October 7th, 2013
Study Supports Loosening Guidelines for Surgery After Stent Implantation
According to current guidelines, noncardiac surgery should be delayed for six weeks after bare-metal stent (BMS) implantation and for one year after drug-eluting stent (DES) implantation, though there is little good evidence to support these recommendations. Stent thrombosis caused by discontinuation of antiplatelet therapy in order to lower the risk of bleeding during surgery is the biggest concern. Now, a new study published in JAMA suggests that the guidelines may be over strict and that delays recommended after DES implantation are longer than warranted.
Mary T. Hawn and colleagues analyzed data from nearly 125,000 VA patients who received a stent between 2000 and 2010. Within this group more than 28,000 (22.5%) had a noncardiac operation within 2 years. Within 30 days, major adverse cardiac events (MACE) occurred in 1980 (4.7%) patients. The unadjusted MACE rate was 5.1% for patients who received a BMS and 4.3% in patients who received a DES (p<.001). Surgery within the first 6 months was associated with a higher risk of MACE. No significant effect was seen after 6 months. (The MACE rate was 11.6% in the first 6 weeks, 6.4% for 6 weeks to 6 months, 4.2% for 6-12 months, and 3.5% for the second year [p < .001].)
After adjusting for other factors, the most significant factors related to MACE were nonelective surgical admission, MI in the 6 months preceding surgery, and a high cardiac risk index. In a case-control analysis using 284 matched pairs, no relationship was observed between MACE and antiplatelet cessation.
The authors acknowledge the limitations of observational studies, and also point out that their study, which mostly contained elderly men, may not be fully applicable to women or younger patients. But, they write, their findings “suggest that underlying surgical and cardiac risk, rather than stent type, are the primary factors associated with perioperative MACE; that event rates stabilize by 6 months; and that APT (antiplatelet therapy) continuation does not substantially mitigate risk. Accordingly, the current focus of the guidelines on differential timing recommendations by stent type may warrant reconsideration, and greater concentration may need to be placed on assessing and optimizing cardiac risk.”
In an accompanying editorial, Emmanouil S. Brilakis and Subhash Banerjee write that the current recommendations for surgery after BMS implantation do not need to change, since the risk of stent thrombosis in patients undergoing surgery is very low after 6 weeks. For DES, however, they recommend that nonurgent operations be postponed until 6 months after the PCI procedure. They recommend that antiplatelet therapy should be continued if possible during the perioperative period to reduce the risk of stent thrombosis. For urgent surgeries in the first 6 months, they recommend that dual or at least single antiplatelet therapy be continued whenever possible. When this is not possible they recommend that a “bridging” strategy with short-acting agents be considered.