Abstract Body (Do not enter title and authors here): Introduction: Heart failure with preserved ejection fraction (HFpEF) is a form of heart failure which is rapidly rising in incidence in the US today. Despite this, no therapies with mortality benefit exist for this syndrome. Previous work with our novel hybrid cardiac targeting peptide (hCTP), a cardiomyocyte-specific cell penetrating peptide, has shown multiple beneficial biological effects (improved calcium handling, anti-inflammatory properties) beyond its transduction abilities. Therefore, we hypothesized that treatment with hCTP in a mouse model of HFpEF would ameliorate the pathophysiology of this disease.

Methods: To establish a HFpEF model, 6-week-old, C57BL/6NJ mice were placed on a high-fat diet (HFD), 60% kCal from lard, and water with 0.5 g/L of an iNOS inhibitor (N-Nitro-L-arginine methylester) to induce hypertension. After 5 weeks of the diet, HFD mice and their littermate controls underwent baseline exercise testing and echocardiograms. Exercise capacity was measured after 2 days of exercise training with 2 days of rest in between; mice were placed on a treadmill at a 10-degree angle and made to run at increasingly fast speeds (5-30 m/min) until exhaustion. Echocardiograms were performed under 1.5% inhalational isoflurane. After baseline testing, the mice were treated with vehicle, or either 2.5 or 5 mg/Kg hCTP, either 3 or 5 days a week (five groups, n = 3 per group). After four weeks of treatment, the mice were again subjected to the same battery of tests and euthanized. Data was compared using two way ANOVA with Sidak’s test to compare measurements pre- and post-treatment.

Results: Treatment with hCTP at either concentration for five days/week led to an increase in running distance from 39.8 m to 116.3 m (p = 0.03, n = 6), compared to changes in control distance from 208.4 m to 157.8 m (p = 0.399). Running distance did not correlate with weight (R² < .001). Treatment with 5 mg/Kg hCTP for 5 days/week led to a normalization of the E/e’ ratio, from 43.3 to 26.9 (p = 0.004, n = 3) compared to a change in the control of 34.7 to 26.1 (p = 0.312). Ejection fractions remained consistent (>55%) across all groups.

Conclusions: Our data suggests that hCTP appears to be a promising treatment in ameliorating some of the physiological effects in a murine model of HFpEF. Gene and protein expression studies in heart tissue are underway. Further work is warranted with a larger sample size.