Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy .2-.5% of

population affected Left ventricular

hypertrophy with myocardial fiber disarray

Interstitial fibrosis

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Hypertrophic cardiomyopathy Familial (autosomal dominant) or sporadic

(50%) Abnormalities in sarcomere proteins

beta-myosin heavy chain (45%--chromosome 14) , cardiac myosin binding protein-C

D/D genotype for ACE alters phenotype with more hypertrophy

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Hypertrophic cardiomyopathy Distribution of hypertrophy

Asymmetric septal hypertrophy most common (septal/posterior wall thickness > 1.5)

Type 1: Hypertrophy anterior septum Type II : Hypertrophy of anterior and inferior

septum Type III: Extensive LVH with sparing of

posterior wall Type IV: Apical hypertrophy

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Hypertrophic cardiomyopathy: May have resting LVOT obstruction, latent obstruction or non-obstructive

Normal systolic function but increased afterload if LVOT obstruction

Dynamic outflow tract obstruction created by anterior motion of mitral leaflet during systole obstructing the outflow tract Venturi forces b/o septal hypertrophy Anterior papillary muscle displacement and abnormally

long anterior mitral leaflet Gradient worse with decreased preload, increased

contractility Primarily diastolic dysfunction

Decreased relaxation Increased stiffness

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Hypertrophic cardiomyopathy: Symptoms

May be asymptomatic Found on screening ECG, echocardiogram

Dyspnea: High LV diastolic pressure because of impaired LV relaxation and increased stiffness. High afterload if LVOT obstruction

Angina: Inadequate coronary arterial blood supply for degree of hypertrophy and increased demand

Syncope: Arrhythmias or hypotension secondary to LVOT obstruction

Palpitations—AF is common Sudden cardiac death: Ventricular fibrillation

Ischemia in HCM Myocardial bridging Impaired vasodilator reserve Decreased capillary density and increased

capillary separation Myocardial fibrosis Small vessel disease/microvascular

dysfunction

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Apical hypertrophic cardiomyopathy Apical segment >/=15 mm Good prognosis (95% survival at 15 years) Often need contrast echo or cardiac MR to

make diagnosis

Apical hypertrophic cardiomyopathy 1/3 of patients had complications—atrial

fibrillation, myocardial infarction, HF, TIA/stroke, VT/VF

May have mid cavitary obstruction and apical aneurysm

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Hypertrophic cardiomyopathy: Signs Spike and dome carotid pulse Triple ripple apical impulse Fourth heart sound (increased filling with

atrial contraction because of decreased LV relaxation)

Systolic ejection murmur of LV outflow tract obstruction Increases if decreased preload ie increases

with standing from squat Murmur of mitral regurgitation

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Hypertrophic cardiomyopathy: Diagnosis Echocardiogram shows left ventricular hypertrophy

in the absence of hypertension or aortic stenosis LVOT obstruction caused by mitral leaflet SAM Eccentric lateral jet of MR

ECG: Usually abnormal Left ventricular hypertrophy Abnormal Q waves

Family history/genetic testing Cardiac MR: LV/RV thickness, late gadolinium

enhancement

Increased wall thickness LVH for other reasons: hypertension, aortic

stenosis, athlete’s heart (< 14 mm) Sigmoid septum of the elderly Infiltrative : amyloidosis, hypereosinophilic

syndrome Children with HCM

Idiopathic (75%) Inborn errors of metabolism (Fabry, Danon disease) Malformation syndromes (Noonan’s) Neuromuscular disorders (Friedrich’s ataxia)

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Brockenbrough-Braunwald-Morrow signAfter a PVC, there is a decrease in carotid pulse pressure in patients with HOCM. Increased contractility results in increased LVOT obstruction.

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Hypertrophic Cardiomyopathy: Management Medical therapy for symptomatic dynamic

LVOT obstruction: Beta-blockers, verapamil, disopyramide

Interventions for symptomatic LVOT obstruction: septal myomectomy or septal alcohol ablation

Prevent death from ventricular arrhythmias: Assess all patients with HCM for SCD risk factors

Syncope, non-sustained VT, family history SCD, exercise induced hypotension, septum > 30mm (class IIA for ICD), gradient > 30 mm Hg, high risk mutations

Defibrillator if VF or sustained VT (class 1)

Septal myectomy 3-15 gm of septal muscle removed Indicated in severely symptomatic patients

with resting LVOT obstruction despite medical therapy

Dramatic improvement of symptoms Probable decrease in SCD rates Complications

VSD LBBB/CHB (5-10%) Aortic regurgitation

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Ethanol ablation: Complications CHB 10-25% RBBB Ventricular

arrhythmias Coronary

dissection Pericardial effusion Large MI

Best suited for older patients with comorbidities

Management of asymptomatic patient with HCM Screen first degree relatives with echo Assess for SCD risk with Holter and stress

test Avoid competitive sports. Avoid extreme

exertion and dehydration Annual F/U No endocarditis prophylaxis No beta-blocker if no symptoms Pregnancy well tolerated—50% chance of

affected child17

Patient with HCM and PAF Beta-blocker Disopyramide if LVOT obstruction Otherwise amiodarone or sotalol Anticoagulation

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Patient with HCM, NYHA class III, severe LVOT obstruction Beta-blocker Disopyramide 100 mg QID or 200 mg TID Surgical myectomy (preferred in younger

patients—90% long term symptom improvement)

Septal alcohol ablation—localized septal infarct

DDD pacing—no long term benefits

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Post-operative severe LVOT obstruction Volume expansion Avoid beta-agonists Phenyephrine iv metoprolol/esmolol

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