Vasoactive inotropic score as a predictor of long-term mortality in patients after off-pump coronary artery bypass grafting

Increased vasoactive-inotropic score (VIS) is a reliable predictor of mortality and morbidity after cardiac surgery. Here, we retrospectively evaluated the association between VIS and adverse outcomes in adult patients after off-pump coronary artery bypass grafting (OPCAB). We included 2149 patients who underwent OPCAB. The maximal VIS was calculated for the initial 48 postoperative hours using standard formulae. The primary outcome was 1-year death. The composite adverse outcome was death, resuscitation or mechanical support, myocardial infarction, revascularization, new-onset atrial fibrillation, infection requiring antibacterial therapy, acute kidney injury, and stroke. Path-analysis was conducted using lactate and prognostic nutritional index (PNI). VIS was associated with 1-year death (odds ratio [OR] 1.07 [1.04-1.10], p < 0.001) and 1-year composite outcome (OR 1.02 [1.0-1.03], p = 0.008). In path-analysis, high VIS showed a direct effect on the increased risk of 1-year death and composite outcome. In the pathway using lactate as a mediating variable, VIS showed an indirect effect on the composite outcome but no significant effect on death. Low PNI directly affected the increased risk of 1-year death and composite outcome, and had an indirect effect on both outcomes, even when VIS was used as a mediating variable. In patients undergoing OPCAB, high VIS independently predicted morbidity and 1-year death. Patients with increased lactate levels following high VIS had an increased risk of postoperative complications, although not necessarily resulting in death. However, patients with poor preoperative nutritional status had an increased risk of unfavourable outcomes, including death, implying the importance of preoperative nutritional support.