Haemostatic function in patients undergoing coronary artery bypass grafting: peroperative perturbations and relations to saphenous vein graft closure

Perioperative Renin-Angiotensin System Inhibitors Improve Major Outcomes of Heart Failure Patients Undergoing Cardiac Surgery: A Propensity-Adjusted Cohort Study

OBJECTIVE

The aim of this study was to study the association of perioperative administration of renin angiotensin system inhibitors (RASi) and clinical outcomes of patients with heart failure (HF) undergoing cardiac surgery.

SUMMARY BACKGROUND DATA

It is controversial whether the perioperative RASi should be administered in HF patients undergoing cardiac surgery.

METHODS

A total of 2338 patients with HF and undergoing CABG and/or valve surgeries at multiple hospitals from 2001 to 2015 were identified from STS database. After adjustment using propensity score and instrumental variable, logistic regression was conducted to analyze the influence of preoperative continuation of RASi (PreRASi) on short-term in-hospital outcomes. Independent risk factors of 30-day mortality, major adverse cardiovascular events (MACE), and renal failure were analyzed by use of stepwise logistic regression. The effects of pre- and postoperative use of RASi (PostRASi) on long-term mortality were analyzed using survival analyses. Stepwise Cox regression was conducted to analyze the independent risk factors of 6-year mortality. The relationships of HF status and surgery type with perioperative RASi, as well as PreRASi-PostRASi, were also evaluated by subgroup analyses.

RESULTS

PreRASi was associated with lower incidences of 30-day mortality [ P < 0.0001, odds ratio (OR): 0.556, 95% confidence interval (CI) 0.405-0.763], stroke ( P =0.035, OR: 0.585, 95% CI: 0.355-0.962), renal failure ( P =0.007, OR: 0.663, 95% CI: 0.493-0.894). Both PreRASi ( P =0.0137) and PostRASi ( P =0.007) reduced 6-year mortality compared with the No-RASi groups.

CONCLUSIONS

Pre- and postoperative use of RASi was associated with better outcomes for the patients who have HF and undergo CABG and/or valve surgeries. Preoperative continuation and postoperative restoration are warranted in these patients.

The safety and efficiency of intravenous administration of tranexamic acid in coronary artery bypass grafting (CABG): a meta-analysis of 28 randomized controlled trials

Background

The safety and efficiency of intravenous administration of tranexamic acid (TXA) in coronary artery bypass grafting (CABG) remains unconfirmed. Therefore, we conducted a meta-analysis on this topic.

Methods

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), PUBMED and EMBASE for randomized controlled trials on the topic. The results of this work are synthetized and reported in accordance with the PRISMA statement.

Results

Twenty-eight studies met our inclusion criteria. TXA reduced the incidence of postoperative reoperation of bleeding (relative risk [RR], 0.46; 95% confidence interval [CI]; 0.31–0.68), the frequency of any allogeneic transfusion (RR, 0.64; 95% CI, 0.52–0.78) and the postoperative chest tube drainage in the first 24 h by 206 ml (95% CI − 248.23 to − 164.15). TXA did not significantly affect the incidence of postoperative cerebrovascular accident (RR, 0.93; 95%CI, 0.62–1.39), mortality (RR, 0.82; 95%CI, 0.53–1.28), myocardial infarction (RR, 0.90; 95%CI, 0.78–1.05), acute renal insufficiency (RR, 1.01; 95%CI, 0.77–1.32). However, it may increase the incidence of postoperative seizures (RR, 6.67; 95%CI, 1.77–25.20). Moreover, the subgroup analyses in on-pump and off-pump CABG, the sensitivity analyses in trials randomized more than 99 participants and sensitivity analyses that excluded the study with the largest number of participants further strengthened the above results.

Conclusions

TXA is effective to reduce reoperation for bleeding, blood loss and the need for allogeneic blood products in patients undergoing CABG without increasing prothrombotic complication. However, it may increase the risk of postoperative seizures.

Electronic supplementary material

The online version of this article (10.1186/s12871-019-0761-3) contains supplementary material, which is available to authorized users.

