Transcript HYPERTROPHIC CARDIOMYOPATHY

HYPERTROPHIC
CARDIOMYOPATHY
Anthony B. King Jr., M.D., F.P.C.C
Cardiac Pacing and
Electrophysiology
Hypertrophic Cardiomyopathy (HCM)
• First described in 1950s
• Inappropriate myocardial hypertrophy in absence of
obvious cause of LVH
• Often the IVS of nondilated LV with hyperdynamic
systolic function
• If there is dynamic pressure gradient in subaortic
area – HOCM (only ¼)
• Abnormal stiffness of LV and impaired filling
(diastolic dysfunction) – high LVEDP > pulmonary
congestion and dyspnea (most common)
HCM
• Overall Prevalence is Low
• 0.2% (1/500) of general population and
in 0.5% of unselected patients referred
for an Echo
• It may be the most common genetically
transmitted cardiac disorder
HCM: Pathology
Macroscopic :
• Marked increase in myocardial mass
• LV cavities are small
• LV> RV
• Atria dilated, often hypertrophied
• Diastolic Dysfunction
• Mitral Regurgitation
Pathological classification of cardiomyopathies
Hypertrophic
Cardiomyopathy
~ all inherited
Normal
Dilated
Cardiomyopathy
~1/3 inherited
viral
toxins
endocrine
HCM:Pattern and Extent of LVH
• Vary from patient to patient, heterogeneity in
amount of LVH in different regions
• Most frequent – ASH, disproportionate
hypertrophy of septum and anterolateral wall
• 30% localized and mild hypertrophy in single
region
• Some in unusual location (posterior portion of
septum, posterobasal free wall and
midventricular)
• Hypertrophy is dynamic, may be seen in infants
but usually develops during adolescence
Apical Cardiomyopathy (ACM)
• Variant with predominant involvement of
Apex
• Common in Japan, ½ of HCM in Japan
• Spadelike configuration during LV angio
• Giant negative T wave in precordial leads
• Absence of gradient, mild symptoms and
benign course
HCM: Histology
• Myocardial hypertrophy and gross disorganization
of muscle bundles – whorled patterns,
abnormalities in cell-to-cell arrangement (disarray)
• Fibrosis, may be extensive –visible scars
• All all HCM have some disarray and most have
involvement of 5% or more of myocardium
• Abnormal intramural coronary arteries with small
lumen size and thickening of vessel wall (.80%) –
may be responsible for myocardial ischemia
Histologic section to show the characteristic myofibre
disarray in addition to hypertrophy in hypertrophic
cardiomyopathy.
HCM: ETIOLOGY
• Autosomal dominant in at least 50%
• Sporadic forms – in some if not all are
due to spontaneous mutation
• Genetic testing not yet easily available
and remains largely a research tool
HCM: Pathophysiology
• SYSTOLE
• DIASTOLE
• MYOCARDIAL ISCHEMIA
HCM
SYSTOLE:
• Dynamic pressure gradient across the LV
outflow tract
A. Small outflow tract – septal hypertrophy
and possible abnormal location of MV
B. SAM or systolic anterior motion of MV
leaflets against septum (venturi effect)
HCM
DIASTOLE
• Diastolic dysfunction rest or stress, whether
with gradient or none, whether symptomatic or
not
• Independent of extent and distribution of LVH
• Increased filling pressure due to poor LV
relaxation and distensability
• Fibrosis and cellular disorganization – less
distensable
HCM
MYOCARDIAL ISCHEMIA
• Increased muscle mass
• Inadequate capillary density
• Elevated diastolic filling pressure
• Abnormal intramural coronary arteries
• Impaired vasodilatory reserve
• Systolic compression of arteries
• Enhanced myocardial O2 demand (increased
wall stress)
HCM: Symptoms
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Very variable
Majority are asymptomatic or just mild
SCD – may be first clinical manifestation
Syncope and SCD in competitive sports
Usually in children, higher mortality in young
In elderly – mild LVH, frequently with outflow
gradients and marked symptoms late in life (after
55)
• More in men but women more severely disabled
HCM: Symptoms
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Dyspnea – increased pulm venous pressure
Angina (75%)
Fatigue, presyncope, syncope – common
Palpitations, PNC, overt CHF and dizziness –
less common
• Severe CHF culminating in Death
• Exacerbated by exertion
ANGINA
• 20% have concurrent CAD
• AMI may occur in absence of narrowing of
extramural arteries
SYNCOPE
• Inadequate CO – outflow gradient or ischemia
• Arrhythmias – SVT (AF) or VT
• In young with VT on Holter – increased risk for
SCD
• In elderly – not an ominous finding
