A comparison of aprotinin and lysine analogues in high-risk cardiac surgery

BACKGROUND

Antifibrinolytic agents are commonly used during cardiac surgery to minimize bleeding and to reduce exposure to blood products. We sought to determine whether aprotinin was superior to either tranexamic acid or aminocaproic acid in decreasing massive postoperative bleeding and other clinically important consequences.

METHODS

In this multicenter, blinded trial, we randomly assigned 2331 high-risk cardiac surgical patients to one of three groups: 781 received aprotinin, 770 received tranexamic acid, and 780 received aminocaproic acid. The primary outcome was massive postoperative bleeding. Secondary outcomes included death from any cause at 30 days.

RESULTS

The trial was terminated early because of a higher rate of death in patients receiving aprotinin. A total of 74 patients (9.5%) in the aprotinin group had massive bleeding, as compared with 93 (12.1%) in the tranexamic acid group and 94 (12.1%) in the aminocaproic acid group (relative risk in the aprotinin group for both comparisons, 0.79; 95% confidence interval [CI], 0.59 to 1.05). At 30 days, the rate of death from any cause was 6.0% in the aprotinin group, as compared with 3.9% in the tranexamic acid group (relative risk, 1.55; 95% CI, 0.99 to 2.42) and 4.0% in the aminocaproic acid group (relative risk, 1.52; 95% CI, 0.98 to 2.36). The relative risk of death in the aprotinin group, as compared with that in both groups receiving lysine analogues, was 1.53 (95% CI, 1.06 to 2.22).

CONCLUSIONS

Despite the possibility of a modest reduction in the risk of massive bleeding, the strong and consistent negative mortality trend associated with aprotinin, as compared with the lysine analogues, precludes its use in high-risk cardiac surgery. (Current Controlled Trials number, ISRCTN15166455 [controlled-trials.com].).

The risk associated with aprotinin in cardiac surgery

BACKGROUND

The majority of patients undergoing surgical treatment for ST-elevation myocardial infarction receive antifibrinolytic therapy to limit blood loss. This approach appears counterintuitive to the accepted medical treatment of the same condition--namely, fibrinolysis to limit thrombosis. Despite this concern, no independent, large-scale safety assessment has been undertaken.

METHODS

In this observational study involving 4374 patients undergoing revascularization, we prospectively assessed three agents (aprotinin [1295 patients], aminocaproic acid [883], and tranexamic acid [822]) as compared with no agent (1374 patients) with regard to serious outcomes by propensity and multivariable methods. (Although aprotinin is a serine protease inhibitor, here we use the term antifibrinolytic therapy to include all three agents.)

RESULTS

In propensity-adjusted, multivariable logistic regression (C-index, 0.72), use of aprotinin was associated with a doubling in the risk of renal failure requiring dialysis among patients undergoing complex coronary-artery surgery (odds ratio, 2.59; 95 percent confidence interval, 1.36 to 4.95) or primary surgery (odds ratio, 2.34; 95 percent confidence interval, 1.27 to 4.31). Similarly, use of aprotinin in the latter group was associated with a 55 percent increase in the risk of myocardial infarction or heart failure (P<0.001) and a 181 percent increase in the risk of stroke or encephalopathy (P=0.001). Neither aminocaproic acid nor tranexamic acid was associated with an increased risk of renal, cardiac, or cerebral events. Adjustment according to propensity score for the use of any one of the three agents as compared with no agent yielded nearly identical findings. All the agents reduced blood loss.

CONCLUSIONS

The association between aprotinin and serious end-organ damage indicates that continued use is not prudent. In contrast, the less expensive generic medications aminocaproic acid and tranexamic acid are safe alternatives.

Efficacy and safety of corticosteroid injections and other injections for management of tendinopathy: a systematic review of randomised controlled trials

BACKGROUND

Few evidence-based treatment guidelines for tendinopathy exist. We undertook a systematic review of randomised trials to establish clinical efficacy and risk of adverse events for treatment by injection.

METHODS

We searched eight databases without language, publication, or date restrictions. We included randomised trials assessing efficacy of one or more peritendinous injections with placebo or non-surgical interventions for tendinopathy, scoring more than 50% on the modified physiotherapy evidence database scale. We undertook meta-analyses with a random-effects model, and estimated relative risk and standardised mean differences (SMDs). The primary outcome of clinical efficacy was protocol-defined pain score in the short term (4 weeks, range 0-12), intermediate term (26 weeks, 13-26), or long term (52 weeks, ≥52). Adverse events were also reported.

