Background: Inflammation-dominated sympathetic sprouting adjacent to the necrotic region following myocardial infarction (MI) has been implicated in the etiology of arrhythmias resulting in sudden cardiac death; however, the mechanisms responsible remain to be elucidated. Although being a key immune mediator, the role of the Notch has yet to be explored. Objective: We investigated whether Notch regulates macrophage responses to inflammation and affects cardiac sympathetic reinnervation in rats undergoing MI. Methods and Results: MI was induced by coronary artery ligation. A high level of NICD was observed in the macrophages that infiltrated the infarct area at 3 days post-MI. The administration of the Notch inhibitor N-N-(3,5-difluorophenacetyl-l-alanyl)-S-phenylglycine-t-butyl ester (DAPT) (i.v. 30 minutes before MI and then daily until sacrifice) decreased the number of macrophages and significantly increased the M2 macrophage activation profile in the early stages as well as attenuated the expression of nerve growth factor (NGF). Eventually, NGF-induced sympathetic hyperinnervation was blunted, as assessed by the immunofluorescence of tyrosine hydroxylase (TH). At 7 days post-MI, the arrhythmia score of programmed electric stimulation in the vehicle-treated infarcted rats was higher than that in rats treated with DAPT. Further deterioration in cardiac function and decreases in the plasma levels of TNF-α and IL-1β were also detected. In vitro studies revealed that LPS/IFN- upregulated the surface expression of NGF in M1 macrophages in a Notch-dependent manner. Conclusions: Notch inhibition during the acute inflammatory response phase is associated with the downregulation of NGF, probably through a macrophage-dependent pathway, thus preventing the process of sympathetic hyperinnervation.