Thromboembolic Events Following Withdrawal of Antiplatelet or Anti-Coagulation Treatment before Cardiac Surgery

Research Article

Austin Cardiol. 2017; 2(1): 1008.

Thromboembolic Events Following Withdrawal of Antiplatelet or Anti-Coagulation Treatment before Cardiac Surgerys

Straarup TS¹, Fedosova M², Tang M³ and Jakobsen CJ¹*

¹Department of Anesthesia, Aarhus University Hospital, Denmark

²Department of Cardiology, Aarhus University Hospital, Denmark

³Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Denmark

*Corresponding author: Carl-Johan Jakobsen, Operation and Intensive Care East, Aarhus University Hospital, Denmark

Received: August 24, 2017; Accepted: September 11, 2017; Published: September 18, 2017


Introduction: Patients for Coronary Artery Bypass Grafting (CABG) are often treated with antiplatelet medications, most frequently Aspirin (ASA) and Adenosine-Diphosphate (ADP) -receptor antagonists. The drugs seem effective in reducing thromboembolic events when awaiting surgery, but carry a risk of increased bleeding and complications. Although inconsistent, the latest recommendation is to continue ASA, but discontinue ADP 5-days before surgery. The aim of this study was to evaluate possible associations between continued antiplatelet treatments and postoperative thromboembolic events.

Methods: A propensity based analysis on data from our mandatory Western Denmark Heart Registry (2007-2014). Eligible procedures were on/off-pump CABG with/without valve replacement (N=10.608). The endpoints were mortality and/or new ischaemic event (CAG/PCI/CABG) within 6 months together with transfusions and in-hospital incidence of stroke, MI and need for dialysis.

Results: Patients continuing ASA had lower risk of postoperative new CAG in crude analysis, but otherwise no differences in outcomes between ASA and controls in crude or adjusted analysis. Postoperative drainage was marginally higher after ASA, but without difference in re-exploration due to bleeding. Comparing Clopidogrel and ASA, the only difference was a lower postoperative risk of stroke in the clopidogrel patients after adjustment. The Clopidogrel patients received more blood-products, bled more and were more often reexplored due to bleeding.

Conclusion: Patients continuing ASA carry a minor risk of increased postoperative bleeding. The risk is increased if clopidogrel is not discontinued before surgery. The continued therapy had no effect on the frequency of postoperative thromboembolic events. The optimal timing of antiplatelet therapy still needs solid evidence.

Keywords: Coronary artery bypass grafting; Antiplatelet treatment; Ischemic events; Postoperative bleeding; Re-exploration

Glossary of Abbreviations

ACS: Acute Coronary Syndrome; ACT: Activated Clotting Time; ADP: Adenosine Diphosphate; AP: Antiplatelet; ASA: Acetylsalicylic Acid; AVR: Aortic Valve Replacement; CABG: Coronary Artery Bypass Grafting; CAG: Coronary Angiography; CPB: Cardiopulmonary Bypass; COLD: Chronic Obstructive Lung Disease; MI: Myocardial Infarction; MVR: Mitral Valve Replacement/ Repair; OR: Odds Ratio; PCI: Percutaneous Coronary Intervention; WDHR: Western Denmark Heart Registry


Patients with ischemic heart disease referred to cardiac surgery are often treated with Antiplatelet (AP) agents like Acetyl Salicylic Acid (ASA), oral Adenosine Diphosphate (ADP-) receptor antagonists and glycoprotein IIb/IIIa receptor inhibitors, but also different types of anticoagulation like Fondaparinux and Dalteparin. The longterm standard of care is the irreversible platelet inhibitor, ASA. The combined or stand- alone treatment with oral ADP-receptor antagonists is recommended for patients with actual or recent Acute Coronary Syndrome (ACS) or Percutaneous Coronary Intervention (PCI) [1-2]. Clopidogrel inhibits platelet activation and thereby aggregation via the ADP-receptor on the platelet membrane.

The only way platelet function can be restored is either by transfusion or by de novo synthesis of platelets. A platelet lifespan is 8-10 days and thus after 3-5 days half the platelets are renewed which is considered sufficient to normalize bleeding time [3]. The uses of the different agents at the time of surgery carry both benefits and risks. The drugs seem effective in reducing thromboembolic events in patients awaiting surgery [4-5], but also carry the risk of increased per- and postoperative bleeding [5-6]. Thus optimal timing for discontinuation of antiplatelet therapy prior to surgery is important. Until recently the international guidelines recommended discontinuing ASA two to ten days before elective cardiac surgery, while they advised that the ADPreceptor antagonists should be withheld for at least five days before elective Coronary Artery Bypass Grafting (CABG) [7-8]. The latest recommendations are to continue ASA [8] but still discontinue ADPreceptor antagonists five days prior to surgery [8-10].

However, the most recent results regarding discontinuation of ASA are still conflicting [11-12]. The aim of the present study was to evaluate if continued AP treatment in connection with cardiac surgery has impact on postoperative thromboembolic complications, with the hypothesis being that this group of patients have an increased risk of postoperative complications including new ischemic events and mortality.

Patients and Methods

An analysis was carried out with data from three cardiac centers registered in the Western Denmark Heart Registry (WDHR) [13] from 2007-2014. The health care in Denmark is fully tax-funded for all Danish residents. Theinvolved centers provide cardiac surgery for a mixed rural-urban population constituting approximately fifty-five percent of the entire Danish population.

Registration in WDHR is mandatory and completed perioperative by the surgeon and attending anesthetist and includes detailed patient-, surgery-, anesthesia-, intensive care related data together with in-hospital complications. Data quality is ensured using automatic validation rules at data entry combined with systematic validation procedures and random spot-checks of data after entry. The database obtains daily mortality information from the Danish Civil Registration system [14], which keeps record on residency, migration, civil- and vital status of all Danish citizens including date of death.

Eligible procedures were CABG, alone or combined with Aortic Valve Replacement (AVR), Mitral Valve Replacement/Repair (MVR) and MAZE procedures for atrial fibrillation or combination, with maximum triple procedures included. Both on-pump and off-pump CABG procedures were included regardless of urgency status. Exclusions were 150 patients scheduled for aortic surgery, 373 patients with invalid civil registration number or missing required information together with 320 patients receiving another treatment than ASA and/or Clopidogrel like Fondaparinux, leaving 10,608 patients in the study cohort (Figure 1). The study was approved by the Danish Data Protection Agency (record number 1-16-02-541- 16). According to Danish law use of data from Danish registers for research does not require ethical approval.