FINDINGS

3824 trials were identified and 41 met inclusion criteria, providing data for 2672 participants. We showed consistent findings between many high-quality randomised controlled trials that corticosteroid injections reduced pain in the short term compared with other interventions, but this effect was reversed at intermediate and long terms. For example, in pooled analysis of treatment for lateral epicondylalgia, corticosteroid injection had a large effect (defined as SMD>0·8) on reduction of pain compared with no intervention in the short term (SMD 1·44, 95% CI 1·17-1·71, p<0·0001), but no intervention was favoured at intermediate term (-0·40, -0·67 to -0·14, p<0·003) and long term (-0·31, -0·61 to -0·01, p=0·05). Short-term efficacy of corticosteroid injections for rotator-cuff tendinopathy is not clear. Of 991 participants who received corticosteroid injections in studies that reported adverse events, only one (0·1%) had a serious adverse event (tendon rupture). By comparison with placebo, reductions in pain were reported after injections of sodium hyaluronate (short [3·91, 3·54-4·28, p<0·0001], intermediate [2·89, 2·58-3·20, p<0·0001], and long [3·91, 3·55-4·28, p<0·0001] terms), botulinum toxin (short term [1·23, 0·67-1·78, p<0·0001]), and prolotherapy (intermediate term [2·62, 1·36-3·88, p<0·0001]) for treatment of lateral epicondylalgia. Lauromacrogol (polidocanol), aprotinin, and platelet-rich plasma were not more efficacious than was placebo for Achilles tendinopathy, while prolotherapy was not more effective than was eccentric exercise.

INTERPRETATION

Despite the effectiveness of corticosteroid injections in the short term, non-corticosteroid injections might be of benefit for long-term treatment of lateral epicondylalgia. However, response to injection should not be generalised because of variation in effect between sites of tendinopathy.

FUNDING

None.

Pharmacological strategies to decrease excessive blood loss in cardiac surgery: a meta-analysis of clinically relevant endpoints

BACKGROUND

Excessive bleeding may complicate cardiac surgery, and is associated with increased morbidity and mortality. Pharmacological strategies to decrease perioperative bleeding have been investigated in a large number of controlled trials, most of which have shown a decrease in blood loss. However, most studies lacked sufficient power to detect a beneficial effect on clinically more relevant outcomes. We did a meta-analysis of all randomised, controlled trials of the three most frequently used pharmacological strategies to decrease perioperative blood loss (aprotinin, lysine analogues [aminocaproic acid and tranexamic acid], and desmopressin).

METHODS

Studies were included if they reported at least one clinically relevant outcome (mortality, rethoracotomy, proportion of patients receiving a transfusion, or perioperative myocardial infarction) in addition to perioperative blood loss. In addition, a separate meta-analysis was done for studies concerning complicated cardiac surgery.

FINDINGS

We identified 72 trials (8409 patients) that met the inclusion criteria. Treatment with aprotinin decreased mortality almost two-fold (odds ratio 0.55 [95% CI 0.34-0.90]) compared with placebo. Treatment with aprotinin and with lysine analogues decreased the frequency of surgical re-exploration (0.37 [0.25-0.55], and 0.44 [0.22-0.90], respectively). These two treatments also significantly decreased the proportion of patients receiving any allogeneic blood transfusion. By contrast, the use of desmopressin resulted in a small decrease in perioperative blood loss, but was not associated with a beneficial effect on other clinical outcomes. Aprotinin and lysine analogues did not increase the risk of perioperative myocardial infarction; however, desmopressin was associated with a 2.4-fold increase in the risk of this complication. Studies in patients undergoing complicated cardiac surgery showed similar results.

INTERPRETATION

Pharmacological strategies that decrease perioperative blood loss in cardiac surgery, in particular aprotinin and lysine analogues, also decrease mortality, the need for rethoracotomy, and the proportion of patients receiving a blood transfusion.

Clinical application of inhibitors of fibrinolysis

The basic proteinase inhibitor from bovine organs, aprotinin, was first identified in 1930 and its effect on enzyme and other biological systems has since been extensively studied. Aprotinin can only be administered intravenously and has a half-life of about 2 hours. Its administration at the start of cardiopulmonary bypass surgery appears to reduce blood loss and to protect against global myocardial ischaemia. Similarly, a smaller infarct size seems to result from early administration of aprotinin within the first hour after myocardial infarction, though further studies are needed to confirm this effect. A combination of aprotinin with tranexamic acid may be effective in preventing or delaying rebleeding after rupture of an intracerebral aneurysm; the addition of aprotinin seems to decrease the incidence of delayed cerebral vasospasm and ischaemic complications which are sometimes noted when tranexamic acid alone is used. Aprotinin is also effective as adjuvant treatment in traumatic haemorrhagic shock. The recommended loading dose is 15,000 to 20,000 KIU/kg bodyweight administered as a short intravenous infusion, followed by 50,000 KIU/hour by continuous infusion. Side effects of aprotinin are very rare. Epsilon-Aminocaproic acid (EACA), p-aminomethylbenzoic acid (PAMBA) and tranexamic acid are synthetic antifibrinolytic amino acids. Saturation of the lysine binding sites of plasminogen with these inhibitors displaces plasminogen from the fibrin surface. On a molar basis tranexamic acid is at least 7 times more potent that epsilon-aminocaproic acid and twice as potent as p-aminomethylbenzoic acid. All 3 compounds are readily absorbed from the gastrointestinal tract and excreted in active form in the urine. The plasma half-life of tranexamic acid is about 80 minutes. The main indications for tranexamic acid are the prevention of excessive bleeding after tonsillectomy, prostatic surgery, and cervical conisation, and primary and IUD-induced menorrhagia. It is possible that gastric and intestinal bleeding can also be reduced as well as recurrent epistaxis. Tranexamic acid could also be useful after ocular trauma. The value of fibrinolysis inhibitors in the prevention of bleeding after tooth extraction in patients with haemophilia is well documented, as is the treatment of hereditary angioneurotic oedema. The usual dose of tranexamic acid is 0.5 to 1g (10 to 15 mg/kg bodyweight) given intravenously 2 to 3 times daily, or 1 to 1.5 g orally 3 to 4 times daily. This dose needs to be reduced in patients with renal insufficiency. The main side effects of tranexamic acid are nausea or diarrhoea.

