. 2019 Dec 9;17(5):298–312. doi: 10.1038/s41569-019-0305-z

Table 2.

Modified Carpentier’s classification of mitral valve morphology and MR aetiology

Type of leaflet motion	Normal mitral valve leaflet		Abnormal mitral valve leaflet
Type of leaflet motion	Leaflet lesion (morphology)	Aetiology: secondary MR	Leaflet lesion (morphology)	Aetiology: primary MR
Type I: normal leaflet motion	Annular dilatation	Dilated cardiomyopathy^a or left atrial dilatation	Leaflet perforation (tear)	Endocarditis
Type II: excess leaflet motion (prolapse or flail)	–	–	Elongation (rupture of chordae or papillary muscle)	Degenerative valve disease, endocarditis, trauma or ischaemic cardiomyopathy^a
Type IIIa: restricted leaflet motion (both in diastole and systole)	–	–	Leaflet thickening (retraction), leaflet calcification, chordal thickening (retraction), fusion or commissural fusion	Rheumatic heart disease, carcinoid heart disease or dilated cardiomyopathy
Type IIIb: restricted leaflet motion (mainly in systole)	Left ventricular dilatation (aneurysm)	Ischaemic cardiomyopathy^a or dilated cardiomyopathy^a	Papillary muscle displacement or chordae tethering	Ischaemic cardiomyopathy^a or dilated cardiomyopathy^a

MR, mitral regurgitation. ^aMixed aetiology.