Left atrial mechanical dispersion as a novel predictor biomarker of new-onset atrial arrhythmias in cardiac amyloidosis

AIMS We aimed to investigate which parameters of left atrial (LA) structure and function could predict new-onset atrial arrhythmias (NOAA) in patients with CA, aiding in improved follow-up. METHODS AND RESULTS We prospectively included patients diagnosed with CA, both light chain (AL) and variant transthyretin (ATTRv) with no history of AA. LA mechanical dispersion (LAMD) was defined as the standard deviation of time-to-peak positive strain and reported as percentage from the R-R interval. The primary outcome was NOAA. 93 patients were included (mean age 54.3 ± 9.8, 58% males), and 44 patients (47%) developed NOAA during a median follow up of 11 (3.5-36.0) months. Patients with NOAA had heavier hearts, worse global LV function, more LV longitudinal impairment, larger atria and worse LA function. LA reservoir strain (LASr) was significantly lower and LAMD significantly higher in patients who developed NOAA. In the multivariate analysis adjusting for confounding factors, a lower LAMD was independently associated with higher risk for NOAA (HR: 1.182, 95% CI: 1.033-1.351, p = 0.015). Patients with LAMD>6.6% had a higher risk for NOAA than those with LAMD≤6.6% (P < 0.001). Furthermore, LAMD>6.6% remained an independent predictor for NOAA in both univariate and multivariate analysis. Five models were created and the model based on LA volume was significantly improved by adding LVGLS, RVFWS and LAMD, but it was not significantly improved by adding LASr. CONCLUSION LAMD is a novel, reproducible and independent predictor of NOAA in patients with CA, being superior and incremental to other imaging predictors.