Cardiomyopathies Flashcards
What are the signs/symptoms of HOCM?
> Chest pain: often occurs during exercise or physical activity, but can also happen at rest.
Dyspnoea
Palpitations
Fainting
Fatigue
Dizziness
Less common:
Peripheral oedema
Heart murmur
HOCM diagnostic steps.
> Clinical evaluation
ECG
Echocardiography–>TTE, Doppler echo to measure pressure gradient across the LVOT.
Cardiac magnetic resonance imaging.
Exercise testing.
Holter monitoring: to detect intermittent arrhythmias.
Additional considerations:
Family screening: screening of first-degree relatives with ECG and echocardiography is recommended to identify asymptomatic carriers.
Risk assessment for sudden cardiac death: assessment includes evaluating factors such as family history, unexplained syncope, and the extent of the left ventricular hypertrophy.
Treatment options for HOCM.
General Management:
Lifestyle modifications, such as avoiding strenuous exercise and dehydration.
Pharmacological Treatment:
Beta-blockers: first-line therapy to reduce symptoms.
Calcium channel blockers: used if beta blockers are not effective or tolerated.
Disopyramide: may be added to beta blockers or calcium channel blockers to reduce the LVOT obstruction.
Invasive procedures:
Septal myectomy: for patients with severe symptoms not controlled by medication.
Alcohol septal ablation: less invasive procedure. It is an alternative to surgery.
Device therapy:
Implantable cardioverter defibrillator: recommended for patients at high risk of sudden cardiac death due to severe arrhythmias.
New developments:
Mavacamten: NICE has recently recommended Mavacamten for treating symptomatic obstructive HCM in adults. It is particularly recommended for those who do not respond adequately to standard treatments.
What is Mavacamten and how does it work?
A medication used to treat HOCM in adults. It is a first-in-class small-molecule allosteric inhibitor of cardiac myosin.
Mechanism of action: Mavacamten works by binding to myosin.
This binding reduces the number of myosin-actin cross-bridges, which are responsible for muscle contraction.
By inhibiting these cross-bridges, Mavacamten decreases the excessive contractility of the heart muscle, allowing it to relax more effectively.
This relaxation reduces the obstruction in the LVOT, improves cardiac filling pressures, and enhances overall cardiac function. As a result, patients experience improved symptoms and functional capacity.
What are the characteristic ECG findings in HOCM?
> Left ventricular hypertrophy: increased praecordial volatages, often meeting the criteria for LVH.
> Dagger-like Q waves.
> ST segment and T-wave abnormalities. Non-specific ST segment and T-wave changes, including T-wave inversion.
> Left atrial enlargement: p mitrale pattern, indicating left atrial enlargement due to diastolic dysfunction.
> Arrhythmias: presence of atrial fibrillation, SVT, premature atrial contractions (PACs), premature ventricular contractions (PVCs), and ventricular tachycardia.
> Giant T-wave inversions: particularly in the apical variant of HOCM (Yamaguchi syndrome), where the apex is thickened.
> Wolff-Parkinson-White syndrome: short PR interval and delta waves, which can be associated with HOCM.
Does HOCM cause primarily systolic or diastolic dysfunction?
Diastolic dysfunction.
What are the risk factors for HCM?
> Genetic factors: often AD inheritance.
> Age: can develop at any age, but symptoms often appear during adolescence.
> Sex: males may experience more severe symptoms compared to females.
> Hypertension: can exacerbate the thickening of the myocardium.
> Coronary artery disease: blockages or abnormal development in the coronary arteries can complicate HCM.
> Physical activity: intense physical activity can trigger symptoms or complications in patients with HCM.
> Obesity: excess body weight can increase strain on the heart, potentially worsening HCM.
How is genetic testing done for HCM? What are the steps?
1) Genetic counselling.
2) Sample collection: blood or saliva sample.
3) Lab analysis:
DNA sequencing.
Gene panels.
4) Interpretation of results:
Variant classification: the identified genetic variants are classified based on their potential to cause disease (e.g., pathogenic, likely pathogenic, variant of uncertain significance, likely benign, benign).
Report generation: detailed report is produced, summarising the findings and implications for patient and family health.
5) Post-test counselling:
Result discussion: the genetic counsellor will discuss the results with the patient.
Family screening.
What are the benefits of genetic testing for HCM?
> Early detection— allows for early intervention.
Personalised management.
Does dilated cardiomyopathy cause predominantly diastolic or systolic dysfunction?
Systolic
What is dilated cardiomyopathy?
A condition characterised by dilation and impaired contraction of the heart’s ventricles, leading to systolic dysfunction. This condition can result in heart failure and other complications.
Pathophysiology of dilated cardiomyopathy.
1) Ventricular dilation:
The left ventricle (and often the right ventricle) becomes enlarged and stretched, leading to a thin and weakened heart muscle.
This dilation reduces the heart’s ability to contract effectively, resulting in decreased ejection fraction and impaired systolic function.
2) Myocardial dysfunction:
The myocytes undergo structural changes, including necrosis and fibrosis, which further impair contractility.
These changes can be triggered by various factors, including genetic mutations, viral infections and exposure to toxins.
3) Neurohormonal activation:
In response to reduced cardiac output, the body activates compensatory mechanisms such as RAAS and the sympathetic nervous system.
These mechanisms initially help maintain blood pressure and perfusion but eventually contribute to further myocardial damage and heart failure progression.
4) Haemodynamic changes:
The dilated ventricles lead to increased end-diastolic volumes and pressures, causing pulmonary congestion and systemic venous congestion.
This results in symptoms, such as dyspnoea, fatigue, and peripheral oedema.
5) Arrhythmias:
The structural and electrical remodelling of the heart increases the risk of arrhythmias, including atrial fibrillation and ventricular tachycardia.
These arrhythmias can further compromise cardiac function and increase the risk of sudden cardiac death.
Causes of DCM.
- Ischaemic heart disease
- Chronic hypertension.
- Infections: viral myocarditis, HIV, Lyme disease e.t.c.
- Toxins: alcohol abuse, cocaine, meth, and chemotherapeutic agents (e.g., doxorubicin, daunorubicin). Heavy metals like cobalt can also cause DCM.
- Metabolic disorders:
>Thyroid disease: both hypo- and hyper-.
>Diabetes mellitus (especially poorly-controlled diabetes mellitus). - Autoimmune diseases: e.g., polymyositis.
- Peripartum cardiomyopathy: pregnancy-related DCM can develop in women during the last month of pregnancy or within five months postpartum.
- Idiopathic: in many cases, the exact cause is unclear.
What is the most common cause of dilated cardiomyopathy?
Ischaemic heart disease (50-60% of cases).
Treatment of DCM.
Pharmacological therapy:
ACEi and ARBs: first-line therapy to reduce afterload and improve symptoms.
Beta-blockers.
Mineralocorticoid antagonists: for further symptom control and mortality reduction.
Diuretics: used to manage fluid overload.
Anticoagulants: recommended for patients with AF or other risk factors for thromboembolism.
Device therapy:
ICD.
Cardiac resynchronisation therapy (CRT) for patients with heart failure and evidence of dyssynchrony on ECG.
Invasive procedures:
LVAD as a bridge to transplant or destination therapy in patients with advanced heart failure.
Heart transplantation.
