Transaortic Chordal Cutting Mitral Valve Repair for Obstructive Hypertrophic Cardiomyopathy with Mild Septal Hypertrophy

Background In severely symptomatic patients with obstructive hypertrophic cardiomyopathy (HCM) and mild septal hypertrophy, mitral valve (MV) abnormalities may play an important role in MV displacement into the left ventricular (LV) outflow tract. Therefore, isolated myectomy may not relieve outflow obstruction and symptoms, and MV replacement is often the surgical alternative. Objectives This study sought to assess the clinical and hemodynamic results of cutting thickened secondary MV chordae combined with a shallow septal muscular resection in severely symptomatic patients with obstructive HCM and mild septal hypertrophy. Methods Clinical features were compared before surgery and at most recent clinical evaluation in 39 consecutive patients with obstructive HCM. Results Over a 23 ± 2 months follow-up, New York Heart Association functional class decreased from 2.9 ± 0.5 pre-operatively to 1.1 ± 1.1 post-operatively (p <0.001), with no patient in class III at most recent evaluation. The resting outflow gradient decreased from 82 ± 43 mm Hg to 9 ± 5 mm Hg (p <0.001) and septal thickness decreased from 17 ± 1 mm to 14 ± 2 mm (p <0.001). No patient had MV prolapse or flail and 1 had residual moderate-to-severe MV regurgitation at most recent evaluation. MV geometry before and after surgery was compared with that of 25 consecutive patients with similar clinical profile and septal thickness that underwent isolated myectomy. After adjustment for differences in pre-operative values between the groups, the post-operative anterior MV leaflet-annulus ratio was 17% greater and tenting area 24% smaller in patients with chordal cutting, indicating that MV apparatus had moved to a more normal posterior position within the LV cavity, preventing MV systolic displacement into the outflow tract and outflow obstruction. Conclusions This procedure relieves heart failure symptoms, abolishes LV outflow gradient, and avoids MV replacement in patients with obstructive HCM and mild septal thickness.