Cardiology > Restrictive Cardiomyopathy

Background

Restrictive cardiomyopathy (RCM) is a myocardial disorder characterized by impaired ventricular filling due to decreased myocardial compliance, while systolic function is typically preserved. The stiff ventricular walls resist diastolic filling, leading to elevated atrial pressures, atrial enlargement, and signs of systemic and pulmonary congestion despite normal or near-normal ejection fraction. 

II) Classification/Types 

By Etiology: 

• • Primary (Idiopathic): No identifiable cause 

• • Secondary (Infiltrative/Systemic): 

• • • Amyloidosis (most common in the U.S.) 

• • • Sarcoidosis 

• • • Hemochromatosis 

• • • Fabry disease 

• • • Endomyocardial fibrosis 

• • • Radiation or chemotherapy-induced myocardial fibrosis 

By Distribution: 

• • Isolated left ventricular involvement 

• • Bi-ventricular restrictive physiology 

By Histopathology: 

• • Infiltrative (e.g., amyloid, sarcoid, hemochromatosis) 

• • Non-infiltrative (e.g., idiopathic, radiation, post-surgical scarring) 

III) Pathophysiology 

Restrictive cardiomyopathy is marked by reduced ventricular compliance due to infiltration or fibrosis of the myocardium. This impairs diastolic filling, elevates atrial and pulmonary venous pressures, and causes atrial dilation. Despite preserved systolic function early on, cardiac output decreases due to poor ventricular filling. Chronically, this leads to pulmonary congestion, systemic venous hypertension, and eventually, symptoms of right and left heart failure. 

IV) Epidemiology 

• • Sex: Varies by etiology (e.g., amyloidosis more common in men) 

• • Age: Most forms manifest in middle-aged to older adults 

• • Geography: Endomyocardial fibrosis prevalent in tropical regions; amyloidosis and hemochromatosis more frequent in high-income countries 

• • Comorbidities: Associated with plasma cell dyscrasias, sarcoidosis, iron overload disorders, radiation therapy, and chronic inflammatory diseases 

Etiology

I) Causes 

• • Infiltrative diseases: Amyloidosis, sarcoidosis, hemochromatosis 

• • Storage diseases: Fabry disease, glycogen storage disease 

• • Non-infiltrative: Idiopathic, scleroderma, radiation fibrosis 

• • Endomyocardial diseases: Endomyocardial fibrosis, hypereosinophilic syndrome 

• • Post-radiation or post-chemotherapy myocardial fibrosis 

II) Risk Factors 

• • Plasma cell dyscrasias (e.g., multiple myeloma) 

• • Chronic granulomatous or inflammatory diseases 

• • History of chest irradiation or chemotherapy 

• • Genetic predisposition (e.g., familial amyloidosis, Fabry disease) 

• • Iron overload states (e.g., thalassemia, frequent transfusions) 

Clinical Presentation

I) History (Symptoms) 

• • Progressive dyspnea, especially on exertion 

• • Fatigue 

• • Orthopnea and paroxysmal nocturnal dyspnea 

• • Peripheral edema 

• • Ascites 

• • Palpitations (from atrial fibrillation) 

• • Syncope (due to low output or arrhythmias) 

• • Symptoms of underlying systemic disease (e.g., neuropathy in amyloidosis) 

II) Physical Exam (Signs) 

Vital Signs: 

• • Normal or low blood pressure 

• • Narrow pulse pressure 

Cardiac Exam: 

• • S4 gallop (diastolic dysfunction) 

• • Jugular venous distention with prominent “y” descent 

• • Diminished apical impulse 

Pulmonary: 

• • Crackles or rales with pulmonary congestion 

Peripheral: 

• • Ascites, hepatomegaly 

• • Peripheral edema 

• • Kussmaul sign (JVP rises with inspiration) 

Differential Diagnosis (DDx)

• • Constrictive pericarditis (mimics RCM closely) 

• • Hypertrophic cardiomyopathy 

• • Dilated cardiomyopathy 

• • Heart failure with preserved ejection fraction (HFpEF) 

