Mitral Annular Calcification and Its Severity in Relation to Left Atrial Reservoir Strain and a Non‐Invasive Left Atrial Stiffness Index

PURPOSE: Mitral annular calcification (MAC) is associated with atrial fibrillation and diastolic dysfunction, but its relationship with left atrial (LA) mechanics is poorly defined. The ratio of E/e' to LA reservoir strain (LASr) is a non-invasive surrogate of, not a direct measure of, LA stiffness. We assessed MAC and its severity against LASr and this LA stiffness index (LASI). METHODS: In this single-center cross-sectional study with prospective recruitment, 112 adults in sinus rhythm with ejection fraction ≥50% (58 with MAC, 54 age- and sex-similar controls) underwent two-dimensional speckle-tracking echocardiography. MAC was graded mild to severe; LASI was calculated as E/e' divided by LASr. RESULTS: LASr was lower (23.2 ± 7.8% vs. 26.7 ± 7.7%, p = 0.018) and LASI higher (0.57 ± 0.30 vs. 0.34 ± 0.20, p < 0.001) in the MAC group. In models excluding the index components, MAC severity was independently associated with higher LASI (β = 0.41, p < 0.001) and MAC presence with lower LASr (-3.6 points, p = 0.016). After clinical adjustment, each 0.1-unit LASI increase was associated with MAC (odds ratio 1.71, 95% CI[1.34-2.17]). LASI discriminated MAC with an area under the curve of 0.762 (0.674-0.851; cut-off 0.31, sensitivity 79%, specificity 63%), which did not differ from E/e' (p = 0.52) or LA volume index (p = 0.48). CONCLUSION: MAC and its severity were associated with impaired LA reservoir function and a higher non-invasive stiffness index. The index did not discriminate MAC better than its simpler components, so these cross-sectional findings are hypothesis-generating.