BACKGROUND Mitral annular calcification (MAC) is characterized by calcium and lipid deposition in the annular fibrosa of the mitral valve. MAC is associated with cardiovascular events but little is known of its association with left atrial (LA) function. METHODS We prospectively obtained 12-lead electrocardiograms (ECGs) and transthoracic echocardiograms (TTE) on patients scheduled for nonemergent echocardiographic assessment at a tertiary care hospital. MAC was graded as 0 = none, 1 = mild, 2 = moderate, 3 = severe. LA linear and volume measurements (stroke volume, LA passive emptying fraction, LA active emptying fraction and LA kinetic energy) were done specifically in addition to commonly measured TTE parameters. RESULTS From the 124 considered for the study, 72 patients remained (aged 68+/-18 years; 44% male) after excluding those with poor ECG tracings and/or poor TTE images. Eighteen patients had MAC; mild MAC = 14, moderate MAC = 3, severe MAC = 1. When patients with MAC were compared to those without MAC, no significant difference was noted, except for LA linear dimension index (2.1+/-0.4 vs. 1.9+/-0.3 cm/m(2); P = 0.03). For those with mild and moderate MAC, a trend was noted toward lower LA function with increasing MAC severity. In addition, significant differences were noted between those with and without interatrial conduction delay, where those with such delay had significantly impaired LA stroke volume (9.8+/-3 vs. 19.93+/-4 ml; P < 0.0001), LA active emptying fraction (18.83+/-8 vs. 65.71+/-9%; P < 0.0001) and LA total/reservoir fraction (39.54+/-6 vs. 75.1+/-6%; P < 0.0001). CONCLUSIONS MAC is associated with increase in LA linear dimension on TTE and may be equally represented with lower overall LA function. Further study in a much larger cohort is warranted to delineate these and other potential associations of MAC.