Comparison of Two Miniaturized Cardiopulmonary Bypass Systems Regarding Inflammatory Response

Cardiopulmonary bypass (CPB) is a known mediator of systemic inflammatory response. Extracorporeal circulations are undergoing continuous modifications and optimizations to achieve better results. Hence we aim to compare the inflammatory response associated with two recent miniature extracorporeal circulation systems during normothermic CPB. We measured plasma levels of cytokines including interleukin (IL)-1β, IL-6, IL-10, tumor necrosis factor-α, migration inhibitory factor (MIF), receptor for advanced glycation endproduct, and cluster of differentiation 40 ligand in 60 consecutive patients during the first 24 h after CPB. The patients were prospectively randomized to one of three trial groups: patients in group A were operated with the minimal extracorporeal circulation circuit (MECC, Maquet, Rastatt, Germany), group B operated with the extracorporeal circulation circuit optimized (ECC.O, Sorin, Italy), and group C operated with a conventional extracorporeal circuit (CECC, Maquet). Arterial blood samples were collected at intervals before, 30 min after initiation, and after termination of CPB. Further samples were collected 6 and 24 h after CPB. IL-10 levels were significantly raised in the CECC group as compared with either of the mini ECC-circuits with a peak concentration at 6 h postoperatively. Human MIF concentrations were significantly higher in the CECC group starting 30 min after CPB and peaking at the end of CPB. The overall reduction in cytokine concentrations in the mini-ECC groups correlated with a lower need for blood transfusion in MECC and a shorter mechanical ventilation time for ECC.O. Normothermic CPB using minimally invasive extracorporeal circulation circuits can reduce the inflammatory response as measured by cytokine levels, which may be beneficial for perioperative preservation of pulmonary function and hemostasis in low risk patients.

Biomarkers in Coronary Artery Bypass Surgery: Ready for Prime Time and Outcome Prediction?

Coronary artery bypass surgery (CABG) is still one of the most frequently performed surgical procedures all over the world. The results of this procedure have been constantly improved over the years with low perioperative mortality rates, with relatively low complication rates. To further improve these outstanding results, the clinicians focused their attention at biomarkers as outcome predictors. Although biological testing for disease prediction has already been discussed many times, the role of biomarkers in outcome prediction after CABG is still controversial. In this article, we reviewed the current knowledge regarding the role of genetic and dynamic biomarkers and their possible association with the occurrence of adverse clinical outcomes after CABG. We also took into consideration that the molecular pathway activation and the possible imbalance may affect hard outcomes and graft patency. We analyzed biomarkers classified in two different categories depending on their possibility to change over time: genetic markers and dynamic markers. Moreover, we evaluated these markers by dividing them, into sub-categories, such as inflammation, hemostasis, renin–angiotensin, endothelial function, and other pathways. We showed that biomarkers might be associated with unfavorable outcomes after surgery, and in some cases improved outcome prediction. However, the identification of a specific panel of biomarkers or of some algorithms including biomarkers is still in an early developmental phase. Finally, larger studies are needed to analyze broad panel of biomarkers with the specific aim to evaluate the prediction of hard outcomes and graft patency.

Stimulated in vivo synthesis of plasminogen activator inhibitor-1 in human adipose tissue

Plasminogen activator inhibitor type-1 (PAI-1) is one of the most important inhibitors of endogenous fibrinolysis. Adipose tissue is a suggested source of the elevated plasma levels of PAI-1 in obesity. The relation between PAI-1 and inflammation is of particular interest, but current knowledge regarding regulation of PAI-1 in adipose tissue is mainly based on animal studies or ex vivo experiments on human cultured adipocytes. So far, no study has described stimulated gene expression and protein synthesis of PAI-1 in vivo in human adipose tissue. We used open heart surgery as a model of acute systemic inflammation. Twenty-two male patients underwent blood sampling and omental and subcutaneous adipose tissue biopsies for gene expression studies before and after surgery. Expression and localisation of PAI-1 antigen was evaluated by immunohistochemistry. After surgery gene expression of PAI-1 increased 27-fold in omental adipose tissue and three-fold in subcutaneous adipose tissue, but no differences were found in tissue-type plasminogen activator (t-PA) mRNA. PAI-1 antigen was localised within endothelial cells and in the adipose tissue interstitium close to vessels. The upregulated gene expression and protein synthesis in adipose tissue was followed by increased concentrations of PAI-1 antigen in plasma. In conclusion, we present for the first time that an acute systemic inflammation in humans increased gene expression and protein synthesis of PAI-1 in adipose tissue and that this increase was most prominent in omental adipose tissue. PAI-1 synthesis in adipose tissue due to acute systemic inflammation may be a link between inflammation and impaired endogenous fibrinolysis.

