  Atrial fibrillation is one of the most frequent cardiac arrhythmias in the
industrialized world and ablation therapy is the method of choice for many
patients. However, ablation scars alter the electrophysiological activation and
the mechanical behavior of the affected atria. Different ablation strategies
with the aim to terminate atrial fibrillation and prevent its recurrence exist
but their impact on the hemodynamic performance of the heart has not been
investigated thoroughly. In this work, we present a simulation study analyzing
five commonly used ablation scar patterns and their combinations in the left
atrium regarding their impact on the pumping function of the heart using an
electromechanical whole-heart model. We analyzed how the altered atrial
activation and increased stiffness due to the ablation scar affect atrial as
well as ventricular contraction and relaxation. We found that systolic and
diastolic function of the left atrium is impaired by ablation scars and that
the reduction of atrial stroke volume of up to 11.43% depends linearly on the
amount of inactivated tissue. Consequently, the end-diastolic volume of the
left ventricle, and thus stroke volume, was reduced by up to 1.4% and 1.8%,
respectively. During ventricular systole, left atrial pressure was increased by
up to 20% due to changes in the atrial activation sequence and the stiffening
of scar tissue. This study provides biomechanical evidence that atrial ablation
has acute effects not only on atrial contraction but also on ventricular
pumping function. Our results have the potential to help tailoring ablation
strategies towards minimal global hemodynamic impairment.
