  The finite element method (FEM) is commonly used in computational cardiac
simulations. For this method, a mesh is constructed to represent the geometry
and, subsequently, to approximate the solution. To accurately capture curved
geometrical features many elements may be required, possibly leading to
unnecessarily large computation costs. Without loss of accuracy, a reduction in
computation cost can be achieved by integrating geometry representation and
solution approximation into a single framework using the Isogeometric Analysis
(IGA) paradigm. In this study, we propose an IGA framework suitable for
echocardiogram data of cardiac mechanics, where we show the advantageous
properties of smooth splines through the development of a multi-patch
anatomical model. A nonlinear cardiac model is discretized following the IGA
paradigm, meaning that the spline geometry parametrization is directly used for
the discretization of the physical fields. The IGA model is benchmarked with a
state-of-the-art biomechanics model based on traditional FEM. For this
benchmark, the hemodynamic response predicted by the high-fidelity FEM model is
accurately captured by an IGA model with only 320 elements and 4,700 degrees of
freedom. The study is concluded by a brief anatomy-variation analysis, which
illustrates the geometric flexibility of the framework. The IGA framework can
be used as a first step toward an efficient workflow for an improved
understanding of, and clinical decision support for, the treatment of cardiac
diseases like heart rhythm disorders.
