Systolic anterior motion occurs after mitral valve repair due to an excess of leaflet tissue versus the anterior lateral height of the orifice of the mitral valve. The posterior leaflet pushes the anterior leaflet into the outflow tract. There are two principal causes for this.
High velocity jets after mitral valve repair strongly suggest leaflet perforation. They're usually simple lesions to re-repair. And if patients are stable and have good ventricular function, it's usually worth a second look on bypass to identify them.