High-Dose Aprotinin in Cardiac Surgery: Is High-Dose High Enough?

Living without aprotinin: the results of a 5-year blood saving program in cardiac surgery

BACKGROUND

After 20 years of regular use in cardiac surgery patients, aprotinin has recently been withdrawn from the market due to many concerns about its safety. For a number of reasons aprotinin has not been available in Italy since 1998. The present study presents an aprotinin-free treatment protocol applied at our institution during the last 5 years, and aims to verify the results of this protocol in terms of allogeneic blood product transfusions, postoperative blood loss and surgical re-exploration rate.

METHODS

Retrospective study on 7988 consecutive patients who underwent cardiac surgery during the years 2003-2007. All the patients received specific hemostasis/coagulation management based on (a) routine use of tranexamic acid, (b) heparin dose-response monitoring, thromboelastography, platelet (PLT) function analysis in a select population of patients, and (c) use of fresh frozen plasma (FFP), PLTs, and desmopressin according to the hemostasis/coagulation profile. Data retrieved from the institutional database were quantity of packed red cells (PRCs), FFP, PLT transfusion rate, blood loss in the first 12 postoperative hours, and surgical re-exploration rate.

RESULTS

PRCs were transfused in 40.4% of patients (with higher rates for selected high-risk subpopulations), FFP in 12.9% and PLTs in 2.6%. Surgical re-exploration rate was 3.7%. With respect to historical controls, a significant reduction of PRCs and FFP transfusions was obtained using closed circuits, point of care coagulation tests, and combination of the two.

CONCLUSION

This aprotinin-free blood saving program is an effective strategy for allogeneic blood products transfusion containment.

Aprotinin stimulates angiogenesis and human endothelial cell migration through the growth factor pleiotrophin and its receptor protein tyrosine phosphatase beta/zeta

Pleiotrophin is an 18 kDa secreted polypeptide growth factor with direct pro-angiogenic and tumorigenic properties. Pleiotrophin is a substrate for proteolytic enzymes, such as plasmin, leading to proteolytic fragments with distinct activities on endothelial cell activation in vitro or angiogenesis in vivo. Aprotinin is a naturally occurring broad spectrum protease inhibitor, used widely in cardiac surgery due to its ability to inhibit plasmin and reduce perioperative bleeding. Since we have seen that aprotinin inhibits proteolysis of pleiotrophin by plasmin, the aim of the present study was to evaluate the possible role of pleiotrophin in the effects of aprotinin on angiogenesis and human endothelial cell migration. Our data demonstrate that aprotinin, in a concentration-dependent manner, is angiogenic in the chicken embryo chorioallantoic membrane assay in vivo and induces human endothelial cell migration in vitro. Aprotinin inhibits pleiotrophin proteolysis and induces expression and secretion of pleiotrophin through an AP-1-dependent transcriptional activation of the pleiotrophin gene, and pleiotrophin seems to mediate the stimulatory effects of aprotinin on cell migration through its receptor protein tyrosine phosphatase beta/zeta. The stimulatory effect of aprotinin on pleiotrophin expression and cell migration may explain, at least partly, the problems observed with the clinical use of aprotinin.

Aprotinin in primary cardiac surgery: operative outcome of propensity score-matched study

BACKGROUND

Some recent multicenter series have questioned the safety of aprotinin in primary cardiac operations. We report a large, single-center experience with aprotinin therapy in primary cardiac operations and discuss the limitations and potential confounders of current treatment strategies.

METHODS

We compared myocardial infarction, neurologic events, renal insufficiency, and operative death after first-time coronary or valve procedures, or both, in 3334 patients treated with full-dose aprotinin with 3417 patients not treated with aprotinin who underwent operation between March 1998 and January 2007. Further analysis was performed for 341 propensity score-matched pairs.

RESULTS

There were substantial differences between the groups. Aprotinin patients were higher risk on account of older age, unstable symptoms, poor ejection fraction, preoperative hemodynamic support, emergency/urgent operations, and combined coronary/valve operations. Postoperative bleeding and blood product transfusion were considerably reduced in aprotinin patients, as was median duration of mechanical ventilation. Aprotinin was neither a predictor of postoperative myocardial infarction, renal insufficiency, neurologic dysfunction, or operative death. Achieving parity between the groups by propensity score matching eliminated the elevated rates of postoperative renal insufficiency, neurologic dysfunction, and operative death observed in aprotinin patients in the unmatched comparison. These adverse outcomes were evenly distributed between matched groups. Conversely, blood transfusion had univariate associations with all adverse outcome measures.