Aprotinin during coronary-artery bypass grafting and risk of death

BACKGROUND

Aprotinin (Trasylol) is used to mitigate bleeding during coronary-artery bypass grafting (CABG). Accumulating evidence suggests that this practice increases mortality.

METHODS

Using electronic administrative records of the Premier Perspective Comparative Database, we studied hospitalized patients with operating-room charges for the use of aprotinin (33,517 patients) or aminocaproic acid (44,682 patients) on the day CABG was performed. We tabulated the numbers of patients with a hospital-discharge status of death and performed three types of analyses: a multivariable logistic-regression analysis (primary analysis); propensity-score matching in the highly selected subcohort of patients who received full amounts of the study drug, who underwent CABG by surgeons who performed 50 or more CABG surgeries during the study period, and for whom information on 10 additional covariates was available because the surgery occurred on hospital day 3 or later; and an instrumental-variable analysis of data from patients whose surgeons showed a strong preference for one of the two study drugs.

RESULTS

In all, 1512 of the 33,517 aprotinin recipients (4.5%) and 1101 of the 44,682 aminocaproic acid recipients (2.5%) died. After adjustment for 41 characteristics of patients and hospitals, the estimated risk of death was 64% higher in the aprotinin group than in the aminocaproic acid group (relative risk, 1.64; 95% confidence interval [CI], 1.50 to 1.78). In the first 7 days after surgery, the adjusted relative risk of in-hospital death in the aprotinin group was 1.78 (95% CI, 1.56 to 2.02). The relative risk in a propensity-score-matched analysis was 1.32 (95% CI, 1.08 to 1.63). In the instrumental-variable analysis, the use of aprotinin was found to be associated with an excess risk of death of 1.59 per 100 patients (95% CI, 0.14 to 3.04). Postoperative revascularization and dialysis were more frequent among recipients of aprotinin than among recipients of aminocaproic acid.

CONCLUSIONS

Patients who received aprotinin alone on the day of CABG surgery had a higher mortality than patients who received aminocaproic acid alone. Characteristics of neither the patients nor the surgeons explain the difference, which persisted through several approaches to control confounding.

Mortality associated with aprotinin during 5 years following coronary artery bypass graft surgery

CONTEXT

Acute safety concerns have been raised recently regarding certain hemorrhage-sparing medications commonly used in cardiac surgery. However, no comprehensive data exist regarding their associations with long-term mortality.

OBJECTIVE

To contrast long-term all-cause mortality in patients undergoing coronary artery bypass graft (CABG) surgery according to use of 2 lysine analog antifibrinolytics (aminocaproic acid and tranexamic acid), the serine protease inhibitor aprotinin, or no antibleeding agent.

DESIGN, SETTING, AND PARTICIPANTS

Observational study of mortality conducted between November 11, 1996, and December 7, 2006. Following index hospitalization (4374 patients; 69 medical centers), survival was prospectively assessed at 6 weeks, 6 months, and annually for 5 years after CABG surgery among 3876 patients enrolled in a 62-center international cohort study. The associations of survival with hemorrhage-sparing medications were compared using multivariable analyses including propensity adjustments.

MAIN OUTCOME MEASURE

Death (all-cause) over 5 years.

RESULTS

Aprotinin treatment (223 deaths among 1072 patients [20.8% 5-year mortality]) was associated with significantly increased mortality compared with control (128 deaths among 1009 patients [12.7%]; covariate adjusted hazard ratio for death, 1.48; 95% confidence interval, 1.19-1.85), whereas neither aminocaproic acid (132 deaths among 834 patients [15.8%]; adjusted hazard ratio for death, 1.03; 95% confidence interval, 0.80-1.33) nor tranexamic acid (65 deaths among 442 patients [14.7%]; adjusted hazard ratio for death, 1.07; 95% confidence interval, 0.80-1.45) was associated with increased mortality. In multivariable logistic regression, either with propensity adjustment or without, aprotinin was independently predictive of 5-year mortality (adjusted odds ratio with propensity adjustment, 1.48; 95% confidence interval, 1.13-1.93; P = .005) among patients with diverse risk profiles, as well as among those surviving their index hospitalization. Neither aminocaproic nor tranexamic acid was associated with increased risk of death.

