HOCM

Question 1

What are the clinical signs of HOCM? (8)

Answer 1

1. Jerky +/- biphasic pulse
2. Double carotid impulse (in NSR)
3. +/- large ‘a’ wave in VP
4. Heaving, non-displaced apex beat with double apical impulse (overloaded LV)
5. S1S2, with S4 (only in NSR)
   5A. Reverse splitting of S2 (severe prolonged LV ejection time)
6. Two different murmurs:
   - ESM over left sternal edge, radiates throughout, sternal and suprasternal, but does not radiate to neck (outflow tract obstruction)
   - Harsh, late peaking
   - PSM over apex radiates to axilla (systolic anterior motion of mitral valve)
   - Murmur accentuated by valsalva maneuver, standing; reduced on squatting and exercise
7. Complications signs:
   - Congestive heart failure
   - Pulmonary hypertension
   - Peripheral signs of IE
8. Features of Friedrichs ataxia or myotonic dystrophy

Question 2

How would you investigate a patient with HOCM?
(basic 3 + further investigations)

Answer 2

1. ECG
   - Left ventricular hypertrophy with deep TWI
   - LA dilatation (biphasic or negative P in V1-2)
   - Q wave in inferior and lateral leads
   - AF
   - LAD
2. CXR: usually normal
   - Cardiomegaly in late stage
   - LAH (double right heart border)
   - Pulmonary congestion
3. TTE
   - LVH
   - Asymmetrical septal hypertrophy
   - Systolic anterior motion of anterior MV leaflet
   - Dynamic LV outflow obstruction
   - Diastolic +/- systolic dysfunction
   - Severe: septal thickness >18mm, outflow tract gradient > 40mmHg at rest
4. Exercise treadmill
   - Poor BP response in exercise
   - Inducible arrhythmias
   - Ischaemia
5. Cardiac MRI - anatomical
6. Holter monitoring - arrhythmias
7. Cardiac catherisation - coronary anatomy, endomyocardial biopsy
8. Genetic testing and familial screening

Question 3

How would you manage a patient with HOCM?

Answer 3

1. Education and counselling, screening of 1st degree relatives
2. Asymptomatic:
   - Avoidance of strenuous excercise and vasodilators.
   - No outflow obstruction -> no therapy needed
   - If outflow obstruction present -> beta blockers
3. Medical therapy in symptomatic

• Beta blockers +/- disopyramide, alternative verapamil
  (caution: verapamil may increase death risk first few doses)
  > Reduces HR, enhance diastolic filling, decreasing contractility
• Diuretics for congestive heart failure
• ACEi, spironolactone, digoxin in end stage heart failure

4. Prevention of sudden death: ICD dual chamber, amiodarone
5. Surgery: alcohol septal ablation, myomectomy (gold standard)
   - Cardiac transplantation in refractory cases

Question 4

What is the prognosis of HOCM?
What are the poor prognostic factors of HOCM?
- Age, symptoms, investigations

Answer 4

Annual mortality rate is 2.5%

Poor prognostic factors:
1. Young age at diagnosis
2. Syncope or cardiac arrest
3. BP drop during exercise
4. Family history of sudden death
5. TTE: LV septal thickness >30mm
6. Holter: NSVT
7. Genetic mutation: myosin binding protein C and troponin T

Question 5

What is HOCM?
(Latest term: hypertrophic cardiomyopathy with/without obstruction)

Answer 5

Genetic disorder - autosomal dominant, missense mutation in genes that encode proteins of cardiac sarcomere

Resulting in left ventricular hypertrophy develops in the absence of causative haemodynamic factor.

Variable penetrance and expression

Occurs in 1 in 500; male and female equal

Question 6

Pathophysiology of HOCM

Answer 6

1. Asymmetrical myocardial hypertrophy in absence of inciting hypertrophy stimuli
2. Interventricular septum hypertrophy, with systolic anterior mitral valve leaflet opposing the septum causing outflow tract gradient and obstruction

Question 7

What are the typical presentations of patients with HOCM? (symptoms)

Answer 7

1. Asymptomatic (majority)
2. Symptomatic
   - Angina, syncope, dyspnoea, palpitation
   - Complications: CCF, AF, IE, thromboembolism/stroke
   - Sudden death (VF) - annual mortality 1%
3. Family history of syncope or sudden death

Question 8

What are the causes of HOCM?

Answer 8

1. Familial (autosomal dominant)
2. Friedreich’s ataxia
3. Idiopathic

Question 9

What are the complications of HOCM? (6)

Answer 9

1. MR
2. IE
3. Angina and IHD
4. Heart failure (both systolic and diastolic)
5. Arrhythmias - AF, VT, VF
6. Sudden death

Question 10

Why is there double apical impulse in HOCM?
What other condition is associated with double apical impulse?
When does double apical impulse disappear?

Answer 10

1. LV heave
2. Prominent presystolic pulse from atrial contraction

Differential: LV aneurysm

Double apical impulse can only be felt in sinus rhythm. Disappears in AF

Question 11

Why is there a prominent “a” wave in HOCM?

Answer 11

Forceful atrial contraction against non-compliant right ventricle

(RV may also be involved in HOCM)

Question 12

What is Brockenbrough
-Braunwauld-Morrow sign?

Answer 12

Paradoxical reduced pulse pressure with increased left ventricular systolic pressure in post-extrasystolic beat (PVC)

Occurs in HOCM and AS

Question 13

What disease conditions are associated with HOCM?
(M: FFWH)

Answer 13

1. Friedreich’s ataxia
2. Fabry’s disease
3. WPW syndrome
4. Hereditary lentiginosis

Question 14

How do you counsel family members and offer screening?

Answer 14

1st degree relatives - 50% affected (autosomal dominant)

Screening: ECG and TTE
- Annual for adolescents (12-18 years old)
- 5-yearly in adults

Question 15

What are the manoeuvers that accentuates, and those that diminishes HOCM murmur?

Answer 15

Accentuates
1. Valsalva - reduces LV volume on straining -> louder
2. Standing - reduces venous return -> louder

Diminishes
1. Squatting - increases venous return, increases LV size thus reducing obstruction -> softer
2. Isometric exercise - increases afterload, increases LV size -> softer