Hypercoagulability and platelet inhibition after OPCAB. Randomized intervention with clopidogrel

OBJECTIVE

Data on graft patency after Off-Pump Coronary Artery Bypass (OPCAB) suggest that the incidence of early graft closure is not increased compared to conventional coronary artery bypass surgery. However, hypercoagulability following OPCAB is still of concern, and acetylsalicylic acid as thromboembolic prophylaxis might be insufficient in the first weeks following OPCAB surgery.

DESIGN

Twenty nine patients were randomly assigned to+/- 75 mg of clopidogrel until 30 days after OPCAB surgery. The follow-up time was 2 months including standard blood samples and thrombelastography (TEG) with a specific platelet inhibition assay, which was evaluated as a part of the study.

RESULTS

In both groups a significant increase in TEG maximum amplitude was found 5 days after surgery. Platelet inhibition showed great variations but was significantly increased in the clopidogrel group (34.1%) vs. control group (11.0%) after 1 month.

CONCLUSION

Hypercoagulability was seen 5 days after OPCAB and could not be demonstrated after 1 month. No clinical effects of the hypercoagulability were observed, and further research is needed to determine if clopidogrel should be recommended after OPCAB.

Coagulation and fibrinolytic protein kinetics in cardiopulmonary bypass

The development of Cardiopulmonary Bypass (CPB) catopulted the field of cardiothoracic surgery into a new dimension--one that changed the lives of individuals with congenital and acquired heart disease worldwide. Despite its contributions, CPB has clear limitations and creates unique challenges for clinicians and patients alike, stemming from profound hemostatic pertubations and accompanying risk for bleeding and possibly thrombotic complications.

Does off-pump coronary artery bypass surgery reduce secretion of plasminogen activator inhibitor-1?

Prior studies showed that postoperative increase in plasminogen activator inhibitor-1 (PAI-1) levels is associated with an increased risk of graft occlusion after coronary artery bypass surgery (CABG). This prospective study aimed to compare the changes of PAI-1 antigen levels after off-pump and on-pump CABG. Forty-four patients admitted for elective CABG were randomised to on-pump (n=22) or off-pump (n=22) surgery. Serum samples were collected for estimation of PAI-1 and tissue plasminogen activator (t-PA) antigen levels preoperatively and 2 h after the operation. The groups were similar in terms of age, weight, gender ratio and extent of coronary disease, left ventricular function and number of grafts per patient. Fibrinogen and t-PA levels increased postoperatively in both the groups when compared with baseline values. After operation, statistical analysis revealed that increase of PAI-1 values was higher in off-pump group (44.1+/-9.1 vs. 25.3+/-6.9) than on-pump group (37.2+/-5.5 vs. 27.3+/-7.8, p=0.002). This study shows that increase in PAI-1 antigen values in patients who undergo off-pump (beating heart) CABG is significantly higher than in those who undergo conventional CABG with cardiopulmonary bypass.

Preoperative C-Reactive Protein Predicts Mid-Term Outcome After Cardiac Surgery

BACKGROUND

C-reactive protein (CRP) is a known risk factor for cardiovascular events in the healthy population and in patients with coronary artery disease. High CRP levels before cardiac surgery are associated with worse short-term outcome, but its role after discharge home remains unknown. The study objective was to evaluate the effect of CRP on short-term and mid-term outcome after cardiac surgery.

METHODS

From August 2000 to May 2004, values for preoperative CRP were available for 597 unselected patients undergoing cardiac operations. CRP was used to divide this cohort in two groups: a low inflammatory status (LHS) group of 354 patients with CRP of less than 0.5 mg/dL, and a high inflammatory status (HIS) group of 243 patients with a CRP of 0.5 mg/dL or more. Follow-up lasted a maximum of 3 years (median, 1.8 +/- 1.5 years) and was 92.6% complete.

