Heart
Cardiomyopathies
Idiopathic restrictive cardiomyopathy

Authors: Saranya Singaravel DCP, DNB (see Authors page)

Revised: 15 November 2016, last major update November 2016

Copyright: (c) 2016, PathologyOutlines.com, Inc.

PubMed Search: idiopathic restrictive cardiomyopathy
Cite this page: Idiopathic restrictive cardiomyopathy. PathologyOutlines.com website. http://pathologyoutlines.com/topic/heartidiopathicrestrictive.html. Accessed May 29th, 2017.
Definition / general
  • Rare heart muscle disease with altered hemodynamic pattern and myocardial compliance, resulting in a restrictive filling pattern and diastolic ventricular dysfunction with normal or near normal systolic function and ventricular wall thickness
  • Abnormal morphology may or may not be present
  • It is a diagnosis of exclusion and no evidence of infiltrative, pericardial or endocardial disease should be present
  • Accounts for 3% - 5% of cardiomyopathies
Essential features
  • Restrictive filling pattern
  • Mutations in sarcomeric protein genes
  • Diagnosis of exclusion



Terminology
  • Also known as primary restrictive cardiomyopathy
Epidemiology
  • Restrictive cardiomyopathy is the least common type of cardiomyopathy
  • Exact prevalence is not known
  • Slightly more common in women (F:M ratio, 1.5:1)
  • More common in adults but can occur in any age group
  • Prognosis is particularly poor in children and two year survival is less than 50%
Pathophysiology
  • Mutations in sarcomeric proteins such as cTnI (a troponin subunit) increase the Ca2+ sensitivity of cardiac myofilaments, increasing the contractility and producing diastolic dysfunction
Etiology
  • Etiology of primary restrictive cardiomyopathy is not clear
  • Mutations have been identified in the sarcomeric protein genes such as cardiac troponin I, troponin T2, beta myosin heavy chain and alpha cardiac actin
  • Autosomal dominant inheritance pattern is seen
  • Familial cases have been documented
  • Cases of restrictive and hypertrophic cardiomyopathy have been seen in the same family and may represent 2 different phenotypes of the same basic sarcomeric disease
  • Mutations in the desmin gene have also been identified - restrictive phenotype is typically accompanied by atrioventricular blocks
Clinical features
  • Most common presentation is congestive heart failure and patients may require transplantation
  • Atrial fibrillation is very common; also elevated systemic and pulmonary venous pressures
  • Jugular venous pressure may be increased
  • Left ventricular impulse is usually normal and palpable
  • Third heart sound may be audible due to rapid ventricular filling
  • Systolic murmurs of mitral and tricuspid regurgitation may also be auscultated
Diagnosis
  • Diagnostic right and left heart catheterization is an important diagnostic modality
  • Pressures in all the chambers and cardiac output are measured according to the Fick method
  • Dip plateau morphology in the LV diastolic pressure tracing is characteristic
  • ECG is invariably abnormal but is nonspecific
  • Predominant rhythm is atrial fibrillation with premature beats and conduction delay
  • QRS voltage is normal
Laboratory
  • Diagnosis can be established on right ventricular endomyocardial biopsy
  • One biopsy fragment may be fixed in glutaraldehyde for electron microscopic evaluation
Radiology description
  • Biatrial enlargement with pulmonary venous congestion and pleural effusions
Radiology images
Images hosted on other servers:

Echocardiographic morphological
features typical of idiopathic RCM

Case reports
Treatment
  • Heart failure is managed medically
  • In cases with atrial fibrillation, antiarrythmics are useful
  • In severe cases, heart transplant may be considered
Gross description
  • Gross examination of the heart shows biatrial dilatation due to increased filling pressures
  • Ventricles are relatively normal sized
  • Ventricular cavity is normal
  • Ventricular wall is abnormal, with a rubbery texture
  • Thickening of the endocardium may be observed
Gross images
Images hosted on other servers:

Left: gross speci-
men demonstrating
prominent biatrial
enlargement

Note the small left ventricle and huge left atrium

Microscopic (histologic) description
  • Microscopic changes are nonspecific and include myocyte hypertrophy, focal or diffuse perimyocytic fibrosis and focal myofiber disarray
Microscopic (histologic) images
Images hosted on other servers:

Right: light
microscopy
showing marked
interstitial fibrosis

Right: histology of
myocardium showing
myocyte disarray and
interstitial fibrosis

Absence of endocardial thickening
along with presence of myocyte
hypertrophy and interstitial fibrosis

Positive stains
Electron microscopy description
  • Diffuse fibrosis of the perimyocyte produces a characteristic lattice of collagen surrounding every myocyte
  • Patients with desmin cardiomyopathy show granulofilamentous intracytoplasmic material
Differential diagnosis
  • Constrictive pericarditis (J Am Coll Cardiol 2016;67:2061)
  • Obliterative endomyocardial disease
  • Specific cardiomyopathies such as amyloidosis and hemochromatosis
Additional references