The right ventricle in mitral regurgitation: evaluation by electron beam tomography

Mitral valve regurgitation affects heart ventricle volumes, which can be accurately measured by electron beam tomography (EBT). Most studies have focused on the left ventricle, but findings have failed to resolve some crucial clinical issues. We reviewed EBT studies of 35 patients with moderate mitral valve regurgitation but no ischemia, aortic valve regurgitation, or left ventricular failure to investigate the relationship between right ventricle volumes and ejection fraction and extent of mitral regurgitation. EBT in cine mode was performed during exercise and at rest in 839 patients from 1990-1994. Sixty-one of these showed evidence of significant mitral regurgitation, 35 of whom met the criteria for inclusion in this study. Left and right end-diastolic and end-systolic volumes were computed from the scans, and ventricular stroke volumes, ejection fractions, regurgitant stroke volume, and regurgitant fraction were computed from these values. Correlation coefficients between ventricular values and regurgitant fraction were computed. Regurgitant fraction was significantly and negatively associated with the ejection fraction in the right ventricle (r = -0.55, p < 0.001) but not in the left. Ten of the 35 patients studied had right ventricular ejection fractions of less than 45%. In addition, there was evidence for a subgroup of cases with moderate amounts of regurgitation and dilation of the right ventricle. It is concluded that reduced right ventricular ejection fraction is a common finding in patients with mitral regurgitation without left ventricular failure. It is most commonly observed in cases with large regurgitant fraction and/or with a large right ventricular end-diastolic volume/left ventricular end-diastolic volume ratio. Identification of mitral regurgitation patients with reduced right ventricular ejection fraction may have clinical significance, indicating a sub-group of patients with more severe disease prior to the development of left ventricular dysfunction.