CONCLUSIONS

Full-dose aprotinin use was not associated with myocardial infarction, neurologic dysfunction, renal insufficiency, or death after coronary or valve operations. We observed less postoperative bleeding and blood product transfusion, and early extubation with the use of aprotinin.

Is aprotinin safe to use in a cohort at increased risk for thrombotic events: results from a randomized, prospective trial in off-pump coronary artery bypass

BACKGROUND

Multiple randomized trials have established a favorable safety profile for aprotinin use during cardiac surgery, but recent database analyses suggest an increased risk of adverse thrombotic events. Our group previously demonstrated that off-pump coronary artery bypass (OPCAB) is linked to a postoperative hypercoagulable state. In this study, we tested whether aprotinin influences thrombotic events after OPCAB.

METHODS

Patients randomly received saline (n = 61) or aprotinin (2 x 10(6) kallikrein inhibiting units (KIU) loading dose, 0.5 x 10(6) KIU/hour [n = 59]) during OPCAB. Aprotinin levels (KIU/mL) were analyzed before, and 30 minutes (peak) and 4 hours after the loading dose. Estimated glomerular filtration rate (eGFR) was calculated daily based on Cockcroft equation with acute kidney injury (AKI) defined as eGFR less than 75% of baseline. Major adverse cardiac and cerebrovascular events (MACCE) were monitored during the first year, including acute graft failure by predischarge computed tomographic angiography.

RESULTS

Compared with placebo, the aprotinin group developed a significantly lower eGFR on day 3 (p < 0.006), but this difference resolved by day 5. Peak aprotinin level correlated with the degree of eGFR decline noted on day 3 (r = 0.56, p < 0.03) and independently predicted postoperative AKI (odds ratio 8.8, p < 0.008). The receiver operating characteristic analysis demonstrated that peak aprotinin level strongly predicts AKI (area under the curve = 0.86, 95% confidence interval 0.69 to 1.00). The percentage of patients reaching the composite MACCE endpoint was significantly reduced in the aprotinin versus placebo group (12 vs 34%, p = 0.01).

CONCLUSIONS

Compared with placebo, aprotinin use was associated with less MACCE but more AKI after OPCAB. The strong relationship between the peak aprotinin level and subsequent AKI suggests weight-based protocols for dosing aprotinin may reduce this risk.

Anti-inflammatory actions of aprotinin provide dose-dependent cardioprotection from reperfusion injury

BACKGROUND AND PURPOSE

Myocardial injury following ischaemia and reperfusion has been attributed to activation and transmigration of polymorphonuclear leukocytes (PMNs) with release of mediators including oxygen-derived radicals and proteases causing damage.

EXPERIMENTAL APPROACH

We studied the serine protease inhibitor aprotinin in an in vivo rabbit model of 1 h of myocardial ischaemia followed by 3 h of reperfusion (MI+R). Aprotinin (10,000 Ukg(-1)) or its vehicle were injected 5 min prior to the start of reperfusion.

KEY RESULTS

Myocardial injury was significantly reduced with aprotinin treatment as indicated by a reduced necrotic area (11+/-2.7% necrosis as percentage of area at risk after aprotinin; 24+/-3.1% after vehicle; P<0.05) and plasma creatine kinase activity (12.2+/-1.5 and 17.3+/-2.3 IU g(-1) protein in aprotinin and vehicle groups, respectively, P<0.05). PMN infiltration (assessed by myeloperoxidase activity) was significantly decreased in aprotinin-treated animals compared to vehicle (P<0.01). Histological analysis also revealed a substantial increase in PMN infiltration following MI+R and this was significantly reduced by aprotinin therapy (44+/-15 vs 102+/-2 PMN mm2 in aprotinin vs vehicle-treated animals, P<0.05). In parallel in vitro experiments, aprotinin inhibited neutrophil-endothelium interaction by reducing PMN adhesion on isolated, activated aortic endothelium. Finally, immunohistochemical analysis illustrated aprotinin significantly reduced myocardial apoptosis following MI+R.

CONCLUSIONS AND IMPLICATIONS

Inhibition of serine proteases by aprotinin inhibits an inflammatory cascade initiated by MI+R. The cardioprotective effect appears to be at least partly due to reduced PMN adhesion and infiltration with subsequently reduced myocardial necrosis and apoptosis.

The effect of aprotinin on outcome after coronary-artery bypass grafting

BACKGROUND

Aprotinin has recently been associated with adverse outcomes in patients undergoing cardiac surgery. We reviewed our experience with this agent in patients undergoing cardiac surgery at Duke University Medical Center.

