Clinical Investigation
Mitral Systolic Anterior Motion and Annulus Calcification
Systolic Anterior Motion of the Mitral Valve in the Presence of Annular Calcification

https://doi.org/10.1016/j.echo.2022.12.011Get rights and content

Highlights

  • In patients with severe MAC+SAM, the mitral valve is translocated anteriorly.

  • A long AML is also found in MAC+SAM.

  • SAM does not occur consistently in severe MAC, implying that hemodynamics may play a role

  • In this series, 10% of SAM patients had severe MAC.

Background

Mitral annular calcification (MAC) has been reported as a possible cause of systolic anterior motion (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 patients 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 hemodynamics may be needed for SAM to develop in patients with severe MAC.

Section snippets

Subject Pool

We queried our echocardiography database from August 2007 through February 2022 to identify the subjects for this research. We first created a study set comprising all those with both severe MAC and SAM (n = 30). These were compared to 30 subjects with similarly severe MAC but no SAM and 30 control subjects without MAC or SAM. The 2 comparator groups were matched by age (±5 years) and sex. Mitral annular calcification height was defined as the anteroposterior dimension of the bar of

Results

For the entire study group (120 subjects), the mean age was 74 ± 10 years (range, 56-95), and 87% of patients were female. Hypertension was prevalent (79%) as were hyperlipidemia (46%) and diabetes (49%; Table 1). Echocardiographic variables for the different groups are displayed in Table 2. Significant differences were found across groups for coaptation point-septal distance, AML length, LVDD, and EF. Prevalence of an upper septal bump ranged from 47% to 60% in the various groups with no

Discussion

Mitral annular calcification is prevalent in the elderly and those with renal dysfunction. However, calcium deposition in the annulus does not appear to follow a predictable pattern. It can migrate onto the leaflets, reducing their mobility and causing stenosis,12 or distort the leaflets, causing regurgitation.13 In this study we have investigated MAC as a possible promoter of SAM of the mitral valve.

Systolic anterior motion of the mitral valve and dynamic LVOT obstruction occur when the

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Conflicts of Interest: None.

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