may present for the first time during adolescence with cardiac
arrest or sudden cardiac death.. There are a large number of mutations. If no mutation identified within a family then screen
first-degree relatives by ECG and echocardiography
- Left ventricular hypertrophy (LVH) max wall thickness >15 mm
- Predominantly diastolic failure
- Increased risk of SVT and VTs. Seen in 1 in 500 adults.
- Differentiation of HCM from aortic stenosis can be difficult
- Some cases are sporadic and not genetic
- Mutations in cardiac sarcomere proteins
- Autosomal dominant inherited usually.
- Rare AR, XLR or de novo.
The degree of outflow obstruction and hypertrophy does not correlate reliably with risk of sudden death
- Mutations in one of the 10 sarcomeric protein genes.
- Sarcomeric proteins mutations of Beta Myosin heavy chain mutation R403Q. Alpha tropomyosin, Cardiac troponin T,
- Cardiac troponin I, Myosin Binding protein C, Actin, Titin, Myosin Light chains
- Myocyte disarray, Myocyte hypertrophy
- Local interstitial fibrosis. Apical form commoner in Japan.
- Mitral valve prolapse
- Noonan's syndrome, WPW syndrome
- Symptomatic LVH
- Arrhythmias (atrial fibrillation as well as malignant ventricular arrhythmias)
- Refractory heart failure
- Sudden cardiac death
- No symptoms and detected on screening due to an event in a family member or national screening
- Jerky pulse. Only 20% have LVOT
- Dyspnoea - diastolic dysfunction
- Syncope or pre-syncope. Sudden cardiac death.
- Athletes often post-exercise e.g. at half time.
- AF which may result in pulmonary oedema.
- JVP: prominent 'a' wave due to forceful atrial contraction against a stiff right ventricle.
- Double or even triple apex beat
- Pansystolic murmur due to MR
- Late systolic murmur due to LVOTO
- HCM murmur louder on standing or Valsalva. Squatting and leg raising can make these murmurs disappear. All other murmurs do the opposite.
- ECG: deep T wave inversion, ST and Q wave "pseudo-infarction" appearance, LAD and LVH. Left and right atrial enlargement.
- Transthoracic Echo:
- 20% have LVOTO. Asymmetrical septal hypertrophy (ASH) MR, Apical hypertrophy seen in Japan.
- Systolic anterior motion (SAM) of the anterior mitral valve leaflet with associated left ventricular outflow tract obstruction and mitral regurgitation
- mid-ventricular obstruction as a result of systolic cavity obliteration
- Diastolic dysfunction, including restrictive physiology.
- The degree of outflow obstruction and hypertrophy does not correlate reliably with the risk of sudden death
- Coronary angiography to exclude CAD.
- Cardiac MRI used for structural cardiac disease.
ECG of patient with HCM
Management: Risk assess
- Beta-blockers are the basis of medical therapy. Amiodarone can be useful.
- Avoid: Digoxin, Nitrates, Diuretics, Vasodilators
- Manage Diastolic Heart Failure. Beta blockers, CCBs
- Arrhythmias: Disopyramide is useful and also decreases outflow gradient. Certain patients will benefit from an AICD.
- ACE inhibitors: caution in case worsen obstruction.
- Other treatments in elderly - alcohol septal ablation. ICD as bridge to cardiac transplantation. Warfarin + amiodarone for AF. Patients need antibiotic prophylaxis for procedures
- Annual Rate of Death/End-stage heart failure/Fatal Stroke 1-2% per year.
Screening of family of Known HCM
- Gene testing for the mutation if known as this can help with risk assessment as some mutations are higher risk
- If no gene anomaly is known within a family then 1st-degree family need ECG and echocardiogram
- If no gene anomaly then children of affected parents are screened every 3 years until puberty, and then annually until 20 years of age.
- If there is no evidence
of HOCM in early adulthood, it is unlikely that the condition will
develop in later life
Identify Higher risk of SCD patients
- Family Hx of sudden death or Unexplained syncope
- LV wall > 3 cm
- Non sustained VT on Holter, Fall in BP with exercise
- Enlarged left atrium, LVOT IS NOT A RISK.
- ICD insertion in those at high risk
- Acronyms: SCD: Sudden cardiac death, CCB : Calcium channel Blockers, LVOTO Left ventricular outflow tract obstruction, MR: Mitral regurgitation