METHODS

We retrieved data on 10,275 consecutive patients undergoing surgical coronary revascularization at Duke between January 1, 1996, and December 31, 2005. We fit data to a logistic-regression model predicting each patient's likelihood of receiving aprotinin on the basis of preoperative characteristics and to models predicting long-term survival (up to 10 years) and decline in renal function, as measured by increases in serum creatinine levels.

RESULTS

A total of 1343 patients (13.2%) received aprotinin, 6776 patients (66.8%) received aminocaproic acid, and 2029 patients (20.0%) received no antifibrinolytic therapy. All patients underwent coronary-artery bypass grafting, and 1181 patients (11.5%) underwent combined coronary-artery bypass grafting and valve surgery. In the risk-adjusted model, survival was worse among patients treated with aprotinin, with a main-effects hazard ratio for death of 1.32 (95% confidence interval [CI], 1.12 to 1.55) for the comparison with patients receiving no antifibrinolytic therapy (P=0.003) and 1.27 (95% CI, 1.10 to 1.46) for the comparison with patients receiving aminocaproic acid (P=0.004). As compared with the use of aminocaproic acid or no antifibrinolytic agent, aprotinin use was also associated with a larger risk-adjusted increase in the serum creatinine level (P<0.001) but not with a greater risk-adjusted incidence of dialysis (P=0.56).

CONCLUSIONS

Patients who received aprotinin had a higher mortality rate and larger increases in serum creatinine levels than those who received aminocaproic acid or no antifibrinolytic agent.

Effect of aprotinin on renal dysfunction in patients undergoing on-pump and off-pump cardiac surgery: a retrospective observational study

BACKGROUND

Aprotinin is used during cardiac surgery for its blood-saving effects. However, reports suggest a possible association between use of this drug and increased renal dysfunction and mortality. We investigated the effect of aprotinin on renal dysfunction in cardiac surgery, considering the cofactors on-pump versus off-pump surgery and co-medication with angiotensin-converting enzyme (ACE) inhibitors.

METHODS

Our analysis included 9875 patients undergoing on-pump or off-pump cardiac surgery from Jan 1, 2000, to Sept 30, 2007. Of these patients, 9106 were included in the retrospective observational study analysis. With propensity-adjusted, multivariate staged logistic regression, we analysed separately the incidence of renal dysfunction in patients receiving aprotinin, tranexamic acid, or no antifibrinolytic treatment in the presence or absence of preoperative ACE inhibitor treatment, for both on-pump and off-pump surgical techniques.

FINDINGS

In 5434 patients undergoing on-pump cardiac surgery, the odds ratio (OR) between aprotinin and an increased risk of renal dysfunction without ACE inhibitor was 1.81 (95% CI 0.79-4.13, p=0.162) and with ACE inhibitor 1.73 (0.56-5.32, p=0.342). In the 848 patients taking ACE inhibitors and undergoing off-pump cardiac surgery, aprotinin was associated with a greater than two-fold increase in the risk of renal dysfunction after off-pump cardiac surgery (OR 2.87 [1.25-6.58], p=0.013).

INTERPRETATION

Our results have shown that aprotinin seems to be safe during on-pump cardiac surgery. However, the combination of aprotinin and ACE inhibitors during off-pump cardiac surgery is associated with a significant risk of postoperative renal dysfunction.

Aprotinin and anaphylaxis: analysis of 12,403 exposures to aprotinin in cardiac surgery

BACKGROUND

Hypersensitivity reactions to the nonspecific proteinase inhibitor aprotinin may occur. The present study evaluates the incidence of hypersensitivity reactions to aprotinin.

METHODS

Data were prospectively collected as part of the institution's quality assurance program. The database was screened for anaphylactic reactions, especially those against aprotinin. The definition of an allergic reaction was predefined. A severe reaction was defined as hemodynamic instability of more than 10 minutes despite high dosages of vasopressors and inotropic medication.

RESULTS

Of 13,315 cardiac operations, 12,403 were done with aprotinin, with 801 reexposures in 697 patients. Eleven reactions to aprotinin (11 of 11,602; 0.09%, 95% confidence interval: 0.05% to 0.16%) were recorded after primary exposure, of which none was severe, while 12 reactions (12 of 801; 1.5%; 95% confidence interval: 0.86% to 2.6%) occurred after reexposure, of which 5 were severe. All severe reactions were in patients reexposed to aprotinin within 6 months after previous exposure. There was no reaction observed in patients reexposed to aprotinin within 3 days after the last exposure (n = 42). The incidence of hypersensitivity reactions was 4.1%, 1.9%, and 0.4% in the less than 6 months, 6 to 12 months, and more than 12 months reexposure intervals, respectively.

