Panax ginseng is commonly used in Chinese medicine and Western herbal preparations. However, it has also been recently noted to be associated with some cardiac pathologies-including cardiogenic shock due to acute anterior myocardial infarction, trans-ischemic attack, and stent thrombosis. This study was aimed to elucidate acute and subacute effects of the low and high doses of standardized Panax ginseng extract (sPGe) on cardiac functions. Rats were randomly assigned to control group, acute low-dose group (ALD), subacute low-dose group (SALD), acute high-dose group (AHD), and subacute high-dose group (SAHD). The cardiac effects of sPGe were evaluated using hemodynamic, biochemical, echocardiographic, genetic, and immunohistopathologic parameters. Mean blood pressures were significantly lower in all sPGe-treated groups compared with the control group. Troponin I and myoglobin levels were increased in the SALD, AHD, and SAHD groups. Mitral E-wave velocity was reduced after sPGe administration in all the groups. Acidophilic cytoplasm and pyknotic nucleus in myocardial fibers were observed in AHD and SAHD groups. Cu/Zn-SOD1 gene expressions were significantly higher in the sPGe-treated groups whereas caveolin 1 and VEGF-A gene expressions were not changed. According to our results, sPGe may have a potential effect to cause cardiac damage including diastolic dysfunction, heart failure with preserved ejection fraction, and reduction of blood pressure depending on the dose and duration of usage. Healthcare professionals must be aware of adverse reactions stemming from the supplementation use, particularly with cardiac symptoms.