Patients who underwent surgery within 12 months of receiving treatment with a drug-eluting stent by PCI had an increased risk of 30-day MI and cardiac death compared with those who did not receive a stent and did not have ischemic heart disease, according to a registry analysis in Denmark.

However, the increased risk was only found within the first month after receiving a drug-eluting stent. Meanwhile, the rates of 30-day all-cause mortality were similar in patients treated with a drug-eluting stent and those who did not receive a stent.

Lead researcher Gro Egholm, MD, PhD, of the Aarhus University Hospital in Denmark, and colleagues published their results online Dec. 13 in the Journal of the American College of Cardiology.

The researchers mentioned that drug-eluting stents are the standard of care for patients undergoing PCIs. They added that patients are advised to take dual antiplatelet therapy for six to 12 months following implantation to reduce the risk of stent thrombosis.

Guidelines in the U.S. recommend delaying surgery for 12 months after receiving a drug-eluting stent unless the risk associated with delaying surgery is higher than the risk of stent thrombosis, according to the researchers. European guidelines recommend postponing elective surgery for six to 12 months for patients with stable coronary artery disease and for 12 months in patients with acute coronary syndrome.

For this study, the researchers identified 22,590 patients in western Denmark who underwent PCI and received a drug-eluting stent between 2005 and 2012. They then linked two registries and found 4,303 patients who underwent surgery. They compared those patients with a control group that underwent similar surgical procedures but had no previous ischemic heart disease.

Patients were excluded if they were treated with balloon dilation alone or with a bare metal stent.

The researchers mentioned that 34 percent of patients undergoing surgery had the operation within the first three months of the index PCI, 25 percent had the operation from 3 to 6 months, 21 percent had the operation from six to nine months and 20 percent had the operation from nine to 12 months.

They said that surgery within the first month after receiving a drug-eluting stent for PCI was associated with a significantly increased risk for all events.

MIs occurred in 1.6 percent of patients in the drug-eluting stent group compared with 0.2 percent of patients in the non-stenting group, while cardiac death occurred in 1 percent and 0.2 percent of patients, respectively. Both of those differences were statistically significant. The rates of all-cause mortality were 3.1 percent and 2.7 percent, respectively, which did not indicate a significant difference.

After the researchers adjusted for emergency surgery, the risks of MI and cardiac death increased for patients in the stenting group versus the non-stenting group, while the risk of all-cause mortality remained the same. When they further adjusted for comorbidities, the risks were similar.

They added that the study had a few limitations, including its retrospective design. They also did not have information on antithrombotic therapy management during surgery for all of the patients. In addition, they mentioned that they did not account for all comorbidities, which could have led to potential bias.

“Further studies are needed to define the optimal approach to antithrombotic therapy in patients undergoing noncardiac surgery in the 12 months after [drug-eluting stent] implantation,” the researchers wrote.