For patients with dangerously narrowed or blocked coronary arteries, a medical procedure known as a percutaneous transluminal coronary angioplasty, commonly referred to as PTCA, is often recommended. This non-surgical procedure involves inserting a catheter with a deflated balloon attached to its tip into the narrowed section of the coronary artery. The balloon is then inflated, causing the artery to widen sufficiently to improve blood flow. Once the appropriate diameter is achieved, the balloon is deflated and removed.

Often, a metal stent (a wire mesh tube) is implanted to prop open an artery that’s recently been cleared using angioplasty. While the stent serves to maintain the artery opening, restenosis often occurs as a result of scar tissue that narrows the lumen, necessitating a repeat procedure in 25% of patients within six months of the original stent placement. Furthermore, because the stent is a foreign body, platelets can adhere to the stent surface, causing a blood clot to form. To prevent a clot from forming, anti-platelet medication is needed for patients with stents; the usual recommendation for patients with bare metal stents (BMS) is aspirin and clopidogrel for six weeks after implantation.

More recent developments in preventing restenosis include use of drug-eluting stents (DES). These specially coated stents deliver drugs directly into the artery to prevent restenosis. Drug-eluting stents are commonly used in the US and in Europe and account for 90% of all stents placed currently. Unfortunately, a serious problem called stent thrombosis is associated with these devices. As a result, it is necessary that patients receive dual anti-platelet therapy with both aspirin and clopidogrel for at least 12 months after DES stent placement. After this time, patients are usually expected to remain on a life-long regimen of aspirin therapy. Even with this regimen, a serious complication known as late stent thrombosis (LST) presents a significant risk of death (45% mortality rate) from myocardial infarction or sudden cardiac death. A recent study published in JAMA (Eisenstein EL et. al) found death rates were significantly increased when clopidogrel was discontinued at 6, 12 and 24 months when compared to patients who remained on this therapy at the same time intervals.

The challenge of managing the surgical candidate with an existing DES presents an interesting dilemma, because currently there are no guidelines to manage the DES patient's perioperative period (the time immediately before, during, and after surgery). A protocol for the perioperative management of patients with intracoronary drug-eluting stents has been developed by Dr. Newsome and colleagues at Wake Forest University Bowman Gray Medical Center (Newsome L, Kutcher M, Ghandi S, Prielipp R, Royster R. A protocol for the perioperative management of patients with intracoronary drug-eluting stents. Anesthesia Patient Safety Foundation Newsletter winter 2006-2007; vol.21 no.4: 81-82.). As Newsome states, "This perioperative period is crucial because 1) surgery induces a hypercoagulable state; 2) surgeons often stop aspirin and or clopidodgrel prior to surgery to minimize risk associated with surgical bleeding, but without consulting their patients' cardiologists; and 3) there is a high likelihood that the DES are not yet endothelialized [completely healed]." Newsome and colleagues at WFU Medical Center developed a unique strategy based on an interdisciplinary approach where interventional cardiologists and anesthesiologists collaborate using both eptifibatide (to prevent platelet activation and adhesion) and heparin (to prevent thrombin formation) as a "bridging therapy" to prevent stent thrombosis in the perioperative period.

Full cooperation and open communication among surgeons, cardiologists, and anesthesiologists is essential to properly assess the needs of each surgical patient. Depending on case specifics, the surgeon may opt to perform the procedure while the patient remains on clopidogrel and aspirin or may instead choose the bridging therapy if risk of surgical bleeding is deemed too great. Protocol is based on information from the cardiologist for each DES patient undergoing surgery and includes type and date of placement of the patient's DES, plus any complexities or complications with stent placement. It is also based on any comorbidities, such as renal problems, diabetes, or depressed ejection fraction. Cardiology consultation/permission is needed to remove the patient from clopidogrel five days prior to surgery. The protocol further dictates that aspirin continues throughout the perioperative period and that the patient is admitted three days prior to surgery to begin bridging therapy (eptifibatide and heparin) and reduce the risk of stent thrombosis. Exact dosing is based on each individual patient's renal function. "Six hours prior to surgery, bridging therapy is discontinued for normal intraoperative platelet function and coagulation to return and allow preoperative anesthesia to be performed." Based on collaboration between cardiology and surgery, the clopidogrel/eptifibatide will be restarted a soon as possible postoperatively.

The serious risk of stent thrombosis will no doubt drive further studies seeking ways to improve and modify the devices as well as manage the perioperative anti-platelet therapy to ensure the safety of DES patients in need of surgery.

To read the update to the FDA statement on drug-eluting stents, visit http://www.fda.gov/.