HCM: PE
• May be normal in asymptomatic w/o gradient
(ACM)
• LV lift and S4
• Displaced apex beat, forceful and diffuse
• Prominent A wave
• Harsh systolic murmur, crescendo-decrescendo,
b/w apex and left sternum
• Holosystolic if with MR
• Murmur augmented by Valsalva, standing,
exercise, nitrates
HCM: ECG
• Usually abnormal
• Normal in 15-25% (localized LVH)
• ST and T abnormalities with LVH – most
common
• QRS complex tallest in midprecordium
• Prominent Q waves (20-50%) – inferior and
precordial (mimic AMI)
• Abnormal axis, P wave abnormality
• WPW – uncommon
• Abnormal AV conduction (BBB, AVB)
HCM: ECHOCARDIOGRAPHY
• Most widely used in evaluation of HCM
• Useful in suspected HCM and screening of
relatives
• Useful in identifying and quantifying
morphologic features (distribution of septal
hypertrophy), functional aspects
(hypercontractile state), hemodynamic findings
(outflow gradient)
HCM: Radionuclide Scanning
• Reversible thallium defects, indicative of
ischemia, common in HCM in absence of
obstructive CAD
• Seen in young patient with history of
syncope and SCD- probable mechanism of
demise in this patients
HCM: Cardiac Catheterization
• Not required for diagnosis
• Reserved when CAD considered or when
invasive modalities considered (DDD pacing,
surgery)
• Phasic narrowing and assoc abnormalities of
flow during systole in LAD and septal
perforators
• LV angio – spadelike deformity, virtual
obliteration of cavity at end systole
• Determine amount of outflow gradient
HCM: Arrhythmias and Holter
• Most common cause of SCD
• Poorly tolerated due to systolic and diastolic
dysfunction
• VA common (>3/4) on Holter
• NSVT – ¼ , SuVT – uncommon
• Overall predictive value is limited
• SupraVT ¼ to ½. AF (10%)
SAECG, HRV – less useful in risk
stratification
EPS – role in identifying high risk for SCD
is controversial and possibly limited
value
Tilt Table Testing – limited value
CXR – findings are variable, from normal
to marked cardiomegaly
HCM: Natural History
• In many asymptomatic or mild which improve
in 5-10 years
• Annual mortality –3% in large referral centers,
1% when all patients included
• SCD higher in children –6%/year
• Clinical deterioration – SLOW
• % of severely symptomatic inc with AGE
HCM: Natural History
• Onset of AF – increase in symptoms
• Progression to LV Dilatation (DCM) 10-15% those with marked septal hypertrophy and has
poor prognosis
• Due to wall thinning and scarring from
ISCHEMIA
• In some children, findings of HCM on Echo
may develop despite a previous normal Echo
(not common in Adults)
Marked LVH
Small Vessel Disease
Functional Alterations
Myocardial Ischemia
Cell death
Replacement Fibrosis
Wall thinning
Cavity enlargement
LV Remodelling
Systolic Dysfunction
Progressive/
refractory CHF
HCM:SCD
“Death is most often sudden in HCM and may
occur in previously asymptomatic patients, in
individuals who were unaware they had the
disease, and in patients with otherwise stable
course.”
• Most common abnormality found in autopsy in
young competitive athletes with SCD.
HCM: SUDDEN CARDIAC DEATH (SCD)
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HIGH RISK
Young age (<30) at diagnosis
FH of HCM with SCD (malignant FH)
Abnormal BP response to exercise
Genetic abnormalities assoc with inc SCD
Hx of Syncope in children
NSVT on 48 Hour Holter
Massive LVH
Brady and disease of AV conduction may play a
role
HCM: Management
• Alleviation of symptoms, prevent complications and
reduction in death.
• No data on asymptomatic patients
• Avoid digitalis unless with AF or CHF
• Cautious diuretic therapy
• Mainstay: Bblockers, alternate: CCB or Both
• Vast majority – only medical, 5-10% require
invasive intervention
• Others: Disopyramide, Amio, Sotalol
• Anticoagulation in AF, Endocarditis Prophylaxis
HCM: Management
INTERVENTIONS:
1. DDD Pacemaker
2. Septal Ablation
3. Surgical – Myectomy, MV Replacement
4. AICD
5. Cardiac Transplantation
HCM: Indications for Pacing
(ACC/AHA Guidelines)
Class I – for sinus node dysfunction or AVB
Class II a – None
Class II b
1. Medically refractory, symptomatic HCM with
significant resting or provoked LV outflow tract
obstruction (evid: C)
Class III
1. Asymptomatic or medically controlled
2. Symptomatic but w/o evid of LV outflow
obstruction
o
ICD experience in HCM
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