Up to 1 billion cardiomyocytes (CMs) die during myocardial infarction (MI), leading to permanent muscle loss and devasting functional impacts. Biomaterial therapies have aimed to passively reinforce the infarcted left ventricle (LV), but their therapeutic impact remains limited as they fail to directly address the loss of functional CMs. In this work, we employed a simulation-guided workflow to design an optimized biomaterial support that can be combined with contractile CMs for implantation after MI. A finite element model (FEM) of the LV post-MI was developed and showed longitudinal reinforcement and active contractility improves ejection fraction (EF) post-MI (+3.39 % and +14.97 %, respectively). To this end, we developed a coordinated remuscularization-reinforcement therapy using engineered human myocardium (EHM) composed of human induced pluripotent stem cell-derived CMs (hiPSC-CMs) integrated with a highly aligned electrospun polycaprolactone (PCL) scaffold. Remuscularization (EHM-only), reinforcement (PCL-only) and its coordinated therapy (PCL-EHM) were evaluated in a rat model of MI. We report successful engraftment of the implants onto the heart with significant maturation of hiPSC-CMs after four weeks in vivo (∼7-fold increase of cTnT area and ∼2-fold increase MLC2v area compared to in vitro cultured controls). Using 4D ultrasound (US), we quantified 3D regional strains and found that the benefits of PCL reinforcement on maintaining LV structure and function were additive with remuscularization by EHM. This additive effect was reflected inimproved regional strain after injury when PCL and EHM were delivered as a composite therapy. This work establishes a promising strategy for synergistic reinforcement and remuscularization of the infarcted heart.