Systolic Anterior Motion of the Mitral Valve in the Presence of Annular Calcification

Background: Mitral annular calcification (MAC) has been reported as a possible cause of systolic anterior mo-tion (SAM) of the mitral valve and dynamic left ventricular outflow tract (LVOT) obstruction. While morphologic features predisposing to SAM in other clinical settings have been described, patients with MAC+SAM have not been systematically investigated. We hypothesized that bulky calcium deposits in the mitral annulus could displace the valve toward the septum, thus promoting development of SAM. Methods: We studied 30 patients with severe MAC who had SAM with septal contact. Three comparator groups (matched for age and sex) were developed: 30 controls without MAC or SAM, 30 with severe MAC but no SAM, and 30 with SAM but no MAC. Results: Significant differences were found across groups for mitral valve coaptation point-septal distance (CSD), anterior mitral leaflet (AML) length, left ventricular diastolic dimension, and ejection fraction. Comparing all MAC subjects (n = 60) with controls, CSD was less (20.5 +/- 4.1 vs 23.2 +/- 3.7 mm, P = .003) and ejection fraction was higher (67.7% +/- 7.8% vs 60.9% +/- 6.4%, P < .0001) in MAC patients. Within MAC subjects AML was longer (21.9 +/- 3.0 vs 17.4 +/- 2.2 mm, P < .0001) and CSD was smaller (18.0 +/- 2.7 vs 23.1 +/- 3.6 mm, P < .0001) when SAM was present despite similar height of the calcium bar in the 2 MAC groups (12.4 +/- 2.9 vs 11.1 +/- 3.1 mm, P = .11). Regression analysis confirmed AML length and CSD as independent predictors of SAM. MAC+SAM pa-tients also had more echocardiographic risk factors for SAM (acute aortomitral angle, small LVOT, long AML, small CSD, and presence of a septal bump) than MAC/no-SAM patients (3.4 +/- 0.9 vs 1.8 +/- 1.0, P < .0001). Conclusions: Bulky MAC appears to contribute to dynamic LVOT obstruction when it accumulates in such a way that the mitral valve is displaced anteriorly toward the septum. However, other features are also associated with SAM in these patients, particularly a long AML. A combination of morphologic features and favorable hemody-namics may be needed for SAM to develop in patients with severe MAC. (J Am Soc Echocardiogr 2023;36:421-7.)