A 28-year-old athlete has a family history of sudden cardiac death. Echo shows asymmetric septal hypertrophy (IVS 18 mm), LVOTO gradient 45 mmHg at rest, and systolic anterior motion (SAM) of mitral valve. He has syncope on exertion. Which investigation best risk-stratifies for SCD in hypertrophic obstructive cardiomyopathy (HOCM)?
- A Exercise stress test — inducible ST depression predicts SCD
- B Holter monitor for 24 hours — single run of NSVT confirms high risk
- C Five-year SCD risk calculated using HCM Risk-SCD calculator (incorporates max wall thickness, LA size, LVOT gradient, family history, unexplained syncope, NSVT, age) ✓
- D Genetic testing for MYH7 mutation — positive result alone mandates ICD implantation
Explanation
The European Society of Cardiology HCM Risk-SCD calculator (validated in the HYPER-HOT registry) is the recommended tool for SCD risk stratification in HCM patients ≥ 16 years. It incorporates: maximum LV wall thickness, LA diameter, max LVOT gradient, family history of SCD, unexplained syncope, age, and presence of NSVT on Holter. ICD implantation is recommended if 5-year SCD risk ≥ 6%. This patient with syncope, significant hypertrophy, and LVOTO at 28 years is likely high risk. Genetic testing identifies causative mutations in ~60% but genotype alone does not dictate ICD — phenotype and risk score guide decisions.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.