Metabolic syndrome increases operative mortality in patients with impaired left ventricular systolic function who undergo coronary artery bypass grafting: a retrospective observational study

BACKGROUND: Metabolic syndrome (MetS) is a prevalent risk factor for coronary artery disease progression. Past studies have shown that MetS and its components tends to increase mortality after coronary artery bypass grafting (CABG), but data on the impact of MetS on postoperative outcome in patients with a left ventricular (LV) ejection fraction (EF) < 50% are still lacking. METHODS: Out of 2300 patients who underwent CABG between 2008 and 2018 in our center, 190 patients were identified as having impaired LV systolic function (EF < 50%). The patients were divided into two groups: those with MetS (n = 87, 45.8%) and those without MetS (n = 103, 54.2%). The influence of MetS on postoperative mortality and major complications was investigated. RESULTS: Postoperative mortality occurred in 12.6% of patients with MetS and in 3.9% of patients without MetS (p < 0.05). Multivariate analysis showed that patients with MetS had a significantly greater risk of mortality compared with patients without MetS (relative risk 7.23, p < 0.05). After adjustment for other risk factors, the risk of mortality was increased 6.47-fold [95% confidence interval (CI):1.25–33.6; p < 0.05] in patients with MetS and diabetes and 5.4-fold (95% CI: 1.12–29.7; p < 0.05) in patients with MetS and without diabetes, whereas it was not significantly increased in patients with diabetes and without MetS. CONCLUSIONS: MetS is an important predictor of increased mortality in patients with LVEF<50% who undergo CABG. The components of MetS have synergistic effect in postoperative mortality. Multifactorial intervention in MetS is required to improve surgical efficacy in these patients.