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7/31/2019 MicrosoftPowerPoint HCM Benson

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Hypertrophic CardiomyopathyWhat is it?

Lee Benson MD

The Hospital for Sick Children,Toronto


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Cardiomyopathies:

conditions in which the heart muscle is abnormal, in the absence ofapparent causes, such as valve disease, hypertension, coronary arterydisease..etc.The names are purely descriptive. There are 3 types of cardiomyopathy:

What is a Cardiomyopathy?

hypertrophic dilated restrictive


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Hypertrophic CardiomyopathyFirst described by the French & Germans

around 1900occurrence of 1 in 500, 1 in 1000 births


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a hypertrophied and non-dilated left ventricle in the

absence of another diseasesmall LV cavity, asymmetrical septal hypertrophy (ASH),

systolic anterior motion of the mitral valve leaflet (SAM)

myocardial disarray: affects relaxation, arrhythmias

intimal hyperplasia of intramural coronary arteries,

endothelial dysfunction, myocardial perfusion defects.

Hypertrophic Cardiomyopathy


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Normal Myocardial disarray


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Types of HCM


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Most common location: subaortic, septal & anterior wall.

Asymmetric hypertrophy (septum and anterior wall):~65%.

Concentric: ~35%.

Apical or lateral wall: ~10% (25% in Japan/Asia):

characteristic giant T-wave inversion laterally & spade-like

left ventricular cavity: more benign.

Patterns of hypertrophy


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Mitral

valve in

normal

position

Non obstructive


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Mitral valve

presses againstseptum

MR

Obstructive


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Symmetric

symmetric orconcentric


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Apical

Small

cavity

remains

Apical Hypertrophy


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Familial HCM disorder of the sarcomere, first reported by Seidman et

al in 1989

occurs as autosomal dominant in 50%

11 different genes on with >400 mutations1) beta-myosin heavy chain;

2) cardiac myosin-binding protein C;

3) cardiac troponin-T;

4) troponin I;5) alpha-tropomyosin;

6 & 7) essential & regulatory myosin light chains;

8) actin;

9) alpha-myosin heavy chain; 10) titin; &11) muscle LIM protein.


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Spirito NEJM 1997


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Pathophysiology of HCMDynamic LV outflow tract obstruction

Diastolic dysfunction (filling)

Myocardial ischemia

Mitral regurgitation

Arrhythmias


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Clinical presentation

Any ageLeading cause of sudden death in competitive

athletes

Triad: DOE, angina, presyncope/syncope.


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Clinical ManifestationAsymptomatic, echocardiographic finding

Symptomaticdyspnea

angina pectoris

fatigue, pre-syncope, syncopepalpitation, PND, CHF, dizziness less frequent

SCD


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Epidemiology and Cause-Specific

Outcome of HypertrophicCardiomyopathy in Children

Colan Circ 2007

PCMR: n=634 (109 familial) IHCM,407>1 year (64.2%) & 227 females

M=F F >1 at diagnosis


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Epidemiology and Cause-Specific

Outcome of HypertrophicCardiomyopathy in Children

Colan Circ 2007

HCM septal:posterior wall ratio ~1.4:1IHCM & familial HCM: no difference in regards to:

race, age at Dx, sex frequency or CHF or survival

CHF at diagnosis: 20.5% 1 year

SF not as enhanced 1 year


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Epidemiology Hypertrophic

Cardiomyopathy in Children

Colan Circ 2007

Outcomes

43 deaths: 30 1 year at time of diagnosis

mode of death: sudden in 8/18 1yearat time of Dx

Over all, IHCM alive after 1 year, had an annual mortality1.0/100 patient-years

1.1 & 0.7 per 100 patient-years for 1 year @ Dx.1 year 99.2% 1 year survival


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Epidemiology Hypertrophic

Cardiomyopathy in Children

Colan Circ 2007


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Sustained ventricular tachycardia & ventricularfibrillation: most likely mechanism of syncope/suddendeath.

Dependant on atrial kick: CO by 40% if atrialfibrillation present.

Arrhythmias


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Management

All first degree relatives: screening

echocardiography/genetic counseling

Avoid competitive athletics

Holter x 48 hours


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non-obstructive HCM: calcium channel antagonists & beta-blockers

obstructive HCM pharmacological treatment relies beta-blockers

& disopyramide initially

myectomy, alcohol ablation (adult) are alternative inyerventions in

the drug refractory patient

atrial fibrillation should be treated aggressively to minimise the

risks of thromboembolism

Symptomatic relief


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patients suffering prior cardiac arrest or sustained VT warrantprophylactic treatment

patients with 2 or more recognized risk factors warrant prophylaxis

patients with 1 risk factor require individualized decision making inrelation to the strength of the risk factor

effective prophylactic treatment includes the use of amiodaroneand/or ICD

clarification of the genotypephenotype relation in HCM may

ultimately assist decision making

Sudden death prophylaxisAll HCM patients should undergo risk stratification for sudden death


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Predictors of outcome at the time of diagnosis

S

urvival%

years

All-cause mortality

HSC

N=1201971 - 2006

Hazar

d:deaths/year

years

All-cause mortality: Hazard

Early phase risks:Higher baseline LVOT gradient

Late phase risks: No robust risks


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All-cause mortality stratified by baseline LVOT gradient

0 mmHg

50 mmHg

100 mmHg

Su

rvival%

Years after diagnosis


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Time-related risk of sudden death

Freedomf

rom

suddend

eath

Years after diagnosis

What is the risk of actually dying suddenly?

Predictors of SD: NONE!


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Recommendations for Athletic Activity

Avoid most competitive sports (whether or not

symptoms and/or outflow gradient are present)

Low-risk older patients (>30 yrs) may participate

in athletic activity if all of the following are

absent


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Recommendations for Athletic ActivityLow-risk older patients (>30 yrs) may participate in athletic activityif all of the following are absent:

VT on Holter monitoring

family history of sudden death due to HCMhistory of syncope or episode of impaired consciousness

severe hemdynamic abnormalities, gradient 50 mm Hg

exercise induced hypotensionmoderate or severe mitral regurgitation

enlarged left atrium (50 mm)

paroxysmal atrial fibrillation

abnormal myocardial perfusion


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HCM vs. Athletes HeartHCM Athlete

+ Unusual pattern of LVH -

+ LV cavity 55 mm +

+ LA enlargement -

+ Bizarre ECG paterns -+ Abnormal LV filling -

+ Female gender -

- thickness with deconditioning +

+ Family history of HCM -

Circulation 1995; 91:1596


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Ob t ti


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Mitral valve

presses againstseptum

MR

Obstructive


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with decreased preload, decreased afterload,

or increased contractility.Venturi effect: anterior mitral valve leaflets &

chordae sucked into outflow tract obstruction, eccentric jet of MR in mid-late

systole.

Left ventricular outflow tract gradient

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