Protracted fibrinolysis resistance following cardiac surgery with cardiopulmonary bypass: A prospective observational study of clinical associations and patient outcomes

BACKGROUND

Surgery on cardiopulmonary bypass (CPB) elicits a pleiomorphic systemic host response which, when severe, requires prolonged intensive care support. Given the substantial cross-talk between inflammation, coagulation, and fibrinolysis, the aim of this hypothesis-generating observational study was to document the kinetics of fibrinolysis recovery post-CPB using ClotPro® point-of-care viscoelastometry. Tissue plasminogen activator-induced clot lysis time (TPA LT, s) was correlated with surgical risk, disease severity, organ dysfunction and intensive care length of stay (ICU LOS).

RESULTS

In 52 patients following CPB, TPA LT measured on the first post-operative day (D1) correlated with surgical risk (EuroScore II, Spearman's rho .39, p < .01), time on CPB (rho = .35, p = .04), disease severity (APACHE II, rho = .52, p < .001) and organ dysfunction (SOFA, rho = .51, p < .001) scores, duration of invasive ventilation (rho = .46, p < .01), and renal function (eGFR, rho = -.65, p < .001). In a generalized linear regression model containing TPA LT, CPB run time and markers of organ function, only TPA LT was independently associated with the ICU LOS (odds ratio 1.03 [95% CI 1.01-1.05], p = .01). In a latent variables analysis, the association between TPA LT and the ICU LOS was not mediated by renal function and thus, by inference, variation in the clearance of intraoperative tranexamic acid.

CONCLUSIONS

This observational hypothesis-generating study in patients undergoing cardiac surgery with cardiopulmonary bypass demonstrated an association between the severity of fibrinolysis resistance, measured on the first post-operative day, and the need for extended postoperative ICU level support. Further examination of the role of persistent fibrinolysis resistance on the clinical outcomes in this patient cohort is warranted through large-scale, well-designed clinical studies.

Sirt3 Deletion Increases Inflammation and Mortality in Polymicrobial Sepsis

Background: Sirtuin 3 (SIRT3) is a nicotinamide adenine dinucleotide (NAD)-dependent deacetylase that confers resilience to cellular stress by promoting mitochondrial activity. Mitochondrial dysfunction is a major driver of inflammation during sepsis. We hypothesize that Sirt3 expression improves survival in polymicrobial sepsis by mitigating the inflammatory response. Materials and Methods: Sirt3 knockout (S3KO) and wild-type (WT) mice underwent cecal ligation and puncture (CLP) or sham surgery. mRNA expression was quantified using quantitative polymerase chain reaction (qPCR) and protein expression was quantified using enzyme-linked immunosorbent assay (ELISA). Spectrophotometric assays were used to quantify serum markers of organ dysfunction. For in vitro studies, bone marrow-derived macrophages (BMDMs) were harvested from S3KO and WT mice and treated with lipopolysaccharide (LPS). Results: After CLP, hepatic Sirt3 levels decreased from baseline by nine hours and remained depressed at 24 hours. Peak serum interleukin-6 (IL-6) protein levels were higher in S3KO mice. In LPS-treated BMDMs, IL-6 mRNA levels peaked earlier in S3KO cells, although peak levels were comparable to WT. Although S3KO mice had decreased median survival after CLP compared with WT, there was no difference in five-day survival or organ dysfunction. Conclusions: Although S3KO mice initially had increased inflammation and mortality, this difference abated with time, and overall survival was comparable between the groups. This pattern is consistent with the timeline of sepsis-induced Sirt3 downregulation in WT mice, and suggests that Sirt3 downregulation occurring in sepsis is at least partially responsible for the initial hyperinflammatory response and subsequent mortality. Our data support upregulation of Sirt3 as a promising therapeutic strategy for further research in sepsis.