SCOTTSDALE, ARIZ. – The presence of a coronary artery stent is not a barrier to noncardiac surgery, but it may change the timing of surgery and perioperative management of the patient, a hospitalist cautions.
Patients who receive bare-metal stents should delay having elective surgery for at least 6 weeks after stent placement, and those who receive a drug-eluting stent should put off elective procedures for at least a year, said Dr. Amir K. Jaffer, professor of medicine and chief of the division of hospital medicine at Rush University Medical Center in Chicago.
© Darren Hester/Fotolia.com
Dr. Jaffer noted that because aspirin is an irreversible inhibitor of platelet cyclooxygenase and the circulating platelet pool is replaced every 7 to 10 days, patients on aspirin as part of their dual-antiplatelet therapy should stop taking the drug from 7 to 10 days before scheduled surgery.
The type of stent, its placement, and the time since placement are just some of the key pieces of information that clinicians need to manage patients, Dr. Jaffer said at a meeting on perioperative medicine sponsored by the University of Miami.
"You want to try to get that [information] card if you can from the patient, about where the stents were placed, and if they don’t have the card handy, you really need to go to the procedure note, because the patient may or may not know if it was a drug-eluting stent," he said.
Other vital pieces of the perioperative puzzle are which coronary vessel the stent was implanted in; when the stent was implanted; what drug, if any (sirolimus or paclitaxel) is eluted by the stent; whether there were surgical or postoperative complications; prior history of stent thrombosis; the patient’s comorbidities; duration of dual-antiplatelet therapy; and how the patient has fared on therapy.
Prior to an elective noncardiac procedure, clinicians must consider patient risk factors, including indication for antithrombotic therapy, risk factors for thrombosis or thromboembolism, and type of antithrombotic agent; and surgical risk factors, including type of procedure, bleeding risk, thromboembolism risk, and time off antithrombotic therapy.
When to stop antithrombotic agents
Dr. Jaffer noted that because aspirin is an irreversible inhibitor of platelet cyclooxygenase and the circulating platelet pool is replaced every 7 to 10 days, patients on aspirin as part of their dual-antiplatelet therapy should stop taking the drug from 7 to 10 days before scheduled surgery.
Thienopyridines/P2Y12 receptor antagonists such as clopidogrel (Plavix) and ticagrelor (Brilinta) work by inhibiting adenosine diphosphate (ADP) receptor-mediated platelet activation and aggregation. Dr. Jaffer said that although guidelines recommend stopping these agents 7 days before surgery, there is evidence to suggest that 5 days may be a sufficient window of safety.
It is also important to take into consideration the pharmacokinetic profiles of the specific antiplatelet agents. For example, ticagrelor has a more rapid onset and greater degree of platelet-aggregation inhibition than clopidogrel, although the time from stopping each agent until the return to near-baseline platelet aggregation is similar, on the order of about 120 hours (5 days) or longer, he said.
Risk varies by surgery type
The type of surgery is also important, as certain procedures – such as neurocranial surgery, spinal canal surgery, and procedures performed in the posterior chamber of the eye – carry a high risk for hemorrhage and are likely to require blood transfusions.
Dr. Amir K. Jaffer
Dr. Jaffer noted that in 2007, the American College of Cardiology and American Heart Association issued a joint advisory on antiplatelet therapy and noncardiac surgery, which warned health care providers about the potentially catastrophic risks of stopping thienopyridines prematurely, which could result in acute stent thrombosis, myocardial infarction, and death. The guidelines recommend waiting a minimum of 6 weeks for noncardiac surgery following implantation of a bare-metal stent, and 1 year after a drug-eluting stent.
He pointed to two studies from the Mayo Clinic published in 2008. The first study showed that the risk of major cardiac adverse events among patients with a bare-metal stent undergoing noncardiac surgery within 30 days of stent placement was approximately 10%, but diminished to 2.7% at 91 days after placement (Anesthesiology 2008;109:588-95). The second study showed that the risk of major cardiac adverse events was 6.1% within 90 days after implantation of a drug-eluting stent, with the risk dwindling to 3.1% after 1 year (Anesthesiology 2008;109:596-604).
If urgent surgery such as a hemicolectomy for colon cancer is required within 6 months of drug-eluting stent implantation, the patient should continue on dual-antiplatelet therapy, Dr. Jaffer said. If the surgery is from 6 months to 1 year after implantation in these patients, the patient should be continued on at least 81 mg aspirin, but if the patient is taking clopidogrel, he or she should have the thienopyridine discontinued 5 days before surgery and the drug resumed as soon as possible after surgery with a 300-mg loading dose, followed by 75 mg daily. If the patient is not yet able to eat, the dual-antiplatelet therapy should be delivered via nasogastric tube, he said.