Abstract & Commentary
Synopsis: Tissue Doppler echocardiography can distinguish between constrictive pericarditis and restrictive cardiomyopathy.
Source: Ha JW, et al. Am J Cardiol. 2004;94:316-319.
Theoretical considerations and anecdotal experience suggest that tissue Doppler echocardiography (TDE) early septal mitral annular velocity (E1) is a relatively load independent measure of left ventricular (LV) relaxation, and accordingly, may be able to differentiate between restrictive cardiomyopathy, where relaxation is abnormal, and constrictive pericarditis, where it is expected to be normal. Thus, Ha and colleagues from the Mayo Clinic studied 75 patients, 38 of whom had biopsy proven cardiac amyloidosis, 23 had surgically confirmed constrictive pericarditis, and 14 had primary restrictive cardiomyopathy by clinical and echo parameters. E1 was significantly higher in those with constrictive pericarditis vs those with restrictive cardiomyopathy or amyloidosis (12.3 vs 5.1 cm/s, P < .001). An E1 > 8 cm/s had a 95% sensitivity and a 96% specificity for constrictive pericarditis. There was no overlap in E1 between constrictive pericarditis and cardiac amyloidosis patients.
The E1 in patients with cardiac amyloidosis was significantly lower than those with primary restrictive cardiomyopathy (4.6 vs 6.3 cm/s, P < .001). Also, left ventricular wall thickness was higher in patients with amyloidosis. Left atrial size and cardiac index were higher in patients with restrictive cardiomyopathy. Ha et al concluded that E1 by TDE can distinguish between constrictive pericarditis and restrictive cardiomyopathy.
Comment by Michael H. Crawford, MD
This study demonstrates that there are characteristic Doppler echo findings in these 3 entities that exhibit restricted left ventricular filling. Constrictive pericarditis has an E1 that is increased ³ 8 cm/s; in restrictive cardiomyopathy atrial size is enlarged, and in cardiac amyloidosis wall thickness is increased. Of these, E1 had the greatest discriminatory accuracy. Thus, if restricted left ventricular filling is shown on echo, TDE E1 will help identify those with constrictive pericarditis, which is potentially curable with surgery.
I usually recommend CT or MRI confirmation of increased pericarditis thickness before recommending surgery. Recently, Ha et al have shown that in up to 20% of patients with constrictive pericarditis, pericardial thickness is normal. However, these are usually early cases or those with effusive constrictive disease, many of whom will improve significantly without surgery. Amyloidosis is usually obvious clinically with the thickened sparkling left ventricular walls on echo and low voltage QRS complexes on ECG. Restrictive cardiomyopathy usually shows large atria and normal sized ventricles, but hemodynamic measures may be similar to those of constrictive pericarditis. Perhaps the most useful catheterization sign of constrictive pericarditis is respirophasic discordance in right and left ventricular pressures, which is usually not seen in restrictive cardiomyopathy. Based on this study, if cardiac catheterization is not desirable, E1 and a complete echo Doppler examination may be highly accurate for distinguishing constrictive pericarditis from restrictive cardiomyopathy.
Dr. Crawford, Professor of Medicine, Associate Chief of Cardiology for Clinical Programs University of California San Francisco, is Editor of Clinical Cardiology Alert.