  We present a loosely coupled scheme for the numerical simulation of the
cardiac electro-fluid-structure interaction problem, whose solution is
typically computationally intensive due to the need to suitably treat the
coupling of the different submodels. Our scheme relies on a segregated
treatment of the subproblems, in particular on an explicit Robin-Neumann
algorithm for the fluid-structure interaction, aiming at reducing the
computational burden of numerical simulations. The results, both in an ideal
and a realistic cardiac setting, show that the proposed scheme is stable at the
regimes typical of cardiac simulations. From a comparison with a scheme with
implicit fluid-structure interaction, it emerges that, while conservation
properties are not fully preserved, computational times significantly benefit
from the explicit scheme. Overall, the explicit discretization represents a
good trade-off between accuracy and cost, and is a valuable alternative to
implicit schemes for fast large-scale simulations.