RESULTS

In-hospital mortality was 8.2% in the HIS group and 3.4% in the LIS group (odds ratio [OR], 2.61; p = 0.02). Incidence of postoperative infections was 16.5% in the HIS group and 5.1% in the LIS group (OR, 3.25; p = 0.0001). Sternal wound infections were also more frequent in the HIS group (10.7% versus 2.8%; OR, 3.43; p = 0.002). During follow-up, the HIS group had worse survival (88.5% +/- 2.9% versus 91.9% +/- 2.5%; OR, 1.93; p = 0.05) and a higher need of hospitalization for cardiac-related causes (73.6% +/- 6% versus 86.5% +/- 3.2%; OR, 1.82; p = 0.05).

CONCLUSIONS

Patients undergoing cardiac surgery with a CRP level of 0.5 mg/dL or more are exposed to a higher risk of in-hospital mortality and postoperative infections. Despite surgical correction of cardiac disease, a high preoperative CRP value is an independent risk factor for mid-term survival and hospitalization for cardiac causes.

Activation of the coagulation system during coronary artery bypass grafting: Comparison between on-pump and off-pump techniques

OBJECTIVE

The activation of the coagulation and fibrinolytic systems and platelet function in patients undergoing coronary artery bypass surgery on-pump or off-pump techniques was compared.

METHODS

Thirty-two patients were randomly assigned to on-pump or off-pump coronary artery bypass grafting. Heparin was given at the same dose. Activation of the coagulation and fibrinolytic systems was evaluated by measurement of several markers. Platelet function was evaluated by in vitro bleeding time test. Blood samples were collected at 7 different times, up to postoperative day 6.

RESULTS

Overall tissue factor production was similar in the two groups. Thrombin formation was more elevated in the on-pump group (P < .001), particularly during the operation; prothrombin fragment 1.2 discharge values were higher than the preoperative ones (P = .002). Levels of tissue-plasminogen activator showed no difference between the groups (P = .1). D-dimers release was higher in the on-pump group (P = .0002). In vitro bleeding time was longer in the on-pump group (P < .0001), particularly in the first 24 hours; it was not prolonged in the off-pump group. In both groups, regardless of aspirin treatment, discharge in vitro bleeding times were lower than the preoperative ones (P < .01).

CONCLUSION

Although the extrinsic coagulation pathway is similarly activated, thrombin formation is more pronounced in patients having on-pump bypass grafting. Patients subjected to off-pump bypass grafting have normally functioning platelets and a weak activation of the fibrinolytic system. At discharge, both groups have preserved platelet function and increased thrombin formation. Further studies with angiographic evaluation are needed to establish a correlation between coagulation parameters, platelet function, and graft patency.

Hypercoagulability affecting early vein graft patency does not exist after off-pump coronary artery bypass

OBJECTIVE

Hypercoagulability may compromise the patency of bypass grafts. The authors hypothesized that perioperative in vitro platelet responses to varying agonists (eg, thrombin, platelet activating factor, collagen, adenosine diphosphate) correlate with early graft thrombosis after off-pump coronary artery bypass grafting (OPCAB).

DESIGN AND PARTICIPANTS

Prospective study of 78 OPCAB patients with 151 venous bypass grafts treated with perioperative aspirin and intraoperative heparin (250 U/kg).

SETTING

Tertiary, academic medical center.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Hypercoagulability, defined by TEG (maximum amplitude [MA]>70 mm), whole-blood aggregometry (>15 ohms after 5 mcl/mL collagen) or hemoSTATUS (Ch5CR>0.5), was serially assessed around OPCAB. An immediate decline in platelet function after surgery and on postoperative day 1 returned to normal by postoperative day 3 in most patients. Graft blood flow was analyzed intraoperatively, and vein biopsies were analyzed for endothelial disruption. Graft patency was assessed by multichannel computed tomography coronary angiography on postoperative day 5. No differences in any of the platelet function assays were noted for the 8 patients with graft thrombosis (n=8 grafts) versus the 68 patients with all patent grafts (n=129 grafts). Ten patients developed a rise in platelet function postoperatively >1 SD above baseline; only 1 developed graft thrombosis (p=not significant v patients with normal platelet function).

