Metabolic Reversal of Low Cardiac Output Syndrome (LCOS) After Coronary Artery Bypass Grafting (CABG)

Objectives Severe nutritional deficiencies may play a causative role in LCOS after CABG. Older cardiac patients have an increased incidence of micronutrient depletions, including thiamine (B1) and zinc (Zn). Both of these deficiencies have been reported to cause reversible cardiomyopathy (CM). We present herein a case of B1 and Zn deficient-LCOS after CABG which resolved with micronutrient repletion (MR). Methods Case Report: A 72-year-old female with a 70–80% midsegment left anterior descending artery (LAD) lesion and left ventricular ejection fraction (LVEF) of 50% underwent elective CABG, mitral valve annuloplasty, Maze procedure, and left atrial appendage clipping. She developed LCOS immediately postoperatively with diffuse hypokinesis, LVEF of 25–30% and an elevated serum lactate (5.8 mmol/L; nl < 2.0). Classical perioperative causes for LCOS were ruled out. Her LVEF did not respond to pressor or inotrope therapy. She started MR on postoperative day # 2. Results Pressors and inotropes were weaned one day after beginning MR. Her lactate level improved and a repeat echocardiogram showed an LVEF of 45–50%. Pretreatment metabolic labs disclosed an undetectable RBC B1 level (nl 70–180 nmol/L) and severely low RBC Zn (19 mcg/dL; nl 60–130). MR was continued orally. On day 16, an echocardiogram showed LVEF of 55–65% with no regional wall motion abnormality and normal right ventricular movement. Conclusions This patient's LCOS post CABG appears to have been due to combined, severe micronutrient deficiencies. Marked clinical improvement occurred after MR administration, with normalization of serum lactate, LVEF and regional wall motion. Aggressive B1 and Zn repletion were given prior to confirmation by laboratory analysis. Clinical suspicion should be raised for B1 and Zn deficiencies when other perioperative LCOS causes are ruled out. This may be particularly important with elevated lactate levels and lack of response to inotrope therapy. MR therapy should be considered for such individuals while awaiting confirmatory laboratory results. Funding Sources None.