Makindo Medical Notes.com

Related Subjects: |Dilated Cardiomyopathy |Hypertrophic cardiomyopathy (HCM - HOCM) |Peripartum cardiomyopathy |Restrictive Cardiomyopathy |Takotsubo Cardiomyopathy

It 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

About

• 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

Aetiology

• Some cases are sporadic and not inherited
• Mutations in cardiac sarcomere proteins
• Autosomal dominant inherited usually.
• Rare AR, XLR or de novo.

Pathology

The degree of outflow obstruction and hypertrophy does not correlate reliably with risk of sudden death

Genetics

• 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

Pathology

• Myocyte disarray, Myocyte hypertrophy
• Local interstitial fibrosis. Apical form commoner in Japan.

Septal hypertrophy

Associations

• Mitral valve prolapse
• Phaeochromocytoma
• Noonan's syndrome, WPW syndrome

Clinical

• No symptoms and detected on screening due to an event in a family member or national screening
• Chest pain (angina), Palpitations
• Jerky pulse. Only 20% have LVOT
• Exertional Dyspnoea - diastolic dysfunction
• Syncope or pre-syncope
• Sudden cardiac death (especially in young athletes)

Risk Factors for Sudden Cardiac Death

Complications

• Symptomatic LVH
• Arrhythmias (atrial fibrillation as well as malignant ventricular arrhythmias)
• Refractory heart failure
• Sudden cardiac death

Examination

• 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
• Pan-systolic 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.

Investigations

• 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

Pharmacologic Management

• Beta-blockers: First-line therapy for symptom relief, particularly for angina and dyspnoea. They reduce heart rate and myocardial oxygen demand.
• Calcium Channel Blockers: Verapamil is often used when beta-blockers are contraindicated or ineffective.
• Disopyramide: An antiarrhythmic with negative inotropic effects, useful in reducing LVOT gradients.
• Avoid vasodilators, diuretics, and high-dose nitrates in HOCM, as they can exacerbate LVOT obstruction.

Non-Pharmacologic Management

• Septal Myectomy: Surgical removal of part of the hypertrophied septum to relieve LVOT obstruction. It is the gold standard for patients with severe obstruction and symptoms.
• Alcohol Septal Ablation: A catheter-based procedure where alcohol is injected into the septal branch of the coronary artery to induce a controlled myocardial infarction, reducing septal thickness and LVOT obstruction.
• Implantable Cardioverter-Defibrillator (ICD): Indicated in high-risk patients for the prevention of sudden cardiac death, particularly in those with a history of ventricular arrhythmias, syncope, or family history of sudden cardiac death.

Lifestyle Modifications

• Avoidance of competitive sports and intense physical exertion, which can trigger arrhythmias or sudden death.
• Regular follow-up to monitor disease progression and adjust treatment as necessary.
• Family screening and genetic counseling for first-degree relatives.

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