CONCLUSIONS

These findings indicate that in addition to the previously reported acute renal and vascular safety concerns, aprotinin use is associated with an increased risk of long-term mortality following CABG surgery. Use of aprotinin among patients undergoing CABG surgery does not appear prudent because safer and less expensive alternatives (ie, aminocaproic acid and tranexamic acid) are available.

A multicenter, double-blind, placebo-controlled trial of aprotinin for reducing blood loss and the requirement for donor-blood transfusion in patients undergoing repeat coronary artery bypass grafting

BACKGROUND

Aprotinin is a serine protease inhibitor that reduces blood loss and transfusion requirements when administered prophylactically to cardiac surgical patients. To examine the safety and dose-related efficacy of aprotinin, a prospective, multicenter, placebo-controlled trial was conducted in patients undergoing repeat coronary artery bypass graft (CABG) surgery.

METHODS AND RESULTS

Two hundred eighty-seven patients were randomly assigned to receive either high-dose aprotinin, low-dose aprotinin, pump-prime-only aprotinin, or placebo. Drug efficacy was determined by the reduction in donor-blood transfusion up to postoperative day 12 and in postoperative thoracic-drainage volume. The percentage of patients requiring donor-red-blood-cell (RBC) transfusions in the high- and low-dose aprotinin groups was reduced compared with the pump-prime-only and placebo groups (high-dose aprotinin, 54%; low-dose aprotinin, 46%; pump-prime only, 72%; and placebo, 75%; overall P = .001). The number of units of donor RBCs transfused was significantly lower in the aprotinin-treated patients compared with placebo (high-dose aprotinin, 1.6 +/- 0.2 U; low-dose aprotinin, 1.6 +/- 0.3 U; pump-prime-only, 2.5 +/- 0.3 U; and placebo, 3.4 +/- 0.5 U; P = .0001). There was also a significant difference in total blood-product exposures among treatment groups (high-dose aprotinin, 2.2 +/- 0.4 U; low-dose aprotinin, 3.4 +/- 0.9 U; pump-prime-only, 5.1 +/- 0.9 U; placebo, 10.3 +/- 1.4 U). There were no differences among treatment groups for the incidence of perioperative myocardial infarction (MI).

CONCLUSIONS

This study demonstrates that high- and low-dose aprotinin significantly reduces the requirement for donor-blood transfusion in repeat CABG patients without increasing the risk for perioperative MI.

Analyses of coronary graft patency after aprotinin use: results from the International Multicenter Aprotinin Graft Patency Experience (IMAGE) trial

OBJECTIVE

We examined the effects of aprotinin on graft patency, prevalence of myocardial infarction, and blood loss in patients undergoing primary coronary surgery with cardiopulmonary bypass.

METHODS

Patients from 13 international sites were randomized to receive intraoperative aprotinin (n = 436) or placebo (n = 434). Graft angiography was obtained a mean of 10.8 days after the operation. Electrocardiograms, cardiac enzymes, and blood loss and replacement were evaluated.

RESULTS

In 796 assessable patients, aprotinin reduced thoracic drainage volume by 43% (P < .0001) and requirement for red blood cell administration by 49% (P < .0001). Among 703 patients with assessable saphenous vein grafts, occlusions occurred in 15.4% of aprotinin-treated patients and 10.9% of patients receiving placebo (P = .03). After we had adjusted for risk factors associated with vein graft occlusion, the aprotinin versus placebo risk ratio decreased from 1.7 to 1.05 (90% confidence interval, 0.6 to 1.8). These factors included female gender, lack of prior aspirin therapy, small and poor distal vessel quality, and possibly use of aprotinin-treated blood as excised vein perfusate. At United States sites, patients had characteristics more favorable for graft patency, and occlusions occurred in 9.4% of the aprotinin group and 9.5% of the placebo group (P = .72). At Danish and Israeli sites, where patients had more adverse characteristics, occlusions occurred in 23.0% of aprotinin- and 12.4% of placebo-treated patients (P = .01). Aprotinin did not affect the occurrence of myocardial infarction (aprotinin: 2.9%; placebo: 3.8%) or mortality (aprotinin: 1.4%; placebo: 1.6%).

CONCLUSIONS

In this study, the probability of early vein graft occlusion was increased by aprotinin, but this outcome was promoted by multiple risk factors for graft occlusion.

Effect of aprotinin on clinical outcomes in coronary artery bypass graft surgery: A systematic review and meta-analysis of randomized clinical trials

OBJECTIVE

Despite proven blood transfusion benefits, aprotinin may be underused in coronary artery bypass grafting. Reluctance to use aprotinin may stem from safety concerns. The current objective was to evaluate clinical outcomes (mortality, myocardial infarction, renal failure, stroke, atrial fibrillation) in patients undergoing coronary artery bypass grafting who receive aprotinin by performing a quantitative overview of published, randomized, controlled trials.

