Fig. 1.

Quantification of atrial function as derived from volumetric analysis and CMR-FT derived strain and strain rate (SR) parameters. Atrial analysis comprised reservoir, conduit and booster pump function. For the calculation of fractional volume changes, atrial volumes were measured in three time frames according to the maximum (Vmax), minimum (Vmin) and atrial volume prior to atrial contraction (Vpac) resulting in ‘EF Total’ corresponding to reservoir function and global atrial function, ‘EF Passive’ corresponding to conduit function and ‘EF Booster’ corresponding to atrial contractile booster pump function (please see equations in the methods section under volumetric analysis). Total strain (ε_s) and peak positive strain rate (SRs) correspond to reservoir function. Passive strain (ε_e) and peak early negative strain rate (SRe) correspond to conduit function. Active strain (ε_a) and peak late negative strain rate (SRa) correspond to contractile booster pump function