CONCLUSIONS

OPCAB is not associated with a significant activation in postoperative platelet function. This study suggests that if hypercoagulability exists after OPCAB, it is not involved in the pathogenesis of arterial thrombotic events such as early bypass graft failure.

Elevated levels of low-density lipoprotein cholesterol, homocysteine, and lipoprotein(a) are associated with the occurrence of symptomatic bypass graft disease 1 year following coronary artery bypass graft surgery

Severe coronary artery bypass graft disease occurs at a rate of approximately 16%-31% within the first year of surgery. Clinical and laboratory variables, including postoperative lipid profiles closest to the 1-year follow-up, lipoprotein(a) levels, and homocysteine levels, were assessed as predictors of early (< or = 1 year) symptomatic coronary artery bypass graft disease. Of 77 living consecutive patients (from the practice of one cardiologist) who underwent bypass surgery, 60 were asymptomatic at 1 year, and 17 had developed recurrent symptoms and had an angiogram that confirmed >50% lesion in at least one saphenous bypass graft. Using multivariate analysis, the strongest predictors of early symptomatic coronary artery bypass graft disease within 1 year of bypass surgery were elevated levels of low-density lipoprotein cholesterol (>100 mg/dL) (odds ratio [OR], 8:1; p=0.034), homocysteine (>10 micromol/L) (OR, 8:1; p=0.019), and lipoprotein(a) (>30 mg/dL) (OR, 4:1; p=0.011). Male gender was associated with a reduced risk (OR, 1:9; p=0.01) of symptomatic graft disease within 1 year of surgery. The authors conclude that low-density lipoprotein, homocysteine, and lipoprotein(a) levels are associated with symptomatic coronary artery bypass graft disease at 1 year after surgery.

Angiotensin-converting enzyme inhibition alters the fibrinolytic response to cardiopulmonary bypass

BACKGROUND

Increased plasminogen activator inhibitor-1 (PAI-1) concentrations after coronary artery bypass grafting (CABG) are associated with increased risk of vein graft occlusion. Because angiotensin II stimulates PAI-1 expression, we tested the hypothesis that preoperative angiotensin-converting enzyme (ACE) inhibition decreases PAI-1 expression after CABG.

METHODS AND RESULTS

We measured the effects of cardiopulmonary bypass (CPB) on PAI-1 antigen and tissue-type plasminogen activator (tPA) antigen and activity in 31 patients taking an ACE inhibitor (ACEI) who were randomized to continue ACEI until the morning of surgery (ACEI group, n=19) or to discontinue it 48 hours before surgery (No-ACEI group, n=12). Arterial blood samples were taken at baseline before CPB, twice during CPB, after separation from CPB, and on postoperative day 1 (POD1). CPB caused an early decrease in PAI-1 antigen, followed by an increase in PAI-1 antigen on POD1 (P<0.001 for effect of time). ACE inhibition attenuated the increase in PAI-1 antigen such that both PAI-1 antigen on POD1 (P=0.013) and the change in PAI-1 antigen from baseline to POD1 (P=0.009) were higher in the No-ACEI group (from 17.0+/-5.0 to 48.7+/-8.8 ng/mL) versus the ACEI group (from 19.9+/-3.4 to 33.1+/-6.2 ng/mL). There was no significant difference between the 2 groups in intraoperative tPA activity (P=0.259); however, the increase in tPA activity was significantly greater in the ACEI group than in the No-ACEI group (P=0.030).

CONCLUSIONS

Preoperative ACEI attenuates the increase in PAI-1 after CABG, suggesting a role for ACE inhibition in reducing the risk of acute graft thrombosis.

Association of lipoprotein(a) excess with early vein graft occlusions in middle-aged men undergoing coronary artery bypass surgery

OBJECTIVE

To assess the relationship of lipoprotein(a) to early vein graft occlusions in patients after coronary artery bypass grafting.