METHODS

MEDLINE, EMBASE, and PHARMLINE (1988-2001) and reference lists of relevant articles were searched for coronary artery bypass grafting studies. Criteria for data inclusion were as follows: (1) random allocation of study treatments, (2) placebo control, (3) enrollment only of patients undergoing coronary artery bypass grafting, (4) no combination with another experimental medication or device, and (5) prophylactic and continuous intraoperative use.

RESULTS

Data from 35 coronary artery bypass grafting trials (n = 3879) confirm that aprotinin reduces transfusion requirements (relative risk 0.61, 95% confidence interval 0.58-0.66) relative to placebo, with a 39% risk reduction. Aprotinin therapy was not associated with increased or decreased mortality (relative risk 0.96, 95% confidence interval 0.65-1.40), myocardial infarction (relative risk 0.85, 95% confidence interval 0.63-1.14), or renal failure (relative risk 1.01, 95% confidence interval 0.55-1.83) risk, but it was associated with a reduced risk of stroke (relative risk 0.53, 95% confidence interval 0.31-0.90) and a trend toward reduced atrial fibrillation (relative risk 0.90, 95% confidence interval 0.78-1.03).

CONCLUSIONS

Aprotinin reduces transfusion requirements. Concerns that aprotinin therapy is associated with increased mortality, myocardial infarction, or renal failure risk is not supported by data from published, randomized, placebo-controlled clinical trials. Evidence for a reduced risk of stroke and a tendency toward reduction of atrial fibrillation occurrence was observed in patients who received aprotinin.

Aprotinin and transfusion requirements in orthotopic liver transplantation: a multicentre randomised double-blind study. EMSALT Study Group

BACKGROUND

Intraoperative hyperfibrinolysis contributes to bleeding during adult orthotopic liver transplantation. We aimed to find out whether aprotinin, a potent antifibrinolytic agent, reduces blood loss and transfusion requirements.

METHODS

We did a randomised, double-blind, placebo-controlled trial in which six liver-transplant centres participated. Patients undergoing primary liver transplantation were randomly assigned intraoperative high-dose aprotinin, regular-dose aprotinin, or placebo. Primary endpoints were intraoperative blood loss and transfusion requirements. Secondary endpoints were perioperative fluid requirements, postoperative blood transfusions, complications, and mortality.

FINDINGS

137 patients received high-dose aprotinin (n=46), regular-dose aprotinin (n=43), or placebo (n=48). Intraoperative blood loss was significantly lower in the aprotinin-treated patients, with a reduction of 60% in the high-dose group and 44% in the regular-dose group, compared with the placebo group (p=0.03). Total amount of red blood cell (homologous and autologous) transfusion requirements was 37% lower in the high-dose group and 20% lower in the regular-dose group, than in the placebo group (p=0.02). Thromboembolic events occurred in two patients in the high-dose group, none in the regular-dose group, and in two patients in the placebo group (p=0.39). Mortality at 30 days did not differ between the three groups (6.5%, 4.7%, and 8.3%; p=0.79).

INTERPRETATION

Intraoperative use of aprotinin in adult patients undergoing orthotopic liver transplantation significantly reduces blood-transfusion requirements and should be routinely used in patients without contraindications.

Prevalence of anaphylactic reactions to aprotinin: analysis of two hundred forty-eight reexposures to aprotinin in heart operations

The efficacy of aprotinin to reduce intraoperative bleeding tendency in cardiac operations has been demonstrated in several studies. Aprotinin is a polybasic polypeptide and has antigenic properties. Anaphylactic reactions to aprotinin have been described. The aim of the present study was to evaluate the prevalence of adverse reactions to reexposure to high-dose aprotinin. The clinical outcome of all patients undergoing heart operations in our institution between 1988 and 1995 with at least two exposures to aprotinin was investigated. There were 248 reexposures to aprotinin in 240 patients: 101 adult and 147 pediatric cases. The total aprotinin doses were 4.9 x 10(6) (interquartile range 2 x 10(6)) KIU (adults) and 1.3 x 10(6) (interquartile range 1.2 x 10(6)) KIU (pediatric patients). The time between the first and second aprotinin exposures was 344 (interquartile range 1039) days. Seven adverse reactions to aprotinin were found (2.8%). The severity of the reaction ranged from mild (no intervention) to severe (longer-lasting circulatory depression despite vasopressor therapy). All patients survived the event. Patients with an interval less than 6 months since the previous exposure had a statistically higher incidence of adverse reactions than patients with a longer interval (5/111 or 4.5% vs 2/137 or 1.5%, p < 0.05). Two patients reacted to a test dose of 10,000 KIU aprotinin. Pretreatment with antihistaminics was done in 60% of the patients. We recommend the following procedure for reexposure with high-dose aprotinin: (1) delay of the first bolus injection of aprotinin until the surgeon is ready to begin cardiopulmonary bypass, (2) test dose of 10,000 KIU aprotinin in all patients with aprotinin treatment, (3) H1/H2 blockade in known or possible reexposures, and (4) avoidance of reexposure within the first 6 months after the previous exposure to aprotinin. With these precautions a reexposure to aprotinin in patients with a high risk of bleeding is justified, because the benefits of aprotinin treatment outweigh the relative risk of a serious allergic reaction.

