Targeting systolic anterior motion and left ventricular outflow tract obstruction in hypertrophic obstructed cardiomyopathy with a MitraClip

AIMS: Hypertrophic obstructive cardiomyopathy (HOCM) with left ventricular outflow tract obstruction frequently involves a systolic anterior motion (SAM) of the anterior mitral leaflet. We hypothesised that SAM could be a new target for MitraClip therapy.

METHODS AND RESULTS: Three patients with HOCM were chosen for MitraClip therapy, due to significant SAM with subsequent mitral regurgitation. Invasive haemodynamic studies (right heart catheterisation, simultaneous transaortic pressure recording, and administration of nitroglycerine) were performed before and after MitraClip implantation, and a six-week follow-up was undertaken. MitraClip implantation was successfully performed with significant reduction of mitral regurgitation and SAM in all patients. Basal peak gradients (before clip: 65±25.5 mmHg; after clip: 7.7±5.0 mmHg) as well as provoked pressure gradients (before clip: 145.3±8.1 mmHg; after clip: 23.2±7.6 mmHg) were significantly reduced after MitraClip implantation. Right heart catheterisation data did not reveal major changes. At six-week follow-up, all patients presented in a persistently improved clinical state (NYHA Class I-II) with insignificant residual MR and continuously reduced LVOT gradients.

CONCLUSIONS: This is the first catheter-based study targeting primarily a SAM in HOCM to reduce LVOT obstruction. The results prove the concept that SAM is more than an epiphenomenon in HOCM. Thus, SAM-induced obstruction might be a valuable target for the MitraClip.