Abstract Body: G Sanadgol*, J Guo*, A van Kampen, A Nahlawi, G Goudot, KM Yaghoubian, J Ruskin*, YS Zhang*, L Ptaszek*
* These authors contributed equally.

Background: Epicardial application of a bioadhesive at the time of experimental myocardial infarction (MI) has been shown to reduce ventricular scar burden in mice. This study assessed the impact of an oxygenated hydrogel (O₂-hydrogel) on post-infarct cardiac function and scar burden in rats.
Method: Experimental MI was performed in Lewis rats (age 12-15 weeks) by permanent ligation of the anterior interventricular artery. There were 3 cohorts in this study: 1. MI followed by epicardial application of hydrogel, 2. MI followed by epicardial application of O₂-hydrogel, and 3. MI with no treatment. Left ventricular (LV) function was evaluated by transthoracic echocardiography (TTE) at baseline, immediately post-MI, and 3 weeks post-MI. LV scar burden was evaluated with histopathology performed 3 weeks post-MI.
Result: Twenty-four rats were analyzed (hydrogel, n= 8; O₂-hydrogel, n= 9; untreated, n=7). LV fractional shortening (FS) measured by TTE 3 weeks post-MI was significantly reduced compared with baseline in untreated rats (44.6±12.4 to 22.3±4.9, P=0.043; Figure 1) and hydrogel treated rats (32.4±6.0 to 14.9±5.2, P=0.018). No significant change in FS was observed in the O₂-hydrogel treatment cohort (39.0±13.9 to 38.1±12.6, P=0.859). LV scar burden in the O₂-hydrogel cohort was significantly lower than in the hydrogel alone and untreated cohorts (11.9% vs 39.9% and 36.2%, respectively; Figure 2).
Conclusion: In this rat model, epicardial application of O₂-hydrogel at the time of experimental MI is associated with greater preservation of LV function and significantly lower scar burden than application of hydrogel alone or no treatment.