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© 2004 European Association of Cardio-Thoracic Surgery
Does use of aprotinin in coronary artery bypass graft surgery affect graft patency?
a Department of Cardiothoracic Surgery, North Staffordshire Royal Infirmary, Stoke, UK
* Corresponding author. Tel.: +44-7801548122 Received October 8, 2003; accepted October 17, 2003
A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether use of aprotinin in coronary artery bypass graft surgery adversely affects graft patency. Altogether 45 papers were identified using the below mentioned search, of which 10 presented the best evidence to answer the clinical question. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results, and study weaknesses of these papers are tabulated. We conclude that aprotinin clearly reduces blood loss, requirement for blood transfusion, and the risk of reoperation for bleeding, but does increase the risk of saphenous vein graft occlusion.
Key Words: Evidence-based medicine; Thoracic surgery; Aprotinin; Graft patency; Meta-analysis
A best evidence topic was constructed according to a structured protocol. This protocol is fully described in the ICVTS [1].
You have referred a patient with unstable angina who is on aspirin and a heparin infusion. You take him to theatre for CABG and the anaesthetist gives him aprotinin according to Hammersmith Protocol (2 million KIU as loading dose before sternotomy, followed by infusion of 0.5 million KIU/h until the end of surgery; 2 million KIU added to the priming volume additionally). After straightforward quadruple bypass grafts he comes off bypass with ease and is transferred to the intensive care unit without any inotropic support. Two hours later the patient develops ST elevation in the inferior leads. Though the patients is stable haemodynamically, a balloon pump is inserted and as arrangement is being made to take him back for re-exploration, the ECG changes revert back to normal and remain so subsequently. Two months later you review this patient who is still getting some angina. An angiogram reveals that two of the vein grafts are now blocked. You wonder whether it was the aprotinin that might have caused this complication.
In [patients undergoing Coronary Arterial Bypass grafting], does [aprotinin] administration [compromise graft patency].
Medline 1966–July 2003 using the OVID interface: [exp Aprotinin/OR Aprotinin.mp/OR Trasylol mp] AND [exp vascular patency/OR graft patency.mp OR exp Graft occlusion, Vascular/OR graft occlusion.mp]. Cochrane database of Systematic Reviews, ACP Journal Club and the Database of Reviews of effects: search performed using keyword ‘Aprotinin’.
Using Medline 45 papers were found of which nine were deemed to be relevant. One paper was also found by cross-checking reference lists. The Cochrane Database of Systematic reviews search found 14 reviews of which one was relevant [2–11]. The papers are presented in Table 1
Alderman et al. presented the IMAGE trial, a study that involved 13 centres with 870 patients [2]. They found a higher occlusion rate in saphenous grafts in the overall study population after aprotinin use, with 15% of patients suffering an occlusion in the Aprotinin group, compared to 11% in the control group. The triallists then adjusted for risk factors even though their study was a randomised controlled trial, which should equalise the incidence of risk factors in the two groups. They then concluded that allowing for these risk factors there was no difference in the occlusion rate. One further study found an increased occlusion rate in the aprotinin group. Laub et al. [10]found a 30% occlusion rate in the aprotinin group compared to no occlusions in the control group. The numbers in this study was, however, very small. Of the remaining studies no significant differences were found although Lemmer [5], Bidstrup [8] and van der Meer [9] found non-significant trends towards poorer patency with aprotinin. Due to the differing findings of these studies we combined their data by meta-analysis using a random effects model to calculate a common odds ratio for the increased of graft occlusion with aprotinin (Fig. 1). We found that the increase in the odds of occlusion was 1.52 (95% C.I. 1.13–2.03) and that this result is significant. We therefore conclude that there is a small but significant increase in graft occlusion in patients undergoing CABG with aprotinin (see Fig. 1).
Of note the amount of blood loss and blood product usage is significantly lower in the patients receiving aprotinin in all the studies. The Cochrane review combined the data from 61 studies and found a 30% reduction in blood transfusion, less blood drainage and a significantly lower incidence of reoperation due to bleeding. Finally we found only one study that investigated total arterial grafting. Jegaden [11] demonstrated a 99.3% patency rate of arterial grafts in his single series of 52 patients who received 143 arterial anastomoses. This report agrees with the reports of high LIMA patency in the other papers and provides evidence that aprotinin is safe for total arterial revascularisation.
Aprotinin clearly reduces blood loss, requirement for blood transfusion, and the risk of reoperation for bleeding, but probably does increase the risk of saphenous vein graft occlusion.
ICVTS on-line discussion Author: Mr. Joel Dunning, RCS Research Fellow, Manchester Royal Infirnary, Dept. Cardiothoracic Surgery, Oxford Road, Manchester M13 3BW, UK Date: 12-Dec-2003 Message: Research never stands still in Cardiac Surgery. Four months after performing this search Taggart et al. [1] published an excellent Double Blind Randomized Trial looking at the safety of Aprotinin in patients receiving total arterial revascularisation. They randomized 34 patients to the control group and 36 patients to the aprotinin group and found that while there was a significant drop in the amount of blood loss, number of units transfused and the number of patients needing transfusion, there was no difference in the number of patients suffering myocardial injury on the basis of troponin T and CK-MB levels. Although the study was only powered to detect a reduction of blood loss and a reduced rate of transfusion rather than to establish the safety of aprotinin for total arterial revascularisation, this study is further important evidence that Aprotinin is safe for use in total arterial revascularisation. References [1]Taggart DA, Djapardy V, Naik M, Davies. A randomized trial of aprotinin (Trasylol) on blood loss, blood product requirement, and myocardial injury in total arterial grafting. JTCVS 126 (4): 1087–1094. Author: Dr. Praveen Varma, Cardio-vascular and thoracic surgery, B8 New Faculty Quarters,Chitra Staff Quarters, Trivandrum, 69501 India Date: 10-Jan-2004 Message: I read with interest the article and the comment posted. The authors conclude that the use of aprotinin is associated with reduced blood loss with reduced usage of blood in CABG. Aprotinin may increase the incidence of graft thrombosis in venous grafts, but may not have any effect in arterial grafts. I wish to draw the attention of the authors to an article published in the Annals of thoracic surgery by Engoren et al. which shows a 70% increased risk of mortality at 5 years in tranfused patients [1]. In an editorial in the same issue, the author highlights the risk of transfusion, especially drawing attention to the 15-fold increase in the inflammatory load to the tranfused patients [2]. Evidence is accumulating that aprotinin is not harmful in arterial grafts, now the question to be answered is whether blood transfusion is more harmful than aprotinin in venous grafts? References [1]Engoren MC, Habib RH, Zacharias A, Schwann TA, Riordan CJ, Durham SJ, Effect of blood transfusion on long term survival after cardiac operation. Ann Thorac Surg 2002;74:1180–86. [2]Speiss BD, Transfusion and outcome in cardiac surgery. Ann Thorac Surg 2002;74:986–87. Author: Mr. Samer Nashef, Consultant Cardiac Surgeon, Papworth Hospital, Cambridge CB3 8RE, UK Date: 12-Jan-2004 Message: Excellent meta-analysis and intuitively makes a lot of sense. The study showing that transfusion is associated with poor outcomes confounds the issue, as there may be a common cause for both transfusion and poor outcomes. What I would like to know, in the light of the aprotinin meta-analysis, is whether it is correct to use aprotinin routinely in standard CABG. I do not. Should I? doi:10.1016/S1569-9293(03)00234-2
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Abstract
1. Introduction
