Letter to the Editor

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Preoperative Aspirin Discontinuation Management and Bleeding Outcome in Elective Coronary Artery Surgery Bojan Biocina1

Ivica Safradin1

1 Department of Cardiac Surgery, University Hospital Center Zagreb,

School of Medicine University of Zagreb, Zagreb, Croatia Thorac Cardiovasc Surg 2013;61:731–732.

Hrvoje Gasparovic1 Address for correspondence Mate Petricevic, MD, Department of Cardiac Surgery, University Hospital Center Zagreb, School of Medicine University of Zagreb, Kispaticeva 12, 10000 Zagreb, Croatia (e-mail: [email protected]).

We read with great interest the recently published study by Al-Lawati et al.1 The purpose of the study was to assess if continuation of aspirin influences bleeding complications following coronary artery bypass grafting (CABG). With respect to preoperative aspirin administration, patients were divided into two groups: Group 1 with late aspirin discontinuation within 7 days before CABG and Group 2 with early discontinuation determined as aspirin withdrawal in more than 7 days before CABG.1 Group 1 had significantly higher extent of postprotamine blood loss (p ¼ 0.034), chest tube output (p ¼ 0.001), and had consumed more blood products than Group 2 (p ¼ 0.01).1 Preoperatively, patients were randomly allocated into either group at the outpatient clinic, thus making study interventional rather than observational in nature. Strategies to prevent bleeding and transfusion outcomes are essential for the successful management of patients, however require comprehensive approach. The lack of objective quantification of platelet function constitutes a major drawback of the study. Expected inhibition of platelet function is not always achieved after aspirin administration. Therefore, the role of aspirin in group of patients receiving aspirin preoperatively should be evaluated in context of possible aspirin resistance. In our recent study,2 we analyzed the proportion of patients with aspirin resistance, both pre- and postoperatively. Considering all CABG patients, we observed 31 of 99 (31.3%) patients with aspirin resistance preoperatively.2 Postoperatively, we registered 46 of 99 (46.5%) CABG patients with aspirin resistance, suggesting platelet hyperactivity.2 Noteworthy, we analyzed the presence of aspirin resistance with respect to the presence of diabetes as a comorbidity.2 Postoperative evaluation of platelet function revealed 24 of 41 (58.5%) patients with aspirin resistance in the diabetic subgroup versus 22 of 58 (38%) in the nondiabetic subgroup, and the

difference in proportion was found to be significant (p ¼ 0.04).2 Those findings could be of great interest to the authors because they reported very high prevalence of diabetics within study cohort,1 in whom aspirin discontinuation before surgery might expose them to adverse ischemic events. The role of preoperative aspirin administration management should be evaluated in context of both bleeding and ischemic events. One limitation of this study by AlLawati et al1 was the lack of data on preoperative adverse events comparison between groups. It would be valuable to compare major adverse cardiac event outcome between two groups in preoperative phase. On contrary, there is evidence that certain patients have an accentuated response to the usual doses of preoperative aspirin that may result in increased perioperative blood loss3 despite intraoperative administration of antifibrinolytics. At our department, we regularly administer a dose of 1 g tranexamic acid (TA) at the induction of anesthesia and after protamine administration.3 In our experience, although useful, TA per se is insufficient to optimize bleeding and transfusion outcomes3 because we observed excessive bleeding in our cohort, which was found to correlate with weak platelet function. The use of pointof-care suitable platelet function analyzers seem to be reasonable in this field. By platelet function assessment, it is possible to distinguish patients with residual platelet reactivity following aspirin administration, thus proclivity to ischemic events, from group with accentuated response to aspirin, therefore, proclivity to excessive bleeding. For patients undergoing CABG, individually tailored aspirin administration management based on platelet function test results, pre- and postoperatively, can reduce both bleeding and ischemic events. We congratulate the authors on their elegant and timely research.

received April 17, 2013 accepted May 13, 2013 published online November 21, 2013

© 2013 Georg Thieme Verlag KG Stuttgart · New York

DOI http://dx.doi.org/ 10.1055/s-0033-1348318. ISSN 0171-6425.

