Stopping Aspirin Before CABG: Timing Depends on Bleeding, Thrombosis Risk

February 09, 2011

February 9, 2011 (Cleveland, Ohio) It makes little difference to the risk of MI, stroke, or death whether chronic aspirin therapy is discontinued earlier than five days or within five days of CABG surgery, according to a single-center observational study [1].

On the other hand, withdrawal of aspirin within five days of surgery in the analysis was associated with greater need for peri- and postoperative transfusion.

That downside to later aspirin withdrawal doesn't necessarily always tip the balance of risk in favor of stopping aspirin earlier, as that could leave some patients at increased risk of preoperative cardiac events, observe the authors, led by Dr Miriam Jacob (Cleveland Clinic, OH), in their report published online January 31, 2011 in Circulation.

Their analysis, they conclude, underscores the need for weighing benefit vs risk in individual patients when deciding how long before CABG to suspend chronic aspirin therapy.

"There was a significant difference in terms of transfusion requirements and a trend of going back to the operating room more frequently if they discontinued aspirin earlier," senior author Dr Leslie Cho (Cleveland Clinic) told heartwire .

"So I think the important thing would be for physicians to assess patients, to weigh the risks and benefits, in terms of bleeding and ischemic end points, from discontinuing aspirin in certain patient populations. For example, if patients are at high risk of bleeding because they're elderly, they're small, or they're female, then perhaps for those patients it would be better to go off aspirin longer than five days [before surgery]."

But those with drug-eluting stents should perhaps stay on aspirin longer, she said. "For those patients, we have to unfortunately accept the bleeding risk, because having stent thrombosis prior to bypass surgery leads to such a detrimental outcome."

The current analysis, the group writes, "to the best of our knowledge . . . is the largest study to date to address the issue of early or late aspirin use before CABG."

In an accompanying editorial [2], Dr Paul S Myles (Alfred Hospital, Melbourne, Australia) notes that "many cardiac surgeons and cardiac surgical institutions are happy for patients to continue their aspirin therapy up to the day of CABG; others strictly reinforce a discontinuation policy." And guidelines from different societies aren't consistent, with the Society for Thoracic Surgeons, the American Society of Chest Physicians, and the American College of Cardiologywith the American Heart Association all weighing in differently. The latter groups jointly recommend aspirin discontinuation seven to 10 days before surgery, according to Myles.

"The underlying cause for such disparate guidelines is, of course, a lack of clear and compelling randomized trial data," he writes. The current study "provides some reassurance as to the comparable postoperative cardiovascular complications after CABG for both early and late discontinuation of aspirin." But a bigger question is "whether or not we should be stopping aspirin at all."

The analysis from Jacob et al looked at 4143 patients on chronic aspirin therapy before CABG performed from 2002 to 2008. Of those, 2298 went off aspirin six or more days before surgery and 1845 had it withdrawn five or fewer days before the procedure. The two groups differed significantly with respect to comorbidities, medications, surgical history, and other features, but a propensity-score analysis produced 1519 well-matched pairs, according to Jacob et al.

The composite rate of in-hospital death, MI, or stroke was about the same for patients who went off aspirin earlier and those who went off it later. And the rates of the composite end point's individual components were not significantly different. But the risk of bleeding during and after the procedure went up with later aspirin withdrawal. Postoperative length of stay was similar, a median of six days for both groups.

Clinical Event and Bleeding Complication Rates for 1519 Matched Pairs by Timing of Chronic Aspirin Withdrawal Before CABG

End point

Aspirin withdrawal >6 d before CABG (%)

Aspirin withdrawal <5 d before CABG (%)

p

In-hospital death, MI, or stroke (primary outcome)

1.7

1.8

0.80

Intraoperative transfusion

20

23

0.03

Postoperative transfusion

26

30

0.009

Outcomes data by chronic aspirin dosage weren't available for this analysis, according to Cho, but "presumably dosage would have an effect." As it goes up, probably so would the risk of bleeding, she said, and there are data to support that from populations with ST-elevation MI and other ACS. 

Jacob et al had no disclosures. Myles disclosed being "a principal investigator for the Australian National Health and Medical Research Council-funded ATACAS trial, an investigator-initiated factorial trial investigating the safety and effectiveness of aspirin and tranexamic acid in coronary artery surgery."

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