Brief review: Coronary drug-eluting stents and anesthesia

Perioperative Complications in Patients with Drug-Eluting Stents: A Three-Year Audit at Geelong Hospital

Drug-eluting stents are a recommended treatment for lesions in the coronary arteries. Stent insertion requires the patient remain on antiplatelet medication for a minimum of six months after insertion. A serious consequence of ceasing antiplatelet medication is late stent thrombosis leading to myocardial infarction in the territory of the drug-eluting stent. Continuing antiplatelet medication can lead to excessive bleeding at the time of surgery. Understanding the risk of complications attributable to bleeding or myocardial ischaemia will help in defining the optimal management of these patients at the time of noncardiac surgery.

This study is a retrospective database analysis and case note review of all patients with drug-eluting stents presenting for noncardiac surgical procedures over a three-year period in one centre.

Twenty-four patients with drug-eluting stents inserted presented for 43 noncardiac surgical procedures. Severe bleeding problems were encountered in one case. Three of 15 patients (20%) who ceased clopidogrel prior to surgery without alternative anti-thrombotic prophylaxis suffered myocardial infarction due to stent thrombosis. Four patients who received alternative anti-thrombotic prophylaxis did not suffer complications. All 19 patients who ceased clopidogrel remained on aspirin prior to surgery.

Patients treated with drug-eluting stents for coronary artery stenosis represent a challenging group of patients for subsequent perioperative management. The risk of myocardial infarction when clopidogrel is stopped prior to surgery is 20%, if alternative anti-thrombotic prophylaxis is not used. This risk persists beyond one year after insertion of drug-eluting stents. Some treatments appear to be effective in reducing the risk of myocardial infarction.

Clopidogrel dilemma for orthopaedic surgeons

BACKGROUND

Patients medicated with clopidogrel who require orthopaedic surgery present a particular challenge. Whether in an emergency or elective situation the orthopaedic surgeon must balance the risks of ceasing clopidogrel versus the risk of increased bleeding that dual antiplatelet therapy generates.

METHOD

This paper reviews the current published evidence regarding the risks of continuing clopidogrel, the risks of discontinuing clopidogrel and associated considerations such as venous thromboprophylaxis.

RESULTS

Little good quality evidence exists in regard to perioperative clopidogrel for orthopaedic surgery. Available evidence across non-cardiac and cardiac surgery were assessed and presented in regards to current practices, blood loss for orthopaedic operations, risks when continuing clopidogrel, risks of stopping clopidogrel and also the consideration of venous thromboembolism.

CONCLUSIONS

The patients at greatest risk, when discontinuing clopidogrel therapy, are those with drug eluting stents who may be at risk of stent thrombosis. Where possible, efforts should be made to continue clopidogrel therapy through the perioperative period, taking precautions to minimize bleeding. If the risk of bleeding is too high, antiplatelet therapy must be reinstated as soon as considered reasonable after surgery. In addition, patients on clopidogrel who sustain a fall or other general trauma need to be carefully assessed because of the possibility of occult bleeding, such as into the retroperitoneal space. Until more definitive evidence becomes available, this review aims to provide a guide for the orthopaedic surgeon in dealing with the difficult dilemma of the patient on clopidogrel therapy, recommending that orthopaedic surgeons take a team approach to assess the individual risks for all patients and consider continuation of clopidogrel therapy perioperatively where possible.

Perioperative management of antiplatelet-drugs in cardiac surgery

The management of coronary patients scheduled for a coronary artery bypass grafting (CABG), who are receiving one or more antiplatelet drugs, is plenty of controversies. It has been shown that withdrawal of antiplatelet drugs is associated with an increased risk of a thrombotic event, but surgery under an altered platelet function also means an increased risk of bleeding in the perioperative period. Because of the conflict recommendations, this review article tries to evaluate the outcome of different perioperative antiplatelet protocols in patients with coronary artery disease undergoing CABG.

