Myocardial Disease

Question 1

Myocarditis describes inflammation of the myocardium. There are a wide range of underlying causes. It should be particularly considered in younger patients who present with chest pain.

What are the causes of myocarditis?

Answer 1

• Viral → coxsackie B / HIV
• Bacteria → diptheria / clostirida
• Spirochaetes → lyme disease
• Protozoa → Chagas’ disease / toxoplasmosis
• Autoimmune
• Drugs → doxorubicin

Question 2

What is the clinical presentation of myocarditis?

Answer 2

• Young patient usually, acute history
• Chest pain
• Dyspnoea
• Arrhythmias

Question 3

Which investigations are done for myocarditis?

Answer 3

• Raised inflammatory markers
• Raised cardiac enzymes
• Raised BNP

ECG → tachycardia / arrhythmias / ST/T wave changes including ST-segment elevation and T wave inversion

Question 4

What is the management of myocarditis?

Answer 4

• Treat underlying cause
• Supportive treatment

Question 5

What are complications of myocarditis (3)?

Answer 5

• Heart failure
• Arrhythmia → sudden death
• Dilated cardiomyopathy (late)

Question 6

The old classification of dilated, restricted and hypertrophic cardiomyopathy has been largely abandoned due to the high degree of overlap. The latest classification of cardiomyopathy by the WHO and American Heart Association reflect this.

What are the two main types of cardiomyopathies?

Answer 6

• Primary → predominantly involving heart
  
  • genetic, mixed or acquired
    ​
• Secondary → pathological myocardial involvement as part of a generalised systemic disorder

Question 7

The two genetic (primary) cardiomyopathies are HOCM and ARVD.

What are features of hypertrophic obstructive cardiomyopathy?

Answer 7

• Autosomal dominant
• Leading cause of sudden death in young athletes
• Due to mutation in gene encoding B-myosin heavy chain protein
• Echo → MR / systolic anterior motion (SAM) of anterior mitral valve / asymmetric septal hypertrophy
• Tx → implantable cardioverter-defibrilator

Question 8

What are the features of arrhythmogenic right ventricular dysplasia (ARVD)?

Answer 8

• Autosomal dominant (also genetic and primary type)
• Right ventricular myocardium replaced by fatty + fibrofatty tissue
• ~50% have mutation of one of several genes encoding desmosome
• ECG → abnormalities in V1-3 / T wave inversion
  
  • Epsilon wave found in 50% - terminal notch in QRS complex

Tx → implantable cardioverter-defibrilator

Question 9

Another primary subset is ‘mixed’, including both dilated and restrictive cardiomyopathies. This category servers as a reminder that many patients will have a genetic predisposition to cardiomyopathy which is then triggered by the secondary process, hence the ‘mixed’ category

What are classic causes of dilated cardiomyopathy?

Answer 9

• Alcohol
• Coxsackie B virus
• Wet beri beri
• Doxorubicin

Question 10

What are classic causes of restrictive cardiomyopathy?

Answer 10

• Amyloidosis
• Post-radiotherapy
• Loeffler’s endocarditis

Question 11

Finally in primary, there are two types of ‘acquired’ cardiomyopathies - peripartum and Takotsubo.

What are key features of peripartum cardiomyopathy?

Answer 11

• Typically develops between last month of pregnancy + 5 months post-partum
• More common = older women / greater parity / multiple gestations

Question 12

What are key features of Takotsubo cardiomyopathy?

Answer 12

• ‘Stress’-induced
• ‘Broken heart syndrome’
• Eg. pt found out family member dies then develops chest pain and features of heart failure
• Transient, apical ballooning of myocardium
• Treatment = supportive

Question 13

What are the secondary cardiomyopathies?

Answer 13