HCN4 and myocardial infarction: However, we have recently demonstrated that ivabradine prevented HCN4 overexpression in the rat model of chronic MI-induced HF, but unexpectedly a two-week dopamine infusion that had detrimental effects on both cardiac hemodynamic and remodeling parameters as well as induced ventricular arrhythmias, was also associated with reduced HCN4 overexpression [62].