Letter by Dasi et al Regarding Article, “Effect of Chronotropy and Inotropy on Stitch Tension in the Edge-to-Edge Mitral Repair” To the Editor:

Timek et al concluded that the septal-lateral (SL) diameter rather than hemodynamic parameters are the main determinants of “Alfieri stitch ” force (ASF) during diastole.1 We found that the arguments presented were not convincing because of an insufficiently detailed hemodynamic characterization. The purely statistical analysis of the problem, excluding instantaneous flow rate data, undermines the potential scientific impact of the excellent in vivo experiments. To elaborate on our criticism, we present a brief summary of the physics that determines ASF, arguments based on the data of Timek et al, and previous data2 that corroborate the physics we describe, and we recommend an analysis to correctly identify the main determinant.3 Diastolic ASF is the force necessary to prevent the fluid pressure that acts on the leaflets from opening them to their natural configu-ration. Fluid pressure on the leaflets is directly proportional to the upstream momentum flux, QV, where is the blood density, Q is the diastolic flow rate, and V is the mean annular blood velocity; which in turn can be shown to be Q2MAA1 from continuity, where MAA is the mitral annular area. The use of dimensional analysis3 yields the same wit