CONCLUSIONS

The risk of hypersensitivity reactions is low after primary exposure to aprotinin. This risk after reexposure reaches a maximum between the fourth day and the 30th day after previous exposure and declines considerably after 6 months. Consequently, application of aprotinin carries a high risk between the fourth and the 30th day after previous exposure, and cannot be recommended for the first 6 months, but is justifiable in previously aprotinin-exposed patients with a high risk of bleeding after this interval.

Cardiac surgery with cardiopulmonary bypass: does aprotinin affect outcome?

BACKGROUND

Aprotinin, a non-specific serine protease inhibitor, has been used for two decades to reduce perioperative blood loss and the risk for allogeneic transfusion in cardiac surgery. This study evaluated the effects of aprotinin on outcome (mortality, cardiac events, renal failure, and cerebrovascular events) in such patients undergoing cardiac surgery with cardiopulmonary bypass.

METHODS

Data were obtained in patients who received a strict blood conservation protocol: no antifibrinolytic therapy when at low risk (n = 854) and aprotinin (n = 1210) when at high risk for blood transfusion. Relative risk of different pre- and intra-operative variables was calculated for the different outcome variables. Backward stepwise logistic regression analysis was used to identify the independent risk factors associated with the different outcome variables. Statistical significance was accepted at P < 0.01.

RESULTS

Postoperative mortality and morbidity were higher in the aprotinin group but this was related to an increased incidence of perioperative risk factors. Mortality was similar to that predicted by the Euroscore. Complex surgery was the only independent variable associated with postoperative cardiac events. Preoperative heart failure, preoperative creatinine > 1.5 mg dl(-1), urgent, and redo surgery were the independent variables associated with postoperative haemodialysis. Age > 70 yr was identified as the only independent variable associated with neurologic dysfunction.

CONCLUSIONS

In the present study, patients receiving aprotinin as part of a strict blood conservation strategy represent a population at high risk for postoperative complications. For the outcome variables studied, aprotinin administration was not identified as an independent risk factor.

Aprotinin in Cardiac Surgery: A Review of Conventional and Novel Mechanisms of Action

Induction of the coagulation and inflammatory cascades can cause multiorgan dysfunction after cardiopulmonary bypass (CPB). In light of these observations, strategies that can stabilize the coagulation process as well as attenuate the inflammatory response during and after cardiac surgery are important. Aprotinin has effects on hemostasis. In addition, aprotinin may exert multiple biologically relevant effects in the context of cardiac surgery and CPB. For example, it decreases neutrophil and macrophage activation and chemotaxis, attenuates release and activation of proinflammatory cytokines, and reduces oxidative stress. Despite these perceived benefits, the routine use of aprotinin in cardiac surgery with CPB has been called into question. In this review, we examined this controversial drug by discussing the classical and novel pathways in which aprotinin may be operative in the context of cardiac surgery.

Effects of Aprotinin on Gene Expression and Protein Synthesis After Ischemia and Reperfusion in Rats

Background— Reperfusion injury of ischemic myocardium has been attributed to neutrophil infiltration, inflammatory activation and cardiac necrosis/apoptosis. Serine protease inhibition with aprotinin is cardioprotective, but the mechanism is unknown.

Methods and Results— We studied aprotinin in a rat model of myocardial ischemia for 20 minutes and reperfusion for 20 minutes, 8 hours or 24 hours. Aprotinin (20 000 IU/kg) given 5 minutes before reperfusion significantly reduced leukocyte accumulation ( P <0.01), myocardial injury (determined by CK depletion, P <0.01) and myocyte apoptosis ( P <0.05) compared with vehicle treated rats. Differential gene expression analysis showed myocardial ischemia plus reperfusion increased expression of proinflammatory genes like P-selectin, E-selectin, intercellular adhesion molecule, tumor necrosis factor-α, tumor necrosis factor-α receptor, interleukin-6, monocyte chemoattractant protein-1, p53, and Fas (CD59). Aprotinin before reperfusion suppressed expression of these inflammatory genes. Finally, differential protein expression analysis demonstrated increased intercellular adhesion molecule-1, tumor necrosis factor-α, and p53 after myocardial ischemia plus reperfusion, and this effect was diminished by aprotinin.

Conclusions— We demonstrated myocardial ischemia plus reperfusion induced leukocyte accumulation, inflammation, gene expression, protein expression and finally tissue injury and showed aprotinin limiting reperfusion injury through each of these stages, even after 24 hours of reperfusion. This effect seems partly attributable to suppression of proinflammatory genes and leukocyte accumulation. This work casts further light on the complex signaling of ischemia and reperfusion.