Another potentially antiarrhythmic effect of ivabradine identified in our study was prevention of HCN4 overexpression in the ventricular cardiomyocytes as early as 24 h after MI induction [25], corroborating previous findings that ivabradine prevented HCN4 overexpression after 3 months of treatment in the post-MI rat [27]. The gene discussed is HCN4; the disease is myocardial infarction.