2. Outline the investigations and what each contributes to diagnosis and risk stratification. [5] [9]
3. Perform the sudden-death risk stratification and state the intervention proven to reduce sudden death, citing the key trial. [5]
4. Describe the family-cascade-screening strategy and the management of a genotype-positive phenotype-negative sibling. [4] [8]
5. Counsel the patient and family on sport and on the prognosis. [9]

Marking anchors

Must-hit

• Diagnoses hypertrophic cardiomyopathy with dynamic left ventricular outflow tract obstruction (the murmur that grows louder on standing as preload falls); identifies the family history of a father's sudden death at 38 as the central risk factor because childhood HCM is usually autosomal dominant (sarcomeric, MYH7 or MYBPC3). [4] [6]
• Orders and interprets ECG, echocardiography (asymmetric hypertrophy, LVOT gradient, systolic anterior motion), Holter (non-sustained VT), exercise testing (BP response), cardiac MRI (late enhancement), and a cardiomyopathy gene panel; integrates them into a sudden-death risk estimate. [5] [9]
• States that high-risk patients are offered an implantable cardioverter-defibrillator, the intervention proven to reduce sudden death in HCM by Maron and colleagues, weighing the burden of inappropriate shocks and lead complications. [5]

Merit

• Names the Alexander 2018 national population-based childhood HCM outcome data to frame the prognosis; demonstrates correct cascade family screening with lifelong surveillance for a genotype-positive phenotype-negative sibling; correctly restricts competitive sport pending an inherited cardiac conditions assessment. [4] [9]

Fail

• Reassures the patient that a brief collapse during sport is a benign faint and permits a return to competitive racing. [4]
• Discharges the family without cascade genetic and clinical screening, or reassures a genotype-positive sibling on a single normal echocardiogram. [8]