Risk of Perioperative MI in Patients with Stents Undergoing Surgery

Abstract & Commentary

By Andrew J. Boyle, MBBS, PhD, Assistant Professor of Medicine, Interventional Cardiology, University of California, San Francisco. Dr. Boyle reports no financial relationships relevant to this field of study.

This article originally appeared in the November 2011 issue of Clinical Cardiology Alert. It was edited by Michael H. Crawford, MD, and peer reviewed by Ethan Weiss, MD. Dr. Crawford is Professor of Medicine, Chief of Clinical Cardiology, University of California, San Francisco, and Dr. Weiss is Assistant Professor of Medicine, Division of Cardiology and CVRI, University of California, San Francisco. Dr. Crawford reports no financial relationships relevant to this field of study, and Dr. Weiss is a scientific advisory board member for Bionovo.

Source: Albaladejo P, et al. Non-cardiac surgery in patients with coronary stents: The RECO study. Heart 2011;97:1566-1572.

Patients who have had percutaneous coronary intervention (PCI) with either bare metal stents (BMS) or drug-eluting stents (DES) require dual antiplatelet therapy until the stent struts are endothelialized. However, patients who have had prior PCI often need to undergo surgery. There is thought to be less risk of perioperative myocardial infarction (MI) when surgery is performed late after PCI; however, the precise risk and the optimal management of dual antiplatelet therapy remains unknown. Albaladejo and colleagues performed a multicenter, prospective, observational study in 47 centers in France to address this question.

They enrolled 1134 patients undergoing non-cardiac surgery (including diagnostic endoscopy). DES were used in 55%, BMS in 32%, and unknown stent type in 13%. DES use was associated with younger age (67 ± 11 vs 70 ± 10 years, P < 0.001), higher prevalence of diabetes (33% vs 22%, P < 0.001), and higher number of stents per patient (2.3 ± 1.4 vs 1.6 ± 0.9, P < 0.001). There were no differences between DES and BMS patients in terms of preoperative antiplatelet therapy and the level of risk of the surgery. Continuation or discontinuation of antiplatelet therapy was not prespecified, but was at the discretion of the physician at the preoperative visit.

The primary endpoints were any major adverse cardiac and cerebrovascular events (MACCE) or hemorrhagic complication. MACCE was defined as MI, stent thrombosis, stroke, heart failure, significant arrhythmia, or cardiogenic shock. Bleeding was considered major if it resulted in death, fall in hemoglobin ≥ 2g/dL, transfusion, extra surgical or medical treatment, or if it was in a critical location (intracerebral, intraspinal, intraocular, pericardial retroperitoneal). All other bleeding was considered minor. All-cause mortality was a secondary endpoint.

MACCE occurred in 10.9%, typically around 3.3 ± 3.8 days after surgery, and was predominantly MI. Patients who experienced MACCE were older (71 ± 10 vs 68 ± 11 years, P < 0.01) and more likely to have heart failure (19.4% vs 8.4%, P < 0.001) and a high American Society of Anesthesiologists classification. There was no difference in gender or type of stent. Independent predictors of MACCE were: complete interruption of antiplatelet therapy for > 5 days preoperatively (odds ratio [OR] 2.11, P < 0.01), preoperative hemoglobin < 10 g/dL (OR 3.0, P = 0.016), creatinine clearance < 30 mL/min (OR 3.5, P < 0.01), urgent surgery (OR 3.1, P < 0.001), and high-risk surgery (OR 3.6, P < 0.001). Importantly, the time interval between stenting and surgery was not predictive of MACCE. Patients who experienced MACCE had a 14.5% mortality. Stent thrombosis (definite, probable, or possible) occurred in 2.5% when the delay from PCI to surgery was < 12 months, and 1.3% when the interval was > 12 months. The rate of stent thrombosis did not differ between DES and BMS. The mortality associated with stent thrombosis was 29%.

Bleeding complications occurred in 9.5%, typically occurred 5.3 ± 5.3 days after surgery, and were at the surgical site in 85%. Patients who experienced bleeding complications had lower body weight (75.7 ± 14.1 kg vs 78.4 ± 14.6 kg, P = 0.04) and a higher rate of congestive heart failure (16.7 vs 8.4%, P = 0.001). Independent predictors of bleeding complications were: preoperative hemoglobin < 10 g/dL (OR 2.6, P < 0.05), creatinine clearance 30-60 mL/min (OR 1.96, P < 0.01), high-risk surgery (OR 3.3, P < 0.001), and time from PCI to surgery < 3 months (OR 2.9, P = 0.001). Patients who experienced bleeding complications had a 12% mortality.

The authors conclude that patients with coronary stents undergoing an invasive procedure are at high risk of perioperative cardiovascular and bleeding complications, and that these are associated with a high mortality. Interruption of antiplatelet therapy > 5 days prior to an invasive procedure increased the rate of MACCE but did not change risk of bleeding.

Commentary

Current guidelines recommend postponing elective surgery for at least 6 weeks after BMS and 12 months after DES. This study is one of the largest series published to date and one of the few that reports both ischemic (MACCE) and bleeding complications together. Several factors are noteworthy in this dataset. Firstly, preoperative anemia and renal impairment predict both bleeding and ischemic complications. This may be because anemia and renal impairment are dangerous per se, or because they are indicators of severe underlying disease that predisposes to post-operative complications. In this series, high-risk surgery was a predictor of postoperative events as well, whereas in other series this has not been the case. One reason for this may be that this cohort included diagnostic endoscopy, which is not really a surgery and should have little bleeding and ischemic risk. This may introduce bias by lowering the rate of complications in the "low risk" category here because some of the low-risk surgeries were not actually surgeries. Many other series do not include endoscopy.

The type of stent (DES vs BMS) had no effect on MACCE. This contradicts the hype and dogma that stent thrombosis is a great danger with DES. In fact, this has been borne out in other series as well. Importantly, this cohort was recruited starting in 2007, when media attention on DES stent thrombosis was at fever pitch. Consequently, many DES patients in this cohort underwent surgery on dual antiplatelet therapy, which may have reduced their perioperative MACCE rate. It is also possible that the high bleeding rate in this study also may have been due to continuation of dual antiplatelet therapy throughout the operative period in many patients. This study does not inform us how to manage dual antiplatelet therapy in every patient with coronary stents prior to every surgery. We must continue to individualize treatment based on the surgical bleeding risk vs the risk of peri-operative MI. But it would seem prudent in light of these data, and other series showing similar findings, that antiplatelet therapy not be ceased for more than 5 days preoperatively.