  We study the Loschmidt echo for quenches in open one-dimensional lattice
models with symmetry protected topological phases. For quenches where dynamical
quantum phase transitions do occur we find that cusps in the bulk return rate
at critical times tc are associated with sudden changes in the boundary
contribution. For our main example, the Su-Schrieffer-Heeger model, we show
that these sudden changes are related to the periodical appearance of two
eigenvalues close to zero in the dynamical Loschmidt matrix. We demonstrate,
furthermore, that the structure of the Loschmidt spectrum is linked to the
periodic creation of long-range entanglement between the edges of the system.
