Doppler echocardiography distinguishes between physiologic and pathologic "silent" mitral regurgitation in patients with rheumatic fever.

Background: The diagnosis of rheumatic fever is based on physical findings (major) and supporting laboratory evidence (minor) as defined by the Jones criteria. Rheumatic carditis is characterized by auscultation of a mitral regurgitant murmur. Doppler echocardiography, however, may detect mitral regurgitation when there is no murmur ("silent" mitral regurgitation), even in normal individuals.

Hypothesis: The hypothesis of this study was that physiologic mitral regurgitation can be differentiated from pathologic "silent" mitral regurgitation by Doppler echocardiography.

Methods: The study group consisted of 68 patients (2-27 years) with normal two-dimensional imaging and Doppler evidence of mitral regurgitation but no murmur. Patients with rheumatic fever (n = 37) met Jones criteria (chorea in 20, arthritis in 17). Patients without rheumatic fever (n = 31) were referred for innocent murmur (n = 7), abnormal electrocardiogram (n = 13), and chest pain (n = 11). Echoes were independently reviewed by two cardiologists blinded to the diagnosis. Pathologic mitral regurgitation was defined as meeting the following four criteria: (1) length of color jet > 1 cm, (2) color jet identified in at least two planes, (3) mosaic color jet, and (4) persistence of the jet throughout systole. Jet orientation was also noted.

Results: Using the above criteria, there was agreement in echo interpretation of pathologic versus physiologic mitral regurgitation in 67 of 68 patients (interobserver variability of 1.5%). Pathologic regurgitation was found in 25 (68%) patients with rheumatic fever but in only 2 (6.5%) patients without rheumatic fever (p < 0.001). The specificity of Doppler for detecting pathologic regurgitation was 94% with a positive predictive value of 93%. The color mitral regurgitant jet was posteriorly directed in all 25 patients with rheumatic fever.

Conclusion: Pathologic "silent" mitral regurgitation of rheumatic fever can be distinguished from physiologic mitral regurgitation using strict Doppler criteria, particularly when the jet is directed posteriorly. These data support the use of Doppler echocardiography as a minor criterion for evaluating patients with suspected rheumatic fever.