Background: Despite the emerging evidence on beneficial effects of probiotics on the cardiovascular system, their impact on the management of ischemic heart diseases and its possible mechanism have not been elucidated. Methods: Four viable probiotics bacterial strains, including Bifidobacterium breve, Lactobacillus casei, Lactobacillus bulgaricus and Lactobacillus acidophilus, at the concentrations of 2×10⁶ colony-forming units/ml were orally administered to the rats daily for 14 days before the induction of infarct-like myocardial injury using isoproterenol. Subsequently, 24 h after myocardial injury, the right carotid artery and the left ventricle were catheterized for recording blood pressure and cardiac parameters. At the end of the experiment, the heart was removed for the evaluation of histopathological and biochemical parameters, as well as tumor necrosis factor-alpha (TNF-α) assay. Results: The induction of acute myocardial injury resulted in significant (P≤0.01) left ventricular (LV) dysfunction, as shown by an increase in LV end-diastolic pressure and a decrease in LV dp/dt max, LV dp/dt min, LV systolic pressure, and blood pressure, as compared with normal rats. Pretreatment with viable probiotics significantly reduced lipid peroxidation and TNF-α level and improved cardiac function (P<0.01). Conclusion: This study shows that viable probiotics have a cardioprotective effect on infarct-like myocardial injury through suppressing TNF-α and oxidative stress damage in a rat model. Probiotic supplements may be used as a new option for prophylaxis in patients at the risk of ischemic heart disease in future.