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.

Renal dysfunction and intravascular coagulation with aprotinin and hypothermic circulatory arrest

High-dose aprotinin was used in 20 patients undergoing primary or repeat operations on the thoracic or thoracoabdominal aorta using cardiopulmonary bypass and hypothermic circulatory arrest. The activated clotting times immediately before the establishment of hypothermic circulatory arrest exceeded 700 seconds in all but 1 patient. Three patients (15%) required reoperation for bleeding. Seven patients died during hospitalization, and 5 had postmortem examination. Platelet-fibrin thrombi were present in multiple organs including the coronary arteries of 4 patients with myocardial infarction or failure, the pulmonary arteries of 2 patients, 1 of whom died of acute right ventricular failure, the brains of 2 patients who sustained a stroke, and the kidneys of 4 patients, 3 of whom had development of renal dysfunction. Renal dysfunction occurred in 13 patients (65%), and all were 65 years of age or older. Five of these patients required hemodialysis. Among 20 age-matched patients who had similar operations without aprotinin, there was one hospital death (5%) from myocardial infarction, and renal dysfunction developed in 1 patient (5%), who did not require dialysis. None of these 20 patients required reoperation for bleeding. Although aprotinin has been shown to reduce blood loss in patients having cardiac operations employing cardiopulmonary bypass, this benefit was not attained in this group of patients with thoracic aortic disease in whom hypothermic circulatory arrest was used. Use of aprotinin in elderly patients undergoing these procedures was associated with an increased risk of renal dysfunction and failure, and of myocardial infarction and death.

Aprotinin in perspective

Aprotinin is a nonspecific serine protease inhibitor extracted from bovine lung. It was first used during cardiopulmonary bypass to inhibit plasmin-induced complement activation. By chance significant reductions of blood loss and blood requirements were noted in treated patients. Subsequent investigation showed improved hemostasis to result from protection of platelet adhesive receptors (Gp Ib) at the onset of cardiopulmonary bypass. Without aprotinin the contact system of plasma is massively activated on first passage through the cardiopulmonary bypass circuit. Activation of the intrinsic coagulation pathway causes thrombin formation, which impairs platelet adhesive function. Aprotinin blocks contact activation of the kallikrein system during cardiopulmonary bypass and in synergy with heparin prevents thrombin formation through inhibition of the intrinsic clotting cascade. It is likely that neither thrombin nor platelets become involved in the blood-foreign surface contact activation process in aprotinin-treated patients. The fact that the hemostatic process is affected from the very beginning of cardiopulmonary bypass is substantiated by the fact that low-dose aprotinin therapy (2 x 10(6) KIU aprotinin added to the pump prime) leads to the same preservative effect on Gp Ib receptors and blood loss as continuous high-dose infusion (6 x 10(6) KIU) throughout the whole surgical procedure. In the presence of heparin aprotinin prolongs the activated clotting time and the in vitro activated partial thromboplastin time. This has important implications for heparin dosage. An inhibitory effect on the endothelial cell anticoagulant function may also have consequences during hypothermic low flow and circulatory arrest states.(ABSTRACT TRUNCATED AT 250 WORDS)

Aprotinin for primary coronary artery bypass grafting: a multicenter trial of three dose regimens

BACKGROUND

High-dose aprotinin reduces transfusion requirements in patients undergoing coronary artery bypass grafting, but the safety and effectiveness of smaller doses is unclear. Furthermore, patient selection criteria for optimal use of the drug are not well defined.

METHODS

Seven hundred and four first-time coronary artery bypass grafting patients were randomized to receive one of three doses of aprotinin (high, low, and pump-prime-only) or placebo. The patients were stratified as to risk of excessive bleeding.

RESULTS

All three aprotinin doses were highly effective in reducing bleeding and transfusion requirements. Consistent efficacy was not, however, demonstrated in the subgroup of patients at low risk for bleeding. There were no differences in mortality or the incidences of renal failure, strokes, or definite myocardial infarctions between the groups, although the pump-prime-only dose was associated with a small increase in definite, probable, or possible myocardial infarctions (p = 0.045).

CONCLUSIONS

Low-dose and pump-prime-only aprotinin regimens provide reductions in bleeding and transfusion requirements that are similar to those of high-dose regimens. Although safe, aprotinin is not routinely indicated for the first-time coronary artery bypass grafting patient who is at low risk for postoperative bleeding. The pump-prime-only dose is not currently recommended because of a possible association with more frequent myocardial infarctions.

