Background Heart failure is associated with impaired myocardial metabolism with a shift from fatty acids to glucose utilization for ATP generation. We hypothesized that cardiac accumulation of toxic lipid intermediates inhibits insulin signaling in advanced heart failure and that mechanical unloading of the failing myocardium corrects impaired cardiac metabolism. Methods and Results We analyzed myocardium and serum of 61 patients with heart failure (BMI 26.5±5.1 kg/m2, age 51±12 years) obtained during left ventricular assist device (LVAD) implantation and at explantation (mean duration 185±156 days) and from 9 controls. Systemic insulin resistance in heart failure was accompanied by decreased myocardial triglyceride and overall fatty acid content but increased toxic lipid intermediates, diacylglycerol and ceramide. Increased membrane localization of protein kinase C isoforms, inhibitors of insulin signaling, and decreased activity of insulin signaling molecules Akt and FOXO, were detectable in heart failure compared to controls. LVAD implantation improved whole body insulin resistance (HOMA-IR: 4.5±0.6 to 3.2±0.5; p<0.05) and decreased myocardial levels of diacylglycerol and ceramide while triglyceride and fatty acid content remained unchanged. Improved activation of the insulin/PI3kinase/Akt signaling cascade after LVAD implantation was confirmed by increased phosphorylation of Akt and FOXO, which was accompanied by decreased membrane localization of protein kinase C isoforms after LVAD implantation. Conclusions Mechanical unloading after LVAD implantation corrects systemic and local metabolic derangements in advanced heart failure leading to reduced myocardial levels of toxic lipid intermediates and improved cardiac insulin signaling.

BACKGROUND The prevalence of heart failure (HF) is rising and the only corrective treatment is cardiac transplantation. Advanced HF is associated with congestive hepatopathy and progressive functional and ultrastructural changes of the liver. We hypothesized that hepatic dysfunction is associated with impaired clinical outcome after heart transplantation. METHODS Data of 617 adult patients (75% males, mean age of 53±12 years, mean BMI of 25±4 and mean ejection fraction of 19±9%) undergoing orthotopic heart transplantation (OHT) were analyzed retrospectively. Deviation from institutional normal ranges was used to define abnormal liver function. Standard model for end Stage liver disease (MELD) scores were calculated and a modified MELD score with albumin replacing INR (modMELD) was created to eliminate the confounding effects of anticoagulation. RESULTS Before OHT, AST, ALT and total bilirubin were elevated in 20%, 18% and 29% of the population, respectively. Total protein and albumin were decreased in 25 and 52% of the population, respectively. By 2 months post-transplantation, percentages of individuals with pathological values decreased significantly except ALT, total protein and albumin, all of which took longer to normalize. Individuals with a higher pre-transplantation MELD or modMELD score had worse outcome 30 days post-transplant and reduced long-term survival over a 10-year follow-up. CONCLUSIONS In this large, single-center retrospective study, we demonstrate dynamics of liver dysfunction after cardiac transplantation and that elevated MELD scores indicating impaired liver function are associated with poor clinical outcome following OHT. Therefore, preoperative liver dysfunction has a significant impact on survival of patients after cardiac transplantation.