preoperative and immediate postoperative aspirin also reduces morbidity

setting of blunt thoracic aortic injury. We agree with the remarksregarding the multiple potential confounding variables, and aswe noted in our article, there is a very real possibility that a typeII error exists. Given these considerations, we agree that the datashow a trend in favor of left heart bypass and shorter cross-clamp times in reducing the risk of paralysis that is clinicallysignificant enough to support the use of left heart bypass in allbut the most unusual circumstances. The fact that cross-clamptimes appeared to play a more critical role when bypass was notused further underscores the potential protective benefit of leftheart bypass. Indeed, we hope that by demonstrating the effi-cacy of cannulating the pulmonary veins, we may encourage theuse of bypass.

Riyad Karmy-Jones, MDMark Meissner, MD

Division of Cardiothoracic SurgeryHarborview Medical CenterThe University of Washington325 Ninth AveSeattle, WA 98104e-mail: karmy@u.washington.edu.

Michael S. Mulligan, MD

Division of Cardiothoracic SurgeryThe University of Washington1959 NE Pacific StBox 356310Seattle, WA 98195

Preoperative and Immediate Postoperative Aspirin AlsoReduces MorbidityTo the Editor:

We read with great interest yet another important article fromthe Northern New England Cardiovascular Disease StudyGroup [1]. We congratulate the authors for highlighting theimportance of preoperative aspirin therapy in reducing mortal-ity. Discontinuing aspirin a week before coronary artery bypassgraft operation is common practice among cardiovascular sur-geons. It is because of the belief that this will reduce postoper-ative blood loss and the need for hematologic support andreexploration. It has been shown that aspirin usage reducesearly graft failure and thus justifies routine early usage aftercoronary artery bypass graft operation [2, 3]. A placebo-controlled, randomized trial, in which aspirin was administeredan hour after the operation, showed improved graft patency,with no significant increase in postoperative blood loss and theincidence of perioperative myocardial infarction [3]. The North-ern New England Study Group demonstrated reduced trends inrates of reexploration [4]. Risks of reexploration in this studywere associated with patient age, level of sickness, and durationand complexity of the procedure. Tuman and colleagues [5]showed no significant difference in blood loss, usage of bloodand clotting factors, and rates of reexploration when aspirin wasused perioperatively in patients undergoing redo coronary ar-tery bypass grafting.

We believe that the continuation of aspirin up to the time ofcoronary artery bypass graft operation reduces the perioperativeincidence of myocardial events. We follow a strict protocol ofcontinuing the preoperative dosage of aspirin (range, 75 to325 mg daily) up to the day of operation and administeringaspirin early postoperatively (between 2 and 6 hours postoper-

atively if there is no excessive blood loss). In our series of 306patients who followed the above protocol, the incidence ofperioperative myocardial infarction was 2%. The postoperativecreatine kinase-MB levels were less then 50 U/L in 85% of thepatients, and the usage of intraaortic balloon pump was 1%. Asfor the blood loss, the average was 873 mL. The reexplorationrate for excessive bleeding was 3.4%.

Although usage of aspirin in the early postoperative period isnow established as a major factor in preventing early graftfailure, preoperative usage up to the time of operation is stilluncommon. The use of aspirin in severe coronary artery diseasewith critical stenotic lesions is known to decrease the incidenceof myocardial events. A concern is stopping aspirin in patientswith unstable critical lesions, which may contribute to instabilityin the perioperative period. It is not common that patients areunstable before operation, but we have had the experience inwhich stable patients admitted for operation had a myocardialevent before operation. Although the results from coronaryartery bypass graft operation are improving, minor modifica-tions in perioperative management may further improve theseresults. We believe there is a need for a larger prospectiverandomized trial to alleviate this fear. More aggressive usage ofaspirin can be important in this era of multiple arterial graftingand off-pump coronary artery bypass grafting.

Javed Hayat, FRCS (C-Th)Wald C. Dihmis, FRCS (C-Th)

The Cardiothoracic CentreThomas DrLiverpool L14 3PE, United Kingdome-mail: javed@jhayat.freeserve.co.uk.

References

1. Dacey LJ, Munoz JJ, Johnson ER, et al. Effects of preoperativeaspirin use on mortality in coronary artery bypass graftingpatients. Ann Thorac Surg 2000;70:1986–90.

2. Goldman S, Copland J, Moritz T, et al. Improvement in earlysaphenous vein graft patency after coronary artery bypasssurgery with antiplatelet therapy: results of Veterans Admin-istration Cooperative Study. Circulation 1988 June;77:1324–32.

3. Gavaghan TP, Gebski V, Baron DB. Immediate postoperativeaspirin improves vein graft patency early and late aftercoronary artery bypass graft surgery. Circulation 1991;83:1526–33.

4. Munoz JJ, Birkmeyer NJO, Dacey LJ, et al. Trends in rates ofreexploration for hemorrhage after coronary artery bypasssurgery. Northern New England Cardiovascular DiseaseStudy Group. Ann Thorac Surg 1999;68:1321–5.

5. Tuman KJ, McCarthy RJ, O’Connor CJ, McCarthy WE, Ivank-ovich AD. Aspirin does not increase allogeneic blood trans-fusion in reoperative coronary artery surgery. Anesth Analg1996;83:1178–84.

ReplyTo the Editor:

We would like to thank Drs Hayat and Dihmis for their com-ments concerning preoperative aspirin use. As they state, aspi-rin use has been associated with improved graft patency and nosignificant increase in hemorrhage or transfusion. Their series ofpatients receiving preoperative aspirin showed superb results asevidenced by low levels of creatine kinase-MB, intraaortic bal-loon pump use, and blood loss. We have continued to lookprospectively at preoperative aspirin use in northern NewEngland. During the last 5 years, a period not included in our

1797Ann Thorac Surg CORRESPONDENCE2001;72:1793–802

© 2001 by The Society of Thoracic Surgeons 0003-4975/01/$20.00Published by Elsevier Science Inc