J Thorac Cardiovasc Surg 2006;132:734
© 2006 The American Association for Thoracic Surgery
Reply to the Editor
Domenico Paparella, MD,
Antonella Galeone, MD,
Giuseppe Scrascia, MD
Division of Cardiac Surgery, University of Bari, Piazza Giulio Cesare 11, Bari 70100, Italy
(Email: paparella{at}tin.it).
Thank you for the invitation to respond to Dr Casati and colleagues' letter. We used an in vitro bleeding time test (Platelet Function Analyzer [PFA]-100) to evaluate platelet function perioperatively at 7 different observation times. Only one of these observations was performed during cardiopulmonary bypass with hemodiluted patients. Fibrinolytic activity can indirectly be measured, evaluating the balance between the promoter of fibrinolysis (tissue-type plasminogen activator) and its inhibitor (plasminogen activator inhibitor 1). In our study1
we observed that tissue-type plasminogen activator levels are not increased, whereas plasminogen activator inhibitor 1 and D-dimer levels are modestly increased after off-pump coronary artery bypass (OPCAB) surgery. These data would suggest that fibrinolysis is not particularly activated during OPCAB surgery. Dr Casati states that an antifibrinolytic agent should be used in patients undergoing OPCAB surgery because he has previously demonstrated2 a significant reduction of postoperative bleeding in patients undergoing OPCAB treated with tranexamic acid (25 patients) compared with patients undergoing OPCAB treated with placebo (25 patients). In their study Casati and colleagues2 were not able to show a significant difference in blood product transfusion between the groups. Moreover, hemoglobin and hematocrit values reported up to 24 hours postoperatively were not influenced by tranexamic acid administration. As we remarked in our article, recent studies with angiographic control have shown a worse graft patency in patients operated on by means of the OPCAB technique compared with those undergoing the on-pump technique. Inaccurate anastomosis rather than a procoagulative state is probably the main cause of these results; nevertheless, this has not been proved. Although numerous investigators have documented profound short-term and midterm coagulative-fibrinolytic and inflammatory alterations in patients undergoing coronary artery bypass grafting surgery, there are no clinical studies that evaluated prospectively and on an appropriate number of patients the value of prothrombotic and proinflammatory markers in predicting early graft occlusion. Existing studies are small and produced conflicting results: Poston and associates3 reported that thrombelastography and whole blood aggregometry do not predict graft occlusion; however, in another study the same authors showed a reduction in platelet sensitivity to aspirin by means of both thrombelastography and aggregometry in patients with early graft failure.4 Karski and coworkers5 have recently demonstrated that tranexamic acid administration does not worsen early saphenous graft patency in patients receiving on-pump coronary artery bypass grafting. However, our results show that in the first 24 hours after the operation, patients undergoing on-pump operations and OPCAB have a different activation of the coagulation and fibrinolytic systems. Consequently, what is safe for patients undergoing on-pump operations might not be safe for those undergoing OPCAB. The reason why we operate on patients with coronary artery disease is to improve their long-term outcome while trying to minimize their perioperative risk. Considering that postoperative bleeding is not a serious complication after OPCAB surgery, we agree with Dr Casati's final remarks: "Further randomized studies, enrolling larger numbers of patients, are needed to confirm the antiinflammatory effects of TA and to rule out the potential risk of thrombotic complications."2
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References
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- Paparella D, Galeone A, Venneri MT, Coviello M, Scrascia G, Marraudino N, et al. Activation of the coagulation system during coronary artery bypass grafting operation. comparison between on pump and off pump techniques. J Thorac Cardiovasc Surg. 2006;131:290-297.[Abstract/Free Full Text]
- Casati V, Della Valle P, Benussi S, Franco A, Gerli C, Baili P, et al. Effects of tranexamic acid on postoperative bleeding and related hematochemical variables in coronary surgery. comparison between on-pump and off-pump techniques. J Thorac Cardiovasc Surg 2004;128:83-91.[Abstract/Free Full Text]
- Poston R, Gu J, Brown J, Gammie J, White C, Manchio J, et al. Hypercoagulability affecting early vein graft patency does not exist after off-pump coronary artery bypass. J Cardiothorac Vasc Anesth 2005;19:11-18.[Medline]
- Poston R, Gu J, Manchio J, Lee A, Brown J, Gammie J, et al. Platelet function tests predict bleeding and thrombotic events after off-pump coronary bypass grafting. Platelet function tests predict bleeding and thrombotic events after off-pump coronary bypass grafting. Eur J Cardiothorac Surg 2005;27:584-591.[Abstract/Free Full Text]
- Karski J, Djaiani G, Carroll J, Iwanochko M, Seneviratne P, Liu P, et al. Tranexamic acid and early saphenous vein graft patency in conventional coronary artery bypass graft surgery. a prospective randomized controlled clinical trial. J Thorac Cardiovasc Surg 2005;130:309-314.[Abstract/Free Full Text]
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About the activation of the coagulation system during on-pump and off-pump coronary surgery and the use of antifibrinolytic drugs
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J. Thorac. Cardiovasc. Surg. 2006 132: 733-734.
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