Hemodynamic effects of levosimendan in low cardiac output syndrome post-CABG refractory to standard inotropic therapy.

BACKGROUND

Low cardiac output syndrome (LCOS) following coronary artery bypass grafting (CABG) remains a major cause of morbidity and mortality. Standard inotropes frequently provide only marginal hemodynamic benefit and are associated with increased myocardial oxygen consumption and arrhythmogenic risk. Levosimendan, a calcium sensitizer with inodilatory properties, may offer more favorable hemodynamics without these adverse effects.

METHODS

In this retrospective study, we evaluated 41 patients with LCOS post-CABG who failed to respond to standard catecholamines, defined by < 20% improvement in cardiac output. Levosimendan (0.1-0.2 µg/kg/min over 24 h) was administered. Hemodynamic parameters including cardiac index (CI), systemic vascular resistance (SVR), mean arterial pressure (MAP), cardiac power index (CPi), and serum lactate were recorded at baseline and at 3, 24, 48, 72, and 96 h post-infusion.

RESULTS

Levosimendan significantly increased CI from 2.08 ± 0.08 to 2.89 ± 0.19 L/min/m2 at 48 h (p = 0.003) and CPi from 0.32 ± 0.01 to 0.50 ± 0.01 W/m2 (p = 0.002). Serum lactate declined from 5.5 ± 0.8 to 2.45 ± 0.4 mmol/L (p = 0.01). SVR decreased from 1334 ± 108 to 1079 ± 73 dyn·s·cm⁻5 (p = 0.09). In contrast, initial norepinephrine/epinephrine/dobutamine therapy resulted in a minor CI increase (2.08 ± 0.08 to 2.15 ± 0.08 L/min/m2; p = 0.05) and no significant improvement in MAP or lactate. With levosimendan no tachycardia or persistent hypotension was observed; catecholamine requirements declined over 72 h.

CONCLUSION

This retrospective single-center case series suggests that levosimendan may be associated with hemodynamic improvement in patients with LCOS after CABG who are unresponsive to standard therapy. However, due to the absence of a control group and the retrospective design, these findings should be considered exploratory and hypothesis-generating.