Cardiac failure is among the most significant conditions associated with acute coronary syndrome. In ischemic heart disease, serious hemodynamic problems are reported in patients with left ventricular dysfunction during the acute phase despite mechanical revascularization. Several positive inotropic agents in addition to intra-aortic balloon pump (IABP) are required to support patients with impaired left ventricular pump function during this phase. Intravenous inotropic agents, beta-mimetics, and phosphodiesterase inhibitors lead to increases in the incidence of arrhythmia and myocardial O(2) consumption owing to their effect of increasing intracellular calcium amount, although they produce rapid hemodynamic improvements in cardiac failure. This causes severe problems particularly in cardiac failure of ischemic origin. Recently, levosimendan, a calcium-sensitizing agent with cardioprotective properties, is being used alone or in combination with IABP in cases with severe left ventricular systolic dysfunction during mechanical revascularization procedures (percutaneous coronary interventions, coronary bypass surgery). This review includes studies with levosimendan in cases not recovering due to myocardial stunning in the acute phase despite mechanical approaches applied.