Hypertrophic cardiomyopathy (HCM)

- associated with Friedreich's ataxia, WPW, phaeochromocytoma, familial lentiginosis
- features: jerky pulse, double apical impulse, LSE systolic thrill with harsh ESM
- ESM increase with Valsalva manoeuvre, GTN, digoxin, standing (decrease venous return) and decrease with squatting, beta blockers, handgrip (increase venous return)
- 45% mutation in B-myosin heavy chain on chromosome 14 , 35% mutation in cardiac myosin binding protein C
- diastolic dysfunction
- echo: asymmetrical septal hypertrophy (left ventricular myocardial segment of 1.5cm or greater thickness) , left ventricular outflow tract gradient, systolic anterior motion of anterior mitral valve cusp
- 12 leads ECG abnormal in 80%, most common are ST segment and T wave abnormalities, followed by left ventricular hypertrophy
- microscopic findings: myocardial cell disarray with myocardial hypertrophy and gross disorganization of muscle bundles
- annual mortality = 1%
- 5 poor prognostic markers of sudden death
 i) syncope
 ii) family history of HCM + sudden death
 iii) maximum left ventricular wall thickness > 3cm
 iv) BP decrease during peak exercise / stress test
 v) non sustained VT
       *No consistent relationship of outflow gradient with risk of sudden death
- treatment : beta blockade reduce outflow gradient during exercise thus reduce risk of rhythm disturbance. ICD (implantable cardioverter defibrillator) is considered for patient with history of collapse (VT). Myomectomy is indicated for patient with significant outflow obstruction and is usually reserved for failed medical therapy