Rheumatic mitral stenosis vs radiation associated MS

Differences between rheumatic mitral stenosis and radiation associated MS

The hallmark of rheumatic mitral stenosis is commissural fusion while there is no commissural fusion in radiation associated mitral stenosis. Splitting of the fused commissures is an important mechanism of relief of obstruction by balloon mitral valvotomy in rheumatic mitral stenosis.

Another important differentiating point between rheumatic mitral stenosis vs radiation associated MS is that subvalvular apparatus is not affected with radiation associated MS while it is a feature of rheumatic mitral stenosis. There is chordal shortening and fusion as well as thickening of the valve leaflets in rheumatic MS.

In radiation induced mitral stenosis, there is severe mitral annular calcification as well as thickening and calcification of aortomitral continuity, sometimes extending into the anterior mitral leaflet. This is also called mitral aortic membrane or aortic mitral curtain, with calcification extending from the non coronary aortic cusp to anterior mitral leaflet.¹

Restriction of motion of the posterior mitral leaflet is not seen with radiation associated MS. Paradoxical anterior motion characteristic of rheumatic mitral stenosis as a result of commissural fusion is also absent in radiation associated mitral stenosis.

Radiation induced MS can occur in up to 15% of those who underwent mediastinal radiation, but with a delay of over a decade. Aortic valve is more often affected than mitral in radiation associated damage and regurgitant lesions are commoner.² Three dimensional echocardiography is useful in delineating the absence of commissural fusion in radiation associated MS, thereby differentiating it clearly from rheumatic MS.

References

1. Hering D, Faber L, Horstkotte D. Echocardiographic features of radiation-associated valvular disease. Am J Cardiol. 2003;92:226-30.
2. Krapf L, Dreyfusa J, Cueffa C, Lepageb L, Brochetb E, Vahaniana A, Messika-Zeitoun D. Anatomical features of rheumatic and non-rheumatic mitral stenosis: potential additional value of three-dimensional echocardiography. Arch Cardiovasc Dis. 2013;106:111-5.