Cardiomyopathies

Restrictive Cardiomyopathy (RCM)

• Infiltration or fibrosis of the myocardium causing impaired ventricular filling with preserved systolic function.
  • Reduced or normal diastolic ventricular cavity volume + stiff ventricular myocardium.
  • Causing high filling pressures with small amounts of volume.
  • Early in course biventricular systolic function is normal, but can deteriorate later in disease.
• Systolic function may diminish in end-stage disease
• Typical have RAPID early diastolic filling on echo (and JVP - Prominent x/y descents)
• NOTE: Constrictive pericarditis vs. restrictive cardiomyopathy --> RV and LV share same space in constrictive pericarditis.  Relative increase in filling of RV, which restricts LV filling and vice versa.  Look for this ventricular interaction on echo.
  • Also restrictive cardiomyopathy have higher BNP levels than constrictive pericarditis. (>800)
• Causes:
  • Infiltrative (rule these out!)
    • Amyoidosis
    • Sarcoidosis
    • Hemochromatosis
  • Non-Infiltrative
    • Scleroderma
    • Radiation
    • Fibrosis following cardiac surgery
    • Myocardial Storage Conditions
    • anthracyclines (doxorubicin, donorubicin)
• Symptoms:
  • Dyspnea, fatigue, peripheral edema
• Exam:
  • Elevated JVP (increases with inspiration - Kussmaul's Sign)
  • Normal LV impulse
  • If advanced: Heptosplenomegaly + Ascites
• DDx:
  • Hypertrophic cardiomyopathy, Dilated cardiomyopathy
  • Constrictive pericarditis: Clinical presentation and physical exam may yield findings identical to RCM.
    • MRI shows pericardial thickening(>5mm), and right heart catheterization demonstrates equalization of diastolic pressures in contrictive pericarditis.
• Diagnosis:

1. ECG Conduction System Disease Low QRS voltage Nonspecific ST-T wave changes Echocardiography Restrictive filling pattern (preserved systolic function) (If infiltrative, myocadium can look granular) Biatrial enlargement R-Heart Catheterization Dip & plateau vetnricular filling ("Square root sign") Pulmonary hypertension Respiratory concordance of ventricles Myocardial Biopsy Detects infiltrative disease (amyoidosis & sarcoidosis)

• Treatment
  • Treat underlying disease
  • Diuretics
    • Can improve symptoms, but hard b/c overdiuresis causes hypotension (preload dependence, no cardiac index)
  • B-Blockers & CCB
    • Can improve diastolic function early in disease. (slow heart rate & increase filling time)
    • Caution: can drop cardiac output
    • CCB: careful in amyloid (causes negative inotropy & conduction problems)
  • Cardiac transplant
    • If no systemic disease

Hypertrophic Cardiomyopathy (HCM)

• Autosomal-dominant disorder of myocardial structural proteins that causes premature, severe LVH
  • A subset of HCM can cause asymmetrical septal hypertrophy causing dynamic outflow tract obstruction (HOCM!)
• Symptoms:
  • Syncope, chest pain, dyspnea
• Exam:
  • If LVOT Obstruction:
    • Systolic crescendo-decrescendo murmur that
      • intensivies with reduction of LV volume (Standing, valsalva)
      • Decreases with increase LV volume (handgrip, raising legs when supine, stand to sit)
  • S4 and sustained apical impulse are characteristic
  • Carotid upstrokes bifid (mid-systolic obstruction)
• Treatment:
  • Agents that DECREASE LV VOLUME (preload) such as nitrates & diuretics increase LVOT obstruction --> contraindicated in HCM!
  •  

Amyoidosis

• Heart failure, hepatomegaly, proteinuria, bruising
• Low voltage ECG (despite increased wall thickness on echo)
• Diagnose with: sPEP, uPEP, abdominal fat pad or gingival biopsy
• Cardiac involvement = BAD prognosis

Sarcoidosis

• Patchy involvement of the myocardium (inflammation & fibrosis due to granuloma formation)
• Myocardium is not replaced or displaced hence ECG = normal!  (not low voltages like Amyoid)
• Systemic Symptoms:
  • Pulmonary Involvement
  • Skin involvement

Giant Cell Myocarditis

• Presents with heart failure & cardiogenic shock within several days (can be up to months) of onset.
  • Often refractory ventricular arrhythmias
• High mortality rate
• Does not have systemic symptoms (unlike amyloid)

Hemodynamics

Giant-Cell Myocarditis

• Form or acute myocarditis (often fatal), affecting those in 40's.
• Characterized by: rapid onset of fulminant heart failure (days-months).
• Refractory ventricular arrhythmias are common.
• Mechanism unknown, thought to be autoimmune.  
• Treatment:
  • Immunosuppressives (steroids etc..) do not change outcomes.
  • Often need mechanical support or transplant.

