Therapy for secondary mitral regurgitation: time to 'cut the chord'?

Secondary mitral regurgitation (MR) is common in patients with dilated or ischaemic cardiomyopathy and conveys an adverse prognosis associated with the degree of MR.1 The principal mechanism underlying the development of secondary MR is related to altered mitral valve geometry resulting from LV remodelling and distortion.1–3 LV dilation causes papillary muscle displacement, which in turn results in leaflet tethering, restricted closure and MR (figure 1).3 Although secondary MR is a common valvular problem, therapy remains problematic. Mitral ring annuloplasty most often performed at the time of coronary artery bypass surgery is the standard surgical therapy. However, the beneficial effects on overall survival of ring annuloplasty for secondary MR are unclear with a relatively high recurrence rate of moderate or greater secondary MR of approximately 30%. There is a need to explore alternate surgical approaches for secondary MR. Figure 1 Mechanism of secondary mitral regurgitation. Spatial relationship between mitral valve apparatus and LV in normal condition (left panel) and pathological condition (ie, secondary mitral regurgitation; right panel). Ao, aorta; LA, left atrium; MR, mitral regurgitation. Adapted from Hung,3 with permission from Elsevier. Tethering of the mitral leaflets, the fundamental mechanism in secondary MR, is effected through the basal chordae that attach to the basal and mid body of the anterior leaflet, often resulting in a bend of the anterior mitral valve leaflet, a sign coined by Alain Carpentier as the ‘seagull wing’.2 This bend in the anterior leaflet represents abnormal tethering by the basal chordae. Limited experimental and clinical studies have demonstrated efficacy in …