Is epsilon-aminocaproic acid as effective as aprotinin in reducing bleeding with cardiac surgery?: a meta-analysis

BACKGROUND

Although aprotinin is known to be effective in reducing postoperative hemorrhage after cardiac surgery, epsilon-aminocaproic acid, an alternative antifibrinolytic, is considerably less expensive. Because the results of 3 small randomized clinical trials comparing these 2 agents directly were inconclusive, we performed a meta-analysis to compare the relative effectiveness and adverse-effect profile of these 2 agents against placebo.

METHODS AND RESULTS

Data from 52 randomized clinical trials published between 1985 and 1998 involving the use of epsilon-aminocaproic acid (n=9) or aprotinin (n=46) in patients undergoing cardiac surgery were abstracted. Our primary outcomes were total blood loss, red blood cell transfusion rates and amounts, reexploration, stroke, myocardial infarction, and mortality. The meta-analysis revealed substantial reductions in total blood loss with epsilon-aminocaproic acid and low-dose aprotinin (each with a 35% reduction versus placebo, P<0.001) and high-dose aprotinin (53% reduction, P<0.001). There were identical reductions in total postoperative transfusions with epsilon-aminocaproic acid (61% reduction versus placebo, P<0. 010) and high-dose aprotinin (62% reduction, P<0.001). The proportion of patients transfused was similarly reduced with epsilon-aminocaproic acid (OR, 0.32; 95% CI, 0.15 to 0.69) and high-dose aprotinin (OR, 0.28; 0.22 to 0.37). Although both drugs reduced rates of reexploration to similar degrees, this effect was statistically significant only with high-dose aprotinin (OR, 0.39; 0. 24 to 0.61). epsilon-Aminocaproic acid and aprotinin had no effect on risks of postoperative myocardial infarction or overall mortality.

CONCLUSIONS

Because the 2 antifibrinolytic agents appear to have similar efficacies, the considerably less-expensive epsilon-aminocaproic acid may be preferred over aprotinin for reducing hemorrhage with cardiac surgery.

The safety of aprotinin and lysine-derived antifibrinolytic drugs in cardiac surgery: a meta-analysis

BACKGROUND

Because of recent concerns about the safety of aprotinin, we updated our 2007 Cochrane review that compared the relative benefits and risks of aprotinin and the lysine analogues tranexamic acid and epsilon aminocaproic acid.

METHODS

We searched electronic databases, including CENTRAL, MEDLINE, EMBASE, Google and Google Scholar for trials of antifibrinolytic drugs used in adults scheduled for cardiac surgery. Searches were updated to January 2008. By comparing aprotinin and the 2 lysine analogues to control, we derived indirect head-to-head comparisons of aprotinin to the other drugs. We derived direct estimates of risks and benefits by pooling estimates from head-to-head trials of aprotinin and tranexamic acid or epsilon aminocaproic acid.

RESULTS

For indirect estimates, we identified 49 trials involving 182 deaths among 7439 participants. The summary relative risk (RR) for death with aprotinin versus placebo was 0.93 (95% confidence interval [CI] 0.69-1.25). In the 19 trials that included tranexamic acid, there were 24 deaths among 1802 participants. The summary RR was 0.55 (95% CI 0.24-1.25). From the risk estimates derived for individual drugs, we calculated an indirect summary RR of death with use of aprotinin versus tranexamic acid of 1.69 (95% CI 0.70-4.10). To calculate direct estimates of death for aprotinin versus tranexamic acid, we identified 13 trials with 107 deaths among 3537 participants. The summary RR was 1.43 (95% CI 0.98-2.08). Among the 1840 participants, the calculated estimates of death for aprotinin compared directly to epsilon aminocaproic acid was 1.49 (95% CI 0.98-2.28). We found no evidence of an increased risk of myocardial infarction with use of aprotinin compared with the lysine analogues in either direct or indirect analyses. Compared with placebo or no treatment, all 3 drugs were effective in reducing the need for red blood cell transfusion. The RR of transfusion with use of aprotinin was 0.66 (95% CI 0.61-0.72). The RR of transfusion was 0.70 (95% CI 0.61-0.80) for tranexamic acid, and it was 0.75 (95% CI 0.58-0.96) for use of epsilon aminocaproic acid. Aprotinin was also effective in reducing the need for re-operation because of bleeding (RR 0.48, 95% CI 0.34-0.67).

INTERPRETATION

The risk of death tended to be consistently higher with use of aprotinin than with use of lysine analogues. Aprotinin had no clear advantages to offset these harms. Either tranexamic acid or epsilon aminocaproic acid should be recommended to prevent bleeding after cardiac surgery.