This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.

Mate Petricevic1

Letter to the Editor References 1 Al-Lawati AA, Muthuswamy V. Continuing Aspirin Causes Higher

Drainage Even under Full Protection with Antifibrinolytics. Thorac Cardiovasc Surg 2013 doi: 10.1055/s-0032-1328927 2 Petricevic M, Biocina B, Konosic S, Kopjar T, Kunac N, Gasparovic H. Assessment of platelet function by whole blood impedance aggregometry in coronary artery bypass grafting patients on ace-

tylsalicylic acid treatment may prompt a switch to dual antiplatelet therapy. Heart Vessels 2013;28(1):57–65 3 Petricevic M, Biocina B, Milicic D, et al. Bleeding risk assessment using multiple electrode aggregometry in patients following coronary artery bypass surgery. J Thromb Thrombolysis 2013; 35(1):31–40

Reply by the Authors of the Original Article Adil Al-Lawati1

Venkitraman Muthuswamy1

1 Department of Cardiothoracic Surgery, Royal Hospital, Muscat,

Oman

Address for correspondence Adil Al-Lawati, FRCSEd, Department of Cardiothoracic Surgery, Royal Hospital, PO Box 111, Code 1331 Seeb, Muscat, Oman (e-mail: [email protected]).

Thorac Cardiovasc Surg 2013;00:731–732.

We thank M. Petricevic and his group in Zagreb for their valuable comments on our recently published article.1 We took notice of their findings2 from their earlier experience in relation to the so-called “aspirin resistance” notably in the diabetic subgroup that forms a high subgroup in our study cohort. Although we accept that our study lacks an objective qualification of platelet function, we must disagree that this is a major drawback for the following two good reasons: 1. The concept of aspirin resistance is still controversial and has not yet being widely accepted. Grosser et al3 in Philadelphia demonstrated that the prevalence of true aspirin resistance in a healthy cohort is rare and that the variability in aspirin responsiveness is mostly accounted for by variability in bioavailability “drug exposure” of enteric coated aspirin. They further added that the concept of aspirin resistance rests on a shaky foundation with unclear mechanism and unclear clinical relevance. 2. Our study was performed to look into bleeding complications in patients exposed to aspirin therapy to the close proximity of CABG operation. We were not addressing thrombotic complications in this study. We think that any study on thrombotic complications rather than bleeding

Thoracic and Cardiovascular Surgeon

Vol. 61

No. 8/2013

complications should include a valuable method of assessing platelet function because when such complications happen in the presence of aspirin, one could then argue on the presence of the entity of aspirin resistance, and it is here indeed that an assessment of platelet function would be essential to make such a study informative and conclusive. 3. Once more we appreciate Dr. Petricevic and his group for their valuable time and comments.

References 1 Al-Lawati AA, Muthuswamy V. Continuing Aspirin Causes Higher

Drainage Even under Full Protection with Antifibrinolytics. Thorac Cardiovasc Surg 2013 doi:10.1055/s-0032-1328927 2 Petricevic M, Biocina B, Konosic S, Kopjar T, Kunac N, Gasparovic H. Assessment of platelet function by whole blood impedance aggregometry in coronary artery bypass grafting patients on acetylsalicylic acid treatment may prompt a switch to dual antiplatelet therapy. Heart Vessels 2013;28(1):57–65 3 Grosser T, Fries S, Lawson JA, Kapoor SC, Grant GR, FitzGerald GA. Drug resistance and pseudoresistance: an unintended consequence of enteric coating aspirin. Circulation 2013;127(3): 377–385

This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.

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Copyright of Thoracic & Cardiovascular Surgeon is the property of Georg Thieme Verlag Stuttgart and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.

Preoperative aspirin discontinuation management and bleeding outcome in elective coronary artery surgery.

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