Abnormal Angle between Interatrial Septum and Mitral Valve Plane: an Unfavorable Predictor for MitraClip Procedure

We report the case of a 30-year-old woman who underwent transcatheter edge-to-edge repair with the MitraClip device for moderate-to-severe secondary mitral regurgitation (effective regurgitant orifice area 0.3 cm², regurgitant volume 38 mL, vena cava 6 mm, blunted pulmonary veins flow) in the context of a bridge-to-transplantation MitraClip strategy for advanced heart failure due to chronic myocarditis. The transthoracic/transesophageal (TT/TE) echocardiography showed severe left ventricular dysfunction (ejection fraction 30%, end-diastolic volume 61 mL/m², end-systolic volume 43 mL/m²), feasible transseptal puncture (47 mm above the plane of coaptation of the leaflets), giant left atrium (LA; 128 mL/m²) (Figure 1A and B) and preserved right ventricular systolic function (tricuspid annular plane excursion 18 mm, s′-tissue doppler imaging 10 cm/s). After an uncomplicated transseptal puncture, the procedure was characterized by several attempts to grasp the mitral leaflets with a MitraClip XTR until the final abortion due to the extreme unfavorable device trajectory in the giant LA (Movies 1 and 2). Indeed, it was impossible to be perpendicular with the MitraClip delivery system to the line of mitral valve coaptation. The patient was discharged and remained on the waiting list for heart transplantation. Afterwards, we realized that there was an extremely unfavorable angle (Å) between the interatrial septum (IAS) and the mitral valve plane (MVP), which was the main cause of the adverse trajectory of the device within the giant LA. Although there is no formal evaluation of this parameter, in clinical practice the range of normal IAS-MVP-Å values is 90°–110°. In this case, the post hoc measurement of the IAS-MVP-Å was > 140° (Figure 1C). This unexpected anatomical condition highlights the importance of better evaluating by TT/TE-echocardiography (before any procedure) the existence of an abnormal IAS-MVP-Å (mostly in case of giant atria) in order to allow a better patient selection and procedural planning for MitraClip procedure.

Figure 1
Comparing cases of patients with giant LA and abnormal (A-C) or normal (D-F) angle between IAS and MVP. Transthoracic echocardiography: apical 4 chamber view (A,D). Transoesophageal echocardiography: 4 chamber view (B,E). Transoesophageal echocardiography, 4 chamber view: post hoc angle measurement (C,F).
LA: left atrium, LV: left ventricle, MVP: mitral valve plane, IAS: interatrial septum, MV: mitral valve.

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