• • Cardiac tamponade 

• • Pulmonary hypertension 

• • Right-sided heart failure from chronic lung disease 

Diagnostic Tests

Initial Tests: 

Transthoracic Echocardiogram (TTE): 

• • Normal ventricular size and wall thickness 

• • Bi-atrial enlargement 

• • Diastolic dysfunction with restrictive filling pattern 

• • Preserved or mildly reduced LVEF 

Transesophageal Echo (TEE): 

• • Better visualization of valve and atrial structures 

• • Excludes thrombus in atrial appendages in atrial fibrillation 

Electrocardiogram (ECG): 

• • Low voltage (especially in amyloidosis) 

• • Atrial fibrillation or flutter 

• • Conduction delays (bundle branch block, AV block) 

Chest X-ray: 

• • Pulmonary congestion 

• • Mild cardiomegaly 

• • Pleural effusions 

BNP/NT-proBNP: 

• • Elevated, often disproportionate to LVEF 

Cardiac MRI: 

• • Key for tissue characterization (e.g., amyloid = global subendocardial late gadolinium enhancement) 

Endomyocardial Biopsy: 

• • Diagnostic in infiltrative diseases (amyloid, sarcoid) 

• • Usually guided by clinical suspicion and imaging 

Cardiac Catheterization: 

• • Confirms elevated diastolic pressures 

• • Helps differentiate from constrictive pericarditis by pressure tracing comparison 

Laboratory Workup: 

• • Serum and urine protein electrophoresis (amyloidosis) 

• • Ferritin and transferrin saturation (hemochromatosis) 

• • Genetic testing if familial cardiomyopathy suspected 

 
Treatment

I) Medical Management: 

Symptom Relief: 

• • Diuretics: For volume overload 

• • Salt and fluid restriction: Particularly in right-sided heart failure 

Rate and Rhythm Control: 

• • Beta-blockers or calcium channel blockers: For diastolic filling time 

• • Anticoagulation: For atrial fibrillation 

Targeted Therapies (Etiology-Specific): 

• • Amyloidosis: Tafamidis (ATTR), chemotherapy for AL amyloidosis 

• • Hemochromatosis: Phlebotomy, iron chelation 

• • Sarcoidosis: Corticosteroids or immunosuppressants 

• • Fabry disease: Enzyme replacement therapy 

Avoid: 

• • Digoxin (especially in amyloidosis—risk of toxicity) 

• • Vasodilators unless compelling indication 

II) Interventional/Surgical: 

• • Cardiac transplant: Reserved for end-stage disease without systemic involvement 

• • Implantable Cardioverter Defibrillator (ICD): In patients with ventricular arrhythmias or high sudden cardiac death risk 

Patient Education, Screening, Vaccines

• • Educate about the chronic and progressive nature of RCM 

• • Monitor for weight gain, dyspnea, edema as signs of decompensation 

• • Avoid dehydration and excessive salt 

• • Genetic counseling in familial cases 

• • Screen first-degree relatives in inherited forms 

Vaccinations: 

• • Influenza annually 

• • Pneumococcal vaccine 

• • COVID-19 vaccination 

Consults

• • Cardiology: All patients with suspected or confirmed RCM 

• • Electrophysiology: If atrial fibrillation or ventricular arrhythmias 

• • Genetics: For familial cardiomyopathies 

• • Hematology/Oncology: For amyloidosis or iron overload disorders 

• • Transplant Team: Evaluation in advanced heart failure 

• • Rheumatology or Immunology: If autoimmune or granulomatous etiology suspected 

Follow-Up

• • Echocardiogram: Every 6–12 months to assess diastolic function and chamber size 

• • Holter Monitor: If palpitations or arrhythmias suspected 

• • Laboratory Monitoring: Based on underlying etiology (e.g., serum light chains, ferritin) 

• • Adjust medications based on symptoms and renal function 

• • Frequent reassessment of transplant eligibility in progressive cases 

• • Emphasis on adherence and early reporting of symptoms