METHODS

We studied 102 male patients (mean age 52.3 +/- 8.6 years) with chest pain occurrence during the first year (mean time 5.3 +/- 3.0 months) after surgical myocardial revascularization. Graft patency was examined by electron-beam computed tomography (n = 102) and quantitative coronary angiography (n = 31).

RESULTS

Patients were divided into 2 groups according to graft patency data: 66 (65%) with occlusions and 36 (35%) without occlusions at follow-up. No significant differences were found between the groups concerning age, smoking, family history of coronary heart disease, previous myocardial infarction, hypertension, serum lipids, and apolipoprotein B. Lipoprotein(a) level was significantly higher in patients with occluded grafts with a median (95% confidence intervals) of 24 mg/dL (17-42 mg/dL) versus 12 mg/dL (6-24 mg/dL) in patients with patent grafts, P <.01. More patients with nonoccluded grafts were taking statins postoperatively: 42% versus 18% of patients with occluded grafts, P <.05. The sensitivity and specificity of electron-beam computed tomography in revealing vein graft occlusion was close to 100%.

CONCLUSION

There is an association between high lipoprotein(a) level and vein graft occlusions in middle-aged men during the first year after coronary artery bypass grafting. Use of statins is associated with a lower rate of vein graft occlusion. Electron-beam tomography could be useful for assessing graft occlusions.

Coagulation and fibrinolytic markers in a two-month follow-up of coronary bypass surgery

OBJECTIVES

The alterations of the coagulation-fibrinolytic profile immediately and up to few days after cardiac surgery have been widely documented. However, less information is available on whether these alterations persist for prolonged periods of time after the operation. In this study we have evaluated the coagulation-fibrinolytic profile of patients who underwent coronary artery surgery with cardiopulmonary bypass during a 2-month follow-up period.

METHODS

Twenty-six patients (age range, 50-75 years) were studied. Blood samples were collected before the intervention and at different time points postoperatively up to 2 months after the operation. Measurement of selected coagulation-fibrinolytic variables was carried out in plasma from 16 patients. Evaluation of tissue factor activity determined as procoagulant activity was performed in peripheral blood mononuclear leukocytes obtained from 10 patients.

RESULTS

Antigenic levels of clottable fibrinogen, prothrombin fragment F1.2, D-dimer, and thrombin-antithrombin complex were significantly increased during the first week after the intervention compared with preoperative values. Prothrombin fragment F1.2 levels returned to normal within 15 days, fibrinogen levels normalized within 30 days, and thrombin-antithrombin complex levels normalized at 45 days, whereas D-dimer values were still significantly higher 60 days postoperatively respective to baseline values. There was a trend toward an increased procoagulant activity from peripheral blood mononuclear leukocytes 4 days after the operation, whereas no changes of factor VII measured either as antigen or in its coagulant and activated forms were recorded throughout the study.

CONCLUSIONS

A marked activation of the coagulation-fibrinolytic system occurs after cardiopulmonary bypass and lasts for at least 2 months thereafter. This finding suggests that these alterations might account for the increased thrombotic risk of these patients during the postoperative period.

Coagulation system activity before coronary artery bypass surgery for unstable angina

OBJECTIVE

To measure coagulation activity immediately prior to coronary artery bypass surgery. Previous reports have shown that a hypercoagulable state and reduced fibrinolytic activity increase the risk of postoperative graft failure.

DESIGN

Fifty patients with unstable angina and ongoing low-molecular-weight heparin antithrombotic treatment for a median of 4 days and 25 stable patients undergoing elective surgery were included.

RESULTS

Antithrombin levels were significantly lower whereas fibrinogen and plasminogen activator inhibitor-1 levels were higher in the unstable patients than in the stable patients. Median preoperative levels of thrombin-antithrombin complex (TAT), prothrombin fragment1+2 (F1+2), fibrin D-dimers and beta-thromboglobulin did not differ significantly in unstable and stable patients. There were signs of activated coagulation with elevated levels of TAT and F1+2 before the operation in half of the unstable patients, who had had chest pain at rest within 48 h preceding the operation and also in one-third of patients undergoing elective surgery.

CONCLUSION

A hypercoagulable state may be present in unstable as well as in stable angina pectoris patients accepted for coronary artery bypass surgery.