Diagnostic Considerations
All causes of diastolic dysfunction are included in the differential diagnosis of restrictive cardiomyopathy (RCM). The more common forms of heart failure with preserved ejection fraction are typically related to advanced age, diabetes, obesity, coronary artery disease (CAD), and left ventricular hypertrophy. Some specific characteristics may help distinguish RCM as a cause, such as low-normal blood pressure, younger age, elevated B-type natriuretic protein (BNP) that is out of proportion to the clinical presentation, persistent positive troponin in the absence of CAD, low voltage-mass ratio on electrocardiography (ECG), increased left ventricular mass, and pericardial effusion. The high prevalence of clinical overlap between RCM and other causes of heart failure, however, continue to make it a diagnostic challenge. [4, 20]
Differentiating RCM from constrictive pericarditis (CP) is imperative. Although RCM has no specific therapy, CP is potentially curable with surgical pericardectomy. [21] Both processes show reduced left ventricular chamber compliance, but RCM is caused by abnormal elastic properties of the myocardium, whereas CP is constrained externally by the pericardium. Myocardial relaxation is impaired in RCM, whereas it remains normal in CP. [13]
The etiology of RCM has been confused with that of CP because of the similarity of their presenting symptoms and diagnostic findings. With respect to their history and clinical profile, pericardial constriction and RCM are often indistinguishable. In addition, the two conditions can coexist in the same patient; for example, radiation therapy affects the myocardium as well as the pericardium. There are certain clinical features, however, that help to differentiate the two conditions (see Table 1 below).
Table 1. Clinical Features of Constrictive Pericarditis and Restrictive Cardiomyopathy (Open Table in a new window)
Clinical Features |
Constrictive Pericarditis |
Restrictive Cardiomyopathy |
History |
Prior history of pericarditis or condition that causes pericardial disease |
History of systemic disease (eg, amyloidosis, hemochromatosis) |
General examination |
… |
Peripheral stigmata of systemic disease |
Systemic examination - Heart sounds |
Pericardial knock, high-frequency sound |
Presence of loud diastolic filling sound S3, Low-frequency sound |
Murmurs |
No murmurs |
Murmurs of mitral and tricuspid insufficiency |
Prior chest radiograph |
Pericardial calcification |
Normal results of prior chest radiograph |
In the past, cardiac catheterization findings were not always conclusive, and the diagnosis of RCM was often made during surgery. Currently, as noninvasive imaging techniques continue to advance, the correct diagnosis can be strongly suggested by structural, mechanical, and hemodynamic findings on echocardiography and cardiac magnetic resonance imaging (CMRI). More advanced tissue tracking software allows myocardial functional data to be determined from both echocardiography and CMRI with equal ease and accuracy. Echocardiography and CMRI are comparable in their ability to differentiate RCM from CP. [22]
Echocardiographic findings consistent with RCM include normal or thickened right ventricular and left ventricular walls, normal or small left ventricular cavity size, and enlarged atria. Doppler ultrasonography shows a restrictive filling pattern of transmitral flow and reduced tissue Doppler peak early-diastolic mitral-annular velocities. In contrast, CP echocardiographic findings may show a plethoric (distended) inferior vena cava (IVC), abnormal septal wall motion, and respiratory variation of left ventricular inflow velocities. [22]
Other conditions to be considered include systemic hypertension, valvular aortic stenosis, and hypertrophic cardiomyopathy, all of which cause impaired diastolic distensibility secondary to left ventricular hypertrophy. The thickened left ventricle could be confused with amyloidosis on echocardiography, but the clinical findings are completely different. The final diagnosis of RCM is most commonly made on the basis of biopsy of fat tissue, such as abdominal wall fat.
Differential Diagnoses
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Restrictive cardiomyopathy. Axial double inversion-recovery magnetic resonance image of the heart in a 30-year-old woman with sarcoidosis demonstrates a normal pericardium.
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Restrictive cardiomyopathy. Axial contrast-enhanced computed tomography scan through the heart (same patient as in the previous image) shows a thin pericardium without calcification. Note the cardiophrenic and internal mammary lymph nodes. The patient had extensive mediastinal and hilar adenopathy, as well as interstitial lung changes.
Tables
Clinical Features |
Constrictive Pericarditis |
Restrictive Cardiomyopathy |
History |
Prior history of pericarditis or condition that causes pericardial disease |
History of systemic disease (eg, amyloidosis, hemochromatosis) |
General examination |
… |
Peripheral stigmata of systemic disease |
Systemic examination - Heart sounds |
Pericardial knock, high-frequency sound |
Presence of loud diastolic filling sound S3, Low-frequency sound |
Murmurs |
No murmurs |
Murmurs of mitral and tricuspid insufficiency |
Prior chest radiograph |
Pericardial calcification |
Normal results of prior chest radiograph |
Investigation |
Constrictive Pericarditis |
Restrictive Cardiomyopathy |
Chest radiograph |
Pericardial calcification |
Atrial dilation causing increased cardiothoracic ratio; normal ventricular size |
CT scanning/MRI |
Pericardial thickening |
No pericardial thickening |
Echocardiography |
Normal-sized ventricles and atria; pericardial effusion may be observed |
Nondilated, normally contracting, nonhypertrophied ventricles and marked dilation of both atria |
Doppler flow velocities on echocardiography |
Respiratory changes (ie, decreased peak transmitral diastolic flow) during inspiration; equalization of the right- and left-sided filling pressures |
No respiratory changes; greater elevation in the left-sided filling pressures |
Catheterization hemodynamics: 1) RVSP 2) RVEDP:RVSP ratio 3) RVEDP/LVEDP equalization |
1) = 50 mm Hg 2) = 0.33 3) = 5-mm Hg difference |
1) = 50 mm Hg 2) = 0.33 3) = 5-mm Hg difference |
Cardiac biopsy |
Normal myocardium |
Often diagnostic, showing abnormal myocardium |
CT = computed tomography; LVEDP = left ventricular end-diastolic pressure; MRI = magnetic resonance imaging; RVEDP = right ventricular end-diastolic pressure; RVSP = right ventricular systolic pressure. |
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