Predicting systolic anterior motion after mitral valve reconstruction: using intraoperative transoesophageal echocardiography to identify those at greatest risk

OBJECTIVES: We set out to determine if intraoperative pre-bypass transoesophageal echocardiography could assist in predicting which patients are at greatest risk for systolic anterior motion (SAM) after mitral valve repair (MVR). METHODS: Three hundred and seventy-five consecutive patients who underwent reconstructive MVR surgery for degenerative disease were included. Data were collected using intraoperative echocardiographic images taken prior to the initiation of cardiopulmonary bypass. Based on the physiology of SAM, we postulated that 11 parameters could be potential risk factors for SAM: left ventricular ejection fraction (LVEF), left ventricular end-systolic dimension, left ventricular end-diastolic dimension (LVEDD), basal septal diameter (basal-interventricular septal diameter in diastole (IVDd)), mid-ventricular septal diameter (mid-IVDd), coaptation-septal distance (c-sept), anterior leaflet height, posterior leaflet height, aorto-mitral angle, mitral annular diameter and left atrial diameter. These parameters were measured and recorded by a blinded single operator. Independent predictors of SAM were identified using multiple logistic regression analysis. RESULTS: Of the 375 patients, 345 (92%) did not develop SAM (No-SAM group), while 30 (8%) developed intraoperative or postoperative SAM (SAM group). The mean age was 56.8 +/- 12.8 and 56.7 +/- 13.8 in the No-SAM and SAM groups, respectively. The incidence of fibroelastic deficiency, forme fruste and Barlow's disease was similar in both groups. All patients received a complete annuloplasty ring as part of the repair. There was no statistical difference in the mean ring size used in each group. EF was similar in the No-SAM (56.2% +/- 8.1) and SAM (57.0% +/- 9.2) P = 0.63) groups. Independent predictors of developing SAM after valve repair were: EDD < 45 mm [odds ratio (OR) 3.90; P = 0.028], aorto-mitral angle <120 degrees (OR 2.74; P = 0.041), coaptation-septum distance < 25 mm (OR 5.09; P = 0.003), posterior leaflet height >15 mm (OR 3.80; P = 0.012) and basal septal diameter = 15 mm (OR 3.63; P = 0.039). CONCLUSIONS: The risk for SAM can be predicted using intraoperative transoesophageal echocardiography. The combination of a smaller left ventricle, tall posterior leaflet, narrow aorto-mitral angle and enlarged basal septum significantly increases the risk for SAM. Knowing these parameters prior to valve repair can assist the surgeon in adjusting their repair technique to minimize the risk.