Non-Cardiac Surgery After Coronary Stenting
Abstract & Commentary
By Michael H. Crawford, MD, Editor
Sources: Wijeysundera DN, et al. Risk of elective major noncardiac surgery after coronary stent insertion A population-based study. Circulation 2012;126:1355-1362. Matteau A, Mauri L. Optimal timing of noncardiac surgery after stents. Circulation 2012;126:1322-1324.
The risks of noncardiac surgery after stent implantation are unclear, but have important implications for patient management. Thus, these investigators from Toronto, Canada, used province-wide revascularization registry data in Ontario and various administrative databases to study more than 8000 patients who had non-cardiac surgery from 2003-2009 and had coronary stent implantation within 10 years before their surgery. About 34% had stent implantation within 2 years of surgery and one-third of these received drug eluting stents. These patients were compared to 300,000 surgical patients who had not had revascularization within 10 years of their surgery. The primary endpoint was a combination of mortality, readmission for acute coronary syndrome, or repeat revascularization for 30 days after surgery. The secondary endpoint was these events 1 year after surgery. The combined endpoint was observed in 2.1% at 30 days and in 9.8% at 1 year. Mortality was 1.2% and 5.2%. Multivariate analysis showed that stent type and the PCI to surgery time interval were associated with both endpoints. The 30-day endpoint was highest for drug-eluting stents and surgery within 45 days (20%). The 30-day events with bare-metal stents were also highest in the first 45 days (6.7%). In the 45- to 180-day interval, the event rate in bare-metal stents was 2.6%, similar to patients without revascularization. For drug-eluting stents, the rate fell to 1.2% after 180 days, which approximated that of the control group. The authors concluded that the optimal delay of non-cardiac surgery after stenting is > 45 days for bare-metal stents and > 180 days for drug-eluting stents.
The major strength of this observational study is the large number of patients included. This allows for substantial sub-populations. For example, 36% were diabetic and 23% had vascular surgery. The study is very relevant to physician decision making in that emergency or urgent surgery patients were excluded because these decisions are often driven by the high risks of the condition requiring surgery. In more elective surgery, considering possible cardiac complications takes the stage. This study suggests the current recommendations that if surgery can be delayed 6 weeks after bare-metal stent placement, it can be accomplished with a low risk of stent thrombosis. The study does not support the current ACC/AHA guidelines to wait 1 year after drug-eluting stent placement, but rather suggests that 6 months may be adequate. This is supported by other smaller studies and is common practice in Europe. On the other hand, for both types of stents after 1 year, the rate of acute cardiac events is equivalent to the rate observed in the control group without stents.
The major limitation to the study is that it is based on registry and administrative data that do not detail drug therapy. We can only assume that standard practices were followed. Also, we don't have details on the coronary anatomy and stenting procedure. In addition, this was a relatively low-risk group with 75% having a revised cardiac risk index of 1-2 and thus, there were very few events. Finally, we don't know the cause of the events. They could be from stent thrombosis, new plaque ruptures, or in-stent restenosis, which is more frequent during the first year after implantation. The accompanying editorial suggests that these weaknesses are profound enough that we should not yet change guidelines.