HCM Mimics

• Athlete's Heart
  • Athlete is elitely trained in exercise with aerobic and anaerobic demands develops LVH.
  • Lesser degree of hypertrophy (<15mm of any wall thickness), cavity volume enlarged due to high volume state  (rather than reduced in HCM)...  Also no LA enlargement.
• Infiltrative causes (Sarcoid, Amyloid) --> often symmetric and concentric wall thickening (HCM is asymmetric)
  • Cardiac MRI or PET helps separate them from HCM (delayed hyper-enhancement).
• Fabrey's Disease (alpha-galactosidase enzyme deficiency)

Complications

• High risk of atrial fibrillation (need atrial kick), may precipirate heart failure and stroke.
• Some patients can progress to dilated CMTHY with impaired systolic function.
• Sudden death, heart failure, stroke.
• Sudden death is infrequent --> more common in young (15-35yo).
  • High risk if :
    • Prev cardiac arrest
    • VTach
    • 1st deg family member with sudden cardiac death with known HCM
    • Recurrent unexplained loss of consciousness (hard to separate from obstructive)
    • Extreme increased wall thickness (>30mm [normal <10mm])
    • Abnormal blunted BP response during exercise, if BP fails to rise during exercise.
    • NSVT (even if asymptomatic on ambulatory ECG).

Management

• Lifestyle changes
  • Level of exercise (Moderate level of exercise - not competitive or strenuous.  Avoid activities that require sudden intense bursts of energy such as full court basketball, soccer, football).  These are considered high risk for provoking sudden death.
• Medical therapy warranted if symptomatic.
  • Beta-Blockers - reduce HR, diastolic filling, LV contarctility, dynamic LVOT obstruction.
  • CCB (verapamil) - can use if don't tolerate BB
    • Do not combine with BB due to negative inotropy (severe bradycardia).
    • Vasodilatory effect can cause worse LVOT obstruction, severe symptoms.
  • Disopyramide
    • Very old antiarrhythmic.  
    • Very negative inotropic agent, used in addition to BB therapy.
    • Can prolong QT interval / QRS duration.  
• Avoid worsening outflow gradient
  • Exercissive diuresis, vasodilators, digoxin.
• Device therapy
  • Pacemaker
    • For those with bradycardia during medical titration
    • Not used to reduce LVOT obstruction.
  • ICD
    • All HCM patients should receive ICD regardless of presence of symptoms.
    • Primary prevention of sudden cardiac death for HCM and multiple RFs for sudden death.
    • Indicated for LV systolic dysfunction with LVEF <35%.
• Heart transplant
  • For refractory symptoms that cannot be managed medically 
    OR
  • Progressive systolic dysfunction
    OR
  • Refractory ventricular arrhythmias
• Atrial Fibrillation
  • Same rules for anticoagulation, but rhythm control may be preferred to maintain ventricular filling.
  • AFib ablation, amiodarone are options.
• Septal Reduction therapy
  • Reduce thickness of basal septum to reduce systolic anterior motion of mitral valves => greater forward flow / (stroke volume).  Very significant surgery!
  • Only for medically-refractory cases, and severe cases.
  • However, operativive mortality is quite low (<1%), improves symptoms, quite effective for LVOT.
  • NEW: Alcohol Septal Ablation
    • Catheter passed into septal perforator artery that supplies the hypertrophied part of ventricle with blood.
    • Alcohol injected into that area, causing therapeutic infarction.
    • Initially area remains thick, but over time will thin, reducing LVOT.
    • No trials comparing these two therapies.  
    • Concern about scar causing future arrhythmias.
• Genetic counselling. (autosomal dominant) --> screen family members.
  • Many genes in effect.  (Sarcomeric proteins).
  • Negative echo in family member does not rule out HCM...
    • 1st degree relatives should undergy q5y echo screening in adulthood to ensure no late-onset HCM.
    • In adolescence echo q1year.