1. HYPERTROPHIC CARDIOMYOPATHY
Anthony B. King Jr., M.D., F.P.C.C
Cardiac Pacing and Electrophysiology

2. 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)

6. 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

7. HCM: Pathology Macroscopic : Marked increase in myocardial mass
LV cavities are small
LV> RV
Atria dilated, often hypertrophied
Diastolic Dysfunction
Mitral Regurgitation

9. 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

10. 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

13. 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

14. Histologic section to show the characteristic myofibre disarray in addition to hypertrophy in hypertrophic cardiomyopathy.

15. 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

16. HCM: Pathophysiology
SYSTOLE
DIASTOLE
MYOCARDIAL ISCHEMIA

17. 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)

18. 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

19. 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)

20. HCM: Symptoms 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

21. HCM: Symptoms 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

22. 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

23. 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

24. 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)

25. 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)

27. 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

28. 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

29. 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%)

30. 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

31. 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

32. 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)

34. 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.

35. HCM: SUDDEN CARDIAC DEATH (SCD)
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
8. Brady and disease of AV conduction may play a role

36. 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

37. HCM: Management INTERVENTIONS: DDD Pacemaker Septal Ablation
Surgical – Myectomy, MV Replacement
AICD
Cardiac Transplantation

38. 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

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