see also:

• cardiomyopathy

• idiopathic hypertrophy of the myocardium resulting in left ventricular hypertrophy (LVH) which is usually assymetric involving the interventricular septum in 2/3rds of cases
• 25% have obstructed outflow at rest, while 70% have obstructed outflow under certain conditions (“dynamic outflow obstruction”)
  • the obstructive variant of HCM, hypertrophic obstructive cardiomyopathy (HOCM) has also historically been known as idiopathic hypertrophic subaortic stenosis (IHSS) and asymmetric septal hypertrophy (ASH).
• 30% have abnormal vascular responses and inability to increase systolic blood pressure during exercise
• one of the commonest causes of sudden death in young athletes and is often asymptomatic prior
• arrhythmias are common especially atrial fibrillation and supraventricular tachycardias.
  • ventricular dysrhythmias also occur and may be a cause of sudden death.
• 50-60% are due to a mutation in one of 9 sarcomeric genes, usually inherited as autosomal dominant or arise de novo
  • 45% of these mutations occur in the β myosin heavy chain gene on chromosome 14 q11.2-3
  • 35% involve the cardiac myosin binding protein C gene
  • an insertion/deletion polymorphism in the gene encoding for angiotensin converting enzyme (ACE) alters the clinical phenotype of the disease
  • troponin T mutations are particularly dangerous and are associated with a 50% mortality before the age of 40
• prevalence is 0.2% - 0.5% of the general population
• a non-obstructive variant of HCM is apical hypertrophic cardiomyopathy, also called Yamaguchi Syndrome or Yamaguchi Hypertrophy, first described in individuals of Japanese descent

• ECG may show:
  • left ventricular hypertrophy (LVH) changes such as:
    • >40 mm S wave in V2
    • +/- flattened or inverted T waves in inf-lat leads
    • +/- ST-T changes although left ventricular hypertrophy (LVH) may be absent in pre-pubescent children
    • +/- increased precordial voltages
    • +/- P ‘mitrale may be seen due to left atrial hypertrophy, which occurs when there is left ventricular diastolic dysfunction
  • LAD or RAD
  • BBB or prolonged PR interval
  • Sinus bradycardia with ectopic atrial rhythm
  • abnormal and prominent Q wave in the anterior precordial and lateral limb leads, short P-R interval with QRS suggestive of preexcitation
    • deep narrow (‘dagger like’) Q waves in the lateral (V5-6, I and AVL) and inferior (II, III and AVF) leads, due to asymmetrical septal hypertrophy.
    • these Q waves are distinct from those of previous myocardial infarction, in that they are typically < 40ms duration whereas infarction Q waves are typically > 40 ms duration
  • giant T wave inversion in apical HCM (mainly in Japanese)
  • see LITFL ECG library
• HOCM can be detected on echo in over 80% of cases

• highly trained athletes can also develop cardiac hypertrophy (‘athlete's heart’).
• ECG changes seen as part of cardiovascular adaptation in an endurance athlete include:
  • sinus bradycardia
  • increased QRS voltage
  • tall peaked T wave
  • J point elevation
  • U waves
• in contrast, the presence of pathological Q waves, left axis deviation, and T wave inversion are indicators of HCM as opposed to the athlete’s heart

• see Brugada syndrome

• see prolonged QTc

• see pre-excitation syndromes including WPW

• patients should be advised not to undergo any exertional stress which could put them at risk of sudden cardiac death
• urgent echocardiogram and cardiology review

• inotropes
• vasodilators such as nitrates
• digoxin
• diuretics

• beta adrenergic blockers
• calcium channel blockers
• antitussives to prevent coughing
• surgery - LV myomectomy
• permament pacemaker
• implanted defibrillator

• wikipedia