[Antiplatelet agents and anticoagulants: management of the anticoagulated surgical patient]

Among the drugs most widely consumed by patients are both antiplatelet agents (aspirin, clopidogrel, ticlopidine) and anticoagulants (acenocoumarol, warfarin, low molecular weight heparin, fondaparinux). The use of these drugs in the perioperative period is an essential concern in patient care due to the need to balance the risk of bleeding against thrombotic risk (arterial or venous), which is increased in surgical patients. The present review highlights three main aspects. Firstly, withdrawal of antiplatelet agents is recommended between 1 week and 10 days before surgery to minimize perioperative bleeding. However, this practice has been questioned because patients without the required antiplatelet coverage may be at greater risk of developing cardiac, cerebral or peripheral vascular complications. Therefore, the recommendation of systematic antiplatelet withdrawal for a specific period should be rejected. Currently, risks should be evaluated on an individual basis to minimize the time during which the patient remains without adequate antiplatelet protection. Secondly, thromboprophylaxis is required in most surgical patients due to the high prevalence of venous thromboembolic disease. This implies the use of anticoagulants and the practice of regional anesthesia has been questioned in these patients. However, with the safety recommendations established by the various scientific societies, this practice has been demonstrated to be safe. Finally, "bridge therapy" in patients anticoagulated with acenocoumarol should be performed on an individual basis rather than systematically without taking into account the thrombotic risks of each patient. The perioperative period involves high arterial and venous thrombotic risk and the optimal use of antiplatelet agents and anticoagulants should be a priority to minimize this risk without increasing hemorrhagic risk. Multidisciplinary consensus is essential on this matter.

Perioperative management of antiplatelet agents in noncardiac surgery

It is common that patients who are scheduled for surgery are treated with antiplatelet agents (APAs) due to their wide indications. The management of these APAs in the perioperative period (acetylsalicylic acid alone, a thienopyridine alone or, in most cases, a combination of them) has a dual perspective: the risk of bleeding when the patient is operated under the effect of the APA against the risk of thrombosis if it has been withdrawn. The main challenges for the anaesthesiologist and the surgeon include patients with a coronary stent (mainly, new drug-eluting coronary stents), those undergoing urgent surgery and those undergoing high bleeding risk surgery. We review current protocols and discuss the most recent proposals for the management of APAs in patients undergoing noncardiac surgery. Current recommendations include the maintenance of aspirin if possible throughout the perioperative period, in order to limit the risks of cardiological, vascular or neurological postoperative events, although this makes it necessary to assume a small risk for haemorrhagic complications in some patients. Nevertheless, there are many circumstances that are not clear yet and, in this situation, it is crucial that patients are treated with a multidisciplinary approach (anaesthesiologists, surgeons, cardiologists and haematologists).

The unresolved issues with risk stratification and management of patients with coronary artery disease undergoing major vascular surgery

PURPOSE

The purpose of this article, with a specific focus on patients undergoing vascular surgery, is to review controversial issues related to mechanisms of perioperative myocardial infarction (MI), coronary artery disease detection, and strategies to reduce perioperative complications. We propose explanations for the many conflicting results that have recently emerged in the literature.Source documents: We searched MEDLINE and reviewed all relevant manuscripts and scientific statements regarding management of patients undergoing non-cardiac surgery.

PRINCIPAL FINDINGS

Identification and prevention of ischemia in patients undergoing vascular surgery remains controversial. While the identification of preoperative ischemia is a marker of a higher perioperative risk, the value of identifying such ischemia has been questioned. We believe this may be, at least in part, due to our limited understanding of perioperative MI. Appropriate management of patients, based on the results of such testing, is likely the key to improving outcomes, and deserves further investigation. Efforts aimed at reducing the ischemic consequences of severe coronary plaques (by revascularization or beta-blocker therapy) have yielded conflicting results. The use of high doses of preoperative beta-blocker therapy may be harmful. Some studies suggest a promising role for statin therapy. Benefits of acetylsalicylic acid must be weighted against the risk of bleeding.

CONCLUSION

Many questions remain unanswered about the impact of detecting inducible ischemia, and the role of revascularization or beta-blockers in patients undergoing vascular surgery. A better understanding of the pathophysiology of perioperative MI is critical, in order to identify the best approach to improve cardiac outcomes in these patients.