To differentiate restrictive cardiomypathy and constrictive pericarditis, features ouring constrictive pericarditis are-

Ref: Harrison's 19th E pg 1573 Table 288-2. Thickened pericardium seen in constrictive pericarditis. Because constrictive pericarditis can be corrected surgically, it is impoant to distinguish chronic constrictive pericarditis from restrictive cardiomyopathy, which has a similar physiologic abnormality (i.e., restriction of ventricular filling).