Aprotinin therapy in cardiac operations: a report on use in 41 cardiac centers in the United Kingdom

Aprotinin, a serine protease inhibitor, has recently been shown to reduce blood loss in cardiac surgical patients. Data on the safety and efficacy of aprotinin therapy administered to 671 cardiac surgical patients in 41 United Kingdom cardiac surgical units have been submitted to interim analysis. The patients studied were in high-risk categories for excessive bleeding, including 457 redo operations and 79 patients with active infective endocarditis. Overall mortality was 12% in redo cases and 5.1% in first-time operations. Adverse events were reported in only 20 patients (3%). Median blood loss at 24 hours after operation was 400 mL, and median transfusion volume throughout the operative and postoperative period was 2 units. These data confirm that the use of aprotinin therapy in high-risk cardiac surgical patients is associated with a low incidence of adverse events.

Perioperative anaphylaxis

The incidence of immune-mediated anaphylaxis during anesthesia ranges from 1 in 10,000 to 1 in 20,000. Neuromuscular blocking agents are most frequently incriminated, followed by latex and antibiotics, although any drug or substance used may be a culprit. Diagnosis relies on tryptase measurements at the time of the reaction and skin tests, specific immunoglobulin E, or basophil activation assays. Treatment consists of rapid volume expansion and epinephrine administration titrated to symptom severity.

Risks of harms using antifibrinolytics in cardiac surgery: systematic review and network meta-analysis of randomised and observational studies

OBJECTIVE

To estimate the relative risks of death, myocardial infarction, stroke, and renal failure or dysfunction between antifibrinolytics and no treatment following the suspension of aprotinin from the market in 2008 for safety reasons and its recent reintroduction in Europe and Canada.

DESIGN

Systematic review and network meta-analysis.

DATA SOURCES

A Cochrane review of antifibrinolytic treatments was chosen as the starting point for this systematic review. Medline, Embase, and the Cochrane register of trials were searched with no date restrictions for observational evidence.

STUDY SELECTION

Propensity matched or adjusted observational studies with two or more of the interventions of interest (aprotinin, tranexamic acid, epsilon-aminocaproic acid, and no treatment) that were carried out in patients undergoing cardiac surgery.

DATA ANALYSIS

Network meta-analysis was used to compare treatments, and odds ratios with 95% credible intervals were estimated. Meta-analyses were carried out for randomised controlled trials alone and for randomised controlled trials with observational studies.

RESULTS

106 randomised controlled trials and 11 observational studies (43,270 patients) were included. Based on the results from analysis of randomised controlled trials, tranexamic acid was associated on average with a reduced risk of death compared with aprotinin (odds ratio 0.64, 95% credible interval 0.41 to 0.99). When observational data were incorporated, comparisons showed an increased risk of mortality with aprotinin on average relative to tranexamic acid (odds ratio 0.71, 95% credible interval 0.50 to 0.98) and epsilon-aminocaproic acid (0.60, 0.43 to 0.87), and an increased risk of renal failure or dysfunction on average relative to all comparators: odds ratio 0.66 (95% credible interval 0.45 to 0.88) compared with no treatment, 0.66 (0.48 to 0.91) versus tranexamic acid, and 0.65 (0.45 to 0.88) versus epsilon-aminocaproic acid.

CONCLUSION

Although meta-analyses of randomised controlled trials were largely inconclusive, inclusion of observational data suggest concerns remain about the safety of aprotinin. Tranexamic and epsilon-aminocaproic acid are effective alternatives that may be safer for patients.

Forty Years of Clinical Aprotinin Use: A Review of 124 Hypersensitivity Reactions

Since its clinical introduction, the anaphylactic potential of aprotinin has been a major concern. World wide, its use is expanding so there is an increased chance that patients have reexposure from various sources. The risk of anaphylaxis is approximately 2.8% in reexposed patients. From 1963 to 2003, 124 cases of aprotinin-induced anaphylaxis were reported in 61 publications. Eleven patients died. The reexposure interval was less than 3 months in 72% (38 of 53 patients). This review looks at the profile of patients at risk so preventive measures may be taken. Past and future exposures have to be taken into account before any aprotinin administration.

The antithrombotic and antiinflammatory mechanisms of action of aprotinin

Aprotinin (Trasylol) is generally regarded to be an effective hemostatic agent that prevents blood loss and preserves platelet function during cardiac surgery procedures requiring cardiopulmonary bypass (CBP). However, its clinical use has been limited by the concern that such a potent hemostatic agent might be prothrombotic, particularly in relation to coronary vein graft occlusion. In this review we present a mechanism of action that challenges such a viewpoint and explains how aprotinin can be simultaneously hemostatic and antithrombotic. Aprotinin achieves these two apparently disparate properties by selectively blocking the proteolytically activated thrombin receptor on platelets, the protease-activated receptor 1 (PAR1), while leaving other mechanisms of platelet aggregation unaffected. We also review recent research leading to the discovery of novel antiinflammatory targets for aprotinin. A better understanding of its mechanisms of action has led to the conclusion that aprotinin is a remarkable drug with the capacity to correct many of the imbalances that develop in the coagulation system and the inflammatory system after CPB. Nonetheless, it has been clinically underused for fear of causing thrombotic complications, a fear